Rockwell Automation 1756-XXXX User Manual
ControlLogix Analog I/O Modules
Catalog Numbers
IR6I, 1756-IT6I, 1756-IT6I2, 1756-OF4, 1756-OF6CI, 1756-OF6VI, 1756-OF8
User Manual
1756-IF16, 1756-IF6CIS, 1756-IF6I, 1756-IF8, 1756-
Important User Information
WARNING
IMPORTANT
ATTENTION
SHOCK HAZARD
BURN HAZARD
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
Automation sales office or online at http://www.rockwellautomation.com/literature/
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.
available from your local Rockwell
) describes some important differences
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.
Identifies information that is critical for successful application and understanding of the product.
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.
Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous voltage may
be present.
Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may reach
dangerous temperatures.
Allen-Bradley, Rockwell Automation, Rockwell Software, RSLogix 5000, Logix5000, RSNetWorx, RSLinx, PowerFlex, DeviceNet, EtherNet/IP, Data Highway Plus-Remote I/O, and TechConnect are trademarks of
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Trademarks not belonging to Rockwell Automation are property of their respective companies.
Summary of Changes
Introduction
New and Updated
Information
Changes throughout this manual revision are marked by change bars, as shown to
the right of this paragraph.
The table explains the new and updated information in this manual.
Section Changes
Chapter 3
Chapter 4
Appendix A
Appendix D
Appendix F
and Chapter 6 Caution for disabling all alarms because it affects the
Using electronic keying with examples of Exact Match,
Compatible, and Disabled Keying.
underrange/overrange detection feature.
Updated I/O specifications.
Updated power-sizing chart and link to an interactive
spreadsheet to calculate total power consumption for
modules in a chassis configuration.
Updated information on interface modules (IFMs)
and pre-wired cables that are available with
analog I/O modules.
Publication 1756-UM009C-EN-P - December 2010 3
Summary of Changes
Notes:
4 Publication 1756-UM009C-EN-P - December 2010
Table of Contents
Preface
What Are ControlLogix
Analog I/O Modules?
Analog I/O Operation in the
ControlLogix System
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Who Should Use This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapter 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
I/O Module in the ControlLogix System . . . . . . . . . . . . . . . . . . . . . . . 17
Module Identification and Status Information . . . . . . . . . . . . . . . . . . . 19
Preventing Electrostatic Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Using RSNetWorx and RSLogix 5000 Software. . . . . . . . . . . . . . . . . . 22
Direct Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Input Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Input Modules in a Local Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Real Time Sample (RTS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Requested Packet Interval (RPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Triggering Event Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Input Modules in a Remote Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Remote Input Modules Connected Via
the ControlNet Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Remote Input Modules Connected Via
the EtherNet/IP Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Output Module Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Output Modules in a Local Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Output Modules in a Remote Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . 30
Remote Output Modules Connected Via
the ControlNet Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Remote Output Modules Connected Via
the EtherNet/IP Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Listen-only Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Multiple Owners of Input Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Configuration Changes in an Input Module with Multiple Owners . . 34
Chapter 3
ControlLogix Analog
I/O Module Features
Publication 1756-UM009C-EN-P - December 2010 5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Common Analog I/O Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Removal and Insertion Under Power (RIUP) . . . . . . . . . . . . . . . . 36
Module Fault Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Configurable Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Electronic Keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Access to System Clock for Timestamp Functions . . . . . . . . . . . . 44
Rolling Timestamp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Producer/Consumer Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table of Contents
Non-isolated Analog
Voltage/Current Input Modules
(1756-IF16, 1756-IF8)
Status Indicator Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Full Class I Division 2 Compliance. . . . . . . . . . . . . . . . . . . . . . . . . 45
Agency Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Field Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Sensor Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Latching of Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Module Inhibiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Relationship Between Module Resolution, Scaling, Data Format . . . . 48
Module Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Scaling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Data Format as Related to Resolution and Scaling . . . . . . . . . . . . 51
Chapter 4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Choose a Wiring Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Single-ended Wiring Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Differential Wiring Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
High-speed Mode Differential Wiring Method . . . . . . . . . . . . . . . 57
