Allen-Bradley 1756-IA16I, 1756-IB16, 1756-IB16IF, 1756-IB16I, 1756-IA32 User Manual
...
ControlLogix Digital I/O Modules
Catalog Numbers 1756-IA8D, 1756-IA16, 1756-IA16I, 1756-IA32, 1756-IB16, 1756-IB16D, 1756-IB16I, 1756-IB16IF, 1756-IB32,
1756-IC16, 1756-IG16, 1756-IH16I, 1756-IM16I, 1756-IN16, 1756-IV16, 1756-IV32, 1756-OA8, 1756-OA8D, 1756-OA8E,
1756-OA16, 1756-OA16I, 1756-OB8, 1756-OB8EI, 1756-OB8I, 1756-OB16D, 1756-OB16E, 1756-OB16I, 1756-OB16IEF,
1756-OB16IEFS, 1756-OB16IS, 1756-OB32, 1756-OC8, 1756-OG16, 1756-OH8I, 1756-ON8, 1756-OV16E, 1756-OV32E,
1756-OW16I, 1756-OX81
User Manual
Important User Information
Solid-state equipment has operational characteristics differing from those of electromechanical equipment. Safety
Guidelines for the Application, Installation and Maintenance of Solid State Controls (publication SGI-1.1
available from
your local Rockwell Automation® sales office or online at http://www.rockwellautomation.com/literature/
) describes some
important differences between solid-state equipment and hard-wired electromechanical devices. Because of this difference,
and also because of the wide variety of uses for solid-state equipment, all persons responsible for applying this equipment
must satisfy themselves that each intended application of this equipment is acceptable.
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.
Allen-Bradley, ControlLogix, ControlLogix-XT, DH+, Data Highway Plus, Integrated Architecture, Rockwell Software, Rockwell Automation, RS Logix, RSNetWorx, and TechConnect are trademarks of Rockwe ll
Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.
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.
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.
IMPORTANT
Identifies information that is critical for successful application and understanding of the product.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 3
Summary of Changes
This manual contains new and updated information. Changes throughout this
revision are marked by change bars, as shown to the right of this paragraph.
Top ic Pag e
Studio 5000™ Logix Designer application is the rebranding of RSLogix™ 5000 software 11
Added the 1756-OB16IEFS module to the list of I/O modules 15
Added content to describe when output data is sent to the 1756-OB16IEFS module in motion
applications
33
Added the 1756-OB16IEFS module to the CIP Sync time section 48
Added the 1756-OB16IEFS module to sections about electronic fusing, diagnostic latching, and
time-scheduled output control
54, 58, 63
Added the 1756-OB16IEFS module to the list of fast I/O modules 83
Added software version requirements for the 1756-OB16IEFS module 84
Added the 1756-OB16IEFS module to the table of connection formats 133
Added the wiring diagram for the 1756-OB16IEFS module 165
Added status indicators for the 1756-OB16IEFS module 179
Added tag definitions for the 1756-OB16IEFS module 202
Added the 1756-OB16IEFS module to the list of IFMs 245
4 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Summary of Changes
Notes:
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 5
Table of Contents
Preface
Studio 5000 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 1
What Are ControlLogix
Digital I/O Modules?
Available Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
I/O Modules in the ControlLogix System . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Module Identification and Status Information. . . . . . . . . . . . . . . . . . . . . . 17
Chapter 2
Digital I/O Operation
in the ControlLogix System
Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Use RSNetWorx and RSLogix 5000 Software . . . . . . . . . . . . . . . . . . . . . . 20
Internal Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Input Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Output Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Direct Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Rack-optimized Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Suggestions for Rack-optimized Connections . . . . . . . . . . . . . . . . . . . 26
Input Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Input Modules in a Local Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
RPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
COS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Trigger Event Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Input Modules in a Remote Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Remote Input Modules Connected via the ControlNet Network. 29
Remote Input Modules Connected via the EtherNet/IP Network 30
Output Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Output Modules in a Local Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Output Modules in a Remote Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Remote Output Modules Connected via the ControlNet Network. 32
Remote Output Modules Connected via the EtherNet/IP Network 33
Listen-only Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Multiple Owner-Controllers of Input Modules . . . . . . . . . . . . . . . . . . . . . 34
Configuration Changes in an Input Module with Multiple Owners . . 35
Chapter 3
Common Module Features
Input Module Compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Output Module Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Common Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Removal and Insertion Under Power. . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Module Fault Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Software Configurable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Electronic Keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Module Inhibiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Table of Contents
Use the System Clock to Timestamp Inputs and Schedule Outputs. 47
Producer/Consumer Communication. . . . . . . . . . . . . . . . . . . . . . . . . . 50
Status Indicator Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Common Features Specific to Input Modules. . . . . . . . . . . . . . . . . . . . . . . 50
Data Transfer on Either Cyclic Time or Change of State . . . . . . . . . 51
Set RPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Enable Change of State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Software Configurable Filter Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Isolated and Nonisolated Varieties of Input Modules . . . . . . . . . . . . 53
Multiple Input Point Densities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Common Features Specific to Output Modules . . . . . . . . . . . . . . . . . . . . . 54
Configurable Point-level Output States. . . . . . . . . . . . . . . . . . . . . . . . . 55
Output Data Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Isolated and Nonisolated Varieties of Output Modules . . . . . . . . . . 56
Multiple Output Point Densities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Electronic Fusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Field Power Loss Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Diagnostic Latch of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Time-scheduled Output Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Fault and Status Reporting between Input Modules and Controllers. . 64
Fault and Status Reporting between Output Modules and Controllers 65
Chapter 4
Diagnostic Module Features
Diagnostic Input Module Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Diagnostic Output Module Compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . 68
Diagnostic Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Diagnostic Latch of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Diagnostic Timestamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
8-Point AC/16-Point DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Point-level Fault Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Features Specific to Diagnostic Input Modules. . . . . . . . . . . . . . . . . . . . . . 71
Diagnostic Change of State for Input Modules . . . . . . . . . . . . . . . . . . 71
Open Wire Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Field Power Loss Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Features Specific to Diagnostic Output Modules . . . . . . . . . . . . . . . . . . . . 75
Field Wiring Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
