Logix 5000 Controllers Design Considerations Reference Manual, 1756-RM094M-EN-P

Reference Manual

Original Instructions

Logix 5000 Controllers Design

Considerations

ControlLogix, GuardLogix, CompactLogix,

Compact GuardLogix, SoftLogix

2 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Logix 5000 Controllers Design Considerations Reference Manual

Important User Information

Read this document and the documents listed in the additional resources section about installation, configuration, and operation of this equipment before

you install, configure, operate, or maintain this product. Users are required to familiarize themselves with installation and wiring instructions in addition to

requirements of all applicable codes, laws, and standards.

Activities including installation, adjustments, putting into service, use, assembly, disassembly, and maintenance are required to be carried out by suitably

trained personnel in accordance with applicable code of practice.

If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be impaired.

In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from the use or application of this

equipment.

The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and requirements associated with

any particular installation, Rockwell Automation, Inc. cannot assume responsibility or liability for actual use based on the examples and diagrams.

No patent liability is assumed by Rockwell Automation, Inc. with respect to use of information, circuits, equipment, or software described in this manual.

Reproduction of the contents of this manual, in whole or in part, without written permission of Rockwell Automation, Inc., is prohibited.

Throughout this manual, when necessary, we use notes to make you aware of safety considerations.

These labels may also be on or inside the equipment to provide specific precautions.

The following icon may appear in the text of this document.

Rockwell Automation recognizes that some of the terms that are currently used in our industry and in this publication are not in alignment

with the movement toward inclusive language in technology. We are proactively collaborating with industry peers to find alternatives to such

terms and making changes to our products and content. Please excuse the use of such terms in our content while we implement these

changes.

WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous environment,

which may lead to personal injury or death, property damage, or economic loss.

ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property

damage, or economic loss. Attentions help you identify a hazard, avoid a hazard, and recognize the consequence.

IMPORTANT Identifies information that is critical for successful application and understanding of the product.

SHOCK HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous

voltage may be present.

BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may

reach dangerous temperatures.

ARC FLASH HAZARD: Labels may be on or inside the equipment, for example, a motor control center, to alert people to

potential Arc Flash. Arc Flash will cause severe injury or death. Wear proper Personal Protective Equipment (PPE). Follow ALL

Regulatory requirements for safe work practices and for Personal Protective Equipment (PPE).

Identifies information that is useful and can help to make a process easier to do or easier to understand.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 3

Table of Contents

Preface

About This Publication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Download Firmware, AOP, EDS, and Other Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Summary of Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Chapter 1

5580 and 5380 Controllers ControlLogix 5580 and GuardLogix 5580 Controllers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

CompactLogix 5380 and Compact GuardLogix 5380 Controllers . . . . . . . . . . . . . . . . . . 12

Process Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Controller Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Extended Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Date and Time Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Programming Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Data Alignment Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Produced and Consumed Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Chapter 2

5480 Controllers CompactLogix 5480 Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Controller Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Extended Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Date and Time Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Programming Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Data Alignment Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Produced and Consumed Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Chapter 3

5570 Controllers and 5370

Controllers

ControlLogix 5570 and GuardLogix 5570 Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

CompactLogix 5370 and Compact GuardLogix 5370 Controllers . . . . . . . . . . . . . . . . . . 22

Controller Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

CompactLogix 5370 and Compact GuardLogix 5370 Controllers . . . . . . . . . . . . . . 23

Controller Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Determine Total Connection Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

System Overhead Percentage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Manage the System Overhead Timeslice Percentage. . . . . . . . . . . . . . . . . . . . . . . . 27

I/O Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Programming Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Produced and Consumed Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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Table of Contents

Chapter 4

Logic Execution Decide When to Use Tasks, Programs, and Routines. . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Specify Task Priorities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Manage User Tasks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Pre-defined Tasks in ControlLogix and CompactLogix Process Controllers . . . . . 33

Considerations that Affect Task Execution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Configure a Continuous Task . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Configure a Periodic Task . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Configure an Event Task . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Guidelines to Configure an Event Task. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Additional Considerations for Periodic and Event Tasks. . . . . . . . . . . . . . . . . . . . . 35

Access the Module Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Develop Application Code in Routines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Comparison of Programming Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Programming Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Inline Duplication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Indexed Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Buffered Routine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Controller Prescan of Logic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Add-On Instruction Prescan Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Custom Tag Initialization During Prescan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Controller Postscan of SFC Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Add-On Instruction Postscan Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Timer Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

SFC Step Timer Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Edit an SFC Online. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Chapter 5

Modular Programming

Techniques

Guidelines for Code Reuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Parameter Name Prefixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Guidelines for Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Guidelines for User-defined Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Naming Conventions for User-Defined Data Types . . . . . . . . . . . . . . . . . . . . . . . . . 48

UDT Member Order Impact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Guidelines for Add-On Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Add-On Instruction Design Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Naming Conventions for Add-On Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Comparison of Subroutines and Add-On Instructions . . . . . . . . . . . . . . . . . . . . . . . 52

Comparison of Partial Import/Export and Add-On Instructions . . . . . . . . . . . . . . . 53

Guidelines for Program Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Comparison of Program Parameters and Add-On Instructions. . . . . . . . . . . . . . . . 55

Compare Controller Organizer and Logical Organizer . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 5

Table of Contents

Chapter 6

Structure Logic According to

Standards

Physical Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Separate a Process Unit into Equipment Modules and Control Modules . . . . . . . . 60

Physical Model Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Procedural Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Identify Operations and Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Procedural Control Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Procedural Control States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Procedural Control Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Procedural Model Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

State Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Chapter 7

Produced and Consumed Data Guidelines for Produced and Consumed Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Guidelines for Produced and Consumed Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Guidelines to Specify an RPI Rate for Produced and Consumed Tags. . . . . . . . . . . . . . 70

Guidelines to Manage Connections for Produced and Consumed Tags. . . . . . . . . . . . . 71

Configure an Event Task Based on a Consumed Tag. . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Compare Messages and Produced/Consumed Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Chapter 8

Data Structures Guidelines for Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Guidelines for Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Indirect Addresses of Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Guidelines for Array Indexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Guidelines for User-defined Data Types (UDT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Select a Data Type for Bit Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Serial Bit Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Guidelines for String Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Configure Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Guidelines for Base Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Create Alias Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Guidelines for Data Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Guidelines for Tag Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Guidelines for Extended Tag Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Tag Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Protect Data Access Control at Tag Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Chapter 9

Communicate with I/O Buffer I/O Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Guidelines to Specify an RPI Rate for I/O Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Communication Formats for I/O Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Direct Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Rack-optimized Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Peer Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

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Table of Contents

Electronic Keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

More Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Guidelines to Manage I/O Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Create Tags for I/O Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Controller Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Runtime/Online Addition of Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Online Addition of Module and Connection Types. . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Design Considerations for Runtime/Online Addition of Modules. . . . . . . . . . . . . . . 95

Chapter 10

Determine the Appropriate

Network

EtherNet/IP Network Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Guidelines for EtherNet/IP Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

ControlNet Network Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Guidelines for ControlNet Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Guidelines for Unscheduled ControlNet Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Compare Scheduled and Unscheduled ControlNet Communication. . . . . . . . . . . . . . . 102

DeviceNet Network Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Guidelines for DeviceNet Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

Chapter 11

Communicate with Other

Devices

Cache Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Message Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Outgoing Unconnected Buffers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Guidelines for Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Guidelines to Manage Message Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Guidelines for Block Transfer Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Map Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Chapter 12

Alarms Guidelines for Tag-Based Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Access Tag-based Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Guidelines for Instruction-based Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Configure Logix-based Alarm Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Automatic Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

Chapter 13

Optimize an Application for Use

with HMI

Linx-based Software Use of Controller Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

HMI Implementation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

Guidelines for FactoryTalk View Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

How a Data Server Communicates with the Controllers . . . . . . . . . . . . . . . . . . . . . . . . 116

Compare RSLinx Classic and FactoryTalk Linx Software. . . . . . . . . . . . . . . . . . . . . . . . 117

Guidelines for Linx-based Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Guidelines to Configure Controller Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Reference Controller Data from FactoryTalk View Software. . . . . . . . . . . . . . . . . 118

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 7

Table of Contents

Chapter 14

Develop Equipment Phases Guidelines for Equipment Phases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Equipment Phase Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

Chapter 15

Manage Firmware Guidelines to Manage Controller Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Compare Firmware Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Guidelines for the Firmware Supervisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

Access Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

8 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Table of Contents

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 9

Preface

About This Publication

This publication provides information to help design and plan Logix 5000™ systems.

Throughout this publication, programming software refers to the following:

• Studio 5000 Logix Designer® application, version 21 or later

• RSLogix 5000® software, version 16 or later

Rockwell Automation recognizes that some of the terms that are currently used in our industry

and in this publication are not in alignment with the movement toward inclusive language in

technology. We are proactively collaborating with industry peers to find alternatives to such

terms and making changes to our products and content. Please excuse the use of such terms

in our content while we implement these changes.

Download Firmware, AOP,

EDS, and Other Files

Download firmware, associated files (such as AOP, EDS, and DTM), and access product release

notes from the Product Compatibility and Download Center at rok.auto/pcdc

Summary of Changes This publication contains the following new or updated information. This list includes

substantive updates only and is not intended to reflect all changes. Changes in the manual are

identified by change bars.

Additional Resources These documents contain additional information concerning related products from Rockwell

Automation. You can view or download publications at rok.auto/literature

Topic Page

Added GuardLogix XT catalog numbers. 11

Updated LINT valid Date/Time range for ControlLogix 5570 and 5370 controllers. 28

Added new topic, Custom Tag Initialization During Prescan. 40

Updated Online Addition of Module and Connection Types. 94

Resource Description

• EtherNet/IP Network Devices User Manual, publication ENET-UM006

• ControlNet Network Configuration User Manual publication CNET-UM001

• DeviceNet Network Configuration User Manual, publication DNET-UM004

EtheNet/IP™, ControlNet®, and DeviceNet® networks

• System Security Design Guidelines Reference Manual, SECURE-RM001

• Configure System Security Features User Manual, SECURE-UM001

• CIP Security with Rockwell Automation Products Application Technique,

SECURE-AT001

System security and CIP Security™

• High Availability System Reference Manual, publication HIGHAV-RM002 High availability systems

• GuardLogix 5580 and Compact GuardLogix 5380 Controller Systems Reference

Manual, publication 1756-RM012

Safety systems

• Replacement Guidelines: Logix 5000 Controllers Reference Manual, publication

1756-RM100

• Logix 5000 Common Procedures Programming Manual, publication 1756-PM001

Logix 5000™ controllers

• ControlLogix 5580 and GuardLogix 5580 Controllers User Manual, publication

1756-UM543

• ControlLogix System User Manual, publication 1756-UM001

• SERCOS and Analog Motion Configuration and Startup User Manual, publication

MOTION-UM001

• Motion Coordinate System User Manual, publication MOTION-UM002

ControlLogix® and GuardLogix® controllers

• CompactLogix 5370 Controllers User Manual, publication 1769-UM021

• CompactLogix 5380 and Compact GuardLogix 5380 Controllers User Manual,

publication 5069-UM001

• 1768 CompactLogix Controllers User Manual, publication 1768-UM001

• 1769 CompactLogix Controllers User Manual, publication 1769-UM011

• 1769 Packaged CompactLogix Controllers Quick Start and User Manual,

publication IASIMP-QS010

CompactLogix™ and Compact GuardLogix controllers

10 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 11

Chapter 1

5580 and 5380 Controllers

This chapter highlights these controllers.

ControlLogix 5580 and

GuardLogix 5580

Controllers

Controller Family Controller Names

5580 controllers ControlLogix® 5580 and GuardLogix® 5580 controllers

5380 controllers CompactLogix™ 5380 and Compact GuardLogix 5380 controllers

Characteristic ControlLogix 5580 and GuardLogix 5580 Controllers

Controller tasks:

• Continuous

•Periodic

•Event

•32

• 1000 programs/task

Event tasks Consumed tag, EVENT instruction triggers, Module Input Data changes, and motion events

User memory

1756-L81E, 1756-L81EK, 1756-L81E-NSE, 1756-L81EXT, 1756-L81EP 3 MB

1756-L82E, 1756-L82EK, 1756-L82E-NSE, 1756-L82EXT 5 MB

1756-L83E, 1756-L83EK, 1756-L83E-NSE, 1756-L83EXT, 1756-L83EP 10 MB

1756-L84E, 1756-L84EK, 1756-L84E-NSE, 1756-L84EXT 20 MB

1756-L85E, 1756-L85EK, 1756-L85E-NSE, 1756-L85EXT, 1756-L85EP 40 MB

1756-L81ES, 1756-L81ESK, 1756-L81EXTS 3 MB +1.5 MB safety

1756-L82ES, 1756-L82ESK, 1756-L82EXTS 5 MB + 2.5 MB safety

1756-L83ES, 1756-L83ESK, 1756-L83EXTS 10 MB +5 MB safety

1756-L84ES, 1756-L84ESK, 1756-L84EXTS 20 MB + 6 MB safety

Built-in ports

Single-port Ethernet port, 10 Mbps/100 Mbps/1 Gbps

1-port USB client

Communication options

• EtherNet/IP™

• ControlNet®

• DeviceNet®

• Data Highway Plus™

• Remote I/O

•SynchLink™

•USB Client

Network nodes

Studio 5000 Logix Designer® application, version 30 or later

1756-L81E, 1756-L81EK, 1756-L81E-NSE, 1756-L81EXT, 1756-L81EP, 1756-L81ES, 1756-L81ESK, 1756-L81EXTS 100

1756-L82E, 1756-L82EK, 1756-L82E-NSE, 1756-L82EXT, 1756-L82ES, 1756-L82ESK, 1756-L82EXTS 175

1756-L83E, 1756-L83EK, 1756-L83E-NSE, 1756-L83EXT, 1756-L83EP, 1756-L83ES, 1756-L83ESK,

1756-L83EXTS, 1756-L84E, 1756-L84EK, 1756-L84E-NSE, 1756-L84EXT, 1756-L84ES, 1756-L84ESK,

1756-L84EXTS

250

1756-L85E, 1756-L85EK, 1756-L85E-NSE, 1756-L85EXT, 1756-L85EP 300

Controller redundancy

Fully supported with Studio 5000 Logix Designer application version 33 later for ControlLogix 5580 controllers. Uses the same

firmware revision as standard ControlLogix 5580 controllers, but requires that redundancy is enabled on the Redundancy tab

of the Controller Properties dialog.

Integrated motion EtherNet/IP

12 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 1 5580 and 5380 Controllers

CompactLogix 5380 and

Compact GuardLogix 5380

Controllers

Characteristic CompactLogix 5380 Controllers and Compact GuardLogix 5380 Controllers

Controller tasks:

• Continuous

•Periodic

•Event

•32

• 1000 programs/task

Event tasks Consumed tag, EVENT instruction triggers, Module Input Data changes, and motion events

User memory

5069-L306ER, 5069-L306ERM 0.6 MB

5069-L310ER, 5069-L310ER-NSE, 5069-L310ERM 1 MB

5069-L320ER, 5069-L320ERM, 5069-L320ERMK, 5069-L320ERP 2 MB

5069-L330ER, 5069-L330ERM, 5069-L330ERMK 3 MB

5069-L340ER, 5069-L340ERM, 5069-L340ERP 4 MB

5069-L350ERM, 5069-L320ERMK 5 MB

5069-L380ERM 8 MB

5069-L3100ERM 10 MB

5069-L306ERS2, 5069-L306ERMS2 0.6 MB + 0.3 MB safety

5069-L310ERS2, 5069-L310ERMS2 1 MB + 0.5 MB safety

5069-L320ERS2, 5069-L320ERMS2,

5069-L320ERS2K, 5069-L320ERMS2K

2 MB + 1 MB safety

5069-L330ERS2, 5069-L330ERMS2,

5069-L330ERS2K, 5069-L330ERMS2K

3 MB + 1.5 MB safety

5069-L340ERS2, 5069-L340ERMS2 4 MB + 2 MB safety

5069-L350ERS2, 5069-L350ERMS2,

5069-L350ERS2K, 5069-L350ERMS2K

5 MB + 2.5 MB safety

5069-L380ERS2, 5069-L380ERMS2 8 MB + 4 MB safety

5069-L3100ERS2, 5069-L3100ERMS2 10 MB + 5 MB safety

Built-in ports

• 2 - Ethernet ports, 10 Mbps/100 Mbps/1 Gbps

•1-port USB client

Communication options

• EtherNet/IP

• USB Client

Network nodes

Studio 5000 Logix Designer application, version 31or later

5069-L306ER, 5069-L306ERM, 5069-L306ERS2, 5069-L306ERMS2 16

5069-L310ER, 5069-L310ER-NSE, 5069-L310ERM, 5069-L310ERS2,

5069-L310ERMS2

5069-L320ER, 5069-L320ERM, 5069-L320ERMK, 5069-L320ERP,

5069-L320ERS2, 5069-L320ERMS2 5069-L320ERS2K, 5069-L320ERMS2K

5069-L330ER, 5069-L330ERM, 5069-L330ERMK, 5069-L330ERS2,

5069-L330ERMS2 5069-L330ERS2K, 5069-L330ERMS2K

5069-L340ER, 5069-L340ERM, 5069-L340ERP, 5069-L340ERS2,

5069-L340ERMS2

5069-L350ERM, 5069-L350ERMK, 5069-L350ERS2, 5069-L350ERMS2

5069-L350ERS2K, 5069-L350ERMS2K

120

5069-L380ERM, 5069-L380ERS2, 5069-L380ERMS2 150

5069-L3100ERM, 5069-L3100ERS2, 5069-L3100ERMS2 180

Controller redundancy Logix Hot Backup - CompactLogix 5380 Controllers only

Integrated motion EtherNet/IP

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 13

Chapter 1 5580 and 5380 Controllers

Process Controllers ControlLogix 5580 and CompactLogix 5380 process controllers are extensions of the Logix

5000™ controller family that focus on plant-wide process control.

The process controllers come configured with a default process tasking model and dedicated

PlantPAx® process instructions that are optimized for process applications and that improve

design and deployment efforts. The process controllers support release 5.0 of the Rockwell

Automation Library of Process Objects.

For more information on the process library, see the Rockwell Automation Library of Process

Objects Reference Manual, publication PROCES-RM200

For more information on process controller application guidelines, see the PlantPAx DCS

Configuration and Implementation User Manual, publication PROCES-UM100

Controller Memory The Logix CPU runs control and motion, communications, and packet processing each on a

separate core.

• The Logix Engine executes the user program, the control task, and the motion task.

• The Communications core manages all Class 3 and unconnected communications via

the Ethernet, USB, and backplane communication ports. Communications do not

interrupt the user task. The System Overhead Time Slice Percentage setting is no longer

available and not necessary.

• The Packet Processing Engine moves all Ethernet Class 1 packets to and from the wire,

and moves all packets to and from the backplane.

The controller allocates memory as needed to help prevent many runtime errors that are

related to free memory. Runtime memory no longer consumes application memory space.

The GuardLogix CPU performs the same functions as the ControlLogix 5580 and

CompactLogix 5380 controllers, with these differences:

• The Logix Engine executes the user program, the control task, the motion task, and the

safety task.

• The Functional Safety Diagnostic Core runs the safety task with inverted data, and

compares the results to the safety task that runs on the Logix Engine.

Logic and Data Memory

Program source code

Tag data

Logix CPU

Logix Engine

Communications Core

Packet Processing Engine

1756 ControlLogix 5580 controllers and CompactLogix 5380 controllers—Memory is in one, contiguous section.

Logic and Data Memory

Program source code

Tag data

Logix CPU

Logix Engine

Communications Core

Packet Processing Engine

1756 GuardLogix 5580 controllers and Compact GuardLogix 5380 controllers—Memory is in one, contiguous section

Functional Safety

Diagnostic Core

14 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 1 5580 and 5380 Controllers

Data Types The controllers support the following data types:

• Numerous IEC 61131-3 elementary data types

• Compound data types

-Arrays

- Predefined structures, such as counters and timers

- User-defined structures

The Logix CPU reads and manipulates 32-bit data values. The minimum memory allocation for

data in a tag is 4 bytes. When you create a standalone tag that stores data that is less than 4

bytes, the controller allocates 4 bytes, but the data only fills the part that it needs.

For more information See Data Structures on page 73

Extended Data Types

The 5380 and 5580 controllers support these extended data types:

The compute, compare, and math instructions support these extended data types for 64-bit

operations.

Data Type

Bits

64…32 31 16 15 8 7 1 0

BOOL

Not allocated Allocated but not used 0 or 1

SINT

Not allocated Allocated but not used -128…+127

INT

Not allocated Allocated but not used -32,768…32,767

DINT Not allocated -2,147,483,648…2,147,483,647

REAL

Not allocated

-3.40282347E

…-1.17549435E

-38

(negative values)

1.17549435E

-38

…3.40282347E

(positive values)

LINT -922337203685477580…+9223372036854775807

Data Type

Bits

64…32 31 16 15 8 7…1 0

USINT Not allocated Allocated but not used Unsigned 0…255

UINT Not allocated Allocated but not used Unsigned 0…65,535

UDINT Not allocated Unsigned 0…4,294,967,295

ULINT Unsigned 0…18,446,744,073,709,551,615

LREAL

-1.7976931348623157E308…-2.2250738585072014E-308 (negative values)

0.0

2.2250738585072014E-308…1.7976931348623157E308 (positive values)

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 15

Chapter 1 5580 and 5380 Controllers

Date and Time Data Types

The 5380 and 5580 controllers support date and time data types to standardize date and time

values in instructions. Standardized values increase the accuracy and reliability of time-

stamped inputs, scheduled outputs, and time-based registration for motion control. These

data types are also helpful for sequence of events, time-stamped data logging and analytics,

and time synchronization within and across systems.

The following instructions support absolute and relative time data types:

•Add (ADD)

•Equal To (EQU)

•Clear (CLR)

• Greater Than or Equal To (GEQ)

• Greater Than (GRT)

• Get System Value (GSV) and Set System Value (SSV)

• Less Than or Equal To (LEQ)

•Less Than (LES)

•Move (MOV)

•Not Equal To (NEQ)

• Subtract (SUB)

You can use the Date and Time Browser dialog box to set a value for any of the date and time

data types. To access the Date and Time Browser dialog box from the Logix Designer

application:

1. Create a tag and set the data type to TIME32, TIME, LTIME, DT or LDT.

2. Select the Monitor Tags tab.

3. Set the Style to an appropriate format for that type.

4. Click the Value field and click the … button.

Data Type Description Literal String Format

Absolute time data types—Use for specific points in time.

DT Date and time. 64-bit storage; units are in microseconds. DT#2020-03-05-08:11:44.345_678

LDT

Long date and time. 64-bit storage; units are in

nanoseconds.

LDT#2020-10-25-11:05:20.123_456_789

Relative time data types—Use for duration or lengths of time. Literal String Display Format

TIME32

Duration of time. 32-bit storage; units are in

microseconds.

T32#2d_3h_1m_22s_123ms_678us

TIME

Duration of time. 64-bit storage; units are in

microseconds.

T#5d_8h_5m_33s_234ms_679us

LTIME

Long duration of time. 64-bit storage; units are in

nanoseconds.

LT#3d_10h_18m_47s_123ms_456us_789ns

16 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 1 5580 and 5380 Controllers

Programming Techniques

For more information See Modular Programming Techniques on page 43.

Data Alignment Rules

The 5580, 5380, and all 64-bit controllers have these data alignment rules on UDTs:

• 8-byte (64-bit) data types (LINT, ULINT, LREAL, TIME, LTIME, DT, and LDT) are placed on

8-byte address boundaries in RAM. The Studio 5000 Logix Designer application

manages this requirement automatically.

• UDTs that have no 8-byte elements retain the existing 4-byte memory allocation rules.

• UDTs that contain 8-byte data types are considered 8-byte data types with a size that is

a multiple of 8 bytes.

• 8-byte data types within a UDT are aligned on an 8-byte boundary.

Produced and Consumed

Data

The controller supports:

• Total number of produced tags 255

• Maximum number of multicast produce tags out of the Ethernet port  32

• Maximum number of consumed tags  255

For more information See Produced and Consumed Data on page 69

Connections The controller supports:

• Dedicated Class 1 (I/O, Produce and Consume, implicit, and so on) connection pool to

support controller node count

• Dedicated Class 3 (HMI, message instructions, explicit, and so on) connection pool to

support up to 512 connections

- This pool is split; 256 incoming and 256 outgoing connections

• 256 cached buffers

• 320 unconnected buffers to establish connections

- This value is fixed and cannot be increased with a CIP™ Generic message

instruction.

Programming Technique Consideration

Subroutines

For Logix Designer application Version 28 and later on 5580 and 5380

controllers:

• JSR calls are limited to 40 input parameters and 40 output parameters.

• There is a maximum of 25 JSR nesting levels.

Add-On Instructions

For 5580 controllers 5380 controllers, you can nest Add-On Instructions up

to 25 levels.

PhaseManager™ equipment phases

The PhaseManager option is support on 5580 and 5380 controllers as of

firmware revision 32.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 17

Chapter 2

5480 Controllers

CompactLogix 5480

Controllers

Characteristic CompactLogix™ 5480 Controllers

Controller tasks:

• Continuous

•Periodic

•Event

•32 tasks

• 1000 programs/task

• All event triggers

Event tasks

Consumed tag, EVENT instruction triggers, Module Input Data changes, and

motion events

User memory

Windows 10 (commercial operating

system on controller)

•RAM: 6 GB

• SSD: 64 GB

Logix control engine

5069-L430ERMW 3 MB

5069-L450ERMW 5 MB

5069-L4100ERMW 10 MB

5069-L4200ERMW 20 MB

Built-in ports

Logix control engine use:

• 3 - Ethernet, 10 Mpbs/100 Mbps/1 Gbps

•1 - USB client

IMPORTANT: Consider the following:

• When the controller operates in Dual-IP mode, each Ethernet port requires a

unique IP address.

• When the controller operates in Linear/DLR mode, the controller uses only one

IP address.

Windows 10 use:

• 1 - Ethernet, 10 Mbps/100 Mbps/1 Gbps

• 2 - USB 3.0 ports

•1 - DisplayPort

Communication options

• Dual-port EtherNet/IP™

• USB Client

Network nodes

Studio 5000 Logix Designer® application, version 32.00.00 or later

5069-L430ERMW

5069-L450ERMW

120

5069-L4100ERMW 180

5069-L4200ERMW

250

5069-L46ERMW

250

Controller redundancy None

Integrated motion

Total axis count

512 (Any combination of physical, virtual,

or consumed axes)

Virtual axis, max 512

Position-loop axis, max 150

Axes/ms, max 100

18 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 2 5480 Controllers

Controller Memory The Logix CPU runs control and motion, communications, and packet processing each on a

separate core.

• The Logix Engine executes the user program, the control task, and the motion task.

• The Communications core manages all Class 3 and unconnected communications via

the Ethernet, USB, and backplane communication ports. Communications do not

interrupt the user task, and you do not need to adjust the System Overhead Time Slice

Percentage.

• The Packet Processing Engine moves all Ethernet Class 1 packets to and from the wire,

and moves all packets to and from the backplane.

The controller allocates memory as needed to help prevent many runtime errors that are

related to free memory. Runtime memory no longer consumes application memory space.

Data Types The controllers support the following data types:

• Numerous IEC 61131-3 elementary data types

• Compound data types

-Arrays

- Predefined structures, such as counters and timers

- User-defined structures

The Logix CPU reads and manipulates 32-bit data values. The minimum memory allocation for

data in a tag is 4 bytes. When you create a standalone tag that stores data that is less than 4

bytes, the controller allocates 4 bytes, but the data only fills the part that it needs.

For more information See Data Structures on page 73

Logic and Data Memory

Program source code

Tag data

Logix CPU

Logix Engine

Communications Core

Packet Processing Engine

1756 CompactLogix 5480 controllers- Memory is in one, contiguous section.

Data Type

Bits

64…32 31 16 15 8 7 1 0

BOOL

Not allocated Allocated but not used 0 or 1

SINT

Not allocated Allocated but not used -128…+127

INT Not allocated Allocated but not used -32,768…32,767

DINT

Not allocated -2,147,483,648…2,147,483,647

REAL

Not allocated

-3.40282347E

…-1.17549435E

-38

(negative values)

1.17549435E

-38

…3.40282347E

(positive values)

LINT -9223372036854775808…+9223372036854775807

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 19

Chapter 2 5480 Controllers

Extended Data Types

The 5480 controller supports these extended data types:

The compute, compare, and math instructions support these extended data types for 64-bit

operations.

Date and Time Data Types

The 5480 controllers support date and time data types to standardize date and time values in

instructions. Standardized values increase the accuracy and reliability of time-stamped

inputs, scheduled outputs, and time-based registration for motion control. These data types

are also helpful for sequence of events, time-stamped data logging and analytics, and time

synchronization within and across systems.

The following instructions support absolute and relative time data types:

•Add (ADD)

•Equal To (EQU)

•Clear (CLR)

• Greater Than or Equal To (GEQ)

• Greater Than (GRT)

• Get System Value (GSV) and Set System Value (SSV)

• Less Than or Equal To (LEQ)

•Less Than (LES)

•Move (MOV)

•Not Equal To (NEQ)

• Subtract (SUB)

Data Type

Bits

64…32 31 16 15 8 7…1 0

USINT

Not

allocated

Allocated but not used Unsigned 0…255

UINT

Not

allocated

Allocated but not used Unsigned 0…65,535

UDINT

Not

allocated

Unsigned 0…4,294,967,295

ULINT Unsigned 0…18,446,744,073,709,551,615

LREAL

-1.7976931348623157E308…-2.2250738585072014E-308 (negative values)

0.0

2.2250738585072014E-308…1.7976931348623157E308 (positive values)

Data Type Description Literal String Format

Absolute time data types—Use for specific points in time.

