Rockwell Automation 1756-OF8I User Manual

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User Manual

ControlLogix Eight-channel Isolated Analog I/O Modules

Catalog Numbers 1756-IF8I, 1756-IRT8I, 1756-OF8I

Important User Information

IMPORTANT

Read this document and the documents listed in the additional resources section about installation, configuration, and operation of this equipment before you install, configure, operate, or maintain this product. Users are required to familiarize themselves with installation and wiring instructions in addition to requirements of all applicable codes, laws, and standards.

Activities including installation, adjustments, putting into service, use, assembly, disassembly, and maintenance are required to be carried out by suitably trained personnel in accordance with applicable code of practice.

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

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

The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or liability for actual use based on the examples and diagrams.

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

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

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

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.

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

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

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

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

ARC FLASH HAZARD: Labels may be on or inside the equipment, for example, a motor control center, to alert people to potential Arc Flash. Arc Flash will cause severe injury or death. Wear proper Personal Protective Equipment (PPE). Follow ALL Regulatory requirements for safe work practices and for Personal Protective Equipment (PPE).

Allen-Bradley, ControlLogix, Integrated Architecture, Logix Designer, Logix5000, Rockwell Software, Rockwell Automation, RSLogix, Studio 5000, an d Studio 5000 Log ix Designer are trademarks of Rockwell Automation, Inc.

Trademarks not belonging to Rockwell Automation are property of their respective companies.

Preface

Isolated Analog I/O Module Operation in the ControlLogix System

ControlLogix Isolated Analog I/O Module Features

Studio 5000 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Chapter 1

Before You Begin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Configure a Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Direct Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Input Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Requested Packet Interval (RPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Input Modules in a Local Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Input Modules in a Remote Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Triggering Event Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Output Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Output Modules in a Local Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Output Modules in a Remote Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Listen-only Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 2

Common Analog I/O Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

CIP Sync Timestamp of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Rolling Timestamp of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Floating Point Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Module Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Module Quality Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Fault and Status Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Configurable Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Latching of Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Module Inhibiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Electronic Keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Exact Match . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Compatible Keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Disabled Keying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Relationship between Module Resolution and Scaling. . . . . . . . . . . . . . . 35

Module Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Scaling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Calibrated Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Calibrated Accuracy at 25 °C (77 °F). . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Module Error over Full Temperature Range . . . . . . . . . . . . . . . . . . . . 39

Error Calculated over Hardware Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 3

Table of Contents

RTD and Thermocouple Error Calculations. . . . . . . . . . . . . . . . . . . . . . . . 39

RTD Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Thermocouple Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Module Error at 25 °C (77 °F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Thermocouple Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Chapter 3 1756-IF8I Isolated Analog Input Module

1756-IRT8I Combined Temperature-sensing Isolated Analog Module

1756-IF8I Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Internal Loop Power Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Multiple Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Notch Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Underrange/Overrange Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Process Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Rate Alarm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Sensor Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Wire Off Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Synchronized Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Module Block and Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Field-side Circuit Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Wire the 1756-IF8I Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Fault and Status Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Chapter 4

1756-IRT8I Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Multiple Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Notch Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Underrange/Overrange Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Process Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Rate Alarm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Sensor Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

10 Ohm Copper Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Wire Off Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Temperature Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Sensor Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Thermocouple Wire Length Compensation . . . . . . . . . . . . . . . . . . . . 81

Synchronized Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Cold Junction Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Module Block and Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Field-side Circuit Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Wire the 1756-IRT8I Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Fault and Status Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

Chapter 5

Table of Contents

1756-OF8I Isolated Analog Output Module

Install ControlLogix Isolated Analog I/O Modules

1756-OF8I Module Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Multiple Output Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Channel Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Ramping/Rate Limiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Hold for Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Clamping/Limiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Clamp/Limit Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Data Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Module Block and Output Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . 98

Field-side Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Drive Different Loads

with the 1756-OF8I Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Wire the 1756-OF8I Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Fault and Status Reporting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Chapter 6

Install the I/O Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Key the Removable Terminal Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Connect Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Connect the Grounded End of the Cable. . . . . . . . . . . . . . . . . . . . . . 110

Connect the Ungrounded End of the Cable . . . . . . . . . . . . . . . . . . . 111

RTB Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

RTB Wiring Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

Assemble the RTB and the Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

Choose Extended-depth Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Cabinet Size Considerations with Extended-depth Housing . . . . 116

Install the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Remove the Removable Terminal Block. . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Remove the Module from the Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Configure ControlLogix Isolated AnalogI/O Modules

Chapter 7

Create a New Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Module Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Edit the Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Connection Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Calibration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Alarm Configuration Tab. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

CJ Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Limit Configuration Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Copy Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

View the Module Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 5

Table of Contents

Chapter 8 Calibrate the ControlLogix Isolated Analog I/O Modules

Troubleshoot Your Module

Difference between Calibrating an Input Module and

an Output Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Calibrate in Program Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Calibrate the Input Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Calibrate the 1756-IF8I Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Calibrate the 1756-IRT8I Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