Choose a Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Features Specific to Non-Isolated Analog Input Modules. . . . . . . . . . 59
Multiple Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Module Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Real Time Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Underrange/Overrange Detection . . . . . . . . . . . . . . . . . . . . . . . . . 61
Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Process Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Rate Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Wire Off Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Use Module Block and Input Circuit Diagrams . . . . . . . . . . . . . . . . . . 67
Field-side Circuit Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Wire the 1756-IF16 Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Wire the 1756-IF8 Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
1756-IF16 Module Fault and Status Reporting . . . . . . . . . . . . . . . . . . 78
1756-IF16 Fault Reporting in Floating Point Mode. . . . . . . . . . . . . . . 79
1756-IF16 Module Fault Word Bits – Floating Point Mode . . . . . 80
1756-IF16 Channel Fault Word Bits – Floating Point Mode . . . . 80
1756-IF16 Channel Status Word Bits – Floating Point Mode. . . . 81
1756-IF16 Fault Reporting in Integer Mode. . . . . . . . . . . . . . . . . . . . . 82
1756-IF16 Module Fault Word Bits – Integer Mode. . . . . . . . . . . 83
1756-IF16 Channel Fault Word Bits – Integer Mode . . . . . . . . . . 83
1756-IF16 Channel Status Word Bits – Integer Mode . . . . . . . . . 84
1756-IF8 Module Fault and Status Reporting . . . . . . . . . . . . . . . . . . . 85
1756-IF8 Fault Reporting in Floating Point Mode. . . . . . . . . . . . . . . . 86
1756-IF8 Module Fault Word Bits – Floating Point Mode . . . . . . 87
1756-IF8 Channel Fault Word Bits – Floating Point Mode . . . . . 87
6 Publication 1756-UM009C-EN-P - December 2010
Sourcing Current Loop Input
Module (1756-IF6CIS) and Isolated
Analog Voltage/Current Input
Module (1756-IF6I)
Table of Contents
1756-IF8 Channel Status Word Bits – Floating Point Mode. . . . . 88
1756-IF8 Fault Reporting in Integer Mode. . . . . . . . . . . . . . . . . . . . . . 89
1756-IF8 Module Fault Word Bits – Integer Mode . . . . . . . . . . . . 90
1756-IF8 Channel Fault Word Bits – Integer Mode . . . . . . . . . . . 90
1756-IF8 Channel Status Word Bits – Integer Mode . . . . . . . . . . 91
Chapter 5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Use the Isolated Power Source on the 1756-IF6CIS . . . . . . . . . . . . . . 94
Power Calculations with the 1756-IF6CIS Module . . . . . . . . . . . . 94
Other Devices in the Wiring Loop . . . . . . . . . . . . . . . . . . . . . . . . . 94
Choose a Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Features Specific to the 1756-IF6I and 1756-IF6CIS Modules . . . . . . 96
Multiple Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Notch Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Real Time Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Underrange/Overrange Detection . . . . . . . . . . . . . . . . . . . . . . . . . 98
Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Process Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Rate Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Wire Off Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Use Module Block and Input Circuit Diagrams . . . . . . . . . . . . . . . . . 104
Field-side Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Wire the 1756-IF6CIS Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Wire the 1756-IF6I Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
1756-IF6CIS or 1756-IF6I Module Fault and Status Reporting . . . . 111
Fault Reporting in Floating Point Mode . . . . . . . . . . . . . . . . . . . . . . . 112
Module Fault Word Bits – Floating Point Mode . . . . . . . . . . . . . 113
Channel Fault Word Bits – Floating Point Mode . . . . . . . . . . . . 113
Channel Status Word Bits – Floating Point Mode . . . . . . . . . . . . 114
Fault Reporting in Integer Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Module Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . . 116
Channel Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . 116
Channel Status Word Bits – Integer Mode. . . . . . . . . . . . . . . . . . 117
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Table of Contents
Temperature-measuring Analog
Modules (1756-IR6I, 1756-IT6I,
and 1756-IT6I2)
Chapter 6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Choose a Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Temperature-measuring Module Features . . . . . . . . . . . . . . . . . . . . . 121
Multiple Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Notch Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Real Time Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Underrange/Overrange Detection . . . . . . . . . . . . . . . . . . . . . . . . 123
Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Process Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Rate Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
10 Ohm Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Wire Off Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Sensor Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Temperature Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Input Signal to User Count Conversion . . . . . . . . . . . . . . . . . . . . 130
Wire Length Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Differences Between the 1756-IT6I and 1756-IT6I2 Modules . . . . . 131
Cold Junction Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Improved Module Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Use Module Block and Input Circuit Diagrams . . . . . . . . . . . . . . . . . 136
Field-side Circuit Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Wire the Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Fault and Status Reporting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Fault Reporting in Floating Point Mode . . . . . . . . . . . . . . . . . . . . . . . 142