No Load Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Field-side Output Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Pulse Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Diagnostic Change of State for Output Modules . . . . . . . . . . . . . . . . 79
Fault and Status Reporting between Input Modules and Controllers. . 79
Fault and Status Reporting between Output Modules and Controllers 81
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 7
Table of Contents
Chapter 5
Fast Module Features
Fast Input Module Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Fast Output Module Compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Fast Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Response Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Features Specific to Fast Input Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Pulse Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Per Point Timestamping and Change of State. . . . . . . . . . . . . . . . . . . 87
Software Configurable Filter Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Dedicated Connection for Event Tasks. . . . . . . . . . . . . . . . . . . . . . . . . 93
Features Specific to Fast Output Modules . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Programmable Fault State Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Pulse Width Modulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Fault and Status Reporting between Input Modules and Controllers 106
Fault and Status Reporting between Output Modules and Controllers 107
Chapter 6
Install ControlLogix I/O Modules
Install the Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Key the Removable Terminal Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Connect the Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
RTB Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
RTB Wiring Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Assemble the Removable Terminal Block and Housing. . . . . . . . . . . . . 119
Choose Extended-depth Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Cabinet Size Considerations with Extended-depth Housing . . . . 121
Install the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Remove the Removable Terminal Block. . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Remove the Module from the Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Chapter 7
Configure ControlLogix
Digital I/O Modules
Configuration Process Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Create a New Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Communication or Connection Formats. . . . . . . . . . . . . . . . . . . . . . 131
Edit the Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Connection Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
View and Change Module Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Chapter 8
Wiring Diagrams
1756-IA8D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
1756-IA16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
1756-IA16I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
1756-IA32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
1756-IB16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
1756-IB16D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
1756-IB16I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
1756-IB16IF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
8 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Table of Contents
1756-IB32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
1756-IC16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
1756-IG16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
1756-IH16I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
1756-IM16I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
1756-IN16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
1756-IV16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
1756-IV32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
1756-OA8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
1756-OA8D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
1756-OA8E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
1756-OA16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
1756-OA16I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
1756-OB8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
1756-OB8EI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
1756-OB8I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
1756-OB16D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
1756-OB16E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
1756-OB16I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
1756-OB16IEF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
1756-OB16IEFS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
1756-OB16IS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
1756-OB32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
1756-OC8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
1756-OG16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
1756-OH8I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
1756-ON8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
1756-OV16E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
1756-OV32E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
1756-OW16I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
1756-OX8I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Appendix A
Troubleshoot Your Module
Status Indicators for Input Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Status Indicators for Output Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Use RSLogix 5000 Software for Troubleshooting . . . . . . . . . . . . . . . . . . 180
Fault Type Determination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Appendix B
Tag Definitions
Standard and Diagnostic Input Module Tags . . . . . . . . . . . . . . . . . . . . . . 183
Standard and Diagnostic Output Module Tags . . . . . . . . . . . . . . . . . . . . 186
Fast Input Module Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Fast Output Module Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
1756-OB16IEF Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
1756-OB16IEFS Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Array Data Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 9
Table of Contents
Appendix C
Use Ladder Logic To Perform
Run Time Services and
Reconfiguration
Using Message Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Processing Real-time Control and Module Services . . . . . . . . . . . . . . . . 214
One Service Performed Per Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Create a New Tag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Enter Message Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
Communication Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Use Timestamped Inputs and Scheduled Outputs
for Standard and Diagnostic I/O Modules. . . . . . . . . . . . . . . . . . . . . 222
Use Timestamped Inputs and Scheduled Outputs
for Fast I/O Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Reset a Fuse, Perform Pulse Test and Reset Latched Diagnostics. 227
Perform a WHO to Retrieve Module Identification and Status. . 228
Review of Tags in Ladder Logic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Appendix D
Choose a Correct Power Supply
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .233
Appendix E
Motor Starters for Digital I/O Modules
Determine the Maximum Number of Motor Starters. . . . . . . . . . . 236
Appendix F
Major Revision Upgrades
If Using a Compatible or Disabled Keying I/O Configuration . . . . . . 238
If Using an Exact Match Keying Configuration . . . . . . . . . . . . . . . . . . . . 238
Appendix G
1492 IFMs for Digital I/O Modules
Cable Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Appendix H
History of Changes
1756-UM058F-EN-P, April 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
1756-UM058E-EN-P, August 2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Glossary
Index
10 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Table of Contents
Notes:
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 11
Preface
This manual describes how to install, configure, and troubleshoot your
ControlLogix® digital I/O modules. There is also a complete listing of digital
input and output modules, including specifications and wiring diagrams. You
must be able to program and operate a ControlLogix controller to efficiently use
your digital I/O module.