Calibrate the Output Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Calibrate the 1756-OF8I Module for a Current Output Type . . . 152

Chapter 9

Status Indicators for the 1756-IF8I Module . . . . . . . . . . . . . . . . . . . . . . . 157

Status Indicators for the 1756-IRT8I Module. . . . . . . . . . . . . . . . . . . . . . 158

Status Indicators for the 1756-OF8I Module . . . . . . . . . . . . . . . . . . . . . . 159

Use Logix Designer Application for Troubleshooting. . . . . . . . . . . . . . . 160

Troubleshoot Incorrect Readings on the Module. . . . . . . . . . . . . . . . . . . 162

1756-IRT8I Module - Incorrect Temperature Readings. . . . . . . . . 162

1756-IRT8I Module - Incorrect RTD Readings . . . . . . . . . . . . . . . . 165

1756-IF8I Module - Incorrect Input Voltage/Current Readings . 168 1756-OF8I Module - Incorrect Output Voltage/Current

Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

Isolated Analog I/O Module Tag Definitions

Choose the Correct Power Supply

1492 Analog Interface Modules

Appendix A

Access the Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

1756-IF8I Module Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Configuration Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Input Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Output Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

1756-IRT8I Module Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

Configuration Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

Input Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

Output Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

1756-OF8I Module Tags. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

Configuration Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

Input Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

Output Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

Appendix B

Power-sizing Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

Appendix C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Index

6 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Preface

This manual describes how to install, configure, and troubleshoot your ControlLogix® isolated analog I/O module.

You must be able to program and operate a ControlLogix controller to efficiently use your isolated analog I/O modules. If you need additional information, refer to Additional Resources on page 8

ControlLogix isolated analog I/O modules convert analog signals to digital values for inputs and convert digital values to analog signals for outputs. Controllers use these signals for control purposes.

By using the producer/consumer network model, ControlLogix isolated analog I/O modules produce information when needed while providing additional system functions.

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 product to program Logix5000

safety, and drive-based solutions.

™ controllers for discrete, process, batch, motion,

™ 5000 software and continue to be the

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.

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 7

Preface

IMPORTANT

In addition to the Studio 5000 Logix Designer™ application, version 21 or later, you can use your ControlLogix isolated analog I/O modules in RSLogix 5000 software, versions 18…20, projects.

You must install Add-on Profiles (AOP) to use the modules in any Logix Designer application or RSLogix 5000 software project.

This publication describes configuration with Logix Designer application.

Some of the tasks that are described in this publication by using the Logix Designer application have slightly different screens when completed by using RSLogix 5000 software. The procedure order required to complete the tasks is primarily the same regardless of the programming application used to do so.

Additional Resources

These documents contain additional information concerning related products

from Rockwell Automation.

Resource Documentation

1756 ControlLogix I/O Specifications, publication

1756-TD002

ControlLogix Digital I/O Modules User Manual, publication 1756-UM058

1756 ControlLogix Chassis and Power Supplies Installation Instructions, publication

1756-IN005

Integrated Architecture and CIP Sync Configuration Application Technique, publication IA-AT003

ControlLogix System User Manual, publication

1756 UM001

Industrial Automation Wiring and Grounding Guidelines, publication 1770-4.1

Product Certifications website, http://

www.ab.com

Provides specifications for ControlLogix analog and digital I/O modules as well as the accessories that can be used with each.

Provides information on how to install, configure, and troubleshoot ControlLogix digital I/O modules.

Provides information on how to install a wide range o f ControlLogix chassis, power supplies, and chassis adapter modules.

Describes how to configure CIP Sync with Integrated Architecture™ products and applications.

Describes how to install, configure, program, and operate a ControlLogix system.

Provides general guidelines for installing a Rockwell Automation industrial system.

Provides declarations of conformity, certificates, and other certification details.

You can view or download Rockwell Automation 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.

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Chapter 1

Isolated Analog I/O Module Operation in the ControlLogix System

Top ic Pag e

Before You Begin 9

Ownership 11

Configure a Module 11

Direct Connections 12

Input Module Operation 14

Output Module Operation 17

Listen-only Mode 18

Before You Begin

ControlLogix controllers use isolated analog I/O modules to control devices in a ControlLogix control system. The modules are installed in a ControlLogix chassis and use a removable terminal block (RTB) or a Bulletin 1492 interface

(1)

module

cable to connect to field-side wiring.

The modules use the producer/consumer network communication model. This communication is an intelligent data exchange between modules and other system devices in which each module produces data without first being polled.

Before you install and use your module, complete the following tasks:

(2)

• Install and ground a 1756 ControlLogix chassis and power supply

. You

can use a standard power supply or a redundant power supply.

For more information on installing 1756 ControlLogix chassis and power supplies, see Additional Resources on page 8

(1) The ControlLogix system has been agency certified using only the ControlLogix RTBs (catalog numbers 1756-TBCH, 1756-TBNH,

1756-TBSH and 1756-TBS6H). Any application that requires agency certification of the ControlLogix system using other wiring termination methods can require application specific approval by the cert ifying agency.