Module Fault Word Bits – Floating Point Mode . . . . . . . . . . . . . 143
Channel Fault Word Bits – Floating Point Mode . . . . . . . . . . . . 143
Channel Status Word Bits – Floating Point Mode . . . . . . . . . . . . 144
Fault Reporting in Integer Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Module Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . . 146
Channel Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . 146
Channel Status Word Bits – Integer Mode. . . . . . . . . . . . . . . . . . 147
Chapter 7
Non-isolated Analog Output
Modules (1756-OF4 and 1756-OF8)
8 Publication 1756-UM009C-EN-P - December 2010
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Choose a Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Non-isolated Output Module Features . . . . . . . . . . . . . . . . . . . . . . . . 150
Ramping/Rate Limiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Hold for Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Open Wire Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Clamping/Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Clamp/Limit Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Data Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
User Count Conversion to Output Signal . . . . . . . . . . . . . . . . . . 153
Use Module Block and Output Circuit Diagrams . . . . . . . . . . . . . . . 154
Isolated Analog Output Modules
(1756-OF6CI and 1756-OF6VI)
Table of Contents
Field-side Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Wire the 1756-OF4 Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Wire the 1756-OF8 Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
1756-OF4 and 1756-OF8 Module Fault and Status Reporting . . . . . 159
1756-OF4 and 1756-OF8 Fault Reporting in Floating Point Mode . 160
Module Fault Word Bits – Floating Point Mode . . . . . . . . . . . . . 161
Channel Fault Word Bits – Floating Point Mode . . . . . . . . . . . . 161
Channel Status Words Bits – Floating Point Mode . . . . . . . . . . . 162
1756-OF4 and 1756-OF8 Fault Reporting in Integer Mode . . . . . . . 163
Module Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . . 164
Channel Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . 164
Channel Status Word Bits – Integer Mode. . . . . . . . . . . . . . . . . . 165
Chapter 8
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Choose a Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Isolated Output Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Ramping/Rate Limiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Hold for Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Clamping/Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Clamp/Limit Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Data Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
User Count Conversion to Output Signal . . . . . . . . . . . . . . . . . . 171
Use Module Block and Output Circuit Diagrams . . . . . . . . . . . . . . . 172
Field-side Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Drive Different Loads with the 1756-OF6CI. . . . . . . . . . . . . . . . . . . 174
Wire the 1756-OF6CI Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Wire the 1756-OF6VI Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
1756-OF6CI and 1756-OF6VI Module Fault, Status Reporting . . . . 179
Fault Reporting in Floating Point Mode . . . . . . . . . . . . . . . . . . . . . . . 180
Module Fault Word Bits – Floating Point Mode . . . . . . . . . . . . . 181
Channel Fault Word Bits – Floating Point Mode . . . . . . . . . . . . 181
Channel Status Word Bits – Floating Point Mode . . . . . . . . . . . . 182
Fault Reporting in Integer Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Module Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . . 184
Channel Fault Word Bits – Integer Mode . . . . . . . . . . . . . . . . . . 184
Channel Status Word Bits in Integer Mode . . . . . . . . . . . . . . . . . 185
Publication 1756-UM009C-EN-P - December 2010 9
Table of Contents
Install ControlLogix I/O Modules
Configure ControlLogix
Analog I/O Modules
Chapter 9
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Install the I/O Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Key the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Connect Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Connect the Grounded End of the Cable . . . . . . . . . . . . . . . . . . 190
Connect the Ungrounded End of the Cable . . . . . . . . . . . . . . . . 192
Three Types of RTBs (each RTB comes with housing) . . . . . . . 192
Recommendations for Wiring Your RTB. . . . . . . . . . . . . . . . . . . 194
Assemble the RTB and the Housing. . . . . . . . . . . . . . . . . . . . . . . . . . 194
Install the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . 195
Remove the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . 196
Remove the Module from the Chassis . . . . . . . . . . . . . . . . . . . . . . . . 197
Chapter 10
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Configuration Process Overview . . . . . . . . . . . . . . . . . . . . . . . . . 200
Create a New Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Communication Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Modify Default Configuration for Input Modules . . . . . . . . . . . . . . . 207
Connection Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Alarm Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Calibration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Configure the RTD Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Configure the Thermocouple Modules . . . . . . . . . . . . . . . . . . . . . . . . 216
Modify Default Configuration for Output Modules . . . . . . . . . . . . . 218
Connection Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Output State Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Limits Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Calibration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Download Configuration Data to the Module . . . . . . . . . . . . . . . . . . 225