DT Date and time. 64-bit storage; units are in microseconds. DT#2020-03-05-08:11:44.345_678

LDT

Long date and time. 64-bit storage; units are in

nanoseconds.

LDT#2020-10-25-11:05:20.123_456_789

Relative time data types—Use for duration or lengths of time. Literal String Display Format

TIME32

Duration of time. 32-bit storage; units are in

microseconds.

T32#2d_3h_1m_22s_123ms_678us

TIME

Duration of time. 64-bit storage; units are in

microseconds.

T#5d_8h_5m_33s_234ms_679us

LTIME

Long duration of time. 64-bit storage; units are in

nanoseconds.

LT#3d_10h_18m_47s_123ms_456us_789ns

20 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 2 5480 Controllers

You can use the Date and Time Browser dialog box to set a value for any of the date and time

data types. To access the Date and Time Browser dialog box from the Logix Designer

application:

1. Create a tag and set the data type to TIME32, TIME, LTIME, DT or LDT.

2. Select the Monitor Tags tab.

3. Set the Style to an appropriate format for that type.

4. Click the Value field and click the … button.

Programming Techniques

For more information See Modular Programming Techniques on page 43.

Data Alignment Rules

The 5480 controllers have these data alignment rules on UDTs:

• 8-byte (64-bit) data types (LINT, ULINT, LREAL, TIME, LTIME, DT, and LDT) are placed on

8-byte address boundaries in RAM. The Studio 5000 Logix Designer application

manages this requirement automatically.

• UDTs that have no 8-byte elements retain the existing 4-byte memory allocation rules.

• UDTs that contain 8-byte data types are considered 8-byte data types with a size that is

a multiple of 8 bytes.

• 8-byte data types within a UDT are aligned on an 8-byte boundary.

Produced and Consumed

Data

The controller supports:

• Total number of produced tags 255

• Maximum number of multicast produce tags out of the Ethernet port  32

• Maximum number of consumed tags  255

For more information See Produced and Consumed Data on page 69

Connections The controller supports the following:

• Dedicated Class 1 (I/O, Produce and Consume, implicit, and so on) connection pool to

support controller node count

• Dedicated Class 3 (HMI, message instructions, explicit, and so on) connection pool to

support up to 512 connections

- This pool is split; 256 incoming and 256 outgoing connections

• 256 cached buffers

• 320 unconnected buffers for establishing connections

- This value is fixed and cannot be increased with a CIP™ Generic message

instruction.

Programming Technique Consideration

Subroutines

For Logix Designer application Version 32.00.00 and later:

• JSR calls are limited to 40 input parameters and 40 output parameters.

• There is a maximum of 25 JSR nesting levels.

Add-On Instructions You can nest Add-On Instructions up to 25 levels.

PhaseManager™ equipment phases

The PhaseManager option is supported on 5480 controllers as of

firmware revision 32.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 21

Chapter 3

5570 Controllers and 5370 Controllers

This chapter highlights these controllers.

ControlLogix 5570 and

GuardLogix 5570

Controllers

Controller Family Controller Names

5570 controllers ControlLogix® 5570 and GuardLogix® 5570 controllers

5370 controllers CompactLogix™ 5370 and Compact GuardLogix 5370 controllers

Characteristic

ControlLogix 5570 Controllers

GuardLogix 5570 Controllers

Armor™ ControlLogix 5570 Controllers

Armor™ GuardLogix® 5570 Controllers

Controller tasks:

•Continuous

•Periodic

•Event

•32

• 1000 programs/task

Event tasks Consumed tag, EVENT instruction triggers, Module Input Data changes, and motion events

User memory

1756-L71, 1756-L71EROM 2 MB

1756-L72, 1756-L72EROM 4 MB

1756-L73, 1756-L73XT, 1756-L73EROM 8 MB

1756-L74 16 MB

1756-L75 32 MB

1756-L71S, 1756-L71EROMS 2 MB +1 MB safety

1756-L72S, 1756-L72EROMS 4 MB + 2 MB safety

1756-L73S, 1756-L73EROMS 8 MB + 4 MB safety

Built-in ports

1756-L71, 1756-L72, 1756-L73, 1756-L73XT, 1756-L74,

1756-L75, 1756-L71S, 1756-L72S, 1756-L73S

1-port USB Client

1756-L71EROM, 1756-L71EROMS, 1756-L72EROM,

1756-L72EROMS, 1756-L73EROM, 1756-L73EROMS

•1-port USB client

• Dual-port EtherNet/IP™, 10 Mpbs/100 Mbps

Communication options

• EtherNet/IP

• ControlNet®

• DeviceNet®

• Data Highway Plus™

• Remote I/O

•SynchLink™

• USB Client

Controller connections 500 connections

Controller redundancy

1756-L71, 1756-L72, 1756-L73, 1756-L73XT, 1756-L74, and 1756-L75 controllers only.

Full support with a separate redundancy firmware revision.

Integrated motion EtherNet/IP

22 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 3 5570 Controllers and 5370 Controllers

CompactLogix 5370 and

Compact GuardLogix 5370

Controllers

Characteristic

CompactLogix 5370 Controllers and Compact GuardLogix 5370 Controllers

Armor CompactLogix 5370 Controllers and Armor Compact GuardLogix 5370 Controllers

Controller tasks:

• Continuous

•Periodic

•Event

•32

• 1000 programs/task

Event tasks Consumed tag, EVENT instruction triggers, and motion events

User memory

1769-L16ER-BB1B 384 KB

1769-L18ER-BB1B, 1769-L18ERM-BB1B, 1769-L18ERM-BB1BK 512 KB

1769-L24ER-QB1B, 1769-L24ER-QBFC1B, 1769-L24ER-QBFC1BK 750 KB

1769-L19ER-BB1B, 1769-L19ER-BB1BK, 1769-L27ERM-QBFC1B,

1769-L30ER, 1769-L30ERK, 1769-L30ER-NSE, 1769-L30ERM,

1769-L30ERMK

1 MB

1769-L33ER, 1769-L33ERK, 1769-L33ERM, 1769-L33ERMK,

1769-L33ERMO

2 MB

1769-L36ERM, 1769-L36ERMO 3 MB

1769-L37ERM, 1769-L37ERMK, 1769-L37ERMO 4 MB

1769-L38ERM, 1769-L38ERMK, 1769-L38ERMO 5 MB

1769-L30ERMS 1 MB + 0.5 MB safety

1769-L33ERMS, 1769-L33ERMSK, 1769-L33ERMOS 2 MB + 1 MB safety

1769-L36ERMS, 1769-L36ERMOS 3 MB + 1.5 MB safety

1769-L37ERMS, 1769-L37ERMSK, 1769-L37ERMOS 4 MB + 1.5 MB safety

1769-L38ERMS, 1769-L38ERMSK, 1769-L38ERMOS 5 MB + 1.5 MB safety

Built-in ports

Dual-port EtherNet/IP

1-port USB Client

Communication options

EtherNet/IP

Embedded switch

Single IP address

DeviceNet

USB Client

Controller connections 256 connections

Network nodes

1769-L16ER-BB1B 4

1769-L18ER-BB1B, 1769-L18ERM-BB1B, 1769-L18ERM-BB1BK,

1769-L19ER-BB1B, 1769-L19ER-BB1BK

1769-L27ERM-QBFC1B, 1769-L30ER, 1769-

L30ERK,1769-L30ER-NSE, 1769-L30ERM, 1769-L30ERMK,

1769-L30ERMS

1769-L33ER, 1769-L33ERK, 1769-L33ERM, 1769-L33ERMK,

1769-L33ERMS, 1769-L33ERMSK, 1769-L33ERMO, 1769-

L33ERMOS

1769-L36ERM, 1769-L36ERMS, 1769-L36ERMO, 1769-L36ERMOS 48

1769-L37ERM, 1769-L37ERMS, 1769-L37ERMO, 1769-L37ERMOS,

1769-L37ERMK, 1769-L37ERMSK

1769-L38ERM, 1769-L38ERMS, 1769-L38ERMO, 1769-L38ERMOS,

1769-L38ERMK, 1769-L38ERMSK

Controller redundancy

Back up via DeviceNet - CompactLogix 5370 L3 Controllers and Compact GuardLogix 5370 L3 controllers only

Logix Hot Backup - CompactLogix 5370 L3 Controllers only

Integrated motion EtherNet/IP

Conformal coating

1769-L30ERK,1769-L30ERMK, 1769-L33ERK, 1769-L33ERMK, 1769-L33ERMSK, 1769-L37ERMK, 1769-L37ERMSK, 1769-L38ERMK,

1769-L38ERMSK

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 23

Chapter 3 5570 Controllers and 5370 Controllers

Controller Memory The Logix CPU executes application code and messages. The backplane CPU transfers I/O

memory and other module data on the backplane. This CPU operates independently from the

Logix CPU, so it sends and receives I/O information asynchronous to program execution.

CompactLogix 5370 and Compact GuardLogix 5370 Controllers

The Logix CPU executes application code and messages.

Controller Connections The controller uses a connection to establish a communication link between two devices.

Connections can be made to the following:

• Controller to local I/O modules or local communication modules

• Controller to remote I/O or remote communication modules

• Controller to remote I/O (rack-optimized) modules

• Produced and consumed tags

•Messages

• Access to programming software

• Linx-based software access for HMI or other software applications

CPU usage is based on the number of devices in the I/O tree. About 6% of the CPU

is used for every 100 devices in the I/O tree.

Logic and Data Memory

Logix CPU Backplane CPU

I/O Memory

Program source code

Tag data

HMI tag group lists

I/O data

I/O force tables

Message buffers

Produced/consumed tags

1756 ControlLogix 5570 controllers - Memory is separated into isolated sections.

Project Documentation Memory

Comment descriptions

Alarm log

Extended tag properties

Controller I/O Task Priority Communication Task Priority

CompactLogix 5370 6 12

I/O Memory

Program source code

Tag data

HMI tag group lists

I/O data

I/O force tables

Message buffers

Produced/consumed tags

CompactLogix 5370 controllers - Memory is separated into isolated segments.

Logix CPU

Logic and Data Memory

Comment descriptions

Alarm log

Extended tag properties

Project Documentation Memory

IMPORTANT The topics in this section apply only to ControlLogix 5570 and earlier

controllers, and CompactLogix 5370 and earlier controllers operation.

24 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 3 5570 Controllers and 5370 Controllers

The controllers have different communication limits.

The limit of connections can ultimately reside in the communication module you use for the

connection. If a message path routes through a communication module, the connection that is

related to the message also counts toward the connection limit of that communication

module.

Determine Total Connection Requirements

The total connections for a controller include both local and remote connections. Counting

local connections is not an issue for CompactLogix controllers. They support the maximum

number of modules that are permitted in their systems.

When designing your CompactLogix 5370 controllers, you must consider these resources:

• EtherNet/IP network nodes

• Controller connections

For more information, see the CompactLogix 5370 Controllers User Manual,

publication 1769-UM021

The ControlLogix controllers support more communication modules than the other controllers,

so you must tally local connections to make sure that you stay within the connection limit.

Communication Attribute 1756-L7x ControlLogix 1756-L6x ControlLogix 1769 CompactLogix CompactLogix 5370 1768 CompactLogix

Connections 500 250 100 256 250

Cached messages 32 for messages and block transfers combined

Unconnected receive buffers 3

Unconnected transmit

buffers

Default 20 (can be increased to 40) Default 10 (can be increased to 40)

Controller Communication Device Supported Connections

ControlLogix

1756-CN2R, 1756-CN2RXT

1756-CN2/B

100 CIP™ connections

(any combination of scheduled and message connections)

128 CIP connections

1756-CNB,1756 -CNBR

64 CIP connections depending on RPI, recommend that you use only 48 connections

(any combination of scheduled and message connections)

1756-EN2F, 1756-EN2T, 1756-EN2TR,

1756-EN2TP, 1756-EN2TXT, 1756-EN3TR

256 CIP connections

128 TCP/IP connections

1756-EN4TR

CIP connected messages:

• 1000 I/O

•528

(1)

512 TCP/IP connections

1756-ENBT

1756-EWEB

128 CIP connections

64 TCP/IP connections

CompactLogix 5370 Built-in Ethernet ports

See the CompactLogix 5370 Controllers User Manual, publication 1769-UM021

, for information on how to

count EtherNet/IP nodes on the I/O Configuration section of the programming software.

(1) There are 1000 explicit connections and 528 implicit connections.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 25

Chapter 3 5570 Controllers and 5370 Controllers

Use this table to tally local connections.

The communication modules that you select determine how many remote connections are

available. Use this table to tally remote connections.

System Overhead

Percentage

The system overhead timeslice specifies the percentage of continuous task execution time

that is devoted to communication and background redundancy functions.

• Message communication is any communication that you do not configure through the

I/O configuration folder of the project, such as MSG instructions.

• Message communication occurs only when a periodic or event task is not running. If

you use multiple tasks, make sure that their scan times and execution intervals leave

enough time for message communication.

• System overhead interrupts only the continuous task.

• The controller performs message communication for up to 1 ms at a time and then

resumes the continuous task.

• Adjust the update rates of the tasks as needed to get the best trade-off between

executing your logic and servicing message communication.

Connection Type Device Quantity x Connections per Module =

Total

Connections

Local I/O module (always a direct connection) x 1 =

SERCOS Motion module x 3 =

ControlNet communication module x 0 =

EtherNet/IP communication module x 0 =

DeviceNet communication module x 2 =

DH+/Remote I/O communication module x 1 =

DH-485 communication module x 1 =

Programming software access to controller x 1 =

Total

IMPORTANT A redundant system uses eight connections in the controller.

Connection Type Device Quantity x Connections per Module = Total Connections

Remote ControlNet communication module

Configured as a direct (none) connection

Configured as a rack-optimized connection

x0 or

Remote EtherNet/IP communication module

Configured as a direct (none) connection

Configured as a rack-optimized connection

x0 or

Remote device over a DeviceNet network

(accounted for in rack-optimized connection for local DeviceNet module)

x0 =

Safety device on a DeviceNet or EtherNet/IP network x 2 =

Other remote communication adapter x 1 =

Distributed I/O module (individually configured for a direct connection) x 1 =

Produced tag and first consumer

Each additional consumer

Consumed tag x 1 =

Connected message (CIP Data Table read/write and DH+™) x 1 =

Block transfer message x 1 =

Linx-based software access for HMI or other software applications x 4 =

FactoryTalk® Linx software for HMI or other software applications x 5 =

Total

26 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 3 5570 Controllers and 5370 Controllers

System overhead functions include the following:

• Communicating with HMI devices and programming software

• Sending and responding to messages

• Alarm management processing

• Redundancy qualification

The controller performs system overhead functions for up to 1 ms at a time. If the controller

completes the overhead functions in less than 1 ms, it resumes the continuous task. The

following chart compares a continuous and periodic task.

The CPU timeslices between the continuous task and system overhead. Each task switch

between user task and system overhead takes additional CPU time to load and restore task

information. You can calculate the continuous task interval as:

ContinuousTime=(100/SystemOverheadTimeSlice%) - 1

The programming software forces at least 1 ms of execution time for the continuous task,

regardless of the system overhead timeslice. This more efficiently uses system resources

because letting shorter execution times of the continuous task exist means switching tasks

more frequently.

Continuous Task Restarts

Periodic Task Restarts

Continuous Task

10% CPU Overhead

Continuous Task

25% CPU Overhead

Periodic Task

CPU Overhead

Example Description

Continuous task

10% CPU overhead

In the top example, the system overhead timeslice is set to 10%. Given 40 ms of code to execute, the continuous task completes the

execution in 44 ms. During a 60 ms period, the controller is able to spend 5 ms on communication processing.

Continuous task

25% CPU overhead

By increasing the system overhead timeslice to 25%, the controller completes the continuous task scan in 57 ms. The controller

spends

15 ms of a 60 ms time span on communication processing.

Periodic task

Placing the same code in a periodic task yields even more time for communication processing. The bottom example assumes that

the code is in a 60 ms periodic task. The code executes to completion and then goes dormant until the 60 ms, time-based trigger

occurs. While the task is dormant, all CPU bandwidth can focus on communication. Because the code takes only 40 ms to execute,

the controller can spend 20 ms on communication processing. Depending on the amount of communication to process during this 20

ms window, it can be delayed as it waits for other modules in the system to process the data that was communicated.

System Overhead Timeslice % Communication Execution (ms) Continuous Task Execution (ms)

10 1 9

20 1 4

33 1 2

50 1 1

66 2 1

80 4 1

90 9 1

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 27

Chapter 3 5570 Controllers and 5370 Controllers

Manage the System Overhead Timeslice Percentage

As the system overhead timeslice percentage increases, time that is allocated to executing

the continuous task decreases. If there is no communication for the controller to manage, the

controller uses the communication time to execute the continuous task.

Individual applications can differ, but the overall impact on communication and scan time

remains the same. The data is based on a ControlLogix5555 controller running a continuous

task with 5000 tags (no arrays or user-defined structures).

IMPORTANT System Overhead Time Slice does not apply to ControlLogix 5580 or

CompactLogix 5380 controllers.

Consideration Description

Continuous task always has at least 1 ms execution time

The programming software forces the continuous task to have at least 1 ms of execution time, regardless of the

setting for the system overhead timeslice. This results in more efficient controller use because excessive

swapping between tasks uses valuable CPU resources.

Impact on communication and scan time

Increasing the system overhead timeslice percentage decreases execution time for the continuous task while it

increases communication performance.

Increasing the system overhead timeslice percentage also increases the amount of time it takes to execute a

continuous task - increasing overall scan time.

Unused portion of system overhead timeslice

You can configure any unused portion of the system overhead timeslice to:

• Run the continuous task, which results in faster execution of application code and increases the variability of

the program scan.

• Process communication, which results in more predictable and deterministic scan time for the continuous

task. (This is for development and testing of an application to simulate communication.)

System overhead

System overhead is the time that the controller spends on message communication and background tasks.

• Message communication is any communication that you do not configure through the I/O configuration folder

of the project, such as MSG instructions.

• Message communication occurs only when a periodic or event task is not running. If you use multiple tasks,

make sure that their scan times and execution intervals leave enough time for message communication.

• System overhead interrupts only the continuous task.

• The system overhead timeslice specifies the percentage of time (excluding the time for periodic or event

tasks) that the controller devotes to message communication.

• System overhead timeslice does not apply to ControlLogix 5580 and CompactLogix 5380 controllers.

• The controller performs message communication for up to 1 ms at a time and then resumes the continuous

task.

• Adjust the update rates of the tasks as needed to get the best trade-off between executing your logic and

servicing message communication.

Program Scan

Time

Tags Per

Second

System Timeslice %

Tags per Second

Program Scan Time in Milliseconds

28 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 3 5570 Controllers and 5370 Controllers

I/O Processing The 5370 controllers use a dedicated periodic task to process I/O data. This I/O task:

• Operates at priority 6.

• Higher-priority tasks take precedence over the I/O task and can affect processing.

• Executes at the fastest RPI you have scheduled for the system.

• Executes for as long as it takes to scan the configured I/O modules.

Data Types The controllers support the following data types:

• Numerous IEC 61131-3 elementary data types

• Compound data types

-Arrays

- Predefined structures, such as counters and timers

- User-defined structures

The Logix CPU reads and manipulates 32-bit data values. The minimum memory allocation for

data in a tag is 4 bytes. When you create a standalone tag that stores data that is less than 4

bytes, the controller allocates 4 bytes, but the data only fills the part that it needs.

For more information See Data Structures on page 73

To embed tag values within a string, you can use the DTOS, RTOS, and CONCAT instructions:

• Use the DTOS or RTOS instructions to convert a value to a string.

• Use the CONCAT instruction to merge characters with another string.

Programming Techniques

For more information See Modular Programming Techniques on page 43.

Data Type

Bits

64…32 31 16 15 8 7 1 0

BOOL

Not allocated Allocated but not used 0 or 1

SINT

Not allocated Allocated but not used -128…+127

INT

Not allocated Allocated but not used -32,768…32,767

DINT Not allocated -2,147,483,648…2,147,483,647

REAL

Not allocated

-3.40282347E

…-1.17549435E

-38

(negative values)

1.17549435E

-38

…3.40282347E

(positive values)

LINT Valid Date/Time range is from 1/1/1970 12:00:00 AM coordinated universal time (UTC) to 12/31/2250 12:00:00 AM UTC

Programming Technique Consideration

Subroutines

For Studio 5000 Logix Designer® Version 28 and later on 5570 and 5370 controllers:

• JSR calls are limited to 40 input parameters and 40 output parameters.

• There is no limit on nesting JSR instructions. However, it is possible that too many nesting levels can cause the

controller to run out of memory and fault.

Add-On Instructions

For 5570 controllers or earlier, and 5370 controllers or earlier, there is no limit on nesting Add-On Instructions.

However, it is possible that too many nesting levels can cause the controller to run out of memory and fault.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 29

Chapter 3 5570 Controllers and 5370 Controllers

Produced and Consumed

Data

The controller supports:

• Total number of produced tags  127

• Maximum number of multicast produce tags out of the CompactLogix Ethernet port 

• Maximum number of consumed tags  250 (or controller maximum)

For more information See Produced and Consumed Data on page 69

Messages The controller supports the following:

• As many outgoing, unconnected buffers as fit in controller memory.

Each buffer uses approximately 1.2 KB of I/O memory.

You can use a CIP Generic message instruction to increase the number of unconnected

buffers. See the Logix 5000™ Controllers Messages Programming Manual, publication

1756-PM012

• Three incoming unconnected buffers

• 32 cached buffers, as of firmware revision 12 and later.

30 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 3 5570 Controllers and 5370 Controllers

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 31

Chapter 4

Logic Execution

The controller operating system is a pre-emptive multitasking system that is IEC 61131-3

compliant.

Decide When to Use Tasks,

Programs, and Routines

Use these considerations to determine when to use a task, program, or routine.

Tasks to configure controller execution

A task provides scheduling and priority information for a set of one or more programs. You can configure tasks as either

continuous, periodic, or event.

Programs to group data and logic

A task contains programs, each with its own routines and program-scoped tags. Once a task is triggered (activated), the

programs that are assigned to the task execute in the order in which they are listed in the Controller Organizer.

Programs are useful for projects that multiple programmers develop. During development, the code in one program that

uses program-scoped tags can be duplicated in a second program to minimize the possibility of tag names colliding.

Tasks can contain programs and equipment phases.

Routines to encapsulate executable code

that is written in one programming language

Routines contain the executable code. Each program has a main routine that is the first routine to execute within a

program. Use logic, such as the Jump to Subroutine (JSR) instruction, to call other routines. You can also specify an optional

program fault routine.

Comparison Task Program and Equipment Phase Routine

Quantity available Varies by controller (4, 6, 8, or 32)

32 program and equipment phases

(combined) per task

100 for ControlLogix® controllers with V23 and

earlier

1000 programs/task for ControlLogix

controllers with V24 and later

Unlimited number of routines per program

Function Determines how and when code is executed

Organizes groups of routines that share a

common data area and function.

Contains executable code (relay ladder, function

block diagram, sequential function chart, or

structured text)

Use

• Most code is expected to reside in a

continuous task

• Use a periodic task for slower processes or

when time-based operation is critical

• Use an event task for operations that

require synchronization to a specific event

• Put major equipment pieces or plant cells

into isolated programs

• Use programs to isolate different

programmers or create reusable code

• Configurable execution order within a task

• Isolate individual batch phases or discrete

machine operations

• Isolate machine or cell functions in a routine

• Use the appropriate language for the process

• Modularize code into subroutines that can be called

multiple times

Considerations

• A high number of tasks can be difficult to

debug

• Can disable output processing on some

tasks to improve performance

• Tasks can be inhibited to help prevent

execution

• Do not configure multiple tasks at the same

priority

• Data spanning multiple programs must be

controller-scoped or a program parameter.

• Listed in the Controller Organizer in the

order of execution

• Subroutines with multiple calls can be difficult to

debug

• Data can be referenced from program-scoped and

controller-scoped areas

• Calling many routines impacts scan time

• Listed in the Controller Organizer as Main, Fault,

and then alphabetically

32 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 4 Logic Execution

Specify Task Priorities Each task in the controller has a priority level. A higher priority task (such as 1) interrupts any

lower priority task (such as 15). The continuous task has the lowest priority; periodic or event

tasks always interrupt continuous tasks.

The controller has these types of tasks.

If a periodic or event task is executing when another is triggered, and both tasks are at the

same priority level, the tasks execute in 1 ms increments until one of the tasks completes

execution.

Priority User Task Description

Highest

— CPU overhead - general CPU operations

— Motion planner - executed at coarse update rate

— Safety task - safety logic

— Redundancy task - communication in redundant systems

— Trend data collection - high-speed collection of trend data values

Priority 1 Event/Periodic User defined

Priority 2 Event/Periodic User defined

Priority 3 Event/Periodic User defined

Priority 4 Event/Periodic User defined

Priority 5 Event/Periodic User defined

Priority 6 Event/Periodic

User defined

1769 CompactLogix™ controllers process I/O as a periodic task based on the chassis RPI

setting

Priority 7 Event/Periodic User defined

Priority 8 Event/Periodic User defined

Priority 9 Event/Periodic User defined

Priority 10 Event/Periodic User defined

Lowest

Priority 11 Event/Periodic User defined

Priority 12 Event/Periodic

User defined

CompactLogix communication and scheduled connection maintenance

Priority 13 Event/Periodic User defined

Priority 14 Event/Periodic User defined

Priority 15 Event/Periodic User defined

Continuous

Lowest priority task. Interrupted by all other tasks including system overhead timeslice (if

applicable.)

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Chapter 4 Logic Execution

Manage User Tasks You can configure these user tasks.

The user tasks that you create appear in the Tasks folder of the controller. The predefined

system tasks do not appear in the Tasks folder and they do not count toward the task limit of

the controller.

Pre-defined Tasks in ControlLogix and CompactLogix Process

Controllers

PlantPAx system release 5.0 adds process controllers to the Logix 5000 family of controllers.

The process controllers offer additional capabilities that are targeted for DCS applications.

The Task folder contains a project structure that consists of four pre-defined periodic tasks:

• Fast (100 ms) – For control fast loops, such as liquid flow or pressure with related

transmitters and pump drives

• Normal (250 ms) – For discrete control, such as motors, pumps, and valves

• Slow (500 ms) – For level, temperature, analysis loops, phases, and batch sequencing

• System (1000 ms) – For slow change temperature control and general controller

operations, such as messaging or status

If you want logic to execute Use this task Description

All of the time Continuous task

The continuous task runs in the background. Any CPU time that is not allocated to other

operations or tasks is used to execute the continuous task.

• The continuous task runs all of the time. When the continuous task completes a full scan, it

restarts immediately.

• A project does not require a continuous task. If used, there can be only one continuous task.

• At a constant period (such as every 100 ms)

• Multiple times within the scan of your other logic

Periodic task

A periodic task performs a function at a specific time interval. Whenever the time for the

periodic task expires, the periodic task:

• Interrupts any lower priority tasks.

• Executes one time.

• Returns control to where the previous task left off.

Immediately when an event occurs Event task

An event task performs a function only when a specific event (trigger) occurs. Whenever the

trigger for the event task occurs, the event task:

• Interrupts any lower priority tasks.

• Executes one time.

• Returns control to where the previous task left off.

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Chapter 4 Logic Execution

Considerations that Affect

Task Execution

This example depicts the execution of a project with these tasks.

Configure a

Continuous Task

When you create a project in the programming software, the Main Task is configured as a

continuous task.

• A controller supports one continuous task, but a continuous task is not required.

• You can configure the task to update output modules at the end of the continuous task.

• You can change the continuous task to either a periodic or event task.

Configure a Periodic Task A periodic task executes automatically based on a preconfigured interval. You can configure

whether the task updates output modules at the end of the periodic task. After the task

executes, it does not execute again until the configured time interval has elapsed.

Consideration Description

Motion planner

The motion planner interrupts all other tasks, regardless of their priority.

• The number of axes and coarse update period for the motion group affect how long and how often the motion planner executes.

• If the motion planner is executing when a task is triggered, the task waits until the motion planner is done.

• If the coarse update period occurs while a task is executing, the task pauses to let the motion planner execute.

Output processing

At the end of a task, the controller performs output processing for the output modules in your system. This processing depends on the

number of output connections that are configured in the I/O tree.

Too many tasks

If you have too many tasks, then the following can occur:

• Continuous task can take too long to complete.

• Other tasks can experience overlaps. If a task is interrupted too frequently or too long, it must be triggered again to complete its

execution.

• Controller communication can be slower.

• If your application is designed for data collection, try to avoid multiple tasks.

Table 1 - Example Task Execution

Task Priority Period Execution Time Duration

Motion planner — 8 ms (course update rate) 1 ms 1 ms

Event task 1 1 — 1 ms

2 ms

Periodic task 1 2 12 ms 2 ms

4ms

Continuous task — — 20 ms 48 ms

Legend: Task executes. Task is interrupted (suspended).