(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 distributor or Rockwell Automation representative.

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 9

, or contact your local

Chapter 1 Isolated Analog I/O Module Operation in the ControlLogix System

IMPORTANT

Removable Terminal Block

• Verify that you have an RTB or IFM and its components.

Table 1 - Types of ControlLogix Isolated Analog I/O Modules

Cat. No. Description RTB Used Page

1756-IF8I 8-point general purpose isolated analog

1756-IRT8I 8-point isolated combined temperature and mV

1756-OF8I 8-point general purpose isolated analog

Figure 1 - Parts Illustration of the ControlLogix Isolated Analog I/O Module

RTBs and IFMs are not included with your module purchase.

current/voltage input module

sensing input module

current/voltage output module

36-pin

(1756-TBCH or

1756-TBS6H)

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

4 Connectors pins - Input/output, power, and grounding connections are made to the module through

5 Locking tab - The locking tab anchors the RTB or IFM cable on the module, maintaining wiring

6 Slots for keying - Mechanically keys the RTB to prevent inadvertently making the wrong wire connections

10 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

devices. Indicators help in troubleshooting anomalies.

these pins with the use of an RTB or IFM.

connections.

to your module.

Isolated Analog I/O Module Operation in the ControlLogix System Chapter 1

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Controller I/O Modules

Ownership

Configure a Module

Every I/O module in the ControlLogix system must be owned by a ControlLogix controller. This controller performs the following:

• Stores configuration data for every module that it owns.

• Resides in the local or remote chassis 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 in the control system.

Each ControlLogix I/O module must continuously maintain communication with its owner to operate normally. Typically, each module in the system has only one owner. Input modules can have more than one owner. Output modules, however, are limited to a single owner.

You use the I/O configuration portion of the Logix Designer application to configure each I/O module. An I/O module can reside in either of the following:

•Local chassis - The chassis in which the owner-controller resides.

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Chapter 1 Isolated Analog I/O Module Operation in the ControlLogix System

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Control ler I/O Modules

Local Chassis Remote Chassis

EtherNet/IP Network

IMPORTANT

•Remote chassis - A chassis that does not contain the module’s ownercontroller but is connected to the local chassis over the EtherNet/IP network or ControlNet network.

Direct Connections

The Logix Designer application transfers configuration data to the controller during the program download. Subsequently, data is transferred to the I/O modules in the local and remote chassis.

The I/O module can operate immediately after the project download from the owner-controller is complete.

A direct connection is a real-time data transfer link between the controller and the device that occupies the slot that the configuration references.

ControlLogix isolated analog I/O modules support only direct connections

When you download module configuration to a controller, the controller attempts to establish a direct connection to each module referenced by the configuration.

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Isolated Analog I/O Module Operation in the ControlLogix System Chapter 1

If controller configuration refers to a chassis slot in the system, the controller periodically checks for the presence of a device there. If a device is detected, the controller sends the configuration, and one of the following occurs:

• If the configuration is appropriate to the module detected, a connection is made and operation begins.

• If the configuration is not appropriate to the module detected, the data is rejected and the Logix Designer application indicates that an error occurred.

The configuration can be inappropriate for any of a number of reasons. For example, a module’s configuration can include a mismatch in electronic keying that prevents normal operation.

The controller maintains and monitors its connection with a module. Any break in the connection, for example, the removal of the module from the chassis while under power, causes a fault.

The Logix Designer application indicates that the fault occurred in the fault status bits associated with the module. The Logix Designer application monitors the fault status bits to annunciate the module’s failures.

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Chapter 1 Isolated Analog I/O Module Operation in the ControlLogix System

IMPORTANT

On-Board Memory

Status Data

Channel Data

Ch 0

Ch 1

Ch 2

Ch 3

Ch 4

Ch 5

Timestamp

Channel Data

Channel Data Ch 6

Ch 7

Input Module Operation

In traditional I/O systems, controllers periodically poll input modules to obtain their input status.

In the ControlLogix system, the controller does not poll the isolated analog input modules. Instead, the modules broadcast their input data, that is, channel and status data, to their backplane periodically.

Requested Packet Interval (RPI)

The RPI is a configurable parameter that defines a specific period of time at which the module broadcasts input data to the backplane. Valid RPI values are 1…750 ms. The default value is 100 ms.

You set the RPI value at initial module configuration and adjust it as necessary only when the controller is in Program mode.

Other ControlLogix analog input modules offer the Real Time Sample (RTS) parameter that determines when channel data is scanned and stored on the module’s on-board memory until broadcast to the chassis backplane.

The 1756-IF8I and 1756-IRT8I modules do not offer the RTS parameter. With these modules, the channel sampling rate is exclusively determined by the RPI value.