Edit Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Reconfigure Module Parameters in Run Mode . . . . . . . . . . . . . . . . . 227
Reconfigure Parameters in Program Mode. . . . . . . . . . . . . . . . . . . . . 229
Configure I/O Modules in a Remote Chassis . . . . . . . . . . . . . . . . . . 230
View Module Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
10 Publication 1756-UM009C-EN-P - December 2010
Calibrate the ControlLogix
Analog I/O Modules
Troubleshoot Your Module
Table of Contents
Chapter 11
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Difference of Calibrating an Input Module and Output Module . . . 234
Calibrating in Either Program or Run Mode . . . . . . . . . . . . . . . . 235
Calibrate Your Input Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Calibrating the 1756-IF16 or 1756-IF8 Modules . . . . . . . . . . . . . 235
Calibrating the 1756-IF6CIS or 1756-IF6I Modules . . . . . . . . . . 241
Calibrating the 1756-IR6I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Calibrating the 1756-IT6I or 1756-IT6I2 . . . . . . . . . . . . . . . . . . . 253
Calibrate Your Output Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Current Meter Calibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Voltage Meter Calibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Chapter 12
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Status Indicators for Input Modules . . . . . . . . . . . . . . . . . . . . . . . 273
Status Indicators for Output Modules . . . . . . . . . . . . . . . . . . . . . 274
Use RSLogix 5000 Software for Troubleshooting . . . . . . . . . . . . . . . 275
Fault Type Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Analog I/O Module Specifications
Analog I/O Tag Definitions
Appendix A
1756-IF6CIS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
1756-IF6I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
1756-IF8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
1756-IF16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
1756-IR6I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
1756-IT6I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304
1756-IT6I2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
1756-OF4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
1756-OF6CI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
1756-OF6VI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
1756-OF8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Appendix B
Integer Mode Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Integer Input Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Integer Output Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
Integer Configuration Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Floating Point Mode Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Floating Point Input Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Floating Point Output Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Floating Point Configuration Tags . . . . . . . . . . . . . . . . . . . . . . . . 334
Publication 1756-UM009C-EN-P - December 2010 11
Table of Contents
Use Ladder Logic To Perform
Run Time Services and
Reconfiguration
Choose Correct Power Supply
Additional Specification
Information
Appendix C
Using Message Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
Processing Real-time Control and Module Services. . . . . . . . . . . 339
One Service Performed Per Instruction . . . . . . . . . . . . . . . . . . . . 340
Create a New Tag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Enter Message Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
Communication Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
Unlatch Alarms in the 1756-IF6I Module . . . . . . . . . . . . . . . . . . 348
Unlatch Alarms in the 1756-OF6VI Module . . . . . . . . . . . . . . . . 351
Reconfiguring a 1756-IR6I Module . . . . . . . . . . . . . . . . . . . . . . . 353
Considerations With This Ladder Logic Example . . . . . . . . . . . . 355
Perform Module Reset Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
Appendix D
Power-sizing Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
Appendix E
Analog to Digital (A/D) Converter Accuracy . . . . . . . . . . . . . . . . . . 361
Calibrated Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
Error Calculated Over Hardware Range . . . . . . . . . . . . . . . . . . . . . . . 363
How Operating Temperature Changes Affect Module Accuracy . . . 363
Gain Drift With Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Module Error Over Full Temperature Range . . . . . . . . . . . . . . . 364
RTD and Thermocouple Error Calculations . . . . . . . . . . . . . . . . . . . 365
RTD Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Thermocouple Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366
Module Error at 25 °C (77 °F) (-12…30 mV Range) . . . . . . . . . 367
Module Error at 25 °C (77 °F) (-12…78 mV Range) . . . . . . . . . 370
Thermocouple Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
Module Resolution (-12…30 mV Range). . . . . . . . . . . . . . . . . . . 374
Module Resolution (-12…78 mV Range). . . . . . . . . . . . . . . . . . . 377
How to Deal with Incorrect Thermocouple Temp Readings . . . 381
Appendix F
1492 AIFMs for Analog
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
I/O Modules
Glossary
Index
12 Publication 1756-UM009C-EN-P - December 2010
Preface
Introduction
Who Should Use This
Manual
Additional Resources
This manual describes how to install, configure, and troubleshoot your
ControlLogix analog I/O module.
You must be able to program and operate a Rockwell Automation
ControlLogix controller to efficiently use your analog I/O modules. If you
need additional information, refer to the related documentation listed below.
The following table lists related ControlLogix products and documentation.