Motion

Planner

Event Task 1

Periodic

Task 1

Continuous

Task

5 1015 20253035404550

Description

1 Initially, the controller executes the motion planner and the I/O task (if one exists).

2 The period for periodic task 1 expires (12 ms), so the task interrupts the continuous task.

The triggers occur for event task 1.

Event task 1 waits until the motion planner is done.

Lower priority tasks experience longer delays.

4 The continuous task automatically restarts.

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Chapter 4 Logic Execution

Configure an Event Task An event task executes automatically based on a trigger event occurring, or if a trigger event

does not occur in a specific time interval. You configure whether the task updates output

modules at the end of the task. After the task executes, it does not execute again until the

event occurs again. Each event task requires a specific trigger.

For more information on event tasks, see:

• Logix 5000™ Controllers Common Procedures Programming Manual,

publication 1756-PM001

• Using Event Tasks with Logix 5000 Controllers, publication LOGIX-WP003

Guidelines to Configure an Event Task

Additional Considerations for Periodic and Event Tasks

Trigger Description

Module Input Data State Change

A remote input module (digital or analog) triggers an event task that is based on the change of state (COS) configuration for the module.

Enable COS for only one point on the module. If you enable COS for multiple points, a task overlap of the event task can occur.

• The ControlLogix sequence of events modules (1756-IB16ISOE, 1756-IH16ISOE) use the Enable Coordinated System Time (CST) Capture

feature instead of COS.

• The embedded input points on the 1769-L16ER-BB1B, 1769-L18ER-BB1B, 1769-L18ERM-BB1B, 1769-L18ERM-BB1B, and 1769-L19ER-BB1BK

modules can be configured to trigger an event task when a COS occurs.

Consumed Tag

Only one consumed tag can trigger a specific event task. Use an Immediate Output (IOT) instruction in the producing controller to signal

the production of new data.

Axis Registration 1 or 2 A registration input triggers the event task.

Axis Watch A watch position triggers the event task.

Motion Group Execution

The coarse update period for the motion group triggers the execution of both the motion planner and the event task. Because the motion

planner interrupts all other tasks, it executes first.

EVENT Instruction Multiple EVENT instructions can trigger the same task.

Guideline Description

Place the I/O module being used to trigger an event

in the same chassis as the controller.

Placing the I/O module in a remote chassis adds more network communication and processing to the response time.

Limit events on digital inputs to one input bit on a

module.

All inputs on a module trigger one event, so if you use multiple bits you increase the chance of a task overlap.

Configure the module to detect change of state on the trigger input and turn off the other bits.

Set the priority of the event task as the highest

priority on the controller.

If the priority of the event task is lower than a periodic task, the event task has to wait for the periodic task to

complete execution.

Limit the number of event tasks.

Increasing the number of event tasks reduces the available CPU bandwidth and increases the chances of task

overlap.

Consideration Description

Amount of code in the event task Each logic element (for example, rung, instruction, or structured text construct) adds to scan time.

Task priority If the event task is not the highest priority task, a higher priority task can delay or interrupt the execution of the event task.

CPS and UID instructions If one of these instructions is active, the event task cannot interrupt the currently executing task. (The task with the CPS or UID.)

Motion planner The motion planner takes precedence over event or periodic tasks

Trends Trend data collection takes precedence over event or periodic tasks.

Output processing

You can disable output processing at the end of a task to reduce the amount of task processing time. The Controller Organizer

displays whether outputs processing is disabled.

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Chapter 4 Logic Execution

Access the Module Object The MODULE object provides status information about a module. To select a particular module

object, set the Object Name operand of the GSV/SSV instruction to the module name. The

specified module must be present in the I/O Configuration section of the controller organizer

and must have a device name.

With the Studio 5000 Logix Designer® application, version 24.00.00 and later, you can access

the MODULE object directly from an Add-On Instruction. Previously, you could access the

MODULE object data, but not from within an Add-On Instruction.

You must create a Module Reference parameter when you define the Add-On Instruction to

access the MODULE object data. A Module Reference parameter is an InOut parameter of the

MODULE data type that points to the MODULE Object of a hardware module. You can use

module reference parameters in both Add-On Instruction logic and program logic.

For more information on the Module Reference parameter, see the Logix 5000 Controllers Add-

On Instructions Programming Manual, publication 1756-PM010

, and the Logix Designer

application online help.

The Path attribute is available with Logix Designer application, version 24.00.00 and later. This

attribute provides a communication path to the module.

For more information on the attributes available in the MODULE object, see the Logix 5000

Controllers General Instructions Reference Manual, publication 1756-RM003

Develop Application Code in

Routines

Each routine contains logic in one programming language. Choose a programming language

that is based on the application.

Section of Code Represents Language to Use

Continuous or parallel execution of multiple operations (not sequenced)

Ladder Diagram(LD)

Boolean or bit-based operations

Complex logical operations

Message and communication processing

Machine interlocking

Operations that service or maintenance personnel can interpret to troubleshoot the machine or process.

Servo motion control

Continuous process and drive control

Function block diagram (FBD)Loop control

Calculations in circuit flow

High-level management of multiple operations

Sequential function chart (SFC)

Repetitive sequences of operations

Batch process

Motion control sequencing (via sequential function chart with embedded structure text)

State machine operations

Complex mathematical operations

Structured text (ST)Specialized array or table loop processing

ASCII string handling or protocol processing

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Chapter 4 Logic Execution

Comparison of Programming Languages

Programming Methods The capabilities of the controllers make different programming methods possible. There are

trade-offs to consider when selecting a programming method.

Inline Duplication

Write multiple copies of the code with different tag references.

Comparison Relay Ladder Logic

Function Block Diagram

(1)

Sequential Function Chart Structured Text

Instruction categories

• Boolean

• General and trig math

• Timers and counters

• Array management

• Diagnostic

• Serial port and messaging

• ASCII manipulation

• Motion control

• General and trig math

• Timers and counters

• Bitwise logical

•Advanced process

• Advanced drive

• Step/action with embedded

structured text

• Transition with structure text

comparisons

• Simultaneous and selection

branches

• Stop element

• General and trig math

• Timers and counters

• Bitwise logical

• Array management

•Diagnostic

•ASCII manipulation

•Specialty CPU control

• Motion control

•Advanced process

• Advanced drive

Editor style

• Graphical rungs

• Unlimited rungs

• Graphical, free-form drawing

• Unlimited sheets

• Graphical, free-form drawing

• Unlimited grid space

•Textual

• Unlimited lines

Monitoring

• Rung animation

• Data value animation

•Force status

• Output and input pin data value

animation

• Active steps animation

• Auto display scroll

• Branch/transition force status

• Tag watch pane

• Context coloring

Comments

•Tag

•Rung

•Tag

• Text box

•Tag

• Text box

• Embedded structured text

comments that are stored in CPU

•Multi-line

•End if line

• Comments that are stored in CPU

(1) FBD functions introduced in Logix Designer application, version 32.00.00 can execute faster, require less memory, and be easier to program and maintain than their FBD counterparts. Most

operators in relay ladder logic are available in FBD as functions.

Benefits

• Uses more memory

• Fastest execution time because all tag

references are defined before runtime

• Easiest to maintain because rung animation

matches tag values

• Requires more time to create and modify

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Chapter 4 Logic Execution

Indexed Routine

Write one copy of code and use indexed references to data stored in arrays.

Buffered Routine

Copy the values of an array into tags to directly reference these buffer tags.

The JSR instruction

passes the index.

Each indexed reference adds

to scan time.

Benefits

• One copy of code is faster to develop

• Slowest execution time because all tag

references are calculated at runtime

• Can be difficult to maintain because the data

monitor is not synchronized to execution

The JSR instruction

passes all control

instance data.

A user-defined structure

consolidates control data.

Direct reference to a local

copy of data.

Benefits

• One copy operation can occur faster than

multiple index offsets

• Minimizes the need to calculate array offsets

at runtime

• The amount of code increases, but so do the

benefits

• Can be difficult to maintain because the data

monitor is not synchronized to execution

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Chapter 4 Logic Execution

Controller Prescan of Logic On transition to Run mode, the controller prescans logic to initialize instructions. The

controller resets all state-based instructions, such as outputs (OTE) and timers (TON). Some

instructions also perform operations during prescan. For example, the ONSR instruction turns

off the storage bit. For information on prescan, see the following resources:

• Logix 5000 Controllers General Instructions Reference Manual, publication 1756-RM003

• Logix 5000 Controllers Process Control and Drives Instructions Reference Manual,

publication 1756-RM006

During prescan, input values are not current and outputs are not written.

Prescan differs from first scan in that the controller does not execute logic during prescan.

The controller executes logic during first scan. The controller sets S:FS for one scan:

• During the first scan that follows prescan.

• During the first scan of a program when it has been uninhibited.

• Each time a step is first scanned (when step.FS is set). You can view the S:FS bit being

set only from the logic that is contained in actions that execute during the first scan of

their parent step (N, L, P, and P1).

Add-On Instruction Prescan Logic

An Add-On Instruction prescan logic routine executes after the main logic executes in Prescan

mode. Use the prescan logic to initialize tag values before execution. For example, set a PID

instruction to Manual mode with a 0% output before its first execution.

When an Add-On Instruction executes in Prescan mode, any required parameters have their

data passed.

• Values are passed to Input parameters from their arguments in the instruction call.

• Values are passed out of Output parameters to their arguments defined in the

instruction call.

Prescan Affects Description

Relay ladder logic The controller resets non-retentive I/O and internal values.

Function block diagram logic

Along with resetting non-retentive I/O and internal values, the controller also

clears the EnableIn parameter for every function block diagram.

Structured text logic

The controller resets bit tags and forces numeric tags to zero .

Use the bracketed assignment operator ([:=]) to force a value to be reset during

prescan.

If you want a tag that is left in its last state, use the non-bracketed assignment

operator (:=).

Sequential function chart logic Embedded structured text follows the same rules as listed previously.

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Chapter 4 Logic Execution

Custom Tag Initialization During Prescan

An Add-On Instruction prescan routine allows you to perform custom tag initialization after the

system-defined initialization is complete. You can use this feature to customize the prescan

initialization of any tag in the project.

When an Add-On Instruction is executed during prescan, the system-defined initialization is

completed by executing the Add-On Instruction logic routine in prescan mode, and then the

Add-On Instruction prescan routine is executed in normal mode to allow customized

initialization.

To accomplish:

• Create an Add-On Instruction with an empty logic routine (such as “PrescanInit”). Define

an inout parameter for each tag you wish to initialize and add the custom initialization

to the prescan routine.

• Add an always false invocation of your Add-On Instruction (“AFI( ) PrescanInit( )” ) to one

of your routines, passing in the tags you wish to initialize.

Benefits of Add-On Instruction Prescan Versus First Scan Routine To Initialize Tags

• Using S:FS requires your initialization to be done in the main routine of each program

(or in a routine that will be executed during first scan).

Add-On Instruction-based initialization is done during prescan (before any logic

executes) so the invocation can be placed anywhere, even in a fault handler. Fault

handlers are prescanned before any other logic and, thereafter, only execute if a major

fault is encountered (where scan time is not a concern).

Additional notes:

- S:FS can be true in scenarios other than program-to-run. For example, in logic

invoked from an SFC step or when a program is uninhibited.

- Since all parameters are inouts, the backing tag is very small (on the order of 4

bytes).

- A false invocation of an Add-On Instruction that has no false routine defined is

skipped so the impact on scan time is extremely small (if you invoke it from a fault

handler, there is no impact to the scan time of the project).

• A firstscan initialization routine must be defined and invoked for each program, and is

required to initialize all desired tags.

- An Add-On Instruction is global and can be invoked from any program so it can be

defined once and simply invoked from each program. Note that this assumes the

tags need to be initialized in the same way (for example, each program represents

one of a set of replicated cells).

- For program scoped tags, the invocation would need to be within the parent program

(or the program-scoped fault handler).

- For cases where a different type of initialization is required, another Add-On

Instruction could be created. Controller-scoped tags could be initialized in a program

or in the controller fault handler.

- If desired, you could expand this approach to make the initialization more flexible/

reusable: for example, you could define additional input parameters to pass the

values you want the tags to be initialized to.

• If you configure your tags in an array or UDT, you could implement a generic initializer

with only two inout parameters: the first parameter being the active tags that will be

initialized, and the second parameter being a duplicate array/structure containing the

initial values (the prescan routine would use a COP instruction to copy the initial values

to the active tags).

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Chapter 4 Logic Execution

Limitations of Add-On Instruction Prescan Initialization

On GuardLogix 5580 and Compact GuardLogix 5380 controllers, the maximum number of

inouts that can be defined for an AOI is 64.

If this limit is a problem:

• You could create multiple prescan Add-On Instructions.

• You could organize tags in UDTs or arrays so they can all be passed into a single inout

parameter.

For information related to First Scan Safety Tag Initialization, see the GuardLogix 5580 and

Compact GuardLogix 5380 Controller Systems Reference Manual, publication 1756-RM012

Controller Postscan of

SFC Logic

SFCs support an automatic reset option that performs a postscan of the actions that are

associated with a step once a transition indicates that the step is completed. Also, every Jump

to Subroutine (JSR) instruction causes the controller to postscan the called routine. During this

postscan:

• Output energize (OTE) instructions are turned off and non-retentive timers are reset.

• In structured text code, use the bracketed assignment operator ([:=]) to have tags

reset.

• In structured text code, use the non-bracketed assignment operator (:=) to have tags

that are left in their last state.

• Selected array faults, that is, 4/20 and 4/83, can be suppressed. When the fault is

suppressed, the controller uses an internal fault handler to clear it. Clearing the fault

causes the postscan process to skip the instruction containing the fault and continue

with the next instruction. This occurs only when SFC instructions are configured for

automatic reset.

Add-On Instruction Postscan Logic

When an Add-On Instruction is called by logic in an SFC Action and the Automatic Reset option

is set, the Add-On Instruction executes in Postscan mode. An Add-On Instruction postscan

routine executes after the main logic executes in Postscan mode. Use the postscan logic to

reset internal states and status values or to disable instruction outputs when the SFC action

completes.

Timer Execution Timers in the controllers store off a portion of the real-time clock each time they are scanned.

The next time through, they compare this stored value against the current clock and then

adjust the ACC value by the difference.

The controller uses native 32-bit data, so there is more space to store the time. The timer

stores 22 bits at 1 ms/bit, which equates to 69.905 minutes

(2**22 / 1000 ms per second / 60 seconds per minute) of padding before a timer overlaps.

If program execution skips timers, it appears as if the timers pause. Actually, the timers are

overrunning themselves. Depending on when the timer logic next executes, the lost time varies

ranges from 0…69.905 minutes.

Program execution can skip executing timers due to the following:

• Subroutine not being called

• Jumping over code

•SFC action

•Inactive SFC step

• Event or periodic task not executing

• Equipment phase state routines

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Chapter 4 Logic Execution

SFC Step Timer Execution

An SFC step timer stores the clock time each time the step executes. On subsequent scans of

the step, the controller compares the current clock time with the last scan and updates the

step timer’s ACC by the difference.

When you pause an SFC and then release the SFC, the step timer jumps forward by the

duration of the pause. If you want a step timer to remain at its position during a pause:

• Latch a recovery bit when the chart pause is released.

• Add an action to the step to store the step timer’s .ACC value and restore that value

when the pause recovery bit is set.

Edit an SFC Online When you edit an SFC online, the software initially makes the changes in the offline project.

When you accept the changes, they are downloaded to the controller. If you transition the

controller to test or untest edits, the controller resets the SFC and starts execution at the

initial step. If you edit an SFC online, do the following:

• Plan when you test or untest edits to coincide with the SFC executing the initial step.

• Place structured text logic in subroutines to minimize the impact of online edits.

• Use an SFR instruction to shift SFC execution to the desired step programmatically.

In some cases, this can result in the SFC being out of sync with the equipment. Program logic

in the initial step to check the last state and use an SFR instruction to change to the

appropriate step, if needed. One method is to set an index number in an action of each step.

Then when the restart occurs, use the SFR instruction to jump to appropriate step based on

the index value.

As of firmware revision 18, the following online edits to an SFC no longer reset the SFC to the

initial step:

• Modified structured text in actions and transitions

• Physically moved steps, actions, and transitions on SFC sheets without changing the

wiring

• Added, deleted, or modified text and description boxes

• Modified indicator tags

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 43

Chapter 5

Modular Programming Techniques

Modular programming guidelines support the delivery of standardized programming

structures, conventions, configurations, and strategies. The goal of modular programming is

to provide consistency.

• Faster and easier development of application software

• Faster and easier testing of application software

• More reliable application software

• Improved maintenance and operation of application software

• Improved interoperability with other equipment and systems

This chapter applies to these controllers.

Controller Family Controller Names

5580 controllers ControlLogix® 5580 and GuardLogix® 5580 controllers

5380 controllers CompactLogix™ 5380 and Compact GuardLogix 5380 controllers

5570 controllers ControlLogix 5570 and GuardLogix 5570 controllers

5370 controllers CompactLogix 5370 and Compact GuardLogix 5370 controllers

5480 controllers CompactLogix 5480 controllers

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Chapter 5 Modular Programming Techniques

Guidelines for Code Reuse

Naming Conventions

The following conventions are guidelines to help make an engineering library more reusable by

other developers. These guidelines also help the resulting applications have a more consistent

look and feel.

• Names that are meaningful (and readable) to people who use the application as a later

date are most effective.

• Names use controller memory and have limited length, so keep them short by using

abbreviations and acronyms. Use mixed case rather than underscore characters to

indicate words.

• When you use acronyms, use those that are common or provided by industry standards.

Names for controller logic components must follow these guidelines.

• The name must start with a letter, either upper or lower case

• The name can contain as many as 40 characters; any mix of upper case letter, lower

case letters, numbers, and underscore characters

• Case is not significant. The controller interprets Mix_Tank the same and mix_tank.

However, the software displays the case as entered

• Underscores are significant. The controller interprets AB_CD as unique from A_BCD

• You cannot have two or more underscore characters in a row

• The name cannot end with an underscore.

Guideline Description

Use user-defined data types (UDTs) to group data.

Within a UDT:

• You can mix data types.

• The tag names that you assign self-document the structure.

Use Add-On Instructions to create standardized modules

of code for reuse across a project.

Use an Add-On Instruction to:

• Encapsulate specific or focused operations, such as a Motor or Valve action. A Conveyor or Tank action is

better managed as a routine.

• Create extensions to the base controller instructions. For example, create an Add-On Instruction to execute an

SLC™ 500 or PLC controller instruction not available in the Logix 5000™ controllers.

• Encapsulate an instruction from one language for use in another language. For example, create a function

block PIDE instruction for use in relay ladder.

Use program parameters to share data between

programs.

Program parameters:

• Are publicly accessible outside of the program.

• Support external HMI external access on an individual basis for each parameter.

Direct access lets the user reference program parameters in logic without configuring parameters in the local

program. For example, if Program A has an output parameter that is called Tank_Level, Program B can reference

the Tank_Level parameter in logic without creating a corresponding parameter to connect to Program A.

Use partial import/export programs, routines, Add-On

Instructions, and code segments to create libraries of

reusable code.

Partial import and export of routines and programs:

• Provides more control over the scope of what is extracted from the project.

• Provides reusable code for larger machine, cell, or unit control.

• Promotes collaboration between multiple engineers, code standardization, and reuse.

The export .L5X file includes all pertinent information, including program configuration, code, user-defined data

types, tags, and descriptions, in an XML-formatted, ASCII text file. Use partial import/export to:

• Distribute code separately from the project .ACD file.

• Edit and create programs and routines by using other editing tools.

Use subroutines to reuse code within a program.

Subroutines:

• Can be created and used in standard and safety applications.

• Pass User-Defined Structures (UDT).

• Pass all input and output Parameters by value.

• Subroutines require the most overhead to pass parameters when called.

• Can only be called from within the program they reside.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 45

Chapter 5 Modular Programming Techniques

Component Name Recommendations

Controller

Area, unit, or units the controller controls, underscore, type of controller

Example:

Controller project

Controller name, the letter C, 1-digit major revision number, underscore, 2-digit minor revision number

Example:

Increment the minor revision number for any documented engineering change according to the code in the

controller (for example, the code for minor process or equipment changes).

Increment the major revision number for any documented engineering change according to the code in the

controller that implements a design change (for example, code that enhances or reduces controller functionality).

Tag

Prefix with the abbreviation of the type of tag

Examples:

I/O or communication module

Controller name, underscore, abbreviation of rack location (L=local, R=remote), underscore, the letter S, 2-digit slot

number, underscore, abbreviation of function

Example Functions:

Examples:

Area/Unit + Type

Controller Name:

Mixing:ControlLogix

Project in controller Mixing_CLX,

Major Revision 1, Minor Revision 02

Application Name:

Mixing_CLX_C2_092.ACD

Interprocessor communication tag IPC_

Input tag I_

Output tag O_

Remote I/O tag RIO_

Control module class tag Device ID_

Equipment module class tag EM_

Equipment phase class tag EP_

Analog input AI

Analog output AO

Discrete input DI

Discrete output DO

Analog input/output combination AIO

Discrete input/output combination DIO

Analog/discrete input/output combination ADIO

Serial data SIO

Motion data MIO

DeviceNet® data DNET

EtherNet/IP™ data ENET

ControlNet® CNET

Remote I/O data RIO

Mixer123 Controller, Local chassis, Slot 4,

Analog Output

Module Name: M123_CLX_L00_S04_AO

Mixer123 Controller, Local chassis, Slot 12,

Discrete Output

Module Name: M123_CLX_L00_S12_DO

Mixer123 Controller, Remote chassis #1, Slot

1, Analog Input

Module Name: M123_CLX_R01_S01_AI

Mixer123 Controller, Remote chassis #1, Slot

2, Analog Output

Module Name: M123_CLX _R01_S02_AO

Mixer123 Controller, Remote chassis #2, Slot

5, Discrete Input

Module Name: M123_CLX _R02_S05_DI

Mixer123 Controller, Remote chassis #2, Slot

6, Discrete Output

Module Name: M123_CLX _R02_S06_DO

Mixer123 Controller, Local chassis, Slot 5,

Remote I/O

Module Name: M123_CLX _R02_S06_RIO

46 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 5 Modular Programming Techniques

Parameter Name Prefixes Programming structures, such as Add-On Instructions and programs support parameters for

passing values. The convention for prefixes is to abbreviate the function of the parameter to

three letters and an underscore, followed by additional text to clarify the specific function.

Parameter Function Prefix Description

Command Cmd_

Designates a command input, either from the operator via the HMI or from the program.

Examples:

• Cmd_Reset: Clear faults and reset the process

• Cmd_JogServo: Jog a servo axis

• Cmd_FillTank: Fill a tank with a liquid

Configuration Cfg_

Designates a configuration value for the structure. Enter from the HMI or as part of a recipe.

Examples:

• Cfg_JogDirection: Selects the direction a servo jogs: 0=Positive, 1=Negative

• Cfg_BulkFill: Selects the fill rate to use: 0=Slow Rate, 1=Fast Rate

• Cfg_UserUnits: Selects the measure of volume to use: 0=mm, 1=m, 2=gal

• Cfg_EnableInterlocks: Enable interlock functionality

• Cfg_EnablePermissive: Enable permissive functionality

Status Sts_

Status of the process within the structure.

Examples:

• Sts_Alarm: An alarm condition (such as a HI/LOW alarm) exists within the process

• Sts_ER: An error with an instruction execution within the process has been detected

• Sts_IndexComplete: The servo index move within the process has completed

• Sts_FillInProcess: The tank filling process is underway

Error Err_

If the Sts_ER bit is on, the Err_ parameter indicates the actual error. This can be either a bit level or value level

indication.

• Bit level error recording supports multiple errors simultaneously, but can require a large number of indicators to

support all error states.

• Value-based error annunciation supports a large quantity of errors within one indicator. However, this approach

requires that errors are annunciated one at a time.

Examples:

• Err_Value: A nonzero value indicates an error condition

• Err_PCamCalcFault: Indicates that an error has occurred in an MCCP

Alarm Alm_

If the Sts_Alm bit is on, the Alm_ parameter indicates which alarm is occurring. This can be either a bit-level or

value-level indication.

• Bit-level alarming supports multiple alarms simultaneously, but can require a large number of indicators to

support all alarm states.

• Value-based alarm annunciation supports a large quantity of alarms within one indicator. However, this approach

requires alarms to be annunciated one at a time.

Examples:

• Alm_Value: A nonzero value indicates an alarm condition

• Alm_TankHI: Indicates that a HI level condition has been detected within a tank

Input Inp_

Real-time data used to drive the process. Designates a connection either to a real input point, a control device, or to

data received from other processes.

Examples:

• Inp_ServoPosition: Variable providing the input value for a position of a servo

• Inp_ServoRegistrationPosition: Input of the registration position of the servo

• Inp_InterlockOK: Input indicating external interlocks are met

• Inp_TankLevel: Variable providing the analog input for a tank’ level

• Inp_TankLevelFillRate

Output Out_

Real-time data driven from the process. Designates a connection to a real output point, a control device, or to data

sent to other processes.

Examples:

• Out_GlueGun1: Output signal to turn of Glue Gun 1

• Out_ServoCorrectionDistance: Output of a servo registration correction distance

• Out_OverflowValve: Output signal to open the Overflow Valve

• Out_TankLevelError: Output of a difference between target and actual fill level of a tank

Reference Ref_

Complex data structures that combine input and output data.These structures pass data into a structure, where

some process is performed. The results are then loaded back into the structure to be passed out of Add-On

Instruction for use elsewhere.

Example:

Ref_PositionCamRecovery: Provides the data set for calculating a Position Cam with all offsets factored in, and the

resulting Position Cam Profile to run in an MAPC instruction

Parameter Par_

Variables that are received from an external source that can be internal or external to the program.

Examples:

• Par_MachineSpeed: Provides a machine's running speed

• Par_TargetFillLevel: Provides a tank's target fill level

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Chapter 5 Modular Programming Techniques

Guidelines for Subroutines Follow these parameter guidelines for subroutines.

Set point Set_

Variables received from an operator or HMI and are not part of an external source.

Examples:

• Set_MachineMaxSpeed: Provides the setting for a machine's maximum permissible speed

• Set_TankHILevel: Provides the setting for a tank's HI alarm limit

Value Val_ Designates a value that might not be the primary output of the structure.

Report Rpt_ Designates a value that is typically used for reporting.

Information Inf_ Non-functional data such as a revision level or name for displaying a faceplate.

Ready Rdy_

Command-ready bits that are typically Booleans calculated inside the control routines to reflect whether the routine

let states change commands. Used with HMI faceplates to enable or disable command buttons.

Program Command

(optional)

PCmd_

Command input for commands typically issued by the application program.

Examples:

• PCmd_ProgReq - Request for Program Mode made by the application (as opposed to Cmd_ProgProgReq)

• PCmd_AutoReq - Request for Auto Mode made by the application (as opposed to Cmd_ProgAutoReq)

Operator Command

(optional)

OCmd_

Command input for commands typically issued by the operator via the HMI.

Examples:

• OCmd_ProgReq - Request for Program Mode made by the operator (as opposed to Cmd_OperProgReq)

• OCmd_AutoReq - Request for Auto Mode made by the operator (as opposed to Cmd_OperAutoReq)

Parameter Function Prefix Description

Guideline Description

Use FBD functions over FBD function blocks

FBD functions are faster, use less memory, and are easier to program than FBD function blocks tasked to perform

the same behavior.

Input and Return parameters depend on the

subroutine logic.

If the subroutine needs to know the previous state of any Return parameters (the values are used elsewhere in the

project), these values should also be Input parameters:

• If the subroutine contains latch/unlatch logic (holding circuits), intended outputs of the subroutine should be

passed into and returned from the subroutine.

• If the subroutine does not contain latch/unlatch logic, intended outputs of the subroutine only need to be returned

from the subroutine.

Pass complete timers in and out of subroutines.

If a subroutine needs a timer, pass the complete timer tag to the subroutine as an input and return the complete

timer tag as an output. Store the timer in a buffer tag outside of the subroutine.

Create a user-defined tag to pass large numbers

Input and Output parameters

Create and pass a UDT if you have several Input and Output parameters to save on execution time. The more

parameters that you pass, the fewer nested JSRs you can perform.

Data types must match

For each parameter in an SBR or RET instruction, use the same data type (including any array dimensions) as the

corresponding parameter in the JSR instruction. Using different data types can produce unexpected results.

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Chapter 5 Modular Programming Techniques

Guidelines for User-defined

Data Types

A UDT lets you organize data logically, so that all of the data associated with a device, such as

a pressure transmitter or variable-frequency drive, can be grouped.

• You can mix data types, such as real or floating point values, counters, timers, arrays,

Booleans, and other UDTs, within one UDT.

• You can copy a UDT from one project to another, and even from one Logix controller

type to another.

• A UDT is self-documenting based on the tag names you assign and provides a logical

representation of parts or subsystems.

Naming Conventions for User-Defined Data Types

UDT Member Order Impact

The order in which members are listed in the UDT can have a significant impact on memory

use if a diverse set of data types are needed. The member data types also affect the alignment

requirements for the UDT. If you are concerned about memory usage, then apply these

guidelines:

• Group like data type members together.