Studio 5000 Environment
The Studio 5000™ Engineering and Design Environment combines engineering
and design elements into a common environment. The first element in the
Studio 5000 environment is the Logix Designer application. The Logix Designer
application is the rebranding of RSLogix™ 5000 software and will continue to be
the product to program Logix5000™ controllers for discrete, process, batch,
motion, safety, and drive-based solutions.
The Studio 5000 environment is the foundation for the future of Rockwell
Automation® engineering design tools and capabilities. It is the one place for
design engineers to develop all the elements of their control system.
12 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Preface
Additional Resources
These documents contain additional information concerning related products
from Rockwell Automation.
You can view or download publications at
http://www.rockwellautomation.com/literature/
. To order paper copies of
technical documentation, contact your local Allen-Bradley distributor or
Rockwell Automation sales representative.
Resource Description
1756 ControlLogix I/O Modules Specifications
Technical Data, publication 1756-TD002
Provides specifications for ControlLogix I/O modules.
ControlLogix High-speed Counter Module User Manual,
publication 1756-UM007
Describes how to install, configure, and troubleshoot the
1756-HSC counter module.
ControlLogix Low-speed Counter Module User Manual,
publication 1756-UM536
Describes how to install, configure, and troubleshoot the
1756-LSC8XIB8I counter module.
ControlLo gix Peer I/O Control Appl ication Techni que,
publication 1756-AT016
Describes typical peer control applications and provides
details about how to configure I/O modules for peer
control operation.
Position-based Output Control with the MAOC Instruction,
publication 1756-AT017
Describes typical applications for using scheduled output
modules with the Motion Axis Output Cam (MAOC)
instruction.
Integrated Architecture and CIP Sync Configuration
Application Technique, publication IA-AT003
Describes how to configure CIP Sync with Integrated
Architecture™ products and applications.
ControlLogix Chassis and Power Supplies Installation
Instructions, publication 1756-IN005
Describes how to install and troubleshoot standard and
ControlLogix-XT versions of the 1756 chassis and power
supplies, including redundant power supplies.
ControlLogix Analog I/O Modules User Manual,
publication 1756-UM009
Describes how to install, configure, and troubleshoot
ControlLogix analog I/O modules.
ControlLogix Data Highway Plus-Remote I/O
Communication Interface Module User Manual,
publication 1756-UM514
Describes how to configure and operate the ControlLogix
DH+™ / Remote I/O module.
ControlLogix-XT Data Highway Plus-Remote I/O
Communication Interface Module Installation
Instructions, publication 1756-IN638
Describes how to install, configure, and troubleshoot the
ControlLogix-XT Data Highway Plus™-Remote I/O
Communication Interface module.
ControlLogix System User Manual,
publication 1756 UM001
Describes how to install, configure, program, and operate
a ControlLogix system.
Industrial Automation Wiring and Grounding Guidelines,
publication 1770-4.1
Provides general guidelines for installing a Rockwell
Automation industrial system.
Product Certifications website, http://ab.com
Provides declarations of conformity, certificates, and other
certification details.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 13
Chapter 1
What Are ControlLogix Digital I/O Modules?
ControlLogix® digital I/O modules are input and output modules that provide
On/Off detection and actuation. By using the producer/consumer network
model, digital I/O modules can produce information when needed while
providing additional system functions.
Available Features
The table lists several features available on ControlLogix digital I/O modules.
Top ic Pag e
Available Features 13
I/O Modules in the ControlLogix System 14
Module Identification and Status Info rmation 17
Feature Description
Removal and Insertion Under Power (RIUP) You can remove and insert modules and removable terminal blocks
(RTB) while power is applied.