At the RPI, the following events occur.

1. The module scans its channels for input data.

2. The module broadcasts the data to its backplane.

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Isolated Analog I/O Module Operation in the ControlLogix System Chapter 1

The input module broadcasts data to the chassis backplane immediately after the scan:

• When the module resides in the local chassis, the controller receives the data immediately.

• When the module resides in a remote chassis, the time elapsed before the controller receives it depends on the configuration of the network connecting the local and remote chassis.

For more information, see Input Modules in a Remote Chassis

Input Modules in a Local Chassis

When an input module resides in a local chassis, as shown on page 11, after the input module broadcasts data to the chassis backplane, the controller receives it immediately.

Input Modules in a Remote Chassis

When an input module resides in a remote chassis, as shown on page 12, it is considered remote input module.

At the RPI, the following events occur.

1. The remote input module scans its channels for input data.

2. The remote input module broadcasts the data to its backplane.

3. The network communication module in the chassis with the I/O module

sends the data over the network to the controller.

Broadcast Method

The isolated analog input module broadcasts data by using one of the following connection methods:

• Multicast - Data is sent to all network devices

• Unicast - Data is sent to a specific controller depending on the

module’s configuration

For more information on guidelines for specifying RPI rates, see the Logix5000 Controllers Design Considerations Reference Manual, publication

1756-RM094

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Chapter 1 Isolated Analog I/O Module Operation in the ControlLogix System

Triggering Event Tasks

ControlLogix isolated analog input modules can trigger an Event task. The Event task causes the controller to execute a section of logic immediately when a triggering event occurs. You can configure the Event task to be triggered if new input data is sent at the RPI.

The following graphic shows an Event task dialog box in Logix Designer application.

Event tasks are useful for synchronizing process variable (PV) samples and proportional integral derivative (PID) calculations.

For more information on Event tasks, see the Logix5000 Controllers Tasks, Programs, and Routines Programming Manual, publication 1756-PM005

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Isolated Analog I/O Module Operation in the ControlLogix System Chapter 1

Output Module Operation

The RPI defines when a controller sends data to the isolated analog output module and when the output module echoes data. The controller sends data to an output module only at the RPI.

When an output module receives new data from the controller, the module multicasts or ‘echoes’ a data value that corresponds to the signal present at its terminals to the rest of the control system. This feature, called Data Echo whether the output module resides in the local or remote chassis.

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 module’s output channels can change values multiple times during a single program scan. The controller does not depend on reaching the end of the program to send data.

, occurs

Output Modules in a Local Chassis

When an output module resides in a local chassis, as shown on page 11, it receives data almost immediately after the owner-controller sends it.

Output Modules in a Remote Chassis

When an output module resides in a remote chassis, as shown on page 12, and is connected to the local chassis via an EtherNet/IP network, the following events occur for the controller to send data to the output module.

1. The controller broadcasts data to its local chassis at one of the following events:

• RPI value

• A programmed Immediate Output (IOT) instruction is executed.

An IOT sends data immediately and resets the RPI timer.

2. The 1756 ControlLogix EtherNet/IP communication module in the local chassis broadcasts the data over the EtherNet/IP network.

3. After receiving the output data, the 1756 ControlLogix EtherNet/IP communication in the remote chassis broadcasts the data to its backplane, that is, the remote chassis.

4. The output module receives the data almost immediately after it is broadcast to the remote chassis backplane.

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Chapter 1 Isolated Analog I/O Module Operation in the ControlLogix System

IMPORTANT

Listen-only Mode

Any controller in the system can listen to the data from any I/O module, that is, input data or ‘echoed’ output data, even if the controller does not own the module.

During the I/O configuration process, you can specify a ‘Listen-Only’ connection. For more information on Connection options when configuring your system, see page 125

When you choose a ‘Listen-Only’ connection, the controller and module establish communication without the controller sending configuration data. In this instance, another controller owns the I/O module.

If any controller uses a ‘Listen-Only’ connection to the module, none of the other connections over the EtherNet/IP network can use the Unicast option.

The ‘Listen-Only’ controller receives multicast data from the I/O module as long as a connection between a controller and I/O module is maintained

If the connection between all owner-controllers and the module is broken, the module stops multicasting data and connections to all ‘Listening controllers’ are also broken.