• Group the ordering from largest to smallest.

• Review layout and adjust order to reduce padding.

These guidelines make the packing of members into the data table allocated for the UDT more

efficient and as small as possible. However, if your larger concern is to group members based

on functionality, then apply the guidelines only within the groups.

Generally, a UDT size is in multiples of 4 bytes and aligned on 4-byte boundaries. However, if a

UDT contains any 64-bit members, then the size of the UDT is a multiple of 8 bytes and aligned

on 8-byte boundaries. Members who themselves are UDTs follow these same alignment rules.

Padding bytes are added as needed to enforce alignment.

Element Description

Prefix_ UDT_

UDT name Function or purpose of the UDT

Examples

Inventory tracking tag UDT_InventoryTracking

Clean-in-place system UDT_CIP

Two-state valve control module in control module UDT_CMV2S

Water addition in equipment module UDT_EM

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Chapter 5 Modular Programming Techniques

Rule Example

Consecutive BOOLs are packed into a SINT host where

each BOOL is represented by 1 bit. If there are more than

8 consecutive BOOLs, then multiple SINT hosts are

created so that all of the BOOLs can be accounted for.

Nine consecutive bools are packed into 2 SINT hosts.

struct t_UDT2 {

union {

struct {

unsigned char bool1 : 1;

unsigned char bool2 : 1;

unsigned char bool3 : 1;

unsigned char bool4 : 1;

unsigned char bool5 : 1;

unsigned char bool6 : 1;

unsigned char bool7 : 1;

unsigned char bool8 : 1;

};

SINT _HUDT20;

};

union {

struct {

unsigned char bool9 : 1;

};

SINT _HUDT29;

};

char pad0;

char pad1;

};

A BOOL array is packed into 32-bit element arrays.

BOOL[64] member array

struct t_udtb {

UDINT bMemArray[2];

};

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Chapter 5 Modular Programming Techniques

Each elementary data type of size n is n-byte aligned.

Padding b

ytes are inserted to enforce the alignment.

DINT members start on 4-byte alignment. LINT members

start on 8-byte alignment.

struct t_UDT12 {

SINT sintMem;

char pad0;

INT DintMem;

SINT sintMem2;

char pad1;

char pad2;

char pad3;

DINT dintMem;

char pad4;

char pad5;

char pad6;

char pad7;

LINT lintMem;

};

The UDT size is in multiples of 4 bytes. If the UDT

contains a 64-bit member, then the UDT size is multiples

of 8 bytes. Padding bytes are inserted at end of the UDT

to enforce the size.

struct t_UDT6 {

SINT sintMem;

SINT sintMem2;

SINT sintMem3;

SINT sintMem4;

SINT sintMem5;

char pad0;

char pad1;

char pad2;

};

struct t_UDT7 {

SINT sintMem;

SINT sintMem2;

SINT sintMem3;

SINT sintMem4;

char pad0;

char pad1;

char pad2;

char pad3;

LINT lintMem;

SINT sintMem5;

char pad4;

char pad5;

char pad6;

char pad7;

char pad8;

char pad9;

char pad10;

};

If the UDT member is array, then it is at least 4-byte

aligned and padding is inserted at end of the member to

make sure that it ends at an at least 4-byte aligned

boundary. It is 8-byte aligned when the array element

type is 64-bit.

struct t_UDT9 {

SINT sintMem;

char pad0;

char pad1;

char pad2;

SINT sintArray[2];

char pad3;

char pad4;

INT intMem;

char pad5;

char pad6;

};

Rule Example

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Chapter 5 Modular Programming Techniques

Guidelines for

Add-On Instructions

An Add-On Instruction encapsulates commonly used functions or device controls. It is not

intended for use as a high-level hierarchical design tool. Once an Add-On Instruction is defined

in a project, it behaves similarly to the built-in instructions that are already available in the

programming software. The Add-On Instruction appears on the instruction toolbar and in the

instruction browser.

Add-On Instruction Design Concepts

To be sure that specific data is passed into or out of the Add-On Instruction, use a required

parameter. A required parameter must be passed as an argument in order for a call to the

instruction for verification. To pass a required parameter in ladder diagrams and in structured

text, specify an argument tag for the parameter.

• In a function block diagram, required Input parameters and Output parameters must be

wired.

• In a ladder diagram, InOut parameters must have an argument tag.

• If a required parameter lacks an associated argument, the routine that contains the call

to the Add-On Instruction does not verify.

Guideline Description

Create Add-On Instructions in relay ladder,

function block diagram, or structured text

languages.

Supports all Add-On Instructions and most built-in instructions. Excludes JSR/SBR/RET, JXR, FOR/BRK (relay ladder),

SFR, SFP, SAR, IOT, and EVENT instructions.

GSV/SSV instructions in an Add-On Instruction cannot reference the Module, Message, Axis, Motion Group, or Coordinate

System class names.

Add-On Instructions support function block, relay ladder, and structured text programming languages. Each of the

Add-On Instruction logic areas can be any language. For example, the main logic can be function block and the prescan

logic can be relay ladder.

You can create safety Add-On Instructions in a safety task.

An Add-On Instruction supports parameters:

• Input (copied in)

• Output (copied out)

• InOut (passed by reference)

• For Version 24 and earlier, you are limited to 512 total parameters: Input parameter + Output parameter + local tags

(no limit on the number of InOut parameters)

• For Version 28 and later, you are limited to 40 InOut parameters, but no limit on the number of Input or Output

parameters)

• 2 MB maximum data instance (parameters and locals)

• Alarm, axis, axis group, coordinate system, message, motion group, and produced/consumed tags must exist at the

program or controller scope and passed as an InOut parameter

• Can include references to controller-scoped tags, program-scoped tags, and immediate values.

• Input and Output parameters are limited to atomic (BOOL, SINT, INT, DINT, REAL) data types. Use the InOut parameter

for LINT, user-defined, and structure data types.

• DINT data types provide optimal execution.

• Default values of parameters and local tags are used to initialize the data structure when a tag is created of the

instruction’s data type. When an existing parameter or local tag's default value is modified, the existing tag instances

for that instruction are not updated. When a parameter or local tag is added to the instruction definition, the tag's

default value is used in the existing tags.

Create and modify offline only.

Online operation supports monitoring.

Modifications to Add-On Instructions are made offline. Make changes once to the Add-On Instruction definition to affect

all instances.

An Add-On Instruction executes like a routine.

A task with a higher execution priority can interrupt an Add-On Instruction. Use a UID/UIE instruction pair to make sure

an Add-On Instruction’s execution is not interrupted by a higher priority task.

If you have many parameters or specialized options, consider multiple Add-On Instructions

Calling many Add-On Instructions impacts scan time

The code within an Add-On Instruction can access

data that is specified only via parameters or

defined as local.

Copy the local data to a parameter if you want to programmatically access it outside of an Add-On Instruction.

Use optional Scan mode logic to set up, initialize,

or reset the Add-On Instruction code.

An Add-On Instruction can have logic along with the main logic for the instruction.

• Prescan logic executes on controller startup.

• Postscan logic executes on SFC Automatic reset.

• EnableInFalse logic executes when rung condition is false.

Apply code signatures to Add-On Instructions for

revision control.

Add-On Instructions can be sealed with a code signature. Use the code signature for revision control and to identify any

changes. For safety controllers, the signature can be used to get TÜV certification for a safety Add-On Instruction. For

more information, see the Logix 5000 Controllers Add-On Instructions Programming Manual, publication 1756-PM010

52 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 5 Modular Programming Techniques

Naming Conventions for Add-On Instructions

Comparison of Subroutines and Add-On Instructions

Component Name Recommendations

Add-On Instruction

Start with the application name.

Add a variant name, is applicable.

Capitalize the first letter in all words in the name.

Example:

Suffix with underscore AOI, if space permits.

Example:

PCam profile display PCamProfileDisplay

PCam profile display PCamProfileDisplay_AOI

Comparison Subroutine Add-On Instructions

Accessibility Within program (multiple copies) Anywhere in controller (single copy)

Parameters Pass by value Pass by value or reference via InOut

Numeric parameters No conversion, you must manage

Automatic data type conversion for Input and Output parameters

InOut parameters must match declared type exactly

Parameters data types

Atomic, arrays, structures

• Atomic data types as In or Out parameters

• LINT, user-defined, and structure data types as InOut

parameters

Parameter checking

None, you must manage Verification checks

Data encapsulation All data at program or controller scope (accessible to anything) Local data is isolated (only accessible within instruction)

Monitor/debug

Logic that is animated with mixed data from multiple calls Logic that is animated with data from one calling instance

Supported programming languages

FBD, LD, SFC, ST FBD, LD, ST

Callable from FBD, LD, SFC, ST FBD, LD, SFC, ST

Protection Locked and View Only Locked and View Only

Documentation Routine, rung, textbox, line

Instruction description, revision information, vendor, rung, textbox,

line, extended help

Execution performance

• JSR/SBR/RTN add overhead

• All data is copied

• Call is more efficient

• InOut passed by reference

Memory use Compact

• Call requires more memory

• All references need additional memory

Edit

Both code and data can be modified offline and online in a

running controller

Code modifications are limited to offline in the project file and

require a new download

Data values associated can be modified online and offline

Import/export

All routines are imported/exported in the full project .L5K file

(protected routines can be excluded or encrypted)

Individual LD rungs and references and tags/UDTs can be

imported/exported via the .L5X file

All Add-On Instructions are imported/exported in the full project

.L5K file (protected instructions can be excluded or encrypted)

Individual Add-On Instruction definitions and code are imported/

exported via the .L5X file

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Chapter 5 Modular Programming Techniques

Comparison of Partial Import/Export and Add-On Instructions

Comparison Partial Import/Export Add-On Instructions

Logic

Any program, equipment phase, routine, Add-On Instruction, or user-

defined data type in the project can be imported/exported via .L5X file.

Create once (single copy) and use anywhere in the same

controller project.

Controller accessibility

Import on-line with a running controller:

• Add programs, routines, and Add-On Instructions

• Existing programs and routines can be replaced

• Create tags and UDTs

• Name collisions are detected automatically and you are prompted to

rename or bind to existing components

• The data values in the controller are maintained and new tags have

their values initialized from the import file

Existing Add-On Instructions can only be edited offline.

New Add-On Instructions can be created online or offline.

Logic checking You resolve conflicts on import.

The software verifies the components that you add to Add-

On Instruction as you create it.

Data

Editing member definitions of an Add-On Instruction maintains the values

that are assigned to the parameters when:

• Inserting, adding, or deleting members

• Rearranging (moving) members

• Renaming members

• Changing the data types of members

Values for members that are both renamed and moved in the same

operation are not to be maintained.

Local data is isolated (only accessible within the

instruction).

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Chapter 5 Modular Programming Techniques

Guidelines for Program

Parameters

Program parameters define a data interface for programs to facilitate data sharing. Data

sharing between programs can be achieved either through pre-defined connections between

parameters or directly through a special notation. Unlike local tags, all program parameters

are publicly accessible outside of the program. Additionally, HMI external access can be

specified on individual basis for each parameter.

Standard (non-Safety) parameters can be created, edited, and deleted while online with the

controller. The following exceptions apply:

• Parameters cannot be deleted while online if they are connected/bound to other

parameters, or if the control logic references them.

• InOut parameters cannot be deleted while online

• InOut bindings can only be changed online through a Partial Import Online (PIO)

operation

A safety parameter cannot be connected with or bound to a standard parameter or controller-

scoped tag. A safety connection cannot be created, modified, or deleted in a safety-locked

project. Input, Output, and Public parameters support the External Access attribute. InOut

parameters do not.

Program Parameter Description

Input

• Input parameters (including members) can only support ONE connection. Only one source can be delivering the value to the input

parameter.

• Input Parameter values are refreshed before each scan of a program. The values do not change during the logic execution so you

do not need to write code to buffer inputs.

• A program can write to its own input parameters.

• Data values for Output parameters that are connected to controller scope tags or Public parameters are copied after the scan of a

program. In a project with multiple tasks, the data copy for a parameter that is of type BOOL, SINT, INT, DINT, LINT, or REAL will not

be interrupted. A task switch can interrupt the data copy from an Output parameter to a controller scope tag or Public parameter,

or any other predefined or user-defined data type.

Output

• Output parameters (including members) can support multiple connections. For example, lets assume you have a BOOL input

parameter in Program A and Program B named Input1a and Input1b. You can connect an output parameter in Program C to Input1a

AND Input1b. As stated earlier, this is often referred to as fanning.

• Output Parameter values are refreshed AFTER each scan of a program. Updated output parameter values are NOT available to the

parameters connected to that output parameter until the program execution is complete.

• Output parameters that are connected to Public parameters or controller scope tags are copied (pushed) at the end of the

program execution.

• An Output parameter can ONLY be connected to an InOut parameter if both the Output and InOut parameters are configured as

Constants.

InOut

• InOut parameters can only support ONE connection. You cannot configure connections to any member of an InOut parameter.

• InOut parameters are passed by REFERENCE, which means they simply point to the base tag. In other words, when an InOut

parameter is used in logic, the current value of the parameter that is connected to the InOut Parameter is used.

• An InOut parameter can ONLY be connected to an Output parameter if both the Output and InOut parameters are configured as

Constants. See the tool tip for Output Parameters for a more detailed explanation.

• InOut parameters CANNOT be changed online, unless using the Partial Import Online (PIO).

Public

• Public parameters can support MULTIPLE connections. You can configure connections to the base Public parameter or any

member of a Public parameter. This includes User-Defined Structures.

• Public parameters are updated when the source is updated. In other words, when a Public parameter value updates, it is

immediately available to any higher priority tasks that are connected to that parameter.

• Public parameters can be aliased to Controller Scope Tags. If this functionality is desired, remember that the alias update is

asynchronous to program execution. The public parameter contains the real-time value of the controller scope tag.

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Chapter 5 Modular Programming Techniques

Comparison of Program Parameters and Add-On Instructions

Compare Controller

Organizer and Logical

Organizer

The Controller Organizer presents program logic how the controller executes the logic. The

Logical Organizer is configurable to present program logic how the user views the system.

Comparison Program Parameters Add-On Instructions

Accessibility Within program (multiple copies) Anywhere in controller (single copy)

Parameters

Input / Output (pass by value), InOut (pass by reference), Public

(pass by value)

Input / Output (pass by value), InOut (pass by reference)

Numeric parameters

• Automatic data type conversion for Input and Output parameters

• InOut parameters must match declared type exactly

• Automatic data type conversion for Input and Output parameters

• InOut parameters must match declared type exactly

Parameters data types

Atomic, strings, arrays, structures

• Atomic data types as In or Out parameters

• LINT, user-defined, and structure data types as InOut parameters

Parameter checking

None, user must manage Verification checks

Data encapsulation

All data at program or controller scope (accessible to anything).

Programs can talk directly and exchange data between them. Local

tags remain private to the Program. Cannot access Local Tags, only

the parameters.

Local data is isolated (only accessible within instruction)

Monitor/debug

Online editable. Logic that is animated with data from one calling instance

Supported programming

languages

FBD, LD, SFC, ST FBD, LD, ST

Callable from FBD, LD, SFC, ST FBD, LD, SFC, ST

Protection — Locked and View Only

Documentation —

Instruction description, revision information, vendor, rung, textbox,

line, extended help

Execution performance

• Programs can talk directly and exchange data between them.

• InOut passed by reference

• Call is more efficient

• InOut passed by reference

Memory use

Compact. One Public parameters can be connected or bound to

multiple Input, Output or InOut parameters to form a shared

memory space.

• Call requires more memory

• All references need additional memory

Edit

Online editable, and supports sub-element connections. Copy /

Paste Programs without disturbing parameter configuration.

Code modifications are limited to offline in the project file and

require a new download

Data values associated can be modified online and offline

56 Rockwell Automation Publication 1756-RM094M-EN-P - November 2022

Chapter 5 Modular Programming Techniques

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 57

Chapter 6

Structure Logic According to Standards

The ANSI/ISA-88.01-1995 (R2006) standard is the most recognized and broadly adopted

standard for modular equipment control. Complementing ISA-88.01 is the ISA-TR88.00.02

technical report, which is also known as PackML. The ISA-TR88.00.02 technical report comes

from the Organization for Machine Automation and Control (OMAC). The OMAC provides

examples of how to apply ISA-88.01 in discrete manufacturing segments.

ISA refers to the International Society of Automation, an ANSI recognized Standards

Development Organization (SDO).

• ISA-88 refers to a specific set of ISA standards, of which ISA88.01 is a subset.

• SP88 refers to the ISA working member group responsible for the creation and

publication of the ISA-88 standards.

ISA-88 provides these models to define and understand the automation control requirements

for manufacturing plants.

Model Description

Physical

The physical model (also known as the equipment model) describes a hierarchical organization of

equipment and the basic control capabilities that are associated with that organization. The

physical model is a representation of the equipment in the plant that makes the product.

Procedural

The procedural model describes a multi-tiered, hierarchical model that defines the process

capability and automation control in relation to the Physical Model to perform a task. The

procedural model is a representation of how to use the equipment (described in the physical

model) to make the product.

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Chapter 6 Structure Logic According to Standards

Physical Model The physical model (also known as the equipment model) describes a hierarchical

organization of equipment and the basic control capabilities that are associated with that

organization. The physical model is a representation of the equipment in the plant that is used

to make the product.

The physical model defines the automation components within a given environment, and

determines modular areas and component interactions.

The physical model shows that an enterprise can contain multiple sites, and a site can contain

multiple areas, down to the equipment modules and control modules that carry out the

manufacturing process.

Enterprise

Site

Area

Process Cell

Unit

Equipment

Module

Control Module

Control ModuleControl Module

Control Module

Equipment

Module

Equipment

Module

Physical Model Component Description

Enterprise The company that owns the facilities.

Site The location of one facility.

Process cell

A collection of one or more units that are linked together to perform a task or multiple tasks of the process for one or more

products in a defined sequence. A process cell contains the units, equipment modules, and control modules that are needed to

make one or more batches.

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Chapter 6 Structure Logic According to Standards

Unit (or machine)

A collection of

related equipment modules and control modules that execute one or more processing activities. The unit

corresponds to the logical grouping of mechanical and electrical assemblies that historically has been called a machine. The

term unit can apply to either a single-function machine or a multi-functional machine.

Equipment module

A functional group of control modules, equipment modules, or both that execute a finite number of activities. The primary

purpose of control in an equipment module is to coordinate the functions of other equipment modules and lower-level control

modules. A process cell, unit, operator, or another equipment module can command an equipment module.

An equipment module can be part of A unit, or a standalone equipment group can include an equipment module in a process cell.

If engineered as a standalone equipment grouping, an equipment module can be an exclusive-use resource or a shared-use

resource. The equipment module combines all necessary physical processing and control equipment that is required to perform

the manufacturing process. The finite tasks that an equipment module is designed to carry out defines the scope of the

equipment module.

The terms control module and equipment module apply to the physical equipment as well as to the equipment entity.

The following are examples of equipment modules.

• A valve matrix used for material transfer between units (shared resource of process cell)

• A level control for a tank (equipment module within a specific unit)

• A vertical form-fill-seal machine’s ‘sealing jaws control’ (equipment module within a discrete unit)

Control module

Control module: A regulating device, state-oriented device, or combination thereof (typically, a collection of sensors, actuators,

and other control modules) that is operated as a single device. Control that is normally found at this level directly manipulates

actuators and other control modules. A control module can direct commands to other control modules, or to actuators that have

been configured as part of the control module. Control of the process is affected through the equipment-specific manipulation

of control modules and actuators. The control module is the lowest level grouping of equipment in the physical model that can

carry out basic control.

The following are examples of control modules.

• An individual sensor or actuator

• A state-oriented device that consists of an on/off automatic block valve with position feedback switches and that is operated

via the set point of the device

• A header that contains several on/off automatic block valves that coordinates the valves to direct flow to one or several

destinations based on the set point directed to the header CM

• A servo-controlled electronic gear or cam function (that is, a discrete unit), including its interlock and permissives.

The following are typical control modules in a programming library:.

•Analog output

• Analog input with scaling and alarms

• Reversing motor

• Variable speed drive

• Solenoid-operated 2-state valve

• Motor-operated 2-state valve

• PID with standard modes and deviation alarms

Physical Model Component Description

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Chapter 6 Structure Logic According to Standards

Separate a Process Unit into Equipment Modules and Control Modules

To create a modular control program, start with one of these approaches.

• Identify the control modules in the process. Then group the control modules into

equipment modules to be supervised and coordinated by procedural controls.

• Determine the units (typically vessels containing a single batch at a time). Then

determine the equipment modules (such as ingredient addition equipment, agitating

equipment, thermal jacket temperature control equipment, and transfer out equipment)

by reviewing the related equipment, piping, and instrumentation on a process and

instrumentation diagram (P&ID). Then determine the control modules that are related to

the equipment states that must be controlled (such as motors, valves, or other process

control loops).

One way to organize application logic in the Controller Organizer is to create a separate folder

for each unit.

Physical Model Naming Conventions

Equipment Modules

Control Modules

Process Cell

Physical Model

Unit

Component Name Recommendations

Site

Short, preferably single character abbreviation, all upper case, of the formal name of the site

Example:

Area

Building number prefixed by a site name, but with no separating underscore

Example:

Cell

Two- to three-character abbreviation of the formal name of the cell

Prefix with an area name and a single underscore (optional)

Example:

Site: My Site Site Name: M

Area: Manufacturing Building (102) Area Name: M102

Cell: Mixing Cell Name: A102_MIX_123

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Chapter 6 Structure Logic According to Standards

Unit

n a unit class, prefix the unit name with UN and an underscore

Example:

In a unit instance, use the unit identification from the piping and instrumentation diagram (P&ID)

All uppercase letters; use underscored instead of dashes

Prefix the unit name with the area name, separated from the unit name by a single underscore

Example:

In a unit program instance, add the unit identifier between the area name and the unit name

Example:

In a unit tag instance, prefix the tag with the unit name

Example:

Equipment module

Area name, underscore, letters EM, underscore, function abbreviation

All uppercase letters

Example:

Control Module

In a control module class, prefix the name with CM and an underscore

Example:

In a control module instance, use all uppercase letters

Area name, underscore, unit name, underscore, instrument name, loop sequence number

Example:

Component Name Recommendations

Unit Class: Mix Tank Unit Name: (Machine)

Unit Class: Packer Unit Name: UN_Pckr

Unit Instance: Mix Tank 1234 Unit Name: A102_MT1234

Machine Instance: Packaging Machine 1234 Unit Name: A102_PKR1234

Unit Instance Program Name: A102_UN02_MT1234

Machine Instance Program Name: A102_UN02_PKR1234

Unit Instance Tag Name: MT1234

Machine Instance Tag Name: PKR1234

EM Instance: Mix Tank 1234 Vessel Agitator EM Name: MT1234_EM_Agitate

EM Instance: Packager 1234 Bag Forming EM Name: PKR1234_EM_BagForming

CM Class: PID Control Loop CM Name: CM_PID

CM Class: Cylinder CM Name: CM_Cylndr

CM Instance: Temperature Controller 01 CM Name: TC_01

CM Instance: Cylinder 01 CM Name: CY01

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Chapter 6 Structure Logic According to Standards

Procedural Model The procedural model describes a multi-tiered, hierarchical model that defines the process

capability and automation control in relation to the physical model to perform a task. The

procedural model is a representation of how to use the equipment (described in the physical

model) to make the product.

The procedural control that is laid out in the procedural model directs the equipment

components, via the component interfaces, to perform the specific tasks out of the available

capabilities, needed to produce a given product.

Combine the procedural model with the physical model to reflect the hierarchy of control and

equipment, as well as the vertical separation between process controls and procedural

controls.

Not all manufacturing processes require the procedural control to reside in the physical

equipment.

In a distributed or flexible process, procedural control can reside outside the equipment, in

what is called the control recipe. Examples of this type of manufacturing are large batch

systems, material handling systems, or automotive assembly systems. Use of the control

recipe lets manufacturers with different automation requirements separate procedural

control and process control.

Procedural Model Component Description

Procedure The general strategy for production within a process cell. A procedure is composed of unit procedures.

Unit procedure A production sequence. Unit procedures are composed of operations.

Operation

The single sequence necessary for the initiation, organization, and control of phases. Operations are composed of

phases.

Phase

The lowest level of a procedure that can accomplish an action.

The intent of a phase is to cause or define a process-oriented action, while the set of steps in the phase is

equipment-specific.

• A phase can be subdivided into smaller parts.

• A phase can issue one or more commands or cause one or more actions.

• The execution of a phase can result in additional commands.

Phase

Operation

Unit

Procedure

Process

Cell

Equipment

Module

Control Module

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Chapter 6 Structure Logic According to Standards

The procedural control is where distributed and flexible control occurs, and where the need

arises for a separation from process control.

Identify Operations and Phases

One way to organize application logic in the Controller Organizer is to add the procedural

model as a separate folder of phases.

Phase

Operation

Unit

Procedure

Equipment

Module

Equipment

Module

Control Module

Procedural Control

in Equipment

Process Control

Equipment Control

Equipment Modules

Control Modules

Process Cell

Physical Model

Unit

Procedural Model

Phases

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Chapter 6 Structure Logic According to Standards

Procedural Control Modes A control mode determines how equipment entities and procedural elements respond to

commands and how they operate. The mode determines how the procedure progresses and

who can affect that progression. For example, in a control module that contains basic control

functions, such as an automatic block valve, the mode determines what drives the valve

position and who can manipulate the position.

The ISA-88 standard defines the following modes.

Procedural Control States The ISA-88 standard defines the following states.

Control Mode Behavior Command

Automatic

(procedural)

Transitions within a procedure are conducted without

interruption as appropriate conditions are met.

Operators can pause the progression, but can not force

transitions.

Automatic

(basic control)

Equipment entities are manipulated by their control

algorithm.

Equipment entities cannot be manipulated directly by the

operator.

Semi-Automatic

(procedural)

Transitions within a procedure are conducted on manual

commands as appropriate conditions are fulfilled.

Operators can pause the progression or redirect the

execution to an appropriate point.Transitions cannot be

forced.

Manual

(procedural)

Procedural elements within a procedure are executed in

the order that is specified by an operator.

Operators can pause the progression or force

transitions.

Manual

(basic control)

Equipment entities are not manipulated by their control

algorithm.

Equipment entities can be manipulated directly by the

operator.

Control State Description

Idle

The procedural element is waiting for a Start command to cause a transition to the

Running state.

Running The procedural element is operating normally.

Complete

The procedural element has run to completion and is now waiting for a reset command

that prompts a transition to Idle.

Pausing

The procedural element or equipment entity received a Pause command. This causes the

procedural element to stop at the next defined safe or stable stop location in its normal

Running logic.

Once the procedural element has stopped, the procedural element automatically

transitions from Pausing to Paused.

Paused

Once the procedural element is paused at a defined stop location, it transitions from a

Pausing to Paused. The Paused state is usually used for short-term pauses. A Resume

command starts a transition to the Running state, and the procedural element resumes

normal operation immediately following the defined stop location.

Holding

The procedural element received a Hold command and is executing its Holding logic to put

the procedural element or equipment entity into a known state. If no sequencing is

required, then the procedural element or equipment entity transitions immediately to the

Held state.

Held

The procedural element completed its Holding logic and proceeded to the Held state. This

state is usually used for a long-term stop. The procedural element or equipment entity

waits for a further command to proceed.

Restarting

The procedural element receives a Restart command while in the Held state and executes

its restart logic to return to the Running state.

If no sequencing is required, then the procedural element or equipment entity transitions

immediately to the Running state.

Stopping

The procedural element received a Stop command and is executing its Stopping logic that

facilitates a controlled normal stop.

If no sequencing is required, then the procedural element or equipment entity transitions

immediately to the Stopped state.

Stopped

The procedural element or equipment entity completed its Stopping logic and waits for a

Reset command to transition to an Idle state.

Aborting

The procedural element received an Abort command and is executing its Abort logic that is

the logic that facilitates a quicker, but not necessarily controlled, abnormal stop.

If no sequencing is required, then the procedural element transitions immediately to the

Aborted state.

Aborted

The procedural element completed its Aborting logic and waits for a Reset command to

transition to the Idle state.

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Chapter 6 Structure Logic According to Standards

Procedural Control

Commands

The ISA-88 standard defines the following commands.

Command Description Valid States

Start Orders the procedural element to begin executing the normal Running logic. Idle

Stop Orders the procedural element to execute the Stopping logic.

Running

Pausing

Paused

Holding

Held

Restarting

Hold Orders the procedural element to execute the Holding logic.

Running

Pausing

Paused

Restarting

Restart

Orders the procedural element to execute the Restarting logic to safely return to the Running

state.

Held

Abort Orders the procedural element to execute the Aborting logic.

Running

Pausing

Paused

Holding

Held

Restarting

Stopping

Stopped

Reset Orders the procedural element to transition to an Idle state.

Complete

Aborted

Stopped

Pause

Orders the procedural element to pause at the next programmed pause transition within its

sequencing logic and await a Resume command before proceeding.

Running

Resume

Orders a procedural element that is in the Paused state, due to either a Pause command or a

Single Step mode, to resume normal operation.