Producer/consumer communication This communication method is an intelligent data exchange between
modules and other system devices in which each module produces
data without first being polled.
System time stamp of data A 64-bit system clock places a time stamp on the transfer of data
between the module and its owner-controller.
Module-level fault reporting and field-side
diagnostic detection
Fault and diagnostic detection capabilities to help you effec tively and
efficiently use your module and troubleshoot your application.
Agency Certification Class 1, Division 2 agency certification for any applic ation that
requires approval.
14 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 1 What Are ControlLogix Digital I/O Modules?
I/O Modules in the
ControlLogix System
ControlLogix modules mount in a ControlLogix chassis and require either a
removable terminal block (RTB) or a Bulletin 1492 wiring interface module
(IFM)
(1)
to connect all field-side wiring.
Before you install and use your module, you must do the following:
• Install and ground a 1756 chassis and power supply. To install these
products, refer to the publications listed in Additional Resources
on
page 12.
• Order and receive an RTB or IFM and its components for your
application.
(1) The ControlLogix system has been agency certified using only the ControlLogix RTB catalog numbers 1756-TBCH, 1756-T BNH,
1756-TBSH, and 1756-TBS6H. Any application that requires agency certification of the ControlLogix system using other wiring
termination methods may require application-specific approval by the certifying agenc y.
IMPORTANT
RTBs and IFMs are not included with your module purchase. See page 116 for
RTBs and page 239
for IFMs.
Table 1 - ControlLogix Digital I/O Modules
Cat. No. Description Page
1756-IA8D 79…132V AC 8-point diagnostic input module 139
1756-IA16 74…132V AC 16-point input module 139
1756-IA16I 79…132V AC 16-point isolated input module 140
1756-IA32 74…132V AC 32-point input module 141
1756-IB16 10…31.2V DC 16-point input module 142
1756-IB16D 10…30V DC diagnostic input module 143
1756-IB16I 10…30V DC 16-point, isolated input module 144
1756-IB16IF 10…30V DC,16-point, isolated, fast peer control input module 145
1756-IB32 10…31.2V DC 32-point input module 146
1756-IC16 30…60V DC 16-point input module 147
1756-IG16 Transitor-transitor logic (TTL) input module 148
1756-IH16I 90…146V DC 16-point isolated input module 149
1756-IM16I 159…265V AC 16-point isolated input module 150
1756-IN16 10…30V AC 16-point input module 150
1756-IV16 10…30V DC 16-point sourcing current input module 151
1756-IV32 10…30V DC 32-point sourcing current input module 152
1756-OA8 74…265V AC 8-point output module
153
1756-OA8D 74…132V AC 8-point diagnostic output module 154
1756-OA8E 74…132V AC 8-point electronically-fused output module 155
1756-OA16 74... 265V AC 16-point output module 156
1756-OA16I 74…265V AC 16-point isolated output module 157
1756-OB8 10…30V DC 8-point output module 158
1756-OB8EI 10…30V DC 8-point electronically-fused, isolated output module 159
1756-OB8I 10…30V DC 8-point isolated output module 160
1756-OB16D 19.2…30V DC 16-point diagnostic output module 161
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 15
What Are ControlLogix Digital I/O Modules? Chapter 1
1756-OB16E 10…31.2V DC 16-point electronically-fused output module 162
1756-OB16I 10…30V DC 16-point isolated output module 163
1756-OB16IEF 10…30V DC,16-point, isolated, fast peer control output module 164
1756-OB16IEFS 10…30V DC, 16-point, isolated, fast, scheduled per point output module 165
1756-OB16IS 10…30V DC scheduled, isolated output module 166
1756-OB32 10…31.2V DC 32-point output module 167
1756-OC8 30…60V DC 8-point output module 168
1756-OG16 Transitor-transitor logic (TTL) output module 169
1756-OH81 90…146V DC 8-point isolated output module 170
1756-ON8 10…30V AC 8-point output module 171
1756-OV16E 10…30V DC 16-point electronically-fused, sinking current output module 172
1756-OV32E 10…30V DC 32-point electronically-fused, sinking current output module 173
1756-OW16I 10…265V, 5-150V DC 16-point isolated contact module 174
1756-OX8I 10…265V, 5-150V DC 8-point isolated contact module 175
Table 1 - ControlLogix Digital I/O Modules (continued)
Cat. No. Description Page
16 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 1 What Are ControlLogix Digital I/O Modules?
Figure 1 - Parts Illustration
40200-M
DC OUTPUT
ST
O
K
01234567
3
5
Removable Terminal Block
6
4
2
1
Item Description
1 Backplane Connector—Interface for the ControlLogix system that connects the module to the
backplane.