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ControlLogix Isolated Analog I/O Module Features

Top ic Pa ge

Common Analog I/O Features 20

Relationship between Module Resolution and Scaling 35

Calibrati on 38

Calibrated Accuracy 38

Error Calculated over Hardware Range 39

RTD and Thermocouple Error Calculations 39

Thermocouple Resolution 43

Chapter 2

ControlLogix isolated analog input modules convert an analog signal to a digital value. The following are example analog signal types to which input modules convert to digital values:

• Vo l t s

• Millivolts

• Milliamps

• Ohms

ControlLogix isolated analog output modules convert a digital value to an analog signal. The following are example analog signal types to which output modules convert digital values:

• Vo l t s

• Milliamps

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

Common Analog I/O Features

The ControlLogix isolated analog I/O modules have the following features:

• CIP Sync Timestamp of Data

• Rolling Timestamp of Data

• Floating Point Data Format

• Module Resolution

• Calibration

• Fault and Status Reporting

• Configurable Software

• Latching of Alarms

• Module Inhibiting

• Electronic Keying

CIP Sync Timestamp of Data

The control system uses a 64-bit system clock. The modules support CIP Sync timestamping by using the 1588 protocol passed throughout the system. The 1588 protocol is defined in the IEEE 1588-2002 standard, publication Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems.

Each input channel scan or new output application is stamped with a CIP Sync timestamp and a single timestamp is returned to the controller for the module with the input data transfer.

You can use this feature for the following:

• To identify the sequence of events in fault conditions or during normal

operation.

It is possible to use the system clock between multiple modules in the same chassis or throughout a system in which a common Time Master is used.

• To measure the change between samples–which likely correlates closely

with the RPI if no samples are missed in the logic–and to detect when a new sample is available for processing via the logic.

You can also use the 1588 Protocol to synchronize sampling for modules across the entire system. By using the Synchronized Sampling feature, described in detail on page 57 input samples precisely with each other when using the same RPI.

and page 81, you can configure multiple modules to coordinate their

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ControlLogix Isolated Analog I/O Module Features Chapter 2

Synchronized Sampling lets you configure a test stand, for example, and take many measurements simultaneously across many modules, if needed, while still precisely coordinating the sampling. With these modules, the synchronized sampling should coordinate within approximately ± 20 μs.

Rolling Timestamp of Data

The rolling timestamp is a continuously running 16-bit rolling timestamp that counts in milliseconds from 0…32,767 ms; where 1 ms = 1 count.

Rolling Timestamp with the 1756-IF8I and 1756-IRT8I Modules

The 1756-IF8I and 1756-IRT8I modules scan their inputs at the RPI, update the input data, and update the rolling timestamp value. Other ControlLogix analog input modules scan their inputs at the RTS, not the RPI.

In either case, though, the controller program uses the last two rolling timestamp values to calculate the interval between the receipt of data or the time at which new data is received.

The rolling value is commonly used with instructions such as the PID and PIDE instructions. Every time a rolling timestamp changes, a PID or PIDE instruction is executed. When you configure a PID instruction for use with a 1756-IF8I and 1756-IRT8I module, set the loop update time equal to the module’s RPI value.

Rolling Timestamp with the 1756-OF8I Module

For the 1756-OF8I module, the rolling timestamp value is updated only when new values are applied to the Digital to Analog Converter (DAC).

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

EXAMPLE

Floating Point Data Format

The modules return channel data to the owner-controller in the IEEE 32-bit floating point data format. In your Logix Designer application, the data type is REAL. You can configure the module to scan its channels and return data as quickly as every 1 ms.

The floating point data format lets you change the data representation of the selected channel. Although the full range of the module does not change, you can scale your module to represent I/O data in specific terms for your application.

When you scale a channel, you select two points that represent signal units, that is, a Low Signal and a High Signal. You also select two points that represent engineering units, that is, Low Engineering and High Engineering.

The Low Signal point equates to the Low Engineering point and the High Signal point matches the High Engineering point.

A 1756-IF8I module used in current mode maintains 0…21 mA range capability. Your application uses a 4…20 mA transmitter.

• If you want to receive values in signal units, configure the module as follows:

– Low Signal = 4 mA – High Signal = 20 mA – Low Engineering = 4 EU – High Engineering = 20 EU

• If you want to receive values in terms of Percent of Full Scale, configure

the module as follows:

– Low Signal = 0 mA – High Signal = 20 mA – Low Engineering = 0% – High Engineering = 100%

By default, module channels used in Current mode are scaled such at 4…20 mA equate to 0…100% engineering units. Other module channels scale 1:1 with respect to signal units and engineering units by default.

Module Resolution

The modules support the following resolutions:

• 1756-IF8I and 1756-IRT8I modules – 24-bit resolution

• 1756-OF8I module – 16-bit resolution

For more information on module resolution, see page 35

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ControlLogix Isolated Analog I/O Module Features Chapter 2

Module Quality Reporting

The modules indicate the quality of channel data returned to the ownercontroller. Data quality represents accuracy. There are levels of data quality reported via module input tags.

The following input tags indicate the level of data quality. In the tag names, x represents the module channel number:

• I.Ch[x].Fault tag - This tag indicates that channel data can be completely inaccurate and cannot be trusted for use in the application. If the tag is set to 1, you cannot trust the data reported. You must troubleshoot the module to correct the cause of the inaccuracy.

Common causes of inaccurate data include the following:

– An overrange or underrange condition exists. – A wire off detection condition has occurred. – A short circuit detection condition has occurred.