Paused

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Chapter 6 Structure Logic According to Standards

Procedural Model Naming Conventions

Component Name Recommendations

Procedure

Use all upper case letters

Prefix with type of procedure (such as RP for recipe procedure), underscore, abbreviation of procedure

Example:

For a procedure executed in a Logix controller, prefix with area name, underscore, cell name, underscore

Example:

Unit procedure

Use all upper case letters

Prefix with UP, underscore, abbreviation of unit procedure

Example:

For a unit procedure executed in a Logix controller, prefix with area name, underscore, unit name, underscore

Example:

Operation

Use all upper case letters

Prefix with OP, underscore, abbreviation of operation

Example:

For an operation executed in a Logix controller, prefix with area name, underscore, unit name, underscore

Example:

Phase

Use all uppercase letters

Unit identifier, underscore, function abbreviation, EP, underscore, abbreviation of phase

Example:

Recipe Procedure Class: Clean Procedure Name: RP_CLEAN

Mixing, Tank: Clean Procedure Name: M102_MIX_RP_CLEAN

Unit Procedure Class: Clean Unit Procedure Name: UP_CLEAN

Unit Procedure Class: Mix Tank Clean

Procedure Name:

M102_TK2333_UP_CLEAN

Operation Class: Steam-In-Place Operation Name: OP_SIP

Mix Tank: Steam-In-Place Operation Operation Name: M102_TK2333_OP_SIP

EP Instance: Mix Tank 1234 Vessel Agitator EP Name: MT1234_EP_Agitate

EP Instance: Packager 1234 Bag Forming EP Name: PKR1234_EP_BagForming

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Chapter 6 Structure Logic According to Standards

State Model A state model helps program the equipment in a structured way, which results in the same

behavior in all equipment throughout the plant

Command Start Stop Hold Restart Abort Reset Pause Resume

Initial State

No Command

State

State Transition Matrix

Idle Running Stopping Aborting

Running Complete Stopping Holding Aborting Pausing

Complete Idle

Pausing Paused Stopping Holding Aborting

Paused Stopping Holding Aborting Running

Holding Held Stopping Restarting Aborting

Held Stopping Holding Aborting

Restarting Running Stopping Holding Aborting

Stopping Stopped Aborting

Stopped Aborting Idle

Aborting Aborted

Aborted Idle

Resetting Idle Stopping Aborting

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Chapter 6 Structure Logic According to Standards

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Chapter 7

Produced and Consumed Data

The controllers support the ability to produce (broadcast) and consume (receive) system-

shared tags.

For two controllers to share produced or consumed tags, both controllers must be in the same

backplane or attached to the same control network. You cannot bridge produced and

consumed tags over two networks.

For more information on produced and consumed tags, see the Logix 5000 Controllers

Produced and Consumed Tags Programming Manual, publication 1756-PM011

Guidelines for Produced and

Consumed Tags

IMPORTANTIMPORTANT The actual number of produced and consumed tags that you can

configure over ControlNet® or EtherNet/IP™ in a project depends on the

connection limits of the communication module through which you

produce or consume the tags.

Guideline Description

You cannot bridge produced and consumed tags over

different networks.

For two controllers to share produced or consumed tags, both controllers must be attached to the same network.

You can produce and consume tags over ControlNet or EtherNet/IP networks.

Create the tag at controller scope. You can only produce and consume (share) controller-scoped tags.

Limit the size of the tag to  500 bytes.

If you produce or consume a tag over a network, the tag must be ≤ 480 bytes. Network transfers require 20 bytes

of data overhead.

Combine data that goes to the same controller.

If you are producing several tags for the same controller:

• Group the data into one or more user-defined structures. This uses fewer connections than producing each

tag separately.

• Group the data according to similar update intervals. To conserve network bandwidth, use a greater RPI for

less critical data.

The following atomic data types can be directly

produced or consumed:

DINT

UDINT

LINT

ULINT

REAL

LREAL

The listed atomic data types can be produced or consumed individually or in arrays. Other atomic data types

(BOOL,SINT,USINT,INT,UINT) cannot be done individually or in arrays and are required to be part of a data

structure to be produced or consumed.

Data structures can be produced or consumed

Data structures include user-defined data types (UDT), strings, add-on-defined, predefined, and module-defined

data structures. Data structures meeting the size requirements can be produced or consumed.

AXIS_CIP_DRIVE Use AXIS_CIP_DRIVE to produce and consume axis data.

The data type in the producer and the consumer must

match.

The data type for a produced or consumed tag must be the same in both the producer and the consumer.

Produce tags that are based on user-defined structures

to non-Logix devices.

The controller produces tags in 32-bit words. For devices that communicate in other word boundaries, such as

16-bit words, the resulting data in the target device can be misaligned. To help avoid misalignment, structure the

produced data in a user-defined structure.

Use a programmatic handshake to help ensure data is

exchanged.

Produced tags continually transmit based on the RPI, so it can be difficult to know when new data arrives. You

can set a bit or increment a counter that is embedded in the produced tag to identify to the consumer that new

data is present. You can also provide a return handshake via a reverse produced/consumed tag, so that the

original producer knows that the consumer received and processed the tag.

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Chapter 7 Produced and Consumed Data

Guidelines for Produced and

Consumed Axis

Guidelines to Specify an RPI

Rate for Produced and

Consumed Tags

When configuring produced and consumed tags, you specify a requested packet interval (RPI)

rate. The RPI value is the rate at which the controller attempts to communicate with the

module.

Use a CPS instruction to buffer produced and consumed

data.

Use the CPS instruction to copy the data to the outgoing tag on the producer side. Then use another CPS

instruction to copy the data into a buffer tag on the consumer side.

The CPS instructions provide data integrity for data structures greater than 32 bits.

Important: The controller inhibits all interrupts while it executes a CPS instruction.

Use unicast EtherNet/IP communication to reduce

broadcast network traffic.

To reduce bandwidth use and preserve network integrity, some facilities block multicast Ethernet packets. You

can configure a produced and consumed tag to use multicast or unicast connections. Unicast connections help

with the following:

• Reduce network bandwidth

• Simplify Ethernet switch configuration

Monitoring produced and consumed data.

Group produced and consumed tags as members in user-defined structures whose first member is a

CONNECTION_STATUS type. This technique helps monitor connection status between controllers without

increasing execution time, such as using a GSV instruction to detect status.

Firmware revisions

When adding the Producer controller to the I/O configuration list of the Consumer controller, the firmware

revision does not have to match. However, the rack size and slot number must be correct.

Guideline Description

You can configure a produced and consumed axis

between controllers in a chassis or over an EtherNet/IP

network.

Controllers that support motion support the AXIS_CIP_DRIVE data type for produced and consumed tags.

Use a produced and consumed axis to synchronize

motion functions across multiple controllers.

Synchronize functions such as:

•PCAM

•GEAR

•MDSC moves

• Scheduled outputs

• Registration events

• Position-based interlocks (handshake)

Guideline Description

Make sure that the RPI is equal to or greater than the

NUT.

You use RSNetWorx™ for ControlNet software to select the network update time (NUT) and the software

schedules the network connections.

RSNetWorx software cannot schedule a ControlNet network if a module and/or produced/consumed tag on the

network has an RPI that is faster than the network update time.

RPI of multicast tags

• For Studio 5000 Logix Designer® application version 24 and earlier: The smallest (fastest) consumer RPI

determines the RPI for the produced tag. If multiple consumers request the same tag, the smallest (fastest)

request determines the rate at which the tag is produced for all consumers.

• For Studio 5000 Logix Designer application version 28 and later: the first consumer of a produce tag

determines the RPI at which data is produced. All subsequent consumers must request the same RPI value as

the first consumer. Otherwise, the subsequent consumers fail to connect.

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Chapter 7 Produced and Consumed Data

Guidelines to Manage

Connections for Produced

and Consumed Tags

Configure an Event Task

Based on a Consumed Tag

An event task executes automatically based on a preconfigured event occurring. One such

event can be the arrival of a consumed tag.

• Only one consumed tag can trigger a specific event task.

• Use an IOT instruction in the producing controller to signal the production of new data.

• When a consumed tag triggers an event task, the event task waits for all data to arrive

before the event task executes.

Compare Messages and

Produced/Consumed Tags

Guideline Description

Minimize the use of produced and consumed tags.

To reduce network traffic, minimize the size of produced and consumed tags. Also, minimize the use of

produced and consumed tags to high-speed, deterministic data, such as interlocks.

Use arrays or user-defined structures.

When sending multiple tags to the same controller, use an array or user-defined structure to consolidate the

data. The byte limit of  500 bytes per produced and consumed tag still applies.

Configure the number of consumers accurately.

Make sure the number of consumers that are configured for a produced tag is the actual number of controllers

that consumes the tag. If you set the number higher than the actual number of controllers, you unnecessarily use

up connections.

The default is two consumers per produced tag.

Multiple produced/consumed connections are linked.

If there are multiple produced and consumed connections between two controllers and one connection fails, all

produced and consumed connections fail.

Consider combining all produced and consumed data into one structure or array so that you only need one

connection between the controllers.

Method Benefits Considerations

Read/Write Message

• Programmatically initiated

• Communication and network resources that are only used when

needed

• Support automatic fragmentation and reassembly of large data

packets, up to as many as 32,767 elements

• Some connections can be cached to improve retransmission

time

• Generic CIP™ message useful for third-party devices

• Delay can occur if resources are not available when needed

• MSG instruction and processing can impact controller scan

(system overhead timeslice)

• Data arrives asynchronous to program scan (use a

programmatic handshake or a UID/UIE instruction pair to reduce

impact, no event task support)

• Can add additional messages online in Run mode.

Produced/Consumed Tag

• Configured once and sent automatically based on requested

packet interval (RPI)

• Multiple consumers can simultaneously receive the same data

from a produced tag

• Can trigger an event task when consumed data arrives

• ControlNet resources are reserved up front

• Does not affect the scan of the controller

• Support limited to Logix 5000™ and PLC-5® controllers, and the

1784-KTCS I/O Linx and select third-party devices

• Limited to 500 bytes over the backplane and 480 bytes over a

network

• Must be scheduled when using ControlNet

• Data arrives asynchronous to program scan (use a

programmatic handshake or CPS instruction and event tasks to

synchronize)

• Connection status must be obtained separately

• You can configure status information for a produced/consumed

tag

• On an EtherNet/IP network, you can configure produced/

consumed tags to use multicast or unicast connections.

• Cannot create additional produced/consumed tags online in Run

mode.

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Chapter 7 Produced and Consumed Data

Notes:

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Chapter 8

Data Structures

The controllers support the following data types:

• Numerous IEC 61131-3 elementary data types

• Compound data types

-Arrays

- Predefined structures, such as counters and timers

- User-defined structures

Guidelines for Data Types

Follow these guidelines depending on the data type for your application.

A tag uses additional memory in the controller to store the tag name and symbol, and allocate

memory for data.

When mixing data types among operand arguments, the system may need to perform type

conversion before and after instruction execution. This requires additional memory and

execution time when compared to using 32-bit operands all with the same data types for the

same operation.

Guideline Description

Use DINT data types whenever

possible

The controllers perform DINT (32 bit) and REAL (32 bit) math operations. DINT

data types use less memory and execute faster than other data types. Use

the following data type:

• DINT for most numeric values and array indexes.

• REAL for manipulating floating point, analog values.

Group BOOL values into arrays

When you use BOOL values, group them into DINT arrays to best use controller

memory and to make the bits accessible via FBC or DDT instructions.

Memory SINT/USINT INT/UINT

DINT/UDINT/

REAL/TIME32

LREAL/LINT/ULINT/TIME/

LTIM E/DT/L DT

Memory that is reserved for a

standalone tag

4 bytes 4 bytes 4 bytes 8 bytes

Memory that is reserved for

data in a user-defined

structure

1 byte

(8-bit aligned)

2 bytes

(16-bit aligned)

4 bytes

(32-bit aligned)

8 bytes

(64-bit aligned)

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Chapter 8 Data Structures

Arrays An array allocates a contiguous block of memory to store a specific data type as a table of

values.

• Tags support arrays in one, two, or three dimensions.

• User-defined structures can contain a single-dimension array as a member of the

structure.

The data type you select for an array determines how the contiguous block of memory gets

used.

This array Stores Data like For Example

One dimension

Tag name

one_d_array

Type

DINT[7]

Dimension 0

Dimension 1

—

Dimension 2

—

Total number of elements = 7

Valid subscript range DINT[a] where a=0…6

Two dimension

Tag name

two_d_array

Type

DINT[4,5]

Dimension 0

Dimension 1

Dimension 2

—

Total number of elements = 4  5 = 20

Valid subscript range DINT[a,b] where a=0…3; b=0…4

Three dimension

Tag name

three_d_array

Type

DINT[2,3,4]

Dimension 0

Dimension 1

Dimension 2

Total number of elements = 2  3  4 = 24

Valid subscript range DINT[a,b,c] where a=0…1; b=0…2, c=0…3

BOOL[96] = 12 bytes

BOOL arrays use 32-bit

increments of memory

SINT[10] = 12 bytes of memory (2 bytes unused)

INT[5] = 12 bytes of memory (2 bytes unused)

DINT[3] = 12 bytes and REAL[3] = 12 bytes

SINT arrays are padded to use

any left over bytes

INT arrays are padded to use

any left over bytes

DINT and REAL arrays use

4-byte increments of memory

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Chapter 8 Data Structures

Guidelines for Arrays

Indirect Addresses

of Arrays

If you want an instruction to access different elements in an array, use a tag in the subscript

of the array (an indirect address). By changing the value of the tag, you change the element of

the array that your logic references.

When you directly reference an element in an array (such as MyArray[20]), uses less memory

and executes faster than an indirect reference (MyArray[MyIndex]). You can also indirectly

address bits in a tag (MyDint.[Index]).

If you use indirect addresses, use DINT tags because other data types require conversion and

execute slower. For each indexed access to data, the controller recalculates the array index. If

you access a specific array element multiple times, copy the data out of the array into a fixed

tag and use that tag in subsequent logic.

You can also use an expression to specify the index value. For example: MyArray[10 + MyIndex].

• An expression uses operators to calculate a value.

• The controller computes the result of the expression and uses it as the index.

• These are valid operators.

Guideline Description

You can create arrays of most data types, except for

ALARM_xxx, AXIS_xxx, COORDINATE_SYSTEM,

ENERGY_xxx, HMIBC, MESSAGE, and MOTION_GROUP

data types.

A subscript identifies an individual element within the array. A subscript starts at 0 and extends to the number of

elements minus 1 (zero based).

• Single-dimension arrays take less memory and execute faster than two-dimension or three-dimension arrays.

• Direct references to array elements execute faster than indexed references.

• An array can be as large as 2 MB.

• If you create an array of structures, the memory for each element is allocated based on the structure definition.

Type of Array Benefit Considerations

Single (1) dimension

• Better support by native file instructions

• Fully supported in user-defined structures and arrays

• Smallest impact (execution time and memory) for

indexed references

• Can create arrays when programming online

• Multiple arrays cannot be indirectly referenced like in

PLC or SLC™ processors (such as, N[N7:0]:5)

• BOOL arrays are not directly supported by file

instructions

• Can be changed only when programming offline

Double (2) dimension

and

Triple (3) dimension

• Can provide a more accurate data representation for a

physical system

• Can emulate PLC file/word indirection with a two-

dimension array

• Can create arrays when programming online

• Larger impact (execution time and memory) for

indexed references

• File manipulation requires extra code and file

instructions

• Can only be changed when programming offline

Nest arrays.

The file instructions offer limited support for arrays. To work with array data, create a user-defined structure with

one array as a member of the structure. Then create an array tag by using the user-defined structure as its data

type.

Select the data type of the array based on the data

and the instructions that manipulate that data.

While SINT and INT arrays can compact more values into a given memory area, they require additional memory and

execution time for each instruction that references the array.

Limit arrays to 2 MB of data.

The maximum array size is 2 MB. The software displays a warning if you try to create an array that is too large. The

software also displays a warning if an array is 1.5…2 MB, even though these sizes are valid.

Edit arrays online and offline.

You can create arrays when online or offline. However, you can modify only the size or data type of an existing array

when offline.

When index equals 1, array[index] points here.

array[0] 4500

array[1] 6000

array[2] 3000

array[3] 2500

When index equals 2, array[index] points here.

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Chapter 8 Data Structures

Guidelines for Array

Indexes

Operator Description Optimal

+Add DINT, REAL

- Subtract/negate DINT, REAL

*MultiplyDINT, REAL

/ Divide DINT, REAL

** Exponent (x to y) DINT, REAL

ABS Absolute value DINT, REAL

ACS Arc cosine REAL

AND Bitwise AND DINT

ASN Arc sine REAL

ATN Arc tangent REAL

COS Cosine REAL

DEG Radians to degrees DINT, REAL

FRD BCD to integer DINT

LN Natural log REAL

LOG Log base 10 REAL

MOD Modulo divide DINT, REAL

NOT Bitwise complement DINT

OR Bitwise OR DINT

RAD Degrees to radians DINT, REAL

SIN Sine REAL

SQR Square root DINT, REAL

TAN Tangent REAL

TOD Integer to BCD DINT

TRN Truncate DINT, REAL

XOR Bitwise exclusive OR DINT

Operator Description Optimal

Guideline Description

Use the SIZE instruction to determine the number of

elements in an array.

By determining the number of elements in an array at runtime, you can write reusable code that adjusts itself to

meet each instance where it is used.

The SIZE instruction returns the number of elements. Arrays are zero-based, so subtract 1 from the result to

determine the last element position.

Use immediate values to reference array elements. Immediate value references to array elements are quicker to process and execute faster than indexed references.

Use DINT tags for array indexes.

DINT tags execute the fastest. SINT, INT, and REAL tags require conversion code that can add additional scan time to

an operation.

Avoid using array elements as indexes.

The controller does not directly support the use of an array element as the index to look up a value in another array.

To work around this, you can create an alias to the element and then use this as the index. Or copy the element to a

base tag and use that base tag as the index.

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Chapter 8 Data Structures

Guidelines for User-defined

Data Types (UDT)

Guideline Description

Group members of the same data type within a

structure.

You can create members of most data types, except for AXIS, COORDINATE_SYSTEM, MOTION_GROUP, and

MESSAGE data types.

Place members that use the same data type in sequence.

The controller aligns every data type along an 8-bit boundary for SINTs, a 16-bit boundary for INTS, or a 32-bit

boundary for DINTs and REALs. BOOLs also align on 8-bit boundaries, but if they are placed next to each other in

a user-defined structure, they are mapped so that they share the same byte.

Arrays within a UDT can only be 1-dimension.

If you include an array as a member, limit the array to one dimension. Multidimension arrays are not permitted in

a user-defined structure.

I/O data that is used in a UDT must be copied into the

members.

If you include members that represent I/O devices, you must use logic to copy the data into the members of the

structure from the corresponding I/O tags.

Make sure that the data type of the structure member matches the I/O data type to avoid data type conversion.

Limit user-defined data types to 500 members.

The controllers limit user-defined structures to 500 members. If you need more, consider nesting structures

within the main structure.

Limit user-defined data types to 2 MB of data.

The maximum UDT size is 2 MB. The software displays a warning if you try to create an UDT that is too large. The

software also displays a warning if the UDT is 1.5…2 MB, even though these sizes are valid.

Limit the size of user-defined structures if they are to

be produced and consumed tags.

Produced and consumed tags are limited to 500 bytes over the backplane and 480 bytes if over a network.

Linx-based software can optimize user-defined structures that are less than 480 bytes. UDT larger than the

noted produced and consumed tag limits must use a MESSAGE instruction (MSG) if they are to be communicated.

Use the appropriate instruction to load data into a

structure.

Load input values into the user-defined structure at the beginning of the program and copy output values from

the user-defined structure at the end of the program.

• Single bit - Examine On (XIC) and Output Energize (OTE) instructions

• Contiguous bits - Bit Field Distribute (BTD) instruction

• Single value - MOV instruction

• Multiple contiguous values -COP/CPS instruction

Use structure descriptions to automatically create tag

descriptions.

Enable the Use Pass-through Description workstation option (Tools > Options > Display) to display the

descriptions you add to the members of structures for each tag that uses that structure data type.

Online and offline editing.

You can create user-defined structures when online or offline. However, you can modify only an existing

structure when offline.

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Chapter 8 Data Structures

Select a Data Type for

Bit Tags

Bits in a controller can exist as: BOOL tags, bits in a BOOL array, bits in elements of a SINT,

USINT, INT, UINT, DINT, UDINT, LINT, ULINT array, members of a user-defined structure, or as

bits in a SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT member of a user-defined structure.

Tag Type Description

BOOL tag Each tag accesses a specific bit. Each tag uses 4 bytes.

Benefits Considerations

• Each bit has a specific tag

• Requires extra bandwidth to communication

• Uses more memory

• Cannot use FBC/DDT bit file instructions

BOOL array A BOOL array combines multiple bits into adjacent words (32-bit words).

Benefits Considerations

• Consolidates multiple bits into one word

• Better use of memory

• Can address all bits in an array by using indirect

addressing

• BOOL data type only supported by bit instructions

• Cannot use file instructions, copy instructions, or

DDT/FBC instructions

DINT array A DINT combines multiple bits into adjacent words.

Benefits Considerations

• Consolidates multiple bits into one word

• File instructions, copy instructions, and DDT/FBC

instructions support DINT arrays

• Lets you access the bits by element (word) and

bit number

• Requires extra planning to indirectly address bits

• Difficult to address bits in the array by using indirect

addressing

User-defined structure A user-defined structure combines multiple bits into adjacent, individually named words.

Benefits Considerations

• Object based

• Consolidates multiple bits into one word

• Third-party MMI/EOI products do not directly support

structures.

• Cannot use FBC/DDT bit file instructions

MyBit:BOOL

BitTable:BOOL[32]

FaultTable:DINT[3]

BitStructure

Bit1:BOOL

Bit2:BOOL

Fault:BitStructure

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Chapter 8 Data Structures

Serial Bit Addresses The Logix 5000 controller supports both of the following addressing modes, but you cannot

use both to reference bits in the same array due to conformance with the IEC 61131-3 standard.

Choose the method that best meets your application needs. You can copy data between arrays

by using both methods.

You can also use an expression to indirectly reference a bit in a DINT array by using a

serialized bit number, as shown in the following example.

Tag

MyBits : DINT[10]

BitRef : DINT

EndTag

MOV(34, BitRef)

XIC(MyBits[BitRef / 32].[BitRef AND 31])

where:

The Diagnostic Detect (DDT) and File Bit Compare (FBC) instructions provide a bit number as a

result of their operation. These instructions are limited to DINT arrays so you can use them to

locate the bit number that is returned from the example above.

Address Mode Description

Serial bit

Serial bit addressing references all bits as a contiguous list (array) of bits. For example, if you

want to reference the third bit in the second word of a B file, specify B3/18. This method is

similar to a BOOL array in a Logix 5000™ controller where you specify FaultBit[18].

Word bit

Word bit addressing identifies a bit within a specific word. For example, B3:1/2 is the same as

B3/18 from the serial bit example. This method is similar to accessing the bits of a SINT, INT,

DINT array in a Logix 5000 controller where you specify FaultTable[1].2.

This expression Calculates the

[BitRef / 32] Element in the DINT array

If the tag MyBits is an INT or SINT, the divisor is 16 or 8, respectively.

[BitRef AND 31] Bit within the element

If the tag MyBits is an INT or SINT, the mask value is 15 or 7, respectively.

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Chapter 8 Data Structures

Guidelines for String

Data Types

String data types are structures that hold ASCII characters. The first member of the structure

defines the length of the string; the second member is an array that holds the actual ASCII

characters.

Configure Tags A tag is a text-based name for an area of controller memory where data is stored. Tags are the

basic mechanism to allocate memory, reference data from logic, and monitor data.

For more information on I/O tags, see Communicate with I/O on page 85

Guideline Description

You can create a string data type that is longer or

shorter than the default string data type.

The default string data type can contain as many as 82 characters. You can create custom-length string data types

that range from 1 to 65535 characters.

Only some instructions support string data types.

These comparison instructions support string tags: EQU, NEQ, GRT, GEG, LES, LEQ, CMP.

These serial port instructions support string tags: ARD, ARL, AWA, AWT.

These string-handling instructions support string tags: STOD, DTOS, STOR, RTOS, CONCAT, MID, FIND, DELETE,

INSERT, UPPER, LOWER, SIZE.

These file instructions support string arrays: FAL, FFL, FFU, LFL, LFU, COP, CPS, FSC.

Use the SIZE instruction to determine the number of

characters in a string.

By determining the number of characters in a string at runtime, you can write reusable code that adjusts itself to

meet each instance where it is used.

Set the LEN field to indicate the number characters

that are present.

The LEN field in the string structure indicates how many characters are in the string. The programming software

and the controller instructions that manipulate strings use the LEN value to determine how many positions in the

string DATA array contain valid characters. Both the programming software and the instructions stop processing

the DATA array once they reach the LEN value.

If you want the tag to Then choose this type

Store a value for use by logic within the project Base

Use another name for an existing tag’s data

(can help simplify long, pre-determined tag names, such as for I/O data or user-

defined structures)

Alias

Send (broadcast) data to another controller Produced

Receive data from another controller Consumed

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Chapter 8 Data Structures

Guidelines for Base Tags Use the following guidelines for base tags.

Create Alias Tags An alias tag lets you create one tag that represents another tag.

• Both tags share the same value as defined by the base tag.

• When the value of a base tag changes, all references (aliases) to the base tag reflect the

change.

Guideline Description

Create standalone atomic tags.

The controller supports pre-defined, standalone tags.

• Atomic tags are listed directly in the Tag Editor and Data Monitor and can easily be found by browsing the alphabetical list.

• Atomic tags can be created online, but the data type can be only modified offline.

Using only atomic tags can impact HMI communication performance as more information must be passed and acted on.

Create user-defined structures

User-defined structures (data types) let you organize your data to match your machine or process.

• One tag contains all data that is related to a specific aspect of your system. This keeps related data together and easy to

locate, regardless of its data type.

• Each piece of data (member) gets a descriptive name.

• You can use the structure to create multiple tags with the same data layout.

• User-defined structure can only be modified offline.

Linx-based software optimizes user-defined structures more than standalone tags.

Use arrays like files to create a group of

similar tags.

An array creates multiple instances of a data type under a common tag name.

• Arrays let you organize a block of tags that use the same data type and perform a similar function.

• You organize the data in one, two, or three dimensions to match what the data represents.

• Arrays can be only modified offline.

• Linx-based software optimizes array data types more than standalone tags.

Minimize the use of BOOL arrays. Many array instructions do not operate on BOOL arrays, making it more difficult to initialize

and clear an array of BOOL data.

Take advantage of program-scoped tags.

If you want multiple tags with the same name, define each tag at the program scope (program tags) for a different program.

This lets you reuse both logic and tag names in multiple programs.

Avoid using the same name for both a controller tag and a program tag. Within a program, you cannot reference a controller

tag if a tag of the same name exists as a program tag for that program.

Use mixed case and the underscore

characters.

Although tags are not case-sensitive (upper case A is the same as lower case a), mixed case is easier to read. For example,

Tank_1 can be easier to read than tank1.

Consider alphabetical order.

The programming software displays tags of the same scope in alphabetical order. To make it easier to monitor related tags,

use similar starting characters for tags that you want to keep together. For example, consider using Tank_North and

Tank_South rather than North_Tank and South_Tank.

Use leading zeroes (0) when numbers are

part of tag names

The programming software uses a simple sort to alphabetize tag names in the Tag Editor and Data Monitor. This means if

you have Tag1, Tag2, Tag11, and Tag12, the software displays them in order as Tag1, Tag11, Tag12, and then Tag2. If you want to

keep them in numerical order, name them Tag01, Tag02, Tag11, and Tag12.

Guideline Description

Upload behavior for alias tags.

For 5370 and 5570 controllers, there are situations when uploading a project file that instruction operands that use alias

references can change. To avoid these situations with ladder instruction operands, do not use:

• Nested aliases (also known as an alias chain)

• Multiple aliases to the same tag

On an upload, the software uses a technique referred to as “best fit” to reconstruct instruction operands and operands that

use an alias can change.

This does not apply to 5380, 5480 and 5580 controllers and on an upload, the aliases for these controllers are faithfully

reproduced.

Alias tags do not affect controller

execution.

During download, the program is compiled into machine executable code and physical memory addresses. While the

existence of an alias requires controller memory to store the name, the program performs the same operation for a

reference with an alias or its associated base tag.

Access alias tags from Linx-based

software.

Because an alias tag appears as a standalone tag to Linx-based software, an alias tag that references a compound array or

structure can require additional communication time. When you reference tags from Linx-based software or other HMI, it can

be fastest to reference base tags directly.

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Chapter 8 Data Structures

Guidelines for Data Scope Data scope defines where you can access tags. Controller-scoped tags and parameters are

accessible by all programs. Local tags are accessible only by the code within a specific

program. Equipment Phases, like Programs, have parameters and local tags.

Isolate portions of a machine or different stations into separate programs or equipment

phases and use program-scoped or phase-scoped tags. This lets you do the following:

• Provide isolation between programs and equipment phases

• Help prevent tag name collisions

• Improve the ability to reuse code

See publication 1756-PM021, Logix 5000 Controllers Program Parameters Programming Manual,

for more information on Parameters.

Guidelines for Tag Names Use the following guidelines when you name tags.