Related Documentation
Cat. No. Resource
1756-A4, 1756-A7, 1756-A10,
1756-A13, 1756-A17
1756-PA72, 1756-PB72, 1756-PA75,
1756-PB75, 1756-PH75, 1756-PC75
1756 digital I/O modules ControlLogix Digital I/O Modules User Manual,
1756-CNB, 1756-CNBR ControlNet Modules in Logix5000 Control Systems,
ControlLogix Chassis, Series B Installation
Instructions, publication
ControlLogix Power Supplies Installation
Instructions, publication
publication
publication
1756-UM058
CNET-UM001
1756-IN080
1756-IN613
1756-DNB DeviceNet Modules in Logix5000 Control Systems
User Manual, publication
1756-DHRIO ControlLogix Data Highway Plus-Remote I/O
Communication Interface Module User Manual,
publication
1756-ENBT, 1769-ENET EtherNet/IP Modules in Logix5000 Control Systems
User Manual, publication
1756-Lx ControlLogix Selection Guide,
publication
1756-Lx ControlLogix System User Manual,
publication
1756-Lx, 1769-Lx, 1789-Lx,
PowerFlex 700S
1756-Lx, 1769-Lx, 1789-Lx, 1794-Lx,
PowerFlex 700S
Logix5000 Controllers Common Procedures
Programming Manual, publication
Logix5000 Controllers General Instructions
Reference Manual, publication
1756-UM514
1756-SG001
1756-UM001
DNET-UM004
ENET-UM001
1756-PM001
1756-RM003
If you need more information on these products, contact your local Rockwell
Automation distributor or sales office. The documentation listed in the Related
Documentation table is available at
http://www..rockwellautomation.com/literature
.
Publication 1756-UM009C-EN-P - December 2010 13
Preface
Notes:
14 Publication 1756-UM009C-EN-P - December 2010
Chapter
1
What Are ControlLogix Analog I/O Modules?
Introduction
This chapter provides an overview of the ControlLogix analog I/O modules
to explain to you how they operate.
Topic Page
I/O Module in the ControlLogix System 17
Parts Illustration of the ControlLogix Analog I/O Module 18
Module Identification and Status Information 19
Preventing Electrostatic Discharge 20
ControlLogix analog I/O modules are interface modules that convert analog
signals to digital values for inputs and convert digital values to analog signals
for outputs. Controllers can then use these signals for control purposes.
By using the producer/consumer network model, ControlLogix analog I/O
modules produce information when needed while providing additional system
functions.
The table lists several features available on ControlLogix analog I/O modules.
ControlLogix Analog I/O Module Features
Feature Description
Removal and insertion
under power (RIUP)
Producer/consumer
communication
Rolling timestamp of data A 15-bit module-specific rolling timestamp with millisecond
Multiple data formats Analog I/O modules offer the option of IEEE 32-bit floating
Module resolution Analog input modules use 16-bit resolution, and analog
On-board features Scaling to engineering units, alarming, and under/overrange
Publication 1756-UM009C-EN-P - December 2010 15
You can remove and insert modules and removable terminal
blocks (RTB) while power is applied.
This communication is an intelligent data exchange
between modules and other system devices in which each
module produces data without first being polled.
resolution that indicates when data was sampled and/or
applied. This timestamp may be used to calculate the
interval between channel or field-side updates.
point or 16-bit integer data formats.
output modules offer 13…16-bit output resolution
(depending on the module type), to detect data changes.
detection, are some examples of the I/O module features.
Chapter 1 What Are ControlLogix Analog I/O Modules?
ControlLogix Analog I/O Module Features
Feature Description
Calibration ControlLogix analog I/O module ships from the factory with
Coordinated system time
(CST) time stamp of data
Agency Certification
factory calibration. You can recalibrate the module
calibration on a channel-by-channel or module-wide basis to
increase accuracy in customer-specific applications,
if necessary.
A 64-bit system clock places a time stamp on the transfer of
data between the module and its owner-controller within
the local chassis.
Full agency certification for in any application that requires
approval.
Agency certification varies depending on the catalog
number. To see a list of the certifications associated with
each catalog number, see
Appendix A
.
16 Publication 1756-UM009C-EN-P - December 2010
What Are ControlLogix Analog I/O Modules? Chapter 1
IMPORTANT
I/O Module in the ControlLogix System
Types of ControlLogix Analog I/O Modules
Cat. No. Description RTB Used Page
1756-IF16 16-point non-isolated analog current/voltage input module
1756-IF8 8-point non-isolated analog current/voltage input module 289
ControlLogix modules mount in a ControlLogix chassis and use a removable
terminal block (RTB) or a Bulletin 1492 interface module
(1)
cable to connect
to all field-side wiring.
Before you install and use your module, you should do the following:
• Install and ground a 1756 chassis and power supply
(2)
. To install these
products, refer to the publications listed in Additional Resources
on page 13.
• Order and receive an RTB or IFM and its components for your
application.
RTBs and IFMs are not included with your
module purchase.