2 Top and bottom guides—Guides provide assistance in seating the RTB or IFM onto the module.
3 Status indicators—Indicators display the status of communication, module health, and input/output
devices. Indicators help in troubleshooting anomalies.
4 Connector pins—Input/output, power, and grounding connections are made to the module through
these pins with the use of an RTB or IFM.
5 Locking tab—The locking tab anchors the RTB or IFM on the module, maintaining wiring connections.
6 Slots for keying—Mechanically keys the RTB to prevent making the wrong wire connections to your
module.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 17
What Are ControlLogix Digital I/O Modules? Chapter 1
Module Identification and
Status Information
Each ControlLogix I/O module maintains specific identification information
that separates it from all other modules. This information assists you in tracking
all the components of your system.
For example, you can track module identification information to know which
modules are located in any ControlLogix chassis at any time. While retrieving
module identity, you can also retrieve module status.
Item Description
Product type Module’s product type, such as digital I/O or analog I/O
Product code Module’s catalog number
Major revision Module’s major revision number
Minor revision Module’s minor revision number
Status Module’s statu s, including these items:
• Controller ownership
• Whether the module has been configured
• Device-specific status, such as the following:
– Self-test
– Update in progress
– Communications fault
– Not owned (outputs in Program mode)
– Internal fault (needs update)
– Run mode
– Program mode (outputs only)
• Minor recoverable fault
• Minor unrecoverable fault
• Major recoverable fault
• Major unrecoverable fault
Vendor Module’s manufacturer vendor, such as Allen-Bradley
Serial number Module’s serial number
Length of ASCII text string Number of characters in module’s text string
ASCII text string Module’s ASCII text string description
IMPORTANT
You must perform a WHO service to retrieve this information. For more
information, refer to page 228
.
18 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 1 What Are ControlLogix Digital I/O Modules?
Notes:
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 19
Chapter 2
Digital I/O Operation in the ControlLogix System
I/O modules are the interface between controllers and field devices in a
ControlLogix system. Digital I/O modules transfer data to devices that require
just one bit to be represented (0 or 1). For example, a switch is open or closed, or
a light is on or off.
Top ic Pa ge
Ownership 20
Use RSNetWorx and RSLogix 5000 Software 20
Internal Module Operation 21
Connec tions 23
Input Module Operation 26
Input Modules in a Local Chassis 27
Input Modules in a Remote Chassis 28
Output Module Operation 31
Output Modules in a Local Chassis 31
Output Modules in a Remote Chassis 32
Listen-only Mode 34
Multiple Owner-Controllers of Input Modules 34
Configuration Changes in an Input Module with Multiple Owners 35
20 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 2 Digital I/O Operation in the ControlLogix System
Ownership
I/O modules in a ControlLogix system can be owned by an RSLogix™ 5000
controller. An owner-controller fulfills these functions:
• Stores configuration data for every module that it owns
• Sends I/O modules configuration data to define module behavior and
begin module operation with the control system
• Resides in a local or remote chassis in regard to the I/O module’s position
Each ControlLogix I/O module must continuously maintain communication
with its owner-controller to operate normally.
Typically, each module in the system will have only one owner-controller. Input
modules can have more than one owner-controller. Output modules, however,
are limited to a single owner-controller.
For more information about using multiple owner-controllers, see Configuration
Changes in an Input Module with Multiple Owners on page 35.
Use RSNetWorx and
RSLogix 5000 Software
The I/O configuration within RSLogix 5000 software generates the
configuration data for each I/O module in the control system, including modules
in a remote chassis. A remote chassis contains the I/O module but not the
module’s owner-controller. A remote chassis can be connected to the controller
via an EtherNet/IP network or a scheduled connection on the
ControlNet network.
Configuration data from RSLogix 5000 software is transferred to the controller
during the program download and subsequently transferred to I/O modules. The
I/O modules in the local or remote chassis are ready to run as soon as the
configuration data has been downloaded. However, to enable scheduled
connections to I/O modules on the ControlNet network, you must schedule the
network by using RSNetWorx™ for ControlNet software.
RSNetWorx software transfers configuration data to I/O modules on a scheduled
ControlNet network and establishes a network update time (NUT) for the
ControlNet network that is compliant with the desired communication options
specified for each module during configuration.
Anytime a controller references a scheduled connection to I/O modules on a
scheduled ControlNet network, you must run RSNetWorx software to configure
the ControlNet network.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 21
Digital I/O Operation in the ControlLogix System Chapter 2
Refer to the following general steps when configuring I/O modules.
1. Configure all I/O modules for a given controller by using
RSLogix 5000 software and download that information to the controller.
2. If the I/O configuration data references a scheduled connection to a
module in a remote chassis connected via the ControlNet network, run
RSNetWorx for ControlNet software to schedule the network.