Controller

scope

Program

scope

Phase

scope

If you want to Then assign this scope

Produce or consume data Controller scope (controller tags)

Use a tag in multiple programs in the same project

Controller scope (controller tags)

Parameters

Use a tag in a message (MSG) instruction

Use motion tags

Reuse the same tag name multiple times for different parts or processes

within a controller

Parameters

Local Tags

Have multiple programmers work on logic and you want to merge logic into

one project

Guideline Description

Create descriptive names but keep them short.

Tag names can be from 140 characters long.

• Each character of the tag name uses 1 byte of controller memory, rounded to a 4-byte boundary.

• For example, a tag name with 1…4 characters uses 4 bytes. A tag name with 5 characters uses 8 bytes.

• Tag names are stored in the controller.

• Use structures to reduce the number and size of tags needed.

Program upload preserves tag names.

Create a naming convention.

Develop a tag-naming convention on electrical drawings or machine design. For example, Conv1_Full_PE101 combines

the sensor function with the photoeye number.

Use correct characters in tag names.

Tag names follow the IEC 61131-3 standard. You can use:

• Letters A through Z.

• Numbers 0…9.

• Underscore character (_).

Tags must start with a letter to avoid confusion with logical expressions. The remaining characters can be any of the

supported characters.

Pad names to improve sort order.

The programming software displays tags in alphabetical order. If you use numbers in your tag names, pad the number

with leading zeros so the names sort in the proper order.

For example, tag names: TS1, TS2, TS3, TS10, TS15, TS20, TS30 display as: TS1, TS10, TS15, TS2, TS20,TS3, and TS30.

Pad the numbers with zero so they display as: TS01, TS02, TS03, TS10, TS15, TS20, TS30.

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Chapter 8 Data Structures

Guidelines for Extended Tag

Properties

Use the following guidelines for extended tag properties.

Tag Descriptions The programming software searches a tag’s origin to locate the first available description.

This reduces the number of descriptions you need to enter. This also verifies that tag

references display associated descriptions.

For more information, see the Create Tag Descriptions Automatically with User-Defined Data

Types White Paper, publication LOGIX-WP004

Guideline Description

Use extended tag properties to define additional information,

such as limits, engineering units, or state identifiers, for

various components within your controller project.

You can define extended tag properties for these components:

•Tag

• Parameter

• User-defined data type

•Add-On Instruction

Some extended tag properties support pass-through for data

structures and arrays.

Pass-through behavior is available for descriptions, state identifiers, and engineering units and is

configurable in data structures and arrays.

Pass-through behavior is not available for limits.

You can read extended properties via logic, but you cannot

write to extended properties values in logic.

• Extended properties must be used as an input operand.

• Alias tags with extended properties cannot be accessed in logic.

• Limits can be configured for input and output parameters in Add-On Instructions. However, limit

extended properties must not be defined on an InOut parameter of an Add-On Instruction.

• Limits cannot be accessed inside Add-On Instruction logic.

• If you read an extended property value in logic, it consumes memory equivalent to an equivalent

program-scoped tag of that data type. If you do not use them in logic, extended tag properties use no

user memory, only extended memory.

If an array tag uses indirect addressing to access limit

extended properties in logic, the following conditions apply.

• If the array tag has limit extended properties that are configured, the extended properties are applied

to any array element that does not explicitly have that particular extended property configured. For

example, if the array tag MyArray has Max configured to 100, then any element of the array that does

not have Max configured inherits the value of 100 when used in logic. However, it is not visible to you

that the value inherited from MyArray is configured in the tag properties.

• At least one array element must have specific limit extended property configured for indirectly

referenced array logic to verify. For example, if MyArray[x].@Max is being used in logic, at least one

array element of MyArray[] must have Max extended property configured if Max is not configured by

MyArray.

• Under the following circumstances a data type default value is used:

– Array is accessed programmatically with an indirect reference.

– Array tag does not have the extended property configured.

– A member of an array does not have the extended property configured.

Guideline Description

Tag descriptions display in the

programming software

according to the tag’s origin.

Type of Tag Description Display in the programming software

Atomic

For a BOOL, SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT, REAL or LREAL tag, the description that is

associated with the tag is the only description available for display.

Alias First the alias tag description, then the base tag description.

User-defined structure and

Add-On Instruction

All members use the description for tag, unless you define a specific description for a member.

For example, MyTimer.DN uses the description for MyTimer if there is no description for MyTimer.DN.

Atomic array

• All references into an array use the description for the array, unless you define a description for an

element of the array.

• For example, MyTable[10] uses the description for MyTable if there is no description for MyTable[10].

• All indexed references into an array use the description for the array.

• For example, MyTable[Index] uses the description for MyTable.

Structure array

All references to a member of a structure in an array default to the array definition, unless you define

a description for the structure member of the array.

For example, Table[0].Field1 uses the description for Table if there is no description for the specific

field.

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Chapter 8 Data Structures

Protect Data Access Control

at Tag Level

New tag attributes define access to tag data at runtime.

You can Use RSLinx® Classic software, version 2.56 or later, RSLinx Enterprise software,

versions 5.21 to 5.90, or FactoryTalk® Linx software version 6.00 or later, for best results with

these tag attributes. Using earlier versions of RSLinx software can result in anomalous

behavior from the data servers with the external access options of Read Only and None.

Tag Attribute Description

External access

Defines how an external application, such as an HMI, historian, or OPC data server, can access a tag. For arrays, this feature applies to the top level

only; for user-defined structure, this feature applies to individual members. Possible values are:

• Read/Write: External applications can both read and modify the tag’s value

• Read Only: External applications can read the tag’s value, but not modify it

• None: External applications can neither read or write the tag’s value

Constant Defines whether a tag value remains constant. Tags with this attribute set cannot be changed programmatically.

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Chapter 9

Communicate with I/O

I/O values update at a period, requested packet interval (RPI), which you configure via Module

Property dialog in the I/O configuration folder of the project. The values update

asynchronously to the execution of logic.

The module sends input values to the controller at the specified RPI. Because this transfer is

asynchronous to the execution of logic, an I/O value in the controller can change in the middle

of a scan.

Buffer I/O Data If you reference an I/O tag multiple times, and the application could be impacted if the value

changes during a program scan, you must buffer the I/O value. You can buffer an I/O tag by

using input parameters or coping into a buffer tag. In your code, reference the buffer tag

rather than the I/O tag.

Buffer I/O data to do the following:

• Help prevent an input or output value from changing during the execution of a program

(I/O updates asynchronous to the execution of logic).

• Copy an input or output tag to a member of a structure or element of an array.

• Help prevent produced or consumed data from changing during the execution of a

program.

• Make sure all produced and consumed data arrives or is sent as a group (not mixed

from multiple transfers).

• Only use the CPS instruction if the I/O data that you want to buffer is greater than 32

bits (or 4 bytes) in size.

Overuse of the CPS instruction can greatly impact controller performance.

If you have a user-defined structure with members that represent I/O devices, you must use

logic to copy the data into the members of the structure from the corresponding I/O tags.

IMPORTANT Use the synchronous copy (CPS) instruction to buffer I/O data. While the

CPS instruction copies data, no I/O updates or other tasks can change the

data. Tasks that attempt to interrupt a CPS instruction are delayed until

the instruction is done. Overuse of the CPS instruction can impact

controller performance by keeping all other tasks from executing.

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Chapter 9 Communicate with I/O

Guidelines to Specify an RPI

Rate for I/O Modules

Configure an RPI rate per module (ControlLogix®) or an RPI rate per controller

(CompactLogix™). The RPI value is the rate at which the controller attempts to communicate

with the module.

Guideline Description

Specify an RPI at 50% of the rate you need new

data.

If you set the RPI faster (specify a smaller number) than what your application needs, it can waste network

resources, such as ControlNet® schedule bandwidth, network processing time, and CPU processing time.

For example, if you need information every 80 ms, set the RPI at 40 ms. The data is asynchronous to the controller

scan, so you sample data twice as often (but no faster), you ensure that you have the most current data.

Group devices with similar performance needs onto

the same module.

By grouping devices with similar performance needs on the same module, you consolidate data transmission to one

module rather than multiple modules. This conserves network bandwidth.

Set the ControlNet™ network update time (NUT)

equal to or less than the fastest RPI.

When configuring a ControlNet network, set the network update time (NUT) equal to or less than the fastest RPI of the

I/O modules and produced/consumed tags in the system. For example, if your fastest RPI is 10 ms, set the NUT to 5

ms for more flexibility in scheduling the network.

In an ControlNet system, use even multiples of the

NUT for the RPI value.

Set the RPI to a binary multiple of the NUT. For example, if the NUT is 10 ms, select an RPI such as 10, 20, 40, 80, or

160 ms.

In a ControlNet system, isolate I/O communication.

If you use unscheduled ControlNet communication or want to be able to add ControlNet I/O at runtime (see page 93

dedicate one ControlNet network to I/O communication only. On the dedicated I/O network, make sure that there is

the following:

•No HMI traffic

•No MSG traffic

• No programming workstations

• No peer-to-peer interlocking in multi-processor system architectures

In an EtherNet/IP™ system, module change of state

is limited to 1/4 of the RPI.

If you configure change of state communication for a module in a remote chassis that is connected via an

EtherNet/IP network, the module can send data only as fast as the module RPI. Initially, the module sends its data

immediately. However, when an input changes, the module data is held at the adapter until 1/4 of the RPI is reached

to avoid overloading the EtherNet/IP network with the module communication.

Data transmission depends on the controller.

The type of controller determines the data transmission rate.

• ControlLogix controllers transmit data at the RPI you configure for the module.

• CompactLogix controllers transmit data at powers of 2 ms (such as 2, 4, 8, 16, 64, or 128). For example, if you

specify an RPI of 100 ms, the data actually transfers at 64 ms.

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Chapter 9 Communicate with I/O

Communication Formats for

I/O Modules

The communication format determines whether the controller connects to the I/O module via

a direct or a rack-optimized connection. The communication format also determines the type

and quantity of information that the module provides or uses.

Direct Connection

Each module passes its data to/from the controller individually. Communication modules

bridge data across networks.

Rack-optimized Connection

The communication module in a remote chassis consolidates data from multiple modules into

one packet and transmits that packet as one connection to the controller.

The rack-optimized format limits data to one 32-bit input word per module in a chassis. If you

place a diagnostic module in a chassis, the rack-optimized format eliminates the value that

the diagnostic module offers. In this case, it’s better to use a direct connection so that the

diagnostic information from the module is passed to the controller.

Benefits Considerations

• Each module can determine its own rate (RPI)

• More data can be sent per module, such as diagnostic

and analog data

• Supports event task communication

• Requires additional connections and network

resources

• This is the only method that is supported in the local

chassis

• I/O data is presented as individual tags

Benefits Considerations

• One connection can service a full chassis of digital

modules

• Reduces network resources and loading

• All Modules are sent at the same rate

• Unused slots are still communicated

• Still need a direct connection for analog and

diagnostic data

• Limited to remote chassis

• I/O data is presented as arrays with alias tags for

each module

Local Chassis Remote Chassis

Controller

Communication

Module

Communication

Module

Digital Inputs

Digital Outputs

Local Chassis Remote Chassis

Controller

Communication

Module

Communication

Module

Digital Inputs

Digital Outputs

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Chapter 9 Communicate with I/O

Peer Control

Output modules let peer ownership of input modules to consume input data to directly control

outputs without requiring controller processing.

The 1756-IB16IF and 1756-IB16IFC modules can be listened to presuming the output module

knows the input data layout and connection information. The configuration from the controller

defines how the peer input data is mapped to the output modules. The controller can use the

other digital points on the module that are not peer-owned as conventional outputs.

The controller can also use the output data it normally sends to the module with consumed

inputs, letting ‘gate-type’ features enabled by controller logic selectively letting application of

the consumed peer input data.

Benefits Considerations

• Faster response time because the controller scan time

is removed from the equation. Data is sent directly to

the output module from the input module.

• Increases controller performance by reducing the

need for event tasks to close loops quickly.

• Each input module has an AND and OR bit mask that

defines the logic that is applied to each input module.

• You must program the controller for proper

relationship with the output modules.

• The peer output module must be in the same chassis

as the input module to maximize response time.

Output Echo

Connection / Peer Control

Output Data

Input Input

Connection Listen Only

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Chapter 9 Communicate with I/O

Electronic Keying Electronic Keying reduces the possibility that you use the wrong device in a control system. It

compares the device that is defined in your project to the installed device. If keying fails, a

fault occurs. These attributes are compared.

The following Electronic Keying options are available.

Carefully consider the implications of each keying option when selecting one.

More Information

For more detailed information on Electronic Keying, see Electronic Keying in Logix 5000™

Control Systems Application Technique, publication LOGIX-AT001.

Attribute Description

Vendor The device manufacturer.

Device Type The general type of the product, for example, digital I/O module.

Product Code The specific type of the product. The Product Code maps to a catalog number.

Major Revision A number that represents the functional capabilities of a device.

Minor Revision A number that represents behavior changes in the device.

Keying Option Description

Compatible Module

Lets the installed device accept the key of the device that is defined in the project when the

installed device can emulate the defined device. With Compatible Module, you can typically

replace a device with another device that has the following characteristics:

• Same catalog number

• Same or higher Major Revision

• Minor Revision as follows:

– If the Major Revision is the same, the Minor Revision must be the same or higher.

– If the Major Revision is higher, the Minor Revision can be any number.

This is the default selection in the Logix Designer application.

Disable Keying

Indicates that the keying attributes are not considered when attempting to communicate

with a device. With Disable Keying, communication can occur with a device other than the

type specified in the project.

ATTENTION: Be cautious when using Disable Keying; if used incorrectly, this option can lead

to personal injury or death, property damage, or economic loss.

We strongly recommend that you do not use Disable Keying.

If you use Disable Keying, you must take full responsibility for understanding whether the

device being used can fulfill the functional requirements of the application.

Exact Match

Indicates that all keying attributes must match to establish communication. If any attribute

does not match precisely, communication with the device does not occur.

IMPORTANT When you change Electronic Keying parameters online, it interrupts

connections to the device and any devices that are connected through the

device. Connections from other controllers can also be broken.

If an I/O connection to a device is interrupted, the result can be a loss of

data.

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Chapter 9 Communicate with I/O

Guidelines to Manage I/O

Connections

Use the following guidelines to administer your I/O modules.

1. The type of I/O module can determine the type of connection.

- Analog modules always use direct connections, except for 1771 analog modules that

use messaging and 1734 analog modules that use Enhanced Rack Optimization.

- Digital modules can use direct or rack-optimized connections. Communication

formats that include optimization in the title are rack-optimized connections; all

other connection options are direct connections.

2. Select the communication format for a remote adapter based on the remote I/O

modules.

3. Use rack-optimized connections to conserve connections.

If you are trying to limit the number of controller and network connections, rack-

optimized connections can help.

4. In some cases, all direct connections work best.

For a remote adapter that is configured for rack-optimized connections, there is always

data that is sent for each slot in the chassis, even if a slot is empty or contains a direct

connection module. There are 12 bytes of data that is transferred for rack-optimized

overhead between the controller and the remote adapter. In addition, the remote

adapter sends 8 bytes per slot to the controller; the controller sends 4 bytes per slot to

the remote adapter.

For a few digital modules in a large chassis, it can be better to use direct connections

because transferring the full chassis information can require more system bandwidth

than direct connections to a few modules.

IMPORTANT Compact 5000™ I/O does not support rack-optimization.

Select If

None

The remote chassis contains only analog modules, diagnostic digital modules, fused

output modules, or communication modules.

On a ControlNet network, use None to add a chassis to the network while the

controller is running.

Rack-optimized

The remote chassis only contains standard, digital input, and output modules

(no diagnostic modules or fused output modules).

For a ControlNet network at runtime (controller is online), you can add new digital

modules to an existing rack-optimized connection, but new rack-optimized

connections can only be added when offline. An EtherNet/IP network supports new

rack-optimized connections both offline and at runtime (online). For more

information, see page 93

Listen Only Rack-optimized

You want to receive I/O module and chassis slot information from a rack-optimized

remote chassis that is owned by another controller.

The runtime capability for listen only rack-optimized connections is the same as for

rack-optimized connections.

Example Description

Remote 17-slot chassis

Slot 0: 1756-CNBR/D

Slots 1…15: analog modules

Slot 16: standard digital module

Option 1: Select Rack Optimization as the communication format for the remote adapter. This example uses 16 controller connections

(15 for analog modules and 1 for the rack-optimized connection). This example also transfers:

• 12 bytes for rack-optimized overhead.

• 12 bytes for the digital module.

• 12 bytes for each of the 15 analog modules, for a total of 180 bytes.

Option 2: Select None as the communication format for the remote adapter. This example also uses 16 controller connections (1 direct

connection to each I/O module). There is no rack-optimized overhead data to transfer.

Recommendation: Option 2 is recommended because it avoids unnecessary network traffic, and thus improves network performance.

Remote 17-slot chassis

Slot 0: 1756-CNBR/D

Slots 1…8: analog modules

Slots 9…16: digital modules

Option 1: Select Rack Optimization as the communication format for the remote adapter. This example uses nine controller connections

(eight for analog modules and one for the rack-optimized connection). This example also transfers:

• 12 bytes for rack-optimized overhead.

• 12 bytes for each of the 8 digital modules, for a total of bytes 96 bytes.

• 12 bytes for each of the 8 analog modules, for a total of 96 bytes.

Option 2: Select Rack Optimization for the communication format of the remote adapter. This example uses 16 controller connections (1

direct connection to each I/O module). There is no rack-optimized overhead data to transfer.

Recommendation: The best option for this example depends on the type of digital I/O modules in the system and other controller

connections. If the total system has many analog modules, diagnostic modules, fused output modules, or produced/consumed tags,

select Option 1 to conserve controller connections. If there are plenty of controller connections available, select Option 2 to reduce

unnecessary network traffic.

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Chapter 9 Communicate with I/O

Create Tags for I/O Data Each I/O tag is automatically created when you configure the I/O module through the

programming software. Each tag name follows this format:

Location:SlotNumber:Type.MemberName.SubMemberName.Bit

If you configure a rack-optimized connection, the software creates a rack-object tag for the

remote communication module. You can reference the rack-optimized I/O module individually,

or by its element within the rack-object tag.

This address variable Is

Location

Identifies network location

LOCAL = local chassis or DIN rail

ADAPTER_NAME = identifies remote adapter or bridge

SlotNumber Slot number of I/O module in its chassis

Type

Type of data:

I = inputC = configuration

O = outputS = status

MemberName Specific data from the I/O module, such as Data and Fault; depends on the module

SubMemberName Specific data that is related to a MemberName

Bit (optional)

Specific point on the I/O module; depends on the size of the I/O module (0…31 for a 32-

point module)

The individual tag that is created for the I/O

module in remote slot 1.

For example, a remote EtherNet communication module

(Remote_ENT2R) has an I/O module in slot 1.

The entry in the rack-object tag for the remote

communication module that identifies the I/O

module in remote slot 1.

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Chapter 9 Communicate with I/O

Controller Ownership When you choose a communication format, you have to choose whether to establish an owner

or listen-only relationship with the module.

There is a noted difference in the ownership of input modules versus the ownership of output

modules.

Mode Description

Owner The owner controller writes configuration data and can establish a connection to the module.

Listen-only

A controller that uses a listen-only connection only monitors the module. It does not write

configuration data and can only maintain a connection to the I/O module when the owner

controller is actively controlling the I/O module.

Controlling This Ownership Description

Input modules

Owner

An input module is configured by a controller that establishes a connection

as an owner. This configuring controller is the first controller to establish an

owner connection.

Once an input module has been configured (and owned by a controller), other

controllers can establish owner connections to that module. This lets

additional owners to continue to receive multicast data if the original owner

controller breaks its connection to the module. All other additional owners

must have the identical configuration data and identical communication

format that the original owner controller has, otherwise the connection

attempt is rejected.

Listen-only

Once an input module has been configured (and owned by a controller), other

controllers can establish a listen-only connection to that module. These

controllers can receive multicast data while another controller owns the

module. If all owner controllers break their connections to the input module,

all controllers with listen-only connections no longer receive multicast data.

Output modules

Owner

An output module is configured by a controller that establishes a connection

as an owner. Only one owner connection can be connected to an output

module. If another controller attempts to establish an owner connection, the

connection attempt is rejected.

Listen-only

Once an output module has been configured (and owned by one controller),

other controllers can establish listen-only connections to that module. These

controllers can receive multicast data while another controller owns the

module. If the owner controller breaks its connection to the output module,

all controllers with listen-only connections no longer receive multicast data.

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Chapter 9 Communicate with I/O

Runtime/Online Addition of

Modules

You can add modules when the controller is in Run mode.

Network Considerations

ControlNet network

You can use:

• 1756-CN2, 1756-CN2R, 1756-CN2RTXT any series modules.

• 1756-CNB, 1756-CNBR series D or later communication modules.

Digital I/O modules can be added as rack-optimized connections if the parent module is already configured with rack-optimized connections.

While you can add a new digital I/O module to an existing rack-optimized connection, you cannot add rack-optimized connections while online.

Digital I/O modules can also be added as direct connections.

Analog I/O modules can be added only as direct connections.

Disable the Change of State (COS) feature on digital input modules because it can cause inputs to be sent more quickly than the RPI.

If you plan to add large amounts of I/O to the ControlNet network, dedicate one ControlNet network for I/O. For the dedicated ControlNet network,

verify that there is little or no:

•HMI traffic.

•MSG traffic.

• Programming workstations.

If the module has a Real Time Sample (RTS), disable it or set to a rate that is greater than the RPI.

Considerations for 1756-CN2, 1756-CN2R, 1756-CN2RXT Modules

You can add I/O modules until you reach these limits:

• 80% of CPU utilization of the 1756-CN2, 1756-CN2R, or 1756-CN2RXT communication module.

• Less than 400,000 unscheduled bytes per second are displayed in RSNetWorx™ for ControlNet software after the network has been scheduled.

Considerations for 1756-CNB, 1756-CNBR Modules

Requested Packet Intervals (RPIs) faster than 25 ms for unscheduled modules can overload the 1756-CNB or 1756-CNBR communication module.

To avoid the overload, make these considerations:

• Use a NUT of 10 ms or more.

• Keep the SMAX and UMAX values as small as possible.

You can add I/O modules until you reach these limits:

• 75% of CPU utilization of the 1756-CNB or 1756-CNBR communication module.

• Plan for a CPU-use increase of 1…4% of the 1756-CNB or 1756-CNBR module for each I/O module you add, depending on RPI.

• 48 connections on the 1756-CNB or 1756-CNBR communication module.

• Less than 400,000 unscheduled bytes per second are displayed in RSNetWorx for ControlNet software after the network has been scheduled.

EtherNet/IP network

The EtherNet/IP I/O modules that you add at runtime can be:

• Added to existing rack-optimized connections

• Added to new rack-optimized connections

• Added as direct connections (you can create rack-optimized connections when adding EtherNet/IP I/O modules at runtime)

You can add I/O modules until you reach the limits of the communication module:

1756-EN4TR,

1756-EN4TRXT Module

1756-EN2TR,

1756-EN3TR

1756-EN2T,

1756-EN2TP,

1756-EN2TXT,

1756-EN2F Module

1756-ENBT Module

5069-AENTR,

5094-AENTxx

COMPACT 5000 I/O

Ethernet Adapter

5069-AEN2TR

COMPACT 5000 I/O

Ethernet Adapter

• 50,000 pps without

CIP Security

• 25,000 pps with

integrity

• 15,000 pps with

integrity and

confidentiality

20,000 pps 10,000 pps 5000 pps

100,000 pps

(total number of

packets from both

Ethernet Ports)

100,000 pps

(total number of

packets from both

Ethernet Ports)

512 TCP connections 128 TCP connections 128 TCP connections 64 TCP connections 32 TCP Connections 32 TCP Connections

CIP™ connected

messages:

1000 I/O

528

(1)

256 CIP™ connected

messages

256 CIP connected

messages

128 CIP connected

messages

80 CIP Connected

Messages

320 CIP Connected

Messages

(1) There are 1000 explicit connections and 528 implicit connections.

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Chapter 9 Communicate with I/O

Online Addition of Module and Connection Types

Module Type and Connection

Method

In Local Chassis

Remote via an

EtherNet/IP Network

Remote via a ControlNet® Network

Configure Hold Last

Output State

Offline Runtime Offline Runtime

Offline Runtime

Offline only

Scheduled Unscheduled Scheduled Unscheduled

Digital - direct Yes Yes Yes Yes Yes Yes — Yes

Yes - 1756 I/O digital

output modules

Digital - rack-optimized — — Yes Yes Yes — Yes —

Yes - 1756 I/O digital

output modules

Analog - direct Yes Yes Yes Yes Yes Yes — Yes Yes

Generic third-party - direct Yes Yes Yes Yes Yes Yes — Yes —

1715 Redundant I/O — — Yes Yes — — — — —

1718/1719 I/O — — Yes Yes — — — —

Yes – both analog and

digital modules

1756-ENx - no connection Yes Yes Yes Yes — — — — —

1756-ENx - rack-optimized — — Yes Yes — — — — —

Generic EtherNet/IP third-

party - direct

—— YesYes — — — — —

1788-EN2FFR or

1788-EN2PAR

—— —— — — Yes Yes —

1788-CN2FFR or

1788-CN2PAR

—— YesYes No Yes — — —

1794 FLEX I/O — — Yes — Yes Yes — —

Yes - Analog output

modules only

1734 POINT I/O — — Yes — Yes Yes — — Yes

1734 POINT Guard I/O™ Yes — Yes — — — — — —

5069 Compact 5000 I/O Yes — Yes

Yes

(1)

—— —— Yes

5069 Compact 5000 I/O Safety

Modules

Yes — Yes — — — — — —

5094 FLEX 5000 — — Yes Yes — — — — Yes

5094 FLEX 5000 I/O Safety

Modules

— — Yes — — — — — Yes

(1) Only supported if adding an entire rack of Compact 5000 I/O modules.

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Chapter 9 Communicate with I/O

Design Considerations for Runtime/Online Addition of Modules

When you design your network, address these considerations to add modules at runtime.

Design Issue Considerations

I/O modules

If you plan to add 1756 I/O modules at runtime, leave space in the local chassis, remote

chassis on a ControlNet network, or remote chassis on an EtherNet/IP network for the I/O

modules you want to add.

Other modules

You can add 1757-FFLDC devices remotely via the unscheduled portion of a ControlNet

network at runtime.

Input transmission

rate

Make sure the RPIs work for the data you want to send and receive.

Make sure the added I/O does not depend on change of state data.

Network topology

On a ControlNet network, install spare taps so you can add modules at runtime without

disrupting the network. Each tap must be terminated not to ground out the system. Check

ControlNet system requirements to determine how many spare taps your network can

support.

• In a ControlNet network with redundant cabling, you can break the trunk and add a tap,

but redundant cabling is lost during the module installation.

• In a ControlNet ring, add a drop off the ring or add new nodes off the coax and disrupt

only part of the network.

• You could remove an existing node and add a repeater off that drop. Then reconnect the

existing node and add any new nodes off the new segment.

On an EtherNet/IP network, reserve some connection points on the switch so that you can

connect additional nodes or switches in the future.

Network

configuration

On a ControlNet network, plan which communication can be scheduled or unscheduled.

On an EtherNet/IP network, all communication is immediate and occurs based on the

module RPI (also referred to as unscheduled).

If you know that you need a new chassis with digital modules in the future, configure the

network and add it to the I/O configuration tree as rack optimized. Then inhibit the

communication adapter until you need the chassis.

Network

performance

You can add modules at runtime until you impact the capacity of the communication

module.

Make sure that you have sufficient communication modules for the connections you plan to

add.

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Chapter 9 Communicate with I/O

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 97

Chapter 10

Determine the Appropriate Network

EtherNet/IP™, ControlNet®, and DeviceNet® networks share a universal set of communication

services. These are the recommended networks for Logix control systems.

Follow these guidelines when planning a network.

Comparison EtherNet/IP Network ControlNet Network DeviceNet Network

Function

Plant management system tie-in (material

handling); configuration, data collection, and

control on a high-speed network

Supports transmission of time critical data

between PLC processors and I/O devices

Connects low-level devices directly to

plant-floor controllers—without

interfacing them through I/O modules

Typical devices networked

Mainframe computers

Programmable controllers

Robots

HMI

I/O

Drives

Process instruments

Programmable controllers

I/O chassis

HMIs

PCs

Drives

Robots

Sensors

Motor starters

Drives

PCs

Push buttons

Low-end HMIs

Barcode readers

PLC processors

Valve manifolds

Data repetition Large packets, data sent regularly

Medium-size packets; data transmissions

are deterministic and repeatable

Small packets; data is sent as needed

Number of nodes, max Network overall: no limit 99 nodes 64 total nodes

Data transfer rate 10 Mbps, 100 Mbps, or 1000 Mbps 5 Mbps 500 Kbps, 250 Kbps, or 125 Kbps

Typical use

Plant-wide architecture

High-speed applications

Redundant Applications

Safety Applications

Redundant applications

Scheduled communication

Supply power and connectivity to

low-level devices.

Design Issue Considerations

Network topology

Plan for future connections.

Plan for additional controllers and/or communication modules to handle future I/O modules.

Consider distances between devices.