• I.Ch[x].Uncertain tag - This tag indicates that channel data can be

inaccurate but it is not known to what degree of inaccuracy. We recommend that you do not use the data for control.

If the tag is set to 1, you know the data can be inaccurate but you must troubleshoot the module to discover what degree of inaccuracy exists.

Common causes of uncertain data include the following:

– The channel is actively being calibrated. – An invalid sensor offset value exists. – The channel’s last data sample failed CRC while the most recent data

sample was valid and used.

We recommend that you monitor these tags in your program to make sure the application is operating as expected with accurate channel input data.

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

Calibration

These modules use precise analog components that maintain their specifications over time. The modules are calibrated at the factory and recalibration is not required.

If desired, you can recalibrate the modules on a channel-by-channel or modulewide basis. For more information, see Calibrated Accuracy on page 38 choose to recalibrate the modules in the future.

if you

Fault and Status Reporting

The modules provide fault and status data along with channel data. Faults are indicated via the status indicators on the front of the module as well as the module tags. Status data is available via the module tags.

• For more information on fault and status reporting via module tags, see the following:

– 1756-IF8I fault and status reporting - page 64 – 1756-IRT8I fault and status reporting - page 92 – 1756-OF8I fault and status reporting - page 102

• For more information on fault reporting via status indicators, see

Chapter 2, Troubleshoot Your Module on page 157

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ControlLogix Isolated Analog I/O Module Features Chapter 2

IMPORTANT

Configurable Software

Use one of the following software applications with your module:

• RSLogix 5000 software, versions 18…20

• Logix Designer application, version 21 or later

You must install Add-on Profiles (AOP) to use the modules in any Logix Designer application or RSLogix 5000 software project.

This publication describes configuration with Logix Designer application. AOPs are available at:

https://download.rockwellautomation.com/esd/ download.aspx?downloadid=addonprofiles

All module feature configuration begins in the I/O configuration portion of the Logix Designer application. In addition to enable or disable module features, you can use the application to interrogate any module for the following module information:

• Serial number

• Revision information

• Catalog number

• Vendor identification

• Error/fault information

• Diagnostic counters

For more information on configurable software and its use, see the following sections:

• Preface

• Chapter 7, Configure ControlLogix Isolated Analog I/O Modules

• Chapter 8, Calibrate the ControlLogix Isolated Analog I/O Modules

• Chapter 9, Troubleshoot Your Module

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

IMPORTANT

Latching of Alarms

This feature latches a module alarm in the set position once the alarm is triggered. The alarm remains on, even if the condition causing it to occur disappears, until the alarm is unlatched.

You must manually unlatch the alarm. You can unlatch the alarm, by using one of the following methods:

• While the project is online, click the Alarm Configuration tab on the Module. Then click Unlatch to unlatch a specific alarm or Unlatch All to unlatch all alarms.

• Change the module output tag for the alarm that you want to unlatch. For example, the Ch[x].LLAlarmUnlatch tag to unlatch a Low Low Alarm.

For more information on module tags, see Appendix A, Isolated Analog I/O

Module Tag Definitions on page 173.

• Use a CIP Generic message.

For more information how to use a CIP Generic message, see Rockwell Automation Knowledgebase article #63046, How to Reset Latched Status of an Analog Module. You can access the article at: (Login required)

https://rockwellautomation.custhelp.com/

To see where to latch alarms, see page 131

and page 133.

Module Inhibiting

This feature suspends the connection between an owner-controller and a module. This process can occur in either of the following ways:

• You write configuration for an I/O module but inhibit the module to prevent it from communicating with the owner-controller.

In this case, the owner does not establish a connection and configuration is not sent to the module until the connection is uninhibited.

• A controller owns a module and has downloaded configuration to it. Data is currently being exchanged over the connection between the devices.

In this case, when you inhibit the module and the owner-controller behaves as if the connection to the module does not exist.

Whenever you inhibit an output module, it enters Program mode and all outputs change to the state configured for the Program mode. For example, if an output module is configured so that the state of the outputs go to zero (0) during Program mode, whenever that module is inhibited, the outputs go to zero (0).

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The following examples are instances where you need to use module inhibiting:

• Multiple controllers own an analog input module. A configuration change is required. You must make the change in the program in all controllers.

In this case, complete the following tasks. a. Inhibit the module. b. Change configuration in all controllers. c. Uninhibit the module.

• You want to upgrade the module. We recommend you complete the following tasks.

a. Inhibit the module. b. Perform the upgrade. c. Uninhibit the module.

• The program includes a module that you do not physically possess and you do not want the controller to continually look for a module that does not exist.

Inhibit the module until it physically resides in the proper slot.

To see where to inhibit a module connection, see page 126

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

Electronic Keying

The electronic keying feature automatically compares the expected module, as shown in the I/O Configuration tree, to the physical module before I/O communication begins. You can use electronic keying to help prevent communication to a module that does not match the type and revision expected.