3. After running RSNetWorx software, perform an online save of the
RSLogix 5000 project to make sure the configuration information that
RSNetWorx software sends to the controller is saved.
Internal Module Operation
ControlLogix I/O modules experience signal propagation delays that must be
accounted for during operation. Some of these delays are user-configurable, and
some are inherent to the module hardware.
For example, there is a small delay, typically less than 1 ms, between when a signal
is applied at the RTB of a ControlLogix input module and when a signal is sent
to the system over the backplane. This time reflects a filter time of 0 ms for a DC
input.
This section offers an explanation of the time limitations with ControlLogix I/O
modules.
Input Modules
As shown in the illustration below, ControlLogix input modules receive a signal
at the RTB and process it internally through hardware, filters, and an ASIC scan
before sending a signal to the backplane via the requested packet interval (RPI) or
at a Change of State (COS) occurrence. The RPI is a configured interval of time
that determines when a module’s data is sent to the controller.
IMPORTANT
You must run RSNetWorx for ControlNet software whenever a new I/O module
is added to a scheduled ControlNet chassis. When a module is permanently
removed from a remote chassis, we recommend that you run RSNetWorx for
ControlNet software to reschedule the network and optimize the allocation of
network bandwidth.
42701
Hardware Delay
Filter Delay
ASIC Delay
Signal Applied
at the RTB
Signal Sent to
the Backplane
22 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 2 Digital I/O Operation in the ControlLogix System
The table defines some of the delay factors that affect the signal propagation on
an I/O module.
Output Modules
ControlLogix output modules receive a signal from the controller and process it
internally via hardware and an ASIC scan before sending a signal to the output
device via the RTB.
Delay Description
Hardware How the module is configured and the variance between the type of modules affects
how the signal is processed.
Filter User configuration varies between modules, thus affecting the signal propagation.
ASIC ASIC scan = 200 µs.
EXAMPLE
A typical delay time can be estimated despite the number of factors that might
contribute. For example, if you are turning on a 1756-IB16 module at 24V DC in
25 °C (77 °F) conditions, the signal propagation delay is affected by these
factors:
• Hardware delay to energize the input (typically 290 µs on the
1756-IB16 module)
• User-configurable filter time of 0, 1, or 2 ms
• ASIC scan of 200 µs
In the worst case scenario with a filter time of 0 ms, the 1756-IB16 module has
a 490 µs signal propagation delay.
These times are not guaranteed. For nominal and maximum delay times for
each module, see the 1756 ControlLogix I/O Modules Specifications Technical
Data, publication 1756-TD002
.
Hardware DelayASIC Delay
42702
Signal Sent from
RTB Output Point
Signal Received
from Controller
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 23
Digital I/O Operation in the ControlLogix System Chapter 2
The table defines some of the delay factors that affect the signal propagation on
an I/O module.
Connections
With ControlLogix I/O modules, a connection is the data transfer link between
a controller and an I/O module. A connection can be one of these types:
• Direct
• Rack-optimized
The table lists the advantages and disadvantages of each connection type.
Delay Description
Hardware How the module is configured and the variance between the type of modules affects
how the signal is processed.
ASIC ASIC scan = 200 µs.
EXAMPLE
A typical delay time can be estimated despite the number of factors that might
contribute. For example, if you are turning on a 1756-OB16E module at 24V DC
in 25 °C (77 °F) conditions, the signal propagation delay is affected by these
factors:
• Hardware delay to energize the input (typically 70 µs on the
1756-OB16E module)
• ASIC scan of 200 µs
In the worst case scenario with a filter time of 0 ms, the 1756-OB16E module
has a 270 µs signal propagation delay.
These times are not guaranteed. See Chapter 8
for nominal and maximum
delay times for each module.
Connection Type Advantages Dis advantages
Direct All input and data echo information is
transferred, including diagnostic
information and fusing data.
With more data transferring over the
network, your system does not operate as
efficiently as with rack connections.
Rack-optimized Connection usage is economized. The
owner-controller has a single RPI value for
each connection.
Input and data echo information is limited
to general faults and data.
24 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 2 Digital I/O Operation in the ControlLogix System
Direct Connections
A direct connection is a real-time data transfer link between the controller and
the device that occupies the slot that the configuration data references. When
module configuration data is downloaded to an owner-controller, the controller
attempts to establish a direct connection to each of the modules referenced by the
data.
If a controller has configuration data referencing a slot in the control system, the
controller periodically checks for the presence of a device there. When a device’s
presence is detected there, the controller automatically sends the configuration
data.
If the data is appropriate to the module found in the slot, a connection is made
and operation begins. If the configuration data is not appropriate, the data is
rejected and an error message appears in the software. In this case, the
configuration data can be inappropriate for any of a number of reasons. For
example, a module’s configuration data may be appropriate except for a mismatch
in electronic keying that prevents normal operation.