Determine resiliency requirements.

Network configuration

On a ControlNet network, plan which communication can be scheduled or can be unscheduled.

On an EtherNet/IP network, all I/O communication is based on the RPI of the module.

Network performance

Make sure that you have sufficient communication modules for the connections you plan to use.

Use available network performance tools.

Chassis

Consolidate communication connections for multiple modules to one network node. Group digital I/O modules into a rack-optimized

connection to reduce the amount of communication and network bandwidth.

Input transmission rate

Make sure the RPIs work for the data you want to send and receive.

Make sure that I/O added at runtime does not depend on change of state data.

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Chapter 10 Determine the Appropriate Network

EtherNet/IP Network

Topology

This section features these controllers, and where applicable, the controllers are known as:

Controller Family Includes these controllers

5580 controllers ControlLogix® 5580 and GuardLogix® 5580 controllers

5380 controllers CompactLogix™ 5380 and Compact GuardLogix 5380 controllers

5570 controllers ControlLogix 5570 and GuardLogix 5570 controllers

5370 controllers CompactLogix 5370 and Compact GuardLogix 5370 controllers

EtherNet/IP Network Example Topologies

• An EtherNet/IP network supports messaging, produced and consumed tags, and

distributed I/O.

• An EtherNet/IP network with 5570 or earlier, and 5370 or earlier controllers supports

half-duplex/full-duplex, 10 Mbps or 100 Mbps operation.

• An EtherNet/IP network with 5580 or 5380 controllers supports full-duplex, 10/100/

1000 Mbps operation.

• An EtherNet/IP network requires no network scheduling.

• There are several methods available to configure EtherNet/IP network parameters

for devices. Not all methods are always available. These methods are device and

configuration dependent:

–DHCP

– Rockwell Automation® BOOTP/DHCP utility

– Programming software

– Studio 5000 Logix Designer® application

– RSNetWorx™ for EtherNet/IP software

–Web browser

–SNMP tools

Application Ideas

• Connectivity to commercial devices (such as cameras and phones)

• Business systems with remote access or sharing data

• Applications with motion or safety on the same network.

• Plant management (material handling)

• Configuration, data collection, and control on a high-speed network

• Time-critical applications with no established schedule

• Inclusion of commercial technologies (such as video over IP)

• Internet/Intranet connection

Ring with Switches

Linear

Star

Parallel

Redundancy

Protocol (PRP)

Device Level Ring

(DLR)

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Chapter 10 Determine the Appropriate Network

Guidelines for EtherNet/IP

Networks

ControlNet Network

Topology

Guideline Description

Use these publications.

• EtherNet/IP Network Devices User Manual ENET-UM006A-EN-P, publication ENET-UM006

• EtherNet/IP Device Level Ring Application Technique, publication ENET-AT007

• EtherNet/IP Design Considerations Reference Manual, publication ENET-RM002

Data transmission depends on the controller.

The type of controller determines the data transmission rate.

• ControlLogix controllers transmit data at the RPI you configure for the module.

• CompactLogix controllers transmit data at powers of 2 ms (such as 2, 4, 8, 16, 64, or 128). For example, if you

specify an RPI of 100 ms, the data actually transfers at 64 ms.

You can add I/O modules at runtime.

You can add I/O modules to remote chassis connected via an EtherNet/IP network to a running controller. You

can configure direct or rack-optimized connections. For more information, see Runtime/Online Addition of

Modules on page 93.

Data transmission rate depends on the RPI.

An EtherNet/IP network broadcasts I/O information to the controller based on the RPI setting. With change of

state (COS) enabled and:

• No data changes, the EtherNet/IP module produces data every RPI.

• Data changes, the EtherNet/IP module produces data at a maximum rate of RPI/4.

Select unicast EtherNet/IP communication whenever

possible.

To reduce bandwidth use and preserve network integrity, some facilities block multicast Ethernet packets.

Multicast is a more efficient method for transmitting data with multiple consumers and redundancy

applications.

You can configure multicast or unicast connections for:

• Produced and consumed tags by using the Logix Designer application

• I/O modules by using the Logix Designer application.

Unicast connections help with the following:

• Let produced and consumed tag communication span multiple subnets

• Reduce network bandwidth.

• Simplify configuration for EtherNet/IP network devices because of unicast default setting for the Logix

Designer application.

ControlNet Network Topology

• A ControlNet network lets both I/O and messaging on the same wire.

• Multiple controllers and their respective I/O can also be placed on the same

ControlNet wire.

• When new I/O is added, or when the communication structure on an existing I/O module

changes, you must use RSNetWorx for ControlNet software to reschedule the network.

• If the network timing changes, every device with scheduled traffic on the network

is affected.

• To reduce the impact of changes, place each CPU and its respective I/O on isolated ControlNet

networks.

• Place shared I/O and produced/consumed tags on a common network available to each CPU

that needs the information.

• Built-in redundant cabling supports I/O network and provides HMI switchover in redundant

ControlLogix system.

Application Ideas

• Default Logix network

• Best replacement for universal remote I/O

• Backbone to multiple distributed DeviceNet networks

• Peer interlocking network

• Common devices include: Logix 5000™ controllers, PanelView™ terminals, I/O modules, and

drives

Shared I/

I/O

I/O I/O

I/O

CPUCPU

ControlNet Network

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Chapter 10 Determine the Appropriate Network

Guidelines for ControlNet

Networks

Guideline Description

Use these publications.

• ControlNet Coax Media Planning and Installation Guide, publication CNET-IN002

• ControlNet Fiber Media Planning and Installation Guide, publication CNET-IN001

• ControlNet Network Configuration User Manual, publication CNET-UM001

Adjust the default RSNetWorx for ControlNet settings.

Change these settings in the RSNetWorx for ControlNet software:

• UMAX (highest unscheduled node on the network)

–Default is 99

– The network takes the time to process the total number of nodes that are specified in this setting, even if

there are not that many devices on the network

– Change to a reasonable level to accommodate the active network devices and additional devices that can

be connected

• SMAX (highest scheduled node on the network)

– Default is 1

– This must be changed for all systems

– Set SMAX < UMAX

Design for at least 400 KB of available, unscheduled

network bandwidth, as displayed by RSNetWorx for

ControlNet software.

Leaving too little bandwidth for unscheduled network communication results in poor message throughput and

slower workstation response.

Unscheduled data transfers on ControlNet occur asynchronous to the program scan and support a maximum of

510 bytes/node per ControlNet NUT.

Place DeviceNet (1756-DNB) communication modules in

the local chassis.

DeviceNet (1756-DNB) communication modules have multiple, 500-byte data packets that impact scheduled

bandwidth. Place these modules in the same chassis as the controller to avoid this data being scheduled over

the DeviceNet network.

If you must place these communication devices in remote chassis, configure the input and output sizes to match

the data that is configured in RSNetWorx for DeviceNet software. This reduces the amount of data that must be

transmitted.

Limit 1756-CNB, 1756-CNBR connections.

For best performance, limit the 1756-CNB, 1756-CNBR to 40…48 connections. Add additional 1756-CNB, 1756-CNBR

modules in the same chassis if you need more connections. To improve system performance, you can add more

modules and split connections among the modules.

If the chassis that contains the CNB module also contains multiple digital I/O modules, configure the CNB

communication format for Rack Optimization. Otherwise, use None.

As a cost savings measure, use 1756-CNB, 1756-CNBR modules in chassis that contain only I/O modules for

traditional adapter functionality. Use the 1756-CN2, 1756-CN2R, 1756-CN2RXT modules in the same chassis as the

controller for traditional scanner functionality.

For additional connections, consider the 1756-CN2,

1756-CN2R, 1756-CN2RXT modules.

The 1756-CN2/B, 1756-CN2R/B, 1756-CN2RTXT communication modules each support 131 connections, and have

higher performance than previous modules.

The 1756-CN2/A, 1756-CN2R/A communication modules each support 100 connections.

If you change network settings, resave each controller

project.

Any time that you edit the network with RSNetWorx for ControlNet software and you save or merge your edits,

connect to each controller in the system with their respective project file and perform a save and upload. This

copies the ControlNet settings into the offline, database file and makes sure that future downloads of the

controller permit it to go online without having to run RSNetWorx for ControlNet software.

You can add I/O modules at runtime.

You can add 1756 I/O modules and some drives to remote chassis connected via ControlNet to a running

controller. It is recommended to use a 1756-CN2/B, 1756-CNB2R/B, or 1756-CN2RXT module as the traditional

scanner in these applications.

Data transmission depends on the controller.

The type of controller determines the data transmission rate.

• ControlLogix controllers transmit data at the RPI you configure for the module.

• CompactLogix controllers transmit data at powers of 2 ms (such as 2, 4, 8, 16, 64, and 128). For example, if you

specify an RPI of 100 ms, the data actually transfers at 64 ms.

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Chapter 10 Determine the Appropriate Network

Guidelines for Unscheduled

ControlNet Networks

Guideline Description

You can run an entire ControlNet network as

unscheduled.

An unscheduled ControlNet network:

• provides for easier network configuration.

• is useful if your I/O updates needs are slower.

• supports the addition of 1756 I/O modules and some drives without placing the controller in Program mode.

• provides an HMI network with fast switchover times in a redundant controller system.

You must still run RSNetWorx for ControlNet software at least once to configure NUT, SMAX, UMAX, and media

configuration settings.

Plan appropriately if you place I/O on an unscheduled

ControlNet network.

Follows these recommendations for I/O on an unscheduled ControlNet network:

• A 1756-CN2, 1756-CN2R Series B or later, or a 1756-CN2RXT is recommended.

• Disable the Change of State (COS) feature on digital input modules because it can cause inputs to be sent

faster than the RPI.

• Set the real-time sample (RTS) on analog cards slower than the RPI

• Dedicate a ControlNet network to I/O only.

• Do not exceed 80% utilization of a 1756-CN2, 1756-CN2R, 1756-CN2RXT communication module.

• Do not exceed 75% utilization of a 1756-CNB, 1756-CNBR communication module.

• Have no more than 48 connections on the 1756-CNB, 1756-CNBR communication module.

• Use a NUT of 10 ms or more.

• Keep the SMAX and UMAX values as small as possible.

1756-CNB, 1756-CNBR only

Set the RPI at 25 ms or slower.

Use RPI of 25 ms or slower for unscheduled modules to avoid overload on the 1756-CNB, 1756-CNBR

communication module. Depending on the RPI, the communication module loading increases 1…4% for each I/O

module added.

1756-CNB, 1756-CNBR only

The RPI affects how many I/O modules you can have.

This chart shows the number of modules and associated RPIs so that you do not exceed 75% utilization of the

1756-CNB, 1756-CNBR communication module.

Additional 1756-CNB, 1756-CNBR Loading

RPI (ms)

Additional CNB Loading %

Maximum Number of I/O Modules in an Unscheduled Network

RPI (ms)

Number of Unscheduled Modules

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Chapter 10 Determine the Appropriate Network

Compare Scheduled and

Unscheduled ControlNet

Communication

DeviceNet Network

Topology

Scheduled ControlNet Communication Unscheduled ControlNet Communication

Deterministic

Less deterministic than scheduled communication

Provides simpler ControlNet installations when scheduled networks are not

required

To add scheduled I/O on the ControlNet network, you must:

• Add the I/O to an offline controller project.

• Download the project to the controller.

• Run RSNetWorx to schedule the network requires network to be scheduled (must

stop the network and put the controller in Program mode to schedule a network).

• Save the controller project.

Can be changed online without impacting the schedule

New modules can affect other modules communicating via unscheduled bandwidth

Supports 1756 I/O modules and some drives

RPI and NUT determine module communication rates RPI determines module communication rates

MSG and HMI traffic can occur on the same network because they are isolated in

unscheduled traffic

MSG and HMI traffic do not affect I/O communication

Recommend 1756-CN2, 1756-CN2R, 1756-CN2RXT

Recommend a dedicate ControlNet network for only I/O modules

MSG and HMI traffic can affect I/O communication

Direct and rack-optimized connections to I/O

Only direct connections to I/O (results in being able to use fewer total I/O modules

because of the connection limits of controllers and communication modules)

Supports any firmware revision of a ControlNet communication module

You can use any 1756-CN2, 1756-CN2R, 1756-CN2RXT communication module

If you use a 1756-CNB, 1756-CNBR communication module, it must be series D or

later

Supports any I/O platform that can communicate via a ControlNet network Supports only 1756 I/O modules

DeviceNet Network Topology

• You need a DeviceNet scanner to connect the controller

to DeviceNet devices.

• You must use RSNetWorx for DeviceNet software to

configure devices and create the scanlist for the

scanner.

• You can configure the network communication rate as

125 Kbps (default and a good starting point), 250 Kbps, or

500 Kbps.

• If each device on the network (except the scanner) sends

 4 bytes of input data and receives  4 bytes of output

data, you can use AutoScan to configure the network.

Application Ideas

• Distributed devices

•Drives network

• Diagnostic information

Device Device Device Device

Single Network

Device

ScannerCPU

Device

Linking

Device

Device Device

CPU

Device

Linking

Device

Device Device

Several Smaller Distributed Networks (Subnets)

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 103

Chapter 10 Determine the Appropriate Network

Guidelines for DeviceNet

Networks

Guideline Description

Use these publications.

• DeviceNet Cable System Manual, publication DNET-UM072

• DeviceNet Network Configuration User Manual, publication DNET-UM004

Use the DeviceNet Tag Generator tool.

The Logix Designer application includes a DeviceNet tag generator tool that creates device-specific structured tags

and logic based on the network configuration in RSNetWorx for DeviceNet software.

The logic copies data to and from the DNB data array tags to the device tags so that data is presented

synchronously

to program scan.

Place DeviceNet (DNB) communication modules in

the local chassis.

Place DNB modules in the local chassis to help maximize performance, especially in ControlLogix systems.

Size the input and output image for the DNB modules to the actual devices that are connected plus 20% for future

growth. If you have to place DNB modules in remote chassis, sizing the input and output images is critical for best

performance.

Verify that the total network data does not exceed

the maximum DNB data table size.

A DNB supports:

• 124, 32-bit input words.

• 123, 32-bit output words.

• 32, 32-bit status words.

You can use RSNetWorx for DeviceNet software offline to estimate network data. Use a second DNB if there is more

network data than one module can support.

Configure slaves first.

Configure device parameters before adding that device to the scanlist. You cannot change the configuration of

many devices once they are already in the scanlist.

If you configure the scanner first, there is a chance that the scanner configuration cannot match the current

configuration for a device. If the configuration does not match, the device does not show up when you browse the

network.

Leave node address 63 open to add nodes.

Devices default to node 63 out-of-the-box. Leave node address 63 unused so you can add a new device to the

network. Then change the address of the new device.

Leave node address 62 open to connect a computer.

Always leave at least one open node number to let a computer be attached to the network if needed for

troubleshooting or configuration.

Don’t forget to set the scanner run bit.

For the scanner to be in Run mode, the controller must be in Run mode and the logic in the controller must set the

scanner run bit.

Make sure that you have the most current EDS files

for

your devices.

RSNetWorx for DeviceNet software uses EDS file to recognize devices. If the software is not properly recognizing a

device, you are missing the correct EDS files. For some devices, you can create an EDS file by uploading information

from the device. Or you can get EDS files from: http://www.ab.com/networks/eds

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Chapter 10 Determine the Appropriate Network

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 105

Chapter 11

Communicate with Other Devices

The MSG instruction asynchronously reads or writes a block of data to another device.

Cache Messages Some types of messages use a connection to send or receive data. Some also give you the

option to either leave the connection open (cache) or close the connection when the message

is done transmitting. This table shows messages that use a connection and whether you can

cache the connection.

A cached connection remains open until one of the following occurs:

• The controller goes to Program mode.

• You rerun the message as uncached.

• Another message is initiated and a cached buffer is needed.

• An intermediate node in the connection goes down.

If the target device is a Select one of these message types

Logix 5000™ controller

CIP™ Data Table Read

CIP Data Table Write

I/O module that you configure with the Studio 5000 Logix

Designer® application

Module Reconfigure

CIP Generic

SERCOS drive

SERCOS IDN Read

SERCOS IDN Write

PLC-5® controller

PLC5 Typed Read

PLC5 Typed Write

PLC5 Word Range Read

PLC5 Word Range Write

SLC™ controller

MicroLogix™ controller

SLC Typed Read

SLC Typed Write

Block transfer module

Block Transfer Read

Block Transfer Write

PLC-3® processor

PLC3 typed read

PLC3 typed write

PLC3 word range read

PLC3 word range write

PLC-2® processor

PLC2 unprotected read

PLC2 unprotected write

Message Type Communication Method Uses Connection Can Cache Connection

CIP data table read or write CIP Yes Yes

PLC2, PLC3, PLC5, or SLC (all types)

CIP

CIP with Source ID

DH+™ Yes Yes

CIP generic N/A

Your option

(1)

(1) You can connect CIP generic messages, but for most applications we recommend that you leave CIP generic messages

unconnected.

Your option

(1)

Block transfer read or write N/A Yes Yes

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Chapter 11 Communicate with Other Devices

Message Buffers The controller has buffers for unconnected messages and for cached messages. Buffers store

incoming and outgoing message data until the controller can process the data.

MSG and Block Transfer

Instructions

Communication Handler

Data To and From

the Controller

Incoming

Outgoing

Unconnected

Buffers

Controller

Connections

(Buffers)

Open/Close Connections

CIP Generic MSG

Unconnected MSG

Uncached Connected CIP MSG or Block Transfer

Cached Connected

MSG or Block Transfer

Cache Buffers

MSG Buffers

BT Buffers

Buffer Description

Outgoing, connected

The outgoing unconnected buffers are for:

• Establishing I/O connections to local I/O modules and remote devices on ControlNet®, EtherNet/IP™, and

remote I/O networks.

• Executing unconnected PLC2, PLC3, PLC5, or SLC (all types) messages over Ethernet/IP or ControlNet

(CIP and CIP with Source ID) networks.

• Initiation of messaging over a DH+™ network (uses 2 buffers, one to open the connection and one to transfer

data).

• Initiation of uncached block transfers.

• Initiation of uncached CIP read/write message instructions.

• Initiation of cached block transfers.

• Initiation of cached CIP read/write messages instructions.

• CIP Generic message instructions.

Incoming,unconnected

The incoming unconnected buffers:

• Initially receive a cached CIP message instruction.

• Receive an uncached CIP message instruction.

• Receive a message over a DH+ network.

• Receive a CIP Generic message instruction.

• Receive a read or write request from a ControlNet PanelView™ terminal (unconnected messaging).

• Initially receive of a read request from an EtherNet/IP PanelView terminal (connected messaging).

• Receive a write request from an EtherNet/IP PanelView terminal (unconnected messaging).

• Receive an initial request from the Logix Designer application to go online.

• Initially receive Linx-based connections.

Cached buffers

The cached buffers are outgoing buffers for messages and block transfers. A cached connection helps message

performance because the connection is left open and does not need to be re-established the next time that it is

executed. A cached connection counts towards the total limit of connections for a controller. A cached connection

is refreshed at the connection RPI. All cached entries are closed when the controller transitions to Program mode.

The first time a cached message is executed, it uses one of the outgoing unconnected buffers. When the

connection is established, it moves into the cached buffer area.

For optimum performance, do not cache more messages or block transfers than there are cached buffers. If you

cache more than the available cached buffers, the controller looks for a connection that has been inactive for the

longest time, closes that connection, and lets a new connection take its place. The controller closes a cached

message or block transfer, depending on which has been inactive the longest. If all cached connections are in use,

the message is executed as connected and, once it is completed, the connection is closed.

You can multiplex cached connections. If a connection is inactive and a message instruction executes that has the

same target and path, it uses that inactive connection. For example, if you have a block transfer read and write to

the same module, interlock the read and write so that only one is active at a time. Then when they are cached, they

use the same cached connection.

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 107

Chapter 11 Communicate with Other Devices

Outgoing Unconnected Buffers

Guidelines for Messages

Guidelines to Manage

Message Connections

IMPORTANT This section does not apply to 5380, 5480, or 5580 controllers.

Buffers Use

1…10

The first 10 buffers (default) are shared for unconnected messaging, initiating connected messaging, establishing I/O

connections, and establishing produced/consumed connections.

11 The 11th buffer is dedicated to establishing I/O and produced/consumed connections.

12…40

The 12th to the 40th buffers are used only for initiating connected messages and executing unconnected messages.

To increase the outgoing buffers to a value higher than 11, execute a CIP generic message to configure that change

each time you transition from Program mode to Run mode.

Guideline Description

Message tags may be created at controller scope or

program scope.

The operating system accesses the information in a message tag asynchronously to the program scan. Along with

the visible fields within the message tag, there are hidden attributes that are only referenced by the background

operating system.

You can use a message to send a large amount of data.

Even though there are network packet limitations (such as 500 bytes on ControlNet and 244 bytes on DH+), the

controller can send a large amount of data from one MSG instruction. When configuring the message, select an

array as the source/destination tags and select the number of elements (as many as 32,767 elements) you want to

send. The controller automatically breaks the array into small fragments and sends all of the fragments to the

destination. On the receiving side, the data appears in fragments, so some application code can be required to

detect the arrival of the last piece.

Do not manipulate the message status bit

Do not change the following status bits of a MSG instruction:

•DN

•EN

•ER

•EW

•ST

Do not change those bits either by themselves or as part of the FLAGS word. If you do, the controller can have a

nonrecoverable fault. The controller clears the project from its memory when it has a nonrecoverable fault.

Guideline Description

Create user-defined structures or arrays.

User-defined structures let you organize your data to match your machine or process.

• One tag contains all data that is related to a specific aspect of your system. This keeps related data together and

easy to locate, regardless of its data type.

• Each individual piece of data (member) gets a descriptive name. This automatically creates an initial level of

documentation for your logic.

• You can use the structure to create multiple tags with the same data layout.

• Linx-based software can optimize user-defined structures more than standalone tags.

Cache connections when appropriate.

If a message executes repeatedly, cache the connection. This keeps the connection open and optimizes execution

time. You can increase execution time if you open a connection each time the message executes.

If a message executes infrequently, do not cache the connection. This closes the connection upon completion of the

message, which frees up that connection for other uses.

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Chapter 11 Communicate with Other Devices

Guidelines for Block

Transfer Messages

Map Tags

A Logix 5000™ controller stores tag names on the controller so that other devices can read or

write data without having to know physical memory locations. Many products only understand

PLC/SLC data tables, so the Logix 5000 controller offers a PLC/SLC mapping function that lets

you map Logix tag names to memory locations.

• You only have to map the file numbers that are used in messages; the other file

numbers do not need to be mapped.

• The mapping table is loaded into the controller and is used whenever a logical address

accesses data.

• You can only access controller-scoped tags (global data).

Follow these guidelines when you map tags.

• Do not use file numbers 0, 1, and 2. These files are reserved for Output, Input, and Status

files in a PLC-5 processor.

• Use PLC-5 mapping only for tag arrays of data type INT, DINT, or REAL. Attempting to

map elements of system structures can produce undesirable effects.

• Use these file types and identifiers.

Guideline Description

Distribute 1771 analog modules across multiple chassis.

To reduce the number of block transfers that one 1771-ACN or 1771-ASB module manages, distribute 1771 analog

modules across multiple chassis.

Isolate different 1771 chassis on different networks.

When you isolate different chassis onto different networks, it diversifies the communication so that no single

network or communication module has to deal with all communication.

Increase ControlNet unscheduled bandwidth.

If you communicate over a ControlNet network, increase the amount of ControlNet unscheduled bandwidth to

permit additional time on the network for data exchange.

See Compare Scheduled and Unscheduled ControlNet Communication on page 102

for more information about

unscheduled bandwidth on a ControlNet network.

Increase the system overhead timeslice percentage on

ControlLogix® 5570 or earlier and CompactLogix™ 5370

or earlier controllers.

Increase the system overhead timeslice to allocate more CPU time to communication processing from the

continuous task.

Interlock block transfer read and write messages to the

same module.

Programmatically interlock block transfer read and write messages to the same module so that both operations

cannot be active simultaneously.

Use the 1756-RIO module for systems with a high number

of block transfer modules.

The 1756-RIO module provides connectivity from a ControlLogix chassis to 1771 I/O and other modules that are

connected via remote I/O. The 1756-RIO module off-loads the burden of performing block transfers from the

controller and increases the number of block transfer operations that can be performed.

For this Logix 5000 array type Use this PLC file identifier

INT array N or B

DINT array L

REAL array F

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 109

Chapter 12

Alarms

The following options are available for alarms.

Alarm Option Description

FactoryTalk® Alarms and Events

The FactoryTalk Alarms and Events system integrates alarming between FactoryTalk View SE applications and the

controllers by embedding an alarming engine in the controllers.

• Uniform, micro-second accurate, time stamps determined at the alarm source

• Server-client model so all clients get the updates simultaneously

• Single connection to controller

• Combines all alarms in the system into one uniform view

• Supports ControlLogix®, CompactLogix™, SLC™, PLC-5®, and non-Rockwell Automation controller

For more information, see FactoryTalk Alarms and Events Configuration Guide, FTAE-RM001

Controller tag-based alarms

Tag-based alarms monitor a tag value to determine the alarm condition. Tag-based alarms are not part of the

logic program and do not increase the scan time for a project.

• Alarms defined on tags with periodic evaluation

• Standards-based design

• Leverages existing FactoryTalk Alarms and Events infrastructure

Only 5380 and 5580 controllers support tag-based alarms.

Controller instruction-based alarms

Instruction-based alarms are generated and maintained by using an instruction in a Logix controller. Two Logix-

based alarm instructions that are available in relay ladder, structured text, and function block diagram.

• The Digital Alarm (ALMD) instruction detects alarms that are based on Boolean (true/false) conditions.

• The Analog Alarm (ALMA) instruction detects alarms that are based on the level or rate of change of analog

values.

Alarm instructions and their specific data types consume a larger portion of controller memory and scan time

than tag-based alarms.

• Alarms are detected at the same time logic is executed

• Alarms events are buffered in controller memory

• Alarms events are pushed to the HMI only on state changes

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Chapter 12 Alarms

Guidelines for Tag-Based

Alarms

Tag-based alarms are useful when you want to maximize controller scan time and when you

want to integrate alarms with legacy or third-party devices.

Access Tag-based Alarms

Instructions can access the members of the following tag-based alarms:

• Alarm conditions that are associated with controller tags.

• Alarm conditions that are associated with local scalar tags, input parameters, output

parameters, or public parameters within the same program.

• Alarm conditions that are associated with input, output, or public parameters of other

programs.

• Alarm definitions that are associated with local tags, input parameters, or output

parameters of an Add-On Instruction.

• Alarm definitions that are associated with local tags, input parameters, or output

parameters of nested Add-On Instructions.

Instructions can access the following alarm sets or members of alarm sets:

• Alarm sets that are associated with the controller or with a program.

• Alarm sets that are associated with controller tags.

• Alarm sets that are associated with local tags, input parameters, output parameters, or

public parameters within the same program.

• Alarm sets that are associated with local tags, input parameters, output parameters, or

public parameters of other programs.

• Alarm sets that are associated with input, output, or public parameters in other

programs.

• Alarm sets that are associated with local tags, input parameters, or output parameters

of an Add-On Instruction.

• An alarm condition or an alarm set of an input, output, or public parameter in another

program.

• Alarm sets that are associated with local tags, input parameters, or output parameters

of nested Add-On Instructions.

Guideline Description

An alarm definition is associated with an Add-On

Instruction (AOI) or a defined data type.

When a tag is created using a data type or an AOI that has alarm definitions, alarms are created automatically

based on the alarm definitions.

You can create an alarm definition for the following components:

• Tag or parameter of an AOI.

• Member of a user-defined data type (UDT)

• Member of a system-defined data type

• Member of a module-defined data type

When a tag uses a data type that has alarm definitions that are associated with it, alarm conditions are

automatically added for the tag based on its alarm definitions.

When an AOI is based on an AOI definition, alarm conditions are automatically added for the AOI instance based

on the alarm definitions that are associated with the AOI definition.

Use the keyword THIS to create modular logic to access

alarm attributes

When the logic executes, the controller replaces THIS with the name of a program, controller, or Add-On

Instruction. The keyword THIS lets you create a logic module that can be inserted in any project on any controller

and still execute correctly. Use ::THIS to represent a controller name, \THIS to represent a program name, and

THIS to represent the name of an Add-On Instruction.

Access individual alarm attributes

Use tag-based alarm attributes as operands in instructions to access tag-based alarm attributes or attributes

from a set of alarms. For example, the alarm set for a controller, program, or for instances of an Add-On

Instruction.

Access alarm set attributes Use alarm set attributes as operands in instructions to access the attributes.

Access individual alarm attributes in Add-On Instruction

definitions

Use individual alarm attributes as operands in Add-On Instruction (AOI) definitions to access the attributes of

alarms that are associated with local tags, input parameters, or output parameters within the same AOI instance.

Access attributes from Add-On Instruction alarm sets

The alarms contained in an Add-On Instruction (AOI) definition, a structured tag of an AOI definition, or an array

tag of an AOI definition can be referenced as an alarm set. Use these alarm set attributes as operands in logic.

When you reference an attribute from an individual alarm, you insert the owner of the alarm in the operand

syntax. Similarly, when you reference an attribute from an AOI alarm set, you insert the alarm set container (the

AOI definition, AOI structured tag, or AOI array tag) in the operand syntax.