36-pin
294
1756-IF6CIS 6-point sourcing current loop input module
279
1756-IF6I 6-point isolated analog current/voltage input module 284
1756-IR6I 6-point isolated RTD input module 299
1756-IT6I 6-point isolated Thermocouple/mV input module 304
1756-IT6I2 6-point isolated Enhanced Thermocouple/mV input module 308
20-pin
1756-OF4 4-point non-isolated analog current/voltage output module 312
1756-OF8 8-point non-isolated analog current/voltage output module 323
1756-OF6CI 6-point isolated analog current output module 316
1756-OF6VI 6-point isolated analog voltage output module 320
(1)
The ControlLogix system has been agency certified using only the ControlLogix RTBs (1756-TBCH, 1756-TBNH,
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 agency. To
see what analog interface modules are used with each ControlLogix analog I/O module, see Appendix F
(2)
In addition to standard ControlLogix power supplies, ControlLogix Redundant Power Supplies are also available
for your application. For more information on these supplies, see the ControlLogix Selection Guide,
publication 1756-SG001
, or contact your local Rockwell Automation distributor or sales representative.
.
Publication 1756-UM009C-EN-P - December 2010 17
Chapter 1 What Are ControlLogix Analog I/O Modules?
Removable Terminal Block
1
2
3
4
5
6
40200-M
Parts Illustration of the ControlLogix Analog I/O Module
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 cable
onto the module.
3 Status indicators - Indicators display the
status of communication, module health,
and input/output devices. Indicators help in
troubleshooting anomalies.
4 Connectors 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 cable on the module,
maintaining wiring connections.
6 Slots for keying - Mechanically keys the
RTB to prevent inadvertently making the
wrong wire connections to your module.
18 Publication 1756-UM009C-EN-P - December 2010
What Are ControlLogix Analog I/O Modules? Chapter 1
IMPORTANT
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 be aware of
exactly what modules are located in any ControlLogix rack at any time. While
retrieving module identity, you can also retrieve the module’s status.
Module Identification and Status Information
Item Description
Product Type Module’s product type, such as Analog I/O
or Digital I/O module
Catalog Code Module’s catalog number
Major Revision Module’s major revision number
Minor Revision Module’s minor revision number
Status Module’s status that shows the following information:
• Controller ownership (if any)
• Whether module has been configured
• Device Specific Status, such as:
• Self-Test
• Flash update in progress
• Communications fault
• Not owned (outputs in program mode)
• Internal fault (need flash update)
• Run mode
• Program mode (output mods only)
• Minor recoverable fault
• Minor unrecoverable fault
• Major recoverable fault
• Major unrecoverable fault
Vendor ID Module manufacturer vendor, for example Allen-Bradley
Serial Number Module serial number
Length of ASCII Text String Number of characters in module’s text string
ASCII Text String Number of characters in module’s text string
You must perform a WHO service to retrieve this information.
Publication 1756-UM009C-EN-P - December 2010 19
Chapter 1 What Are ControlLogix Analog I/O Modules?
ATTENTION
Preventing Electrostatic Discharge
This module is sensitive to electrostatic discharge.
This equipment is sensitive to electrostatic discharge, which
can cause internal damage and affect normal operation. Follow
these guidelines when you handle this equipment:
• Touch a grounded object to discharge potential static.
• Wear an approved grounding wriststrap.
• Do not touch connectors or pins on component
boards.
• Do not touch circuit components inside the equipment.
• If available, use a static-safe workstation.
• When not in use, store the equipment in appropriate
static-safe packaging.
20 Publication 1756-UM009C-EN-P - December 2010
Analog I/O Operation in the ControlLogix System
Chapter
2
Introduction
I/O modules are interfaces between the controller and the field devices that
comprise the ControlLogix system. Analog signals, which are continuous, are
converted by the module and used by the controller to mandate field-device
results.
This chapter describes how analog I/O modules operate within the
ControlLogix system.
Topic Page
Ownership 21
Using RSNetWorx and RSLogix 5000 Software 22
Direct Connections 23
Input Module Operation 24
Input Modules in a Local Chassis 24
Real Time Sample (RTS) 24
Requested Packet Interval (RPI) 25
Input Modules in a Remote Chassis 27
Output Module Operation 29
Output Modules in a Local Chassis 29
Output Modules in a Remote Chassis 30
Listen-only Mode 32
Multiple Owners of Input Modules 33
Configuration Changes in an Input Module with Multiple Owners 34
Ownership
Publication 1756-UM009C-EN-P - December 2010 21
Every I/O module in the ControlLogix system must be owned by a
ControlLogix controller. This owner-controller:
• stores configuration data for every module that it owns.
• can be local or remote in regard to the I/O module’s position.
• sends the I/O module configuration data to define the module’s
behavior and begin operation within the control system.
Each ControlLogix I/O module must continuously maintain communication
with its owner to operate normally.
Chapter 2 Analog I/O Operation in the ControlLogix System
Typically, each module in the system will have one owner only. Input modules
can have more than one owner. Output modules, however, are limited to a
single owner.