The controller maintains and monitors its connection with a module. Any break
in the connection causes the controller to set fault status bits in the data area
associated with the module. Breaks in the connection can be caused by a module
fault or the removal of the module from the chassis while under power.
RSLogix 5000 software monitors fault status bits to annunciate module failures.
Rack-optimized Connections
When a digital I/O module is located in a remote chassis with respect to its
owner-controller, you can choose Rack Optimization or Listen-only Rack
Optimization during module configuration. The option you choose depends on
the communication module configuration. If the communication module uses
Listen-only Rack Optimization, then the I/O module must also use Listen-only
Rack Optimization.
A rack-optimized connection economizes bandwidth between owner-controllers
and digital I/O modules in the remote chassis. Rather than having several direct
connections with individual RPI values, an owner-controller has a single rack
connection with a single RPI value. That RPI value accommodates all digital I/O
modules in the remote chassis.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 25
Digital I/O Operation in the ControlLogix System Chapter 2
The input, or data echo, information is limited to general faults and data. No
additional status, such as diagnostic information, is available.
The illustration below shows how a rack-optimized connection eliminates the
need for three separate connections. The owner-controller in the local chassis
communicates with all the I/O modules in the remote chassis but uses only one
connection. The ControlNet communication module sends data from the
modules simultaneously at the RPI.
Figure 2 - Rack-optimized Connection
IMPORTANT
Because rack-optimized connections are applicable only in applications that
use a remote chassis, you must configure the communication format , as
described in Chapter 7
, for both the remote I/O module and the remote
1756-CNB module or EtherNet/IP module.
Make sure you configure both modules for rack optimization. If you choose a
different communication format for each module, the controller makes two
connections to the same chassis (one for each format) and the same data
travels across the ControlNet network.
If you use rack optimization for both modules, you preserve bandwidth and
configure your system to operate more efficiently.
IMPORTANT
Each controller can establish connections, in any combination of direct or rackoptimized. In other words, you can use a rack-optimized connection between
an owner-controller and multiple remote I/O modules while simultaneously
using a direct connection between that same controller and any other I/O
modules in the same remote chassis.
Local Chassis
Remote Chassis
ControlNet Network
41021
One Connection for
All Remote I/O
26 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 2 Digital I/O Operation in the ControlLogix System
Suggestions for Rack-optimized Connections
We recommend that you use a rack-optimized connection for these applications:
• Standard digital I/O modules
• Non-fused digital output modules
• Owner-controllers running low on connections
Input Module Operation
In traditional I/O systems, controllers poll input modules to obtain their input
status. In the ControlLogix system, a controller does not poll digital input
modules. Instead, the modules multicast their data either upon change of state
(COS) or requested packet interval (RPI). The frequency depends on the
options chosen during configuration and whether the input module is local or
remote. This method of communication uses the Producer/Consumer model.
The input module is the producer of input data and the controller is the
consumer of the data.
All ControlLogix inputs are updated asynchronously in relation to the
controller’s task execution. In other words, an input may be updated in the
controller at any time during the controller’s execution of the tasks it is
configured to run. The input device determines when the input is sent based on
its configuration.
An input module’s behavior also varies depending upon whether it operates in the
local chassis or in a remote chassis. The following sections detail the differences in
data transfers between local and remote installations.
IMPORTANT
Rack-optimized connections are available only to digital I/O modules.
However, do not use a rack-optimized connection for diagnostic I/O modules or
fused output modules. Diagnostic and fused output data will not be
transferred over a rack-optimized connection. This defeats the purpose of using
those modules.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 27
Digital I/O Operation in the ControlLogix System Chapter 2
Input Modules in a
Local Chassis
When a module resides in the same chassis as the owner-controller, the following
two configuration parameters affect how and when an input module multicasts
data:
• Requested packet interval (RPI)
• Change of state (COS)
RPI
The RPI defines the slowest rate at which a module multicasts its data to the
owner-controller. The time ranges from 200 µs…750 ms and is sent to the module
with all other configuration parameters. When the specified time frame elapses,
the module will multicast data. This is also called a cyclic update.
COS
COS instructs the module to transfer data whenever a specified input point
transitions from On to Off or Off to On. The transition is referred to as a change
of state.
COS configuration occurs on a per-point basis, but all module data is multicast
when any point enabled for COS changes state. COS is more efficient than RPI
because it multicasts data only when a change occurs.
For example, if an input is changing state consistently every two seconds and the
RPI is set at 750 ms, the data transfer will look like the illustration.
IMPORTANT
The module’s COS feature defaults to Enabled for both On to Off and Off to On.
IMPORTANT
You must specify an RPI regardless of whether you enable COS. If a change does
not occur within the RPI timeframe, the module still will multicast data at the
rate specified by the RPI.