For each module in the I/O Configuration tree, the user-selected keying option determines if, and how, an electronic keying check is performed. Typically, three keying options are available:

• Exact Match

• Compatible Keying

• Disable Keying

You must carefully consider the benefits and implications of each keying option when selecting between them. For some specific module types, fewer options are available.

Electronic keying is based on a set of attributes unique to each product revision. When a Logix5000 controller begins communicating with a module, this set of keying attributes is considered.

Attribute Description

Vendor The manufacturer of the module, for example, Rockwell Automation/Allen-Bradley.

Product Type The general type of the module, for example, communication adapter, AC drive, or digital

Product Code The specific type of module, generally represented by its catalog number, for example,

Major Revision A number that represents the functional capabilities and data exchange formats of the

Minor Revision A number that indicates the module’s specific firmware revision. Minor Revisions

I/O.

1756-IRT8I.

module. Typically, although not always, a later, that is higher, Major Revision supports at least all of the data formats supported by an earlier, that is lower, Major Revision of the same catalog number and, possibly, additional ones.

typically do not impact data compatibility but can indicate performance or behavior improvement.

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ControlLogix Isolated Analog I/O Module Features Chapter 2

IMPORTANT

You can find revision information on the Module Definition dialog box.

Figure 2 - Module Definition Dialog Box

Changing electronic keying selections online can cause the I/O communication connection to the module to be disrupted and can result in a loss of data.

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

EXAMPLE

IMPORTANT

Module Configuration Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16D Major Revision = 3 Minor Revision = 1

Physical Module Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16D Major Revision = 3 Minor Revision = 2

Communication is prevented

Exact Match

Exact Match Keying requires all keying attributes, that is, Vendor, Product Type, Product Code (catalog number), Major Revision, and Minor Revision, of the physical module and the module created in the software to match precisely to establish communication. If any attribute does not match precisely, I/O communication is not permitted with the module or with modules connected through it, as in the case of a communication module.

Use Exact Match keying when you need the system to verify that the module revisions in use are exactly as specified in the project, such as for use in highlyregulated industries. Exact Match keying is also necessary to enable Automatic Firmware Update for the module via the Firmware Supervisor feature from a Logix5000 controller.

In the following scenario, Exact Match keying prevents I/O communication:

The module configuration is for a 1756-IB16D module with module revision

3.1. The physical module is a 1756-IB16D module with module revision 3.2. In this case, communication is prevented because the Minor Revision of the module does not match precisely.

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ST01234567

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ST 89 10 111213 1415

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CAL

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O K

ST 89 1011 121314 15

DIAGNOSTIC

Changing electronic keying selections online can cause the I/O Communication connection to the module to be disrupted and can result in a loss of data.

ControlLogix Isolated Analog I/O Module Features Chapter 2

EXAMPLE

Module Configuration Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16D Major Revision = 3 Minor Revision = 3

Physical Module Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16D Major Revision = 3 Minor Revision = 2

Communication is prevented

ANALOG INPUT

ST0 1 2 34 5 6 7

ST 89 1011 121314 15

O K

CAL

OKFORCE SDRUN

Logix5575

DC INPUT

FLT89101112131415

ST01234567

ST 89 10 111213 1415

O K

FLT0 12 3 4 5 6 7

DIAGNOSTIC

Compatible Keying

Compatible Keying indicates that the module determines whether to accept or reject communication. Different module families, communication adapters, and module types implement the compatibility check differently based on the family capabilities and on prior knowledge of compatible products.

Compatible keying is the default setting. Compatible keying lets the physical module accept the key of the module configured in the software, provided that the configured module is one the physical module is capable of emulating. The exact level of emulation required is product and revision specific.

With Compatible keying, you can replace a module of a certain Major Revision with one of the same catalog number and the same or later, that is higher, Major Revision. In some cases, the selection makes it possible to use a replacement that is a different catalog number than the original. For example, you can replace a 1756-CNBR module with a 1756-CN2R module.

Release notes for individual modules indicate the specific compatibility details.

When a module is created, the module developers consider the module’s development history to implement capabilities that emulate those of the previous module. However, the developers cannot know future developments. Because of this, when a system is configured, we recommend that you configure your module by using the earliest, that is, lowest, revision of the physical module that you believe will be used in the system. By doing this, you can avoid the case of a physical module rejecting the keying request because it is an earlier revision than the one configured in the software.

In the following scenario, Compatible keying prevents I/O communication:

The module configuration is for a 1756-IB16D module with module revision

3.3. The physical module is a 1756-IB16D module with module revision 3.2. In this case, communication is prevented because the minor revision of the module is lower than expected and.cant be incompatible with 3.3.