For more information on the increased flexibility provided by multiple owners
and the ramifications of using multiple owners, see
Input Module with Multiple Owners
on
page 34
Configuration Changes in an
.
Using RSNetWorx and RSLogix 5000 Software
The I/O configuration portion of the RSLogix5000 programming software
generates the configuration data for each I/O module in the control system,
whether the module is in a local or remote chassis. A remote chassis, also
known as networked, contains the I/O module but not the module’s
owner-controller. A remote chassis can be connected to the controller via a
scheduled connection on the ControlNet network or an
EtherNet/IP network.
RSLogix 5000 configuration data is transferred to the controller during the
program download and subsequently transferred to the appropriate I/O
modules. I/O modules in the local chassis, and modules in a remote chassis
connected via the EtherNet/IP network, or unscheduled connections on the
ControlNet network, 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.
Running 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.
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
programming 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.
22 Publication 1756-UM009C-EN-P - December 2010
Analog I/O Operation in the ControlLogix System Chapter 2
IMPORTANT
3. After running RSNetWorx software, perform an online save of the
RSLogix 5000 project so the configuration information that
RSNetWorx software sends to the controller is saved..
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.
Direct Connections
ControlLogix analog I/O modules use direct connections only.
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, and one of the following events occurs:
• 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 displays 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, such as removal of the module from the chassis while
under power, causes the controller to set fault status bits in the data area
associated with the module. The RSLogix 5000 programming software
monitors this data area to annunciate the module’s failures.
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On-Board Memory
Status Data
Channel Data
Channel Data
Channel Data
Channel Data
Channel Data
Channel Data
Ch 0
Ch 1
Ch 2
Ch 3
Ch 4
Ch 5
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2
Input Module Operation
Input Modules in a Local Chassis
In traditional I/O systems, controllers poll input modules to obtain their input
status. In the ControlLogix system, a controller does not poll analog input
modules after a connection is established. Instead, the modules multicast their
data periodically. The frequency depends on the options chosen during
configuration and where in the control system that input module physically
resides.
An input module’s behavior 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 these set-ups.
When a module resides in the same chassis as the owner-controller, the
following two configuration parameters will affect how and when an input
module produces data:
Real Time Sample (RTS)
•
•
Requested Packet Interval (RPI)
Real Time Sample (RTS)
This configurable parameter, which is set during the initial configuration by
using RSLogix5000 software, instructs the module to perform two
basic operations:
1. Scan all of its input channels and store the data into on-board memory.
2. Multicast the updated channel data (as well as other status data) to the
backplane of the local chassis.
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On-Board Memory
Status Data
Channel Data
Channel Data
Channel Data
Channel Data
Channel Data
Channel Data
Ch 0
Ch 1
Ch 2
Ch 3
Ch 4
Ch 5
Tim estamp
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IMPORTANT
Requested Packet Interval (RPI)
This configurable parameter also instructs the module to multicast its channel
and status data to the local chassis backplane.
The RPI, however, instructs the module to produce the current contents of its
on-board memory when the RPI expires, (that is, the module does not update
its channels prior to the multicast).
The RPI value is set during the initial module configuration by
using RSLogix 5000 software. This value can be adjusted when
the controller is in Program mode.
The module will reset the RPI timer each time an RTS is performed. This
operation dictates how and when the owner-controller in the local chassis will
receive updated channel data, depending on the values given to these
parameters.
If the RTS value is less than or equal to the RPI, each multicast of data from
the module will have updated channel information. In effect, the module is
only multicasting at the RTS rate.
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Chapter 2 Analog I/O Operation in the ControlLogix System
RTS
100 ms - Updated data
RPI
25 ms - Same input data
as the previous RTS
25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400
Time (ms)
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IMPORTANT
If the RTS value is greater than the RPI, the module produces at both the RTS
rate and the RPI rate. Their respective values will dictate how often the
owner-controller will receive data and how many multicasts from the module
contain updated channel data.
In the example below, the RTS value is 100 ms and the RPI value is 25 ms.
Only every fourth multicast from the module will contain updated channel
data.
Triggering Event Tasks
When configured, ControlLogix analog input modules can trigger an event
task. The event task lets you execute a section of logic immediately when an
event (that is, receipt of new data) occurs.
Your ControlLogix analog I/O module can trigger event tasks every RTS, after
the module has sampled and multicast its data. Events tasks are useful for
synchronizing process variable (PV) samples and proportional integral
derivative (PID) calculations.
ControlLogix analog I/O modules can trigger event tasks at
every RTS but not at the RPI. For example, in the illustration
above, an event task can be only triggered every 100 ms.