41381
= COS Multicast
= RPI Multicast
250 500 750
1 Second
1250 1500 1750
2 Seconds 3 Seconds
2250 2500 2750 3250
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Chapter 2 Digital I/O Operation in the ControlLogix System
Because the RPI and COS functions are asynchronous to the program scan, it is
possible for an input to change state during program scan execution. The point
must be buffered to prevent this from occurring. To buffer the point, you can
copy the input data from your input tags to another structure and use the data
from there.
Trigger Event Tasks
When configured, ControlLogix digital input modules can trigger an event task.
The event task lets you execute a section of logic immediately when an event, or
receipt of new data, occurs.
Your ControlLogix digital I/O module can trigger event tasks whenever module
input data changes state. Refer to these considerations when using a digital input
module to trigger an event task:
• Only one input module can trigger a specific event task.
• Input modules trigger the event task based on the module’s COS
configuration. The COS configuration defines which points prompt the
module to produce data if they turn On or Off. This production of data
triggers the event task.
• Typically, enable COS for only one point on the module. If you enable
COS for multiple points, a task overlap of the event task may occur.
For more information on event tasks, refer to the Logix5000 Controllers Tasks,
Programs, and Routines Programming Manual, publication 1756-PM005
.
Input Modules in a
Remote Chassis
If an input module physically resides in a chassis other than where the
owner-controller resides, the role of the RPI and the module’s COS behavior
changes slightly with respect to getting data to the owner.
The RPI and COS behavior still define when the module will multicast data
within its own chassis, as described in the previous section. But, only the value of
the RPI determines when the owner-controller will receive it over the network.
TIP
To minimize traffic and conserve bandwidth, use a larger RPI value if COS is
enabled and the module is in the same chassis as its owner-controller.
Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 29
Digital I/O Operation in the ControlLogix System Chapter 2
Remote Input Modules Connected via the ControlNet Network
When an RPI value is specified for an input module in a remote chassis
connected by a scheduled ControlNet network, in addition to instructing the
module to multicast data within its own chassis, the RPI also reserves a spot in
the stream of data flowing across the ControlNet network.
The timing of this reserved spot may or may not coincide with the exact value of
the RPI. But, the control system will guarantee that the owner-controller will
receive data at least as often as the specified RPI.
As shown in the illustration below, the input data within the remote chassis is
multicast at the configured RPI. The ControlNet communication module sends
input data back to the owner-controller at least as often as the RPI.
Figure 3 - Remote Input Modules on ControlNet Network
The module’s RPI and reserved spot on the network are asynchronous to each
other. This means there are best and worst case scenarios as to when the
owner-controller will receive updated data from the module in a remote chassis.
Best Case RPI Multicast Scenario
In the best case scenario, the module performs an RPI multicast with updated
channel data just before the reserved network slot is made available. In this case,
the remotely-located owner receives the data almost immediately.
40947
ControlNet Network
Local Chassis Remote Chassis
Multicast Data
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Chapter 2 Digital I/O Operation in the ControlLogix System
Worst Case RPI Multicast Scenario
In the worst case scenario, the module performs an RPI multicast just after the
reserved network slot has passed. In this case, the owner-controller will not
receive data until the next available network slot.
When selecting values for the remotely located module’s RPI, system throughput
is optimized when its RPI value is a power of two times the current NUT
running on the ControlNet network.
For example, the following table shows recommended RPI values for a system by
using a NUT of 5 ms.
Remote Input Modules Connected via the EtherNet/IP Network
When remote digital input modules are connected to the owner-controller via an
EtherNet/IP network, data is transferred to the owner-controller at these times:
• At the RPI, the module produces data within its own chassis.
• At the COS (if enabled), the 1756 EtherNet/IP communication module
in the remote chassis immediately sends the module’s data over the
network to the owner-controller as long as it has not sent data within a
timeframe that is one-quarter the value of the digital input module’s RPI.
This prevents flooding the network with data.
For example, if a digital input module uses an RPI = 100 ms, the
EtherNet/IP module sends module data immediately on receiving it if
another data packet was not sent within the last 25 ms.
For more information about specifying an RPI rate, see the Logix5000
Controllers Design Considerations Reference Manual,
publication 1756-RM094
.
IMPORTANT
Enabling the COS feature on an input module in a remote chassis allows the
module to multicast data at both the RPI rate and when the input changes
state. This helps to reduce the worst case time.
Table 2 - Recommended RPI Values for System by Using NUT of 5 ms
NUT=5 ms x2
0
x2
1
x2
2
x2
3
x2
4
x2
5
x2
6
x2
7
Optimal RPI
Valu es ( ms)
5 ms 10 ms 20 ms 40 ms 80 ms 160 ms 320 ms 640 ms
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