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Chapter 12 Alarms

Instruction cannot access the members of the following tag-based alarms:

• Alarm conditions that are associated with local tags in other programs.

• Alarm definitions that are associated with the parent Add-On Instruction.

• Alarm definitions that are associated with tags or parameters of the parent Add-On

Instruction.

Instruction cannot access the members of the following alarm sets:

• Alarm sets that are associated with local tags in other programs.

• Alarm sets that are associated with the parent Add-On Instruction.

• Alarm sets that are associated with tags or parameters of the parent Add-On

Instruction.

Instructions cannot access the following alarm attributes:

• Evaluation period, alarm condition types, and expressions.

• Time-related attributes that have LINT data types.

• Attributes that have STRING data types.

• Reference type attributes, such as associate tags, target tags, and input tags.

Guidelines for

Instruction-based Alarms

Instruction-based alarms are useful when you want timestamps on alarm or you want to

integrate alarms without modifying the HMI displays.

Guideline Description

Estimate increased controller memory use for each

alarm.

The alarm instructions use new alarm data types that contain state information and time stamps for each alarm.

Estimate this memory use in the controller:

• 2 KB per FactoryTalk Alarms and Events subscriber that receives alarms from the controller

• There is a maximum of 16 subscribers per controller. Most applications only require one subscriber to a

controller to provide data to many FactoryTalk View SE clients.

• 2.2 KB per alarm (typical), depends on use of associated tags

Alarm instructions increase total controller scan time.

The ALMD instructions and ALMA instructions affect total scan time. See Logix 5000™ Controllers Instruction

Execution Time and Memory Use Reference Manual, publication 1756-RM087

for execution times for your

controller firmware.

An alarm state change is any event that changes the condition of the alarm, such as acknowledgment or

suppression of the alarm. Creating dependencies on related alarms to minimize the potential for many alarms to

change state simultaneously (alarm bursts). Large alarm bursts can have a significant impact on application

code scan time.

IMPORTANT: In redundancy systems, consider scan time impact due to crossloading alarm tag data. For more

information, see the ControlLogix 5580 Redundant Controller User Manual, publication 1756-UM015.

You can edit or add an alarm instruction online.

Online edits of new and existing alarms are automatically sent to the subscribers. You do not have to re-

subscribe to receive the updated information. Online changes automatically propagate from the controller alarm

structure to the rest of the architecture.

In relay ladder, how you define the alarm values on the

instruction determines whether you can access those

values programmatically through the alarm structure.

When you create an alarm instruction, you also create an alarm data type for that alarm. For example,

MyDigitalAlarm of data type DigitalAlarm. In relay ladder, the following values are shown on the instruction:

•ProgAck

•ProgReset

• ProgDisable

•ProgEnable

If you enter a value or assign a tag to these faceplate parameters (such as AckSection1All), the value or tag value

is automatically written to the alarm structure each time the instruction is scanned.

If you want to programmatically access the alarm structure, you must assign the structure tag to the faceplate.

For example, to use MyAnalogAlarm.ProgAck in logic, assign the tag MyAnalogAlarm.ProgAck on the faceplate to

the ProgAck parameter.

Test alarm behavior from within the Logix Designer

application.

On the Status tab of the alarm dialog, monitor the alarm condition, acknowledge an alarm, disable an alarm,

suppress an alarm, or reset an alarm. Use the dialog selections to see how an alarm behaves, without needing an

operational HMI.

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Chapter 12 Alarms

Configure Logix-based

Alarm Instructions

Reduce mistakes by making sure that alarms are

noticed.

Shelving an alarm removes the alarm from the operator view for a period of time. It is like suppressing an alarm,

except that shelving is time-limited. If an alarm is acknowledged while it is shelved, it remains acknowledged

even if it becomes active again. It becomes unacknowledged when the shelve duration ends provided the alarm

is still active at that moment.

Increase productivity by eliminating nuisance alarms.

Set a duration (ms) on the ALMA instruction to specify how long an alarm condition must exist before being

reported.

Apply the duration to individual, analog alarm levels.

High availability of alarm data helps reduce material

losses.

Previous to revision 31, the alarm log in the controller stores the last 10,000 alarm state transitions in a circular

log. This replaces the alarm buffer in controllers with firmware earlier than revision 21.

Guideline Description

Option Description

Message string

The message string (maximum of 255 characters, including embedded text) contains the information to display to the

operator regarding the alarm. Besides entering text, you can also embed variable information. In the alarm message

editor, select the variable that you want and add it anywhere in the message string.

You cannot programmatically access the alarm message string from the alarm tag. To change the alarm message

based on specific events, configure one of the associated tags as a string data type and embed that associated tag in

the message.

You can maintain alarm messages in multiple languages. Either enter the different languages in the associated

language versions of the Logix Designer application or in an import/export (.CSV or .TXT) file.

Associated tags

You can select as many as four additional tags from the controller project to associate with the alarm. These tags are

sent with an alarm message to the alarm server. Associated tags can be BOOL, INT, SINT, DINT, REAL, or string data

types. For example, a digital alarm for a pressure relief valve can also include information such as pump speed and

system pressure, and tank temperature.

Optionally, embed the associated tags into the message text string.

Severity

Use the configurable severity range from 1…1000 to rank the importance of an alarm. A severity of 1 is for low-priority

alarms; a severity of 1000 is for an emergency condition.

You can configure how the FactoryTalk ranges are presented to the operator. The operator can also filter on alarm

levels. For example, a maintenance engineer can filter to see only those alarms at severity 128.

Alarm class

Use the alarm class to group related alarms. Specify the alarm class the same for each alarm you want in the same

class. The alarm class is case-sensitive.

For example, specify class Control Loop to group all alarms for PID loops.

You can then display and filter alarms at the HMI based on the class. For example, an operator can display all tank

alarms or all PID loop alarms.

The alarm class does not replace subscription to specific alarms. The FactoryTalk View SE Alarm object graphics have

configuration options to determine which controller alarms an operator sees.

View command

Execute a command on the operator station when requested by an operator for a specific alarm. This lets an operator

execute any standard FactoryTalk View command, such as call specific faceplates and displays, execute macros,

access help files, and launch external applications. When the alarm condition occurs and is displayed to the operator, a

button on the summary and banner displays lets the operator run an associated view command.

Defaults

The Parameters tab of the alarm instruction properties lets you define values for instruction parameters. You can

return the parameters to factory defaults and you can define your own set of instruction defaults. The instruction

defaults you assign are defaults for only that instance of the instruction.

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Chapter 12 Alarms

Automatic Diagnostics Automatic Diagnostics provide device diagnostics to HMIs and other clients, with zero

programming. You need:

• ControlLogix 5580, GuardLogix 5580, CompactLogix 5380, Compact GuardLogix 5380, or

CompactLogix 5480 controller with firmware revision 33 or later.

• FactoryTalk View SE version 12 or later to add the Automatic Diagnostic object to

FactoryTalk View displays. See the FactoryTalk View Site Edition User's Guide,

publication VIEWSE-UM006

• FactoryTalk Alarms and Events version 6.20 or later to subscribe to the diagnostic

messages created in the controller. See the FactoryTalk Alarms and Events System

Configuration Guide, publication FTAE-RM001

The diagnostics include device description conditions and state events. Diagnostics based on

the device definition (such as fault or open wire) are sent to a compatible Rockwell Automation

HMI device or software, and displayed on the Automatic Diagnostic Event Summary object.

Automatic Diagnostics is enabled by default with firmware revision 33.00 or later. You can

disable and enable the whole feature while online or offline from the Controller Properties

dialog box. You can also disable Automatic Diagnostics for a specific device in the device’s

configuration.

When Automatic Diagnostics is enabled, there is little impact to device and network

performance.

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Chapter 12 Alarms

Notes:

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 115

Chapter 13

Optimize an Application for Use with HMI

Rockwell Automation offers these HMI (human machine interface) platforms.

Software products that provide plant-floor device connectivity for HMI applications include:

•RSLinx® Classic software

• FactoryTalk Linx software (formerly RSLinx Enterprise)

Linx-based Software Use of

Controller Memory

The amount of memory that Linx-based software needs depends on the type of data Linx-

based software reads. These equations provide a memory estimate.

You can consolidate tags into an array or a structure to reduce the communication overhead

and the number of connections that are used to obtain the data.

Platform Description

PanelView™ 5000 terminal Dedicated, machine-level HMI running Studio 5000 View Designer® software

PanelView Plus terminal

Dedicated, machine-level HMI running FactoryTalk® View Machine Edition

software

FactoryTalk® View software

Product family that consists of:

• FactoryTalk View ME (Machine Edition) software for an open, machine-level

HMI; also runs on PanelView Plus terminals

• FactoryTalk View Site Edition Station software for a single-workstation,

supervisory-level HMI

• FactoryTalk View Site Edition distributed software for a multi-server,

multi-client, supervisory-level HMI"

IMPORTANT This topic does not apply to 5380, 5480, or 5580 controllers.

Linx-based software overhead (per

connection)

_____ * 1345 = ___ bytes (four connections by default)

Individual tags _____ * 45 = ___ bytes

Arrays / structures _____ * 7 = ___ bytes

Total = ___ bytes

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Chapter 13 Optimize an Application for Use with HMI

HMI Implementation Options

Most third-party HMIs are limited to direct communication similar to the multiple HMI method.

Guidelines for FactoryTalk

View Software

For the latest information on guidelines for FactoryTalk View Site Edition Software, see the

Knowledgebase Technote FactoryTalk View SE Distributed System Design Considerations.

How a Data Server

Communicates with the

Controllers

Linx-based software acts as a data server to optimize communication to HMI applications.

Linx-based software groups data items into one network packet to reduce:

• The number of messages that are sent over the network.

• The number of messages a controller processes.

1. When Linx-based software first connects to a controller, it queries the tag database and

uploads definitions for all controller-scoped tags. If there are multi-layer, user-defined

structures that are controller-scoped, Linx-based software just queries the upper layer.

2. When the HMI client requests data, Linx-based software queries the definitions for

program-scoped tags and the lower layers of multi-layer user-defined structures.

3. Linx-based software receives requests for data items from local or remote HMI/EOI

clients and combines multiple requests in optimized packets. Each data item is a

simple Logix tag, array, or user-defined structure. Each optimized packet can be as

large as 480 bytes of data and can contain one or more data items.

4. The controller allocates unused system memory to create an optimization buffer to

contain the requested data items.

- One optimization buffer can contain as much data as can fit into one 480-byte

packet (optimization is limited to 480 bytes).

- If you use the Logix Designer application to monitor controller RAM, you can see used

memory increase. (Note that this does not apply to 5380, 5480, or 5580 controllers.)

- The controller creates an optimization buffer for each Linx-based optimization

packet in the scan.

Method Benefits Considerations

Single HMI

• All HMI/EOI support this method

• Limited number of controller connections

• No server to configure and manage

• Local control and monitoring

• Single point of failure for visualization

• Only one person can monitor one display at a time

Multiple, Independent HMI

• All HMI/EOI support this method

• The same HMI screens can be viewed at multiple stations

• Multiple people can monitor different parts of system

simultaneously

• Each HMI gets its own data

• No central server to configure and manage

• Local control and monitoring

• More controller connections are required

• Additional burden on controller to service all communication

(controller resource impact)

• No sharing of data except through the controller

• Adding additional HMIs has larger increase on system

Client/Server HMI

• The same HMI screens can be viewed at multiple stations

• Server provides data to multiple clients

• Fewer controller connections required

• Impact on system is smaller than with multiple HMIs

• Administer application at the server, not individually at the

clients or multiple, independent HMIs

• Server is a point of failure for all HMIs, unless you implement

redundancy

• Little communication overhead savings if each client wants

different data

• Networking knowledge that is required

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 117

Chapter 13 Optimize an Application for Use with HMI

Compare RSLinx Classic

and FactoryTalk Linx

Software

The Logix Designer application defaults to RSLinx Classic software. With version 31 or later,

you can configure the Logix Designer application to use RSLinx Classic or FactoryTalk Linx

software.

Optimized Array Tags

Standalone Tags

Tags on Scan in Linx-based Software

Kbytes of Memory Needed

Comparison RSLinx Classic Software

FactoryTalk Linx Software

(1)

Supported platforms

Microsoft® Windows operating systems. For the latest information regarding software platform support, see the Product Compatibility and

Download Center: http://www.rockwellautomation.com/global/support/pcdc.page

Data server

OPC data server

Preferred data server for PLC/SLC platforms and applications that

require complex network routings

Maximum 10 clients per data server

Factory Talk Live data server

Preferred data server for Logix 5000™ platforms

Maximum 20 clients per data server

PLC/SLC systems Maximum 20 controllers per data server via an Ethernet network Maximum 20 controllers per data server via an Ethernet network

Logix 5000 systems

Maximum:

• 10 controllers per data server via an Ethernet network

• 10,000 active (on-scan) tags per data server

• Three RSLinx data servers per controller

Maximum:

• 20 controllers per data server via an Ethernet network

• 20,000 active (on-scan) tags per data server

• Three FactoryTalk Linx data servers per controller

User interface and event logs Yes

• Available user interfaces are FactoryTalk Studio software and

FactoryTalk Administration Console software

• Event logs are available with FactoryTalk Diagnostics software

Benefits

• Supports topic switching with redundant ControlLogix® system

• Supports user-defined tag optimization

• RSLinx Gateway software consolidates multiple HMI requests to

reduce network traffic

• Works with an integrated OPC server

• Automatically handles Logix tag changes

• FactoryTalk Live Data software consolidates multiple HMI

requests to reduce network traffic

Considerations

• Requires HMI to be restarted if a Logix 5000 controller is reloaded

with changes to tags on scan

• Default is four connections for a read and one connection for a write

• Supports redundant shortcut paths to primary and secondary

ControlLogix redundancy pairs. For more information, see

ControlLogix 5580 Redundant Controller User Manual, publication

1756-UM015

• Optimization is limited to array tags

• FactoryTalk Gateway software provides OPC support

• Default is four connections for a read and one connection for a

write

(1) With version 6.00, RSLinx Enterprise is known as FactoryTalk Linx.

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Chapter 13 Optimize an Application for Use with HMI

Guidelines for Linx-based

Software

Guidelines to Configure

Controller Tags

Reference Controller Data from FactoryTalk View Software

This table shows how to reference data in a FactoryTalk View tag address.

When addressing a Logix 5000 string tag, use the address syntax

[OPC_Topic]StringTag.Data[0],SC82 to address a SINT array. The string data is stored in the

SINT array .Data of the string tag, and you address the first element of this array (.Data[0]).

The maximum number of characters in a STRING tag is 82. If you need more characters, then

create your own user-defined structure to hold the characters.

To write data into a Logix 5000 string tag from an HMI or external source, set the L.EN field to

indicate the number of characters that are in the string. The Logix Designer application and

the controller use the .LEN value to determine how many characters are present.

Guideline Description

Use Linx-based software as the data server for multiple

HMIs.

For multiple HMI stations:

• Leverage remote OPC (RSLinx Classic software) or FactoryTalk software (FactoryTalk Linx software) for data

collection.

• Only the RSLinx data server is expected to have an active topic.

• Do not configure or use topics on the HMI stations.

• Linx-based software does not need to be on the HMI stations.

Do not use too many RSLinx stations.

The performance of tag collection decreases as the more RSLinx stations collect data from the same controller.

Use an RSLinx Gateway station and have the other data collection stations use remote OPC for data collection.

Account for delay time when adding/removing scanned

tags.

When switching from one HMI screen to another, it takes time to put items in the controller on scan and take

items off scan. Part of this time delay is because the controller allocates system memory for the optimization

buffer.

To minimize this delay, when switching between HMI screens, put the items in the HMI screens on scan and leave

them on scan. For example, you can create a data log to keep the items on scan. Then when switching between

HMI screens, data collection continues without interruption.

FactoryTalk Linx and FactoryTalk View Site Edition software account for this time delay. When HMI screens

change, these applications deactivate tags rather than remove them from scan.

Guideline Description

Use INT data types with third-party products.

Most third-party operator interface products do not support DINT (32-bit) data types. However, there are additional

performance and memory-use considerations when you use INT data types.

FactoryTalk View software supports native Logix 5000 data types (including BOOL, SINT, INT, DINT, and REAL),

structures, and arrays.

Group related data in arrays.

Most third-party operator interface products do not support user-defined structures. Arrays also make sure that

data is in contiguous memory, which optimizes data transfer between the controller and Linx-based software or

other operator interfaces.

Arrays of tags transfer more quickly and take up less memory than groups of individual tags.

Use Linx-based OPC services.

Use Linx-based OPC services to bundle multiple tag requests into one message to reduce communication overhead.

OPC provides better optimization than DDE.

Logix 5000 Array Data Type Description PLC File Identifier FactoryTalk View Tag Data Type

BOOL Value of 0, 1, or -1 B Digital

SINT 8-bit integer A Byte

INT 16-bit integer N Integer

DINT 32-bit integer L Long Integer

LINT 64-bit integer value to store date and time values No PLC identifier Not supported

REAL Floating point F Floating Point

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 119

Chapter 14

Develop Equipment Phases

The PhaseManager™ option of the Studio 5000 Logix Designer® application gives you a state

model for your equipment. It includes the following components:

• Phase to run the state model

• Equipment phase instructions for programming the phase

•PHASE data type

Guidelines for Equipment

Phases

Guideline Description

Use a separate phase for each activity of the

equipment.

Each phase is a specific activity that the equipment performs.

• Use one phase for standalone machines.

• Make sure that each phase does an independent activity.

• Keep the total number of phases and programs in a project within the limit of programs for the controller.

• List the equipment that goes with each phase.

Complete one state model for each phase.

Each phase runs its own set of states. A state model divides the operating cycle of the equipment into a series of

states.

• Decide which state to use for the initial state after power-up.

• Start with the initial state and work through the model.

• Use only the states you need; skip those states that do not apply.

• Use subroutines for producing and standby states.

The state model of an equipment phase is similar to the S88 state model. U.S. standard ISA S88.01-1995 and its

IEC equivalent IEC 61512-1-1998 is commonly referred to as S88. It is a set of models, terms, and good practices

for the design and operation of manufacturing systems.

Separate phase code from equipment code.

One advantage of a phase is that it lets you separate the procedures (recipes) for how to make the product from

the control of the equipment that makes the product. This makes it easier to execute different procedures for

different products by using the same equipment.

Separate normal execution from exceptions.

A state model makes it much easier to separate the normal execution of your equipment from any exceptions

(faults, failures, off-normal conditions).

• Use a prestate routine to watch for faults.

• A prestate routine is not a phase state routine. Create a routine like you do for any program and assign it as

the prestate routine for the equipment phase program.

• Use a state bit to limit code to a specific state.

• The Logix Designer application automatically makes a tag for each phase. The phase tag has bits that identify

the state of the phase. For example, My_Phase.Running.

Use Equipment Phases in redundant systems.

PhaseManager has been tested for compatibility with ControlLogix® redundancy systems. See the ControlLogix

Enhanced Redundancy System, firmware revision 16.81, Release Notes, publication 1756-RN650

, for more

information.

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Chapter 14 Develop Equipment Phases

Equipment Phase

Instructions

The equipment phase instructions are available in relay ladder and structured text

programming languages. You can use them in relay ladder routines, structured text routines,

and SFC actions.

For more information, see the PhaseManager User Manual, publication LOGIX-UM001

If you want to: Use this instruction:

Signal a phase that the state routine is complete so go to the next state. Phase State Complete (PSC)

Change the state or substate of a phase. Equipment Phase Command (PCMD)

Signal a failure for a phase. Equipment Phase Failure (PFL)

Clear the failure code of a phase. Equipment Phase Clear Failure (PCLF)

Initiate communication with FactoryTalk® Batch software. Equipment Phase External Request (PXRQ)

Clear the NewInputParameters bit of a phase. Equipment Phase New Parameters (PRNP)

Create breakpoints within the logic of a phase. Equipment Phase Paused (PPD)

Take ownership of a phase to either:

• Prevent another program or FactoryTalk Batch software from commanding a phase.

• Make sure another program or FactoryTalk Batch software does not already own a phase.

Attach to Equipment Phase (PATT)

Relinquish ownership of a phase. Detach from Equipment Phase (PDET)

Override a command. Equipment Phase Override (POVR)

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 121

Chapter 15

Manage Firmware

The controllers, I/O modules, and other devices use firmware that you can update on your own.

You choose the firmware revision level and decide when to update the firmware.

Guidelines to Manage

Controller Firmware

Guideline Description

Maintain software versions and firmware revisions at

the same major revision levels.

At release, a specific version of software supports the features and functions in a specific revision of firmware. To

use a specific revision of firmware, you must have the corresponding software version. This combination of

software and firmware is considered to be compatible.

A revision number consists of a major and minor revision number in this format xx.yyy.

Use digitally signed firmware to maintain firmware

integrity.

Controllers support digitally signed firmware for additional security.

Document firmware revisions. Include software version and firmware revision information in electrical drawings and other project documentation.

Read the associated release notes.

Always read the release notes that accompany new software versions and firmware revisions before you install

them. The release notes help you to understand what has improved and changed, and also help you determine

whether you must modify your application because of the changes. In most cases, your application runs normally

following an update.

Configure modules so that the controller

automatically updates firmware.

Controller firmware, revision 16, includes a Firmware Supervisor feature that lets controllers automatically update

devices. To use the Firmware Supervisor:

• You can update Local and remote modules while in Program or Run modes, as long as their electronic keying

configurations are set to Exact Match and the ControlFLASH™ Software supports the modules.

• Firmware kits reside on the removable media in the controller.

Control that users have access to change firmware

revisions.

ControlFLASH software, version 8.0 and later, is integrated with FactoryTalk® Security software so you can establish

update or no update privileges for users.

Use the ControlFLASH kit manager to update only the

firmware you need or have.

With ControlFLASH software, version 8.0 and later, you can:

• View available firmware kits before updating a device.

• Import and export kits to create custom kits.

• Delete kits as single devices or as groups by catalog number and device type.

• Support third-party applications to push/pull kits as needed.

Where Is the

Major revision

Updated every release there is a functional change.

yyy

Minor revision

Updated anytime there is a change that does not affect function or interface.

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Chapter 15 Manage Firmware

Compare Firmware Options Controllers ship with basic firmware that supports only updating the controller firmware to the

required revision. You must update the firmware to a revision that is compatible with your

version of the Studio 5000 Logix Designer® application.

For more information, see these publications:

• ControlFLASH Plus Quick Start Guide, publication CFP-QS001

• ControlFLASH Firmware Upgrade Software User Manual, publication 1756-UM105

ControlFLASH and ControlFLASH Plus Software AutoFlash Function Controller-based Firmware Supervisor

Standalone tool.

Manually launch from desktop icon or program list.

ControlFLASH Plus™ integrates with the Product

Compatibility and Download Center and with

FactoryTalk® Security software.

Integrated with the Logix Designer application.

The software automatically checks the controller,

motion module, and SERCOS drive firmware during a

project download. If the firmware is out of date or

incompatible, the software prompts you to update the

firmware.

Integrated on the controller removable media and run by

the controller without user intervention.

Controllers automatically update modules on keying

mismatch situations.

Supports controllers, communication modules, I/O

modules, motion modules, and newer SERCOS drives,

and many other devices.

ControlFLASH Plus also supports component

products.

Supports the same devices as the ControlFLASH™

Software.

Supports local and remote devices that:

• Are in the I/O tree and configured as Exact Match.

• Support firmware updates via the ControlFLASH

Software.

• The hardware revision supports the firmware that is

stored for that Exact Match device.

Supports valid CIP™ path to the device to update,

such as serial, DeviceNet®, ControlNet®, and

EtherNet/IP™ connections.

Supports valid CIP path to the device to update, such as

serial, DeviceNet, ControlNet, and EtherNet/IP

connections.

Supports all communication paths to devices that reside

in the controller I/O tree and that also support the

ControlFLASH Software.

The firmware must already be on removable media in the

controller.

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Chapter 15 Manage Firmware

Guidelines for the Firmware

Supervisor

The Firmware Supervisor feature can automatically load firmware when you replace a device

in the system.

• OEMs who build multiple machines a month can have the controller update all modules

and devices in the system without user intervention.

• Machines with strict regulation can require specific firmware revisions for the devices

to maintain certification. The Firmware Supervisor helps make sure that devices are at

the correct firmware revision.

• Maintenance personnel replacing failed hardware can install the replacement device

and the controller automatically updates the device with the correct firmware revision.

Guideline Description

The Firmware Supervisor can update any Rockwell

Automation® device that:

• Can be placed in the I/O Configuration tree

• Has electronic keying that is configured as Exact

Match

• Normally can be updated with ControlFLASH software

The Firmware Supervisor works on local I/O modules and distributed modules via EtherNet/IP, SERCOS, and

ControlNet networks. On DeviceNet networks, the Firmware Supervisor supports local devices only, such as

scanners and linking devices that reside in the I/O tree of the controller project. Because you cannot directly

place a remote DeviceNet device in the I/O tree, the Firmware Supervisor does not manage remote DeviceNet

devices.

The Firmware Supervisor supports:

• Controllers that support removable media (except for redundant controllers).

• The Firmware Supervisor does not manage the firmware of other standard controllers in the I/O Configuration

tree.

• Safety products, including GuardLogix® Safety controllers and 1791ES CompactBlock™ Guard I/O™ EtherNet/IP

modules.

The Firmware Supervisor does not manage the firmware of POINT Guard I/O™ modules or 1791DS CompactBlock

Guard I/O DeviceNet modules.

SERCOS drives that support updates over a SERCOS network:

• 1394 drives, firmware revision 1.85 and later.

• Kinetix® 6000 drives, firmware revision 1.85 and later.

• Ultra™ 3000 drives, firmware revision 1.50 and later.

• 8720MC drives, firmware revision 3.85 and later.

Non-modular, distributed I/O products that sit directly on the network without an adapter. Distributed I/O

products that require an adapter, such as POINT I/O™ or FLEX™ I/O modules, are not supported. Instead, the

Firmware Supervisor manages the firmware for the adapters.

The Firmware Supervisor does not support PanelView™ Plus terminals, since the terminals do not support the

ControlFLASH software.

For the Firmware Supervisor to manage firmware for a

device, the device must have its electronic keying that

is configured for Exact Match.

Other modules can exist in the I/O Configuration that are not configured as Exact Match, but the Firmware

Supervisor does not maintain the firmware for those modules.

To disable the Firmware Supervisor for a specific device:

Change the electronic keying for that device to something besides Exact Match.

Disable Firmware Supervisor from either an SSV instruction or the Nonvolatile Memory tab of the controller

properties.

Removable media must be formatted properly.

If you have a Secure Digital card with 4 GB memory or more, format the card FAT32. If you have a Secure Digital

card with less than 4 GB memory, format the card FAT16.

Make sure that the removable media is not locked. The Secure Digital card has a lock feature. The card must be unlocked to write to the card.

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Chapter 15 Manage Firmware

Access Firmware The Logix Designer application ships with firmware update kits. Firmware revisions are also

available on the Rockwell Automation website.

5. Go to https://www.rockwellautomation.com/global/support/download-center/

overview.page?

6. Under Drivers and Firmware, click Find Drivers and Firmware.

For modules that are managed by the Firmware

Supervisor, each controller must store the firmware

files on removable media.

Enable the Firmware Supervisor, from the Nonvolatile Memory tab of the controller properties. Click Load/Store.

From the Automatic Firmware Updates pull-down menu, choose Store to copy it to removable media.

The computer that runs the Logix Designer application must have:

• ControlFLASH Software installed.

• The required firmware kits in the ControlFLASH default directory for the modules the Firmware Supervisor is to

maintain. The Logix Designer application moves firmware kits from your computer to the removable media in

the controller for the Firmware Supervisor to use.

• Controller firmware and application logic are managed outside of Firmware Supervisor on the Nonvolatile

Memory tab. Firmware Supervisor adds to the ability to store controller firmware and logic on the removable

media. If you disable the Firmware Supervisor, you disable the Firmware Supervisor updates and not the

controller firmware updates that still occur when the controller image is reloaded.

Enable or disable the automatic firmware updates by

using GSV and SSV instructions.

You can monitor the status of automatic firmware

updates.

Monitor the status of automatic firmware updates on the Nonvolatile Memory tab on the controller properties.

To monitor the status of automatic firmware updates for a specific module, use GSV instructions. This example

shows that the Firmware Supervisor encountered the wrong hardware revision for 1756-OB16D module.

Guideline Description

Rockwell Automation Publication 1756-RM094M-EN-P - November 2022 125

Index

access

firmware

124

module object 36

access the module object

add-on instruction

first scan initialization

guidelines

postscan logic 41

prescan

alias tags

creating

applications

HMI

115

array

guidelines

index

guidelines

indirect addresses

tag storage

automatic diagnostics 113

base tag

guidelines

bit tags

block-transfer messages

guidelines

108

buffer

message storage

106

routine 38

cache

messages

105

code reuse

guidelines

communication

Linx-based software data packets

116

module connections

MSG instruction 105

comparison

import/export, add-on instructions

program parameters, add-on instructions

programming languages

scheduled and unscheduled ControlNet

102

subroutines, add-on instructions 52

configuration

Logix-based alarms

112