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ControlNet network
Multicast data
40947
Local Chassis Remote Chassis
Input Modules in a Remote Chassis
If an input module physically resides in a remote chassis, the role of the RPI
and the module’s RTS behavior change slightly with respect to getting data to
the owner-controller, depending on what network type you are using to
connect to the modules.
Remote Input Modules Connected Via the ControlNet Network
When remote analog I/O modules are connected to the owner-controller via a
scheduled ControlNet network, the RPI and RTS intervals still define when
the module will multicast data within its own chassis (as described in the
previous section). However, only the value of the RPI determines how often
the owner-controller will receive it over the 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 guarantees that the owner-controller
receives 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 bridge module sends input
data back to the owner-controller at least as often as the RPI.
The ‘reserved’ spot on the network and the module’s RTS are asynchronous to
each other. This means there are best and worst Case scenarios as to when the
owner-controller will receive updated channel data from the module in a
networked chassis.
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Chapter 2 Analog I/O Operation in the ControlLogix System
TIP
TIP
Best Case RTS Scenario
In the best case scenario, the module performs an RTS multicast with updated
channel data just before the ‘reserved’ network slot is made available. In this
case, the remotely-located owner-controller receives the data almost
immediately.
Worst Case RTS Scenario
In the worst case scenario, the module performs an RTS multicast just after
the ‘reserved’ network slot has passed. In this case, the owner-controller will
not receive data until the next scheduled network slot.
Because it is the RPI and not the RTS that dictates when the
module’s data will be sent over the network, we recommend
the RPI value be set less than or equal to the RTS to make sure
that updated channel data is received by the owner-controller
with each receipt of data.
Remote Input Modules Connected Via the EtherNet/IP Network
When remote analog input modules are connected to the owner-controller via
an EtherNet/IP network, data is transferred to the owner-controller in the
following way:
• At the RTS or RPI (whichever is faster), the module broadcasts data
within its own chassis.
• The 1756 Ethernet bridge 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 time frame that is one-quarter the
value of the analog input module’s RPI.
For example, if an analog input module uses an RPI = 100 ms, the
Ethernet module sends module data immediately on receiving it if
another data packet was not sent within the last 25 ms.
The Ethernet module will either multicast the module’s data to all
devices on the network or unicast to a specific owner-controller
depending on the setting of the Unicast box, as shown on
For more information, see the Guidelines to Specify an RPI
Rate for I/O Modules section in the Logix5000 Controllers
Design Considerations Reference Manual,
publication
1756-RM094
.
page 209
.
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Data sent from owner at the RPI
Owner-controller Output module
Output Module Operation
The RPI parameter governs exactly when an analog output module receives
data from the owner-controller and when the output module echoes data. An
owner-controller sends data to an analog output module only at the period
specified in the RPI. Data is not sent to the module at the end of the
controller’s program scan.
When an analog output module receives new data from an owner-controller
(that is, every RPI), the module automatically multicasts or ‘echoes’ a data
value that corresponds to the analog signal present at the output terminals to
the rest of the control system. This feature, called Output Data Echo, occurs
whether the output module is local or remote.
Depending on the value of the RPI, with respect to the length of the controller
program scan, the output module can receive and ‘echo’ data multiple times
during one program scan.
When the RPI is less than the program scan length, the controller effectively
allows the module’s output channels to change values multiple times during a
single program scan because the output module is not dependent on reaching
the end of the program to send data.
Output Modules in a Local Chassis
When specifying an RPI value for an analog output module, you instruct the
controller when to broadcast the output data to the module. If the module
resides in the same chassis as the owner-controller, the module receives the
data almost immediately after the controller sends it.
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Chapter 2 Analog I/O Operation in the ControlLogix System
ControlNet
Output data at least as often as RPI
Immediate backplane
transfers to module
Data sent from owner
at module’s RPI rate
Owner-controller ControlNet Bridge module ControlNet Bridge module Output module
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Output Modules in a Remote Chassis
If an output module resides in a remote chassis, the role of the RPI changes
slightly with respect to getting data from the owner-controller, depending on
what network type you are using to connect to the modules.
Remote Output Modules Connected Via the ControlNet Network
When remote analog output modules are connected to the owner-controller
via a scheduled ControlNet network, in addition to instructing the controller
to multicast the output 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 output module will
receive data at least as often as the specified RPI.
The ‘reserved’ spot on the network and when the controller sends the output
data are asynchronous to each other. This means there are best and worst case
scenarios as to when the module will receive the output data from the
controller in a networked chassis.
Best Case RPI Scenario
In the best case scenario, the controller sends the output data just before the
‘reserved’ network slot is available. In this case, the remotely-located output
module receives the data almost immediately.
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