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

EXAMPLE

IMPORTANT

Module Configuration Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16D Major Revision = 2 Minor Revision = 1

Physical Module Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16D Major Revision = 3 Minor Revision = 2

Communication is allowed

In the following scenario, Compatible keying lets I/O communication occur:

The module configuration is for a 1756-IB16D module with module revision

2.1. The physical module is a 1756-IB16D module with module revision 3.2. In this case, communication is allowed because the major revision of the physical module is higher than expected and the module determines that it is compatible with the prior major revision.

Logix5575

ST01234567

FLT0 12 3 4 5 6 7

ST 89 10 111213 1415

FLT89101112131415

OKFORCE SDRUN

ANALOG INPUT

DC INPUT

CAL

ST0 1 2 34 5 6 7

O K

ST 89 1011 121314 15

DIAGNOSTIC

Changing electronic keying selections online can cause the I/O communication connection to the module to be disrupted and can result in a loss of data.

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ControlLogix Isolated Analog I/O Module Features Chapter 2

EXAMPLE

Module Configuration Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IA16 Major Revision = 3 Minor Revision = 1

Physical Module Vendor = Allen-Bradley Product Type = Analog Input Module Catalog Number = 1756-IF16 Major Revision = 3 Minor Revision = 2

Communication is prevented

Disabled Keying

Disabled Keying indicates the keying attributes are not considered when attempting to communicate with a module. Other attributes, such as data size and format, are considered and must be acceptable before I/O communication is established. With Disabled keying, I/O communication can occur with a module other than the type specified in the I/O Configuration tree with unpredictable results. We generally do not recommend using Disabled keying.

ATTENTION: Be extremely cautious when using Disabled keying; if used incorrectly, this option can lead to personal injury or death, property damage, or economic loss.

If you use Disabled keying, you must take full responsibility for understanding whether the module being used can fulfill the functional requirements of the application.

In the following scenario, Disable keying prevents I/O communication:

The module configuration is for a 1756-IA16 digital input module. The physical module is a 1756-IF16 analog input module. In this case, communication is prevented because the analog module rejects the data formats that the digital module configuration requests.

Logix5575

ST01234567

FLT0 12 3 4 5 6 7

ST 89 10 111213 1415

FLT89101112131415

OKFORCE SDRUN

ANALOG INPUT

DC INPUT

CAL

ST0 1 2 34 5 6 7

O K

ST 89 1011 121314 15

DIAGNOSTIC

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

EXAMPLE

IMPORTANT

Module Configuration Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IA16 Major Revision = 2 Minor Revision = 1

Physical Module Vendor = Allen-Bradley Product Type = Digital Input Module Catalog Number = 1756-IB16 Major Revision = 3 Minor Revision = 2

Communication is allowed

In the following scenario, Disable keying lets I/O

communication occur:

The module configuration is for a 1756-IA16 digital input module. The physical module is a 1756-IB16 digital input module. In this case, communication is allowed because the two digital modules share common data formats.

Changing electronic keying selections online can cause the I/O communication connection to the module to be disrupted and can result in

a loss of data.

To see where to configure Electronic Keying, see page 126.

Logix5575

ST01234567

FLT0 12 3 4 5 6 7

ST 89 10 111213 1415

FLT89101112131415

OKFORCE SDRUN

ANALOG INPUT

DC INPUT

CAL

ST0 1 2 34 5 6 7

O K

ST 89 1011 121314 15

DIAGNOSTIC

34 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

ControlLogix Isolated Analog I/O Module Features Chapter 2

Relationship between Module Resolution and Scaling

The following concepts must be explained in conjunction with each other:

• Module Resolution

• Scaling

Module Resolution

Resolution is the smallest degree of change that the module is capable of detecting. Module resolution represents a fixed number of counts across the module’s theoretical operating range.

• 1756-IF8I and 1756-IRT8I modules support 24-bit resolution.

The 24 bits represent 16,777,216 counts.

• 1756-OF8I module supports 16-bit resolution.

The 16 bits represent 65,536 counts.

Resolution on Input Modules

The theoretical operating range is the full range across which the module can operate. For example, a 1756-IF8I module in Current mode has a theoretical operating range = -25.1…25.1 mA. The 24-bit resolution and 16,777,216 counts are available across 50.2 mA which yields our calculated 2.99 nA/count resolution.

However, when the 1756-IF8I module operates in Current mode, it is configured for an input range = 0…20 mA. This range limits the input to a 0…21 mA actual range capability.

The number of counts on a module is fixed. Module actual range capabilities, however, narrow operating ranges from the theoretical and result in supporting fewer counts. Using the example above, the 0…21 mA actual range capability represents 5,815,117 counts, that is, slightly more than 22.5 bits.

Divide the actual range capability by the number of counts in that range to determine the value of each count. The input range you choose during module configuration determines the value of each count. It does not determine the number of counts in that range. Therefore, module resolution across the usable input operating range is not always 24 bits.

Resolution on Output Module

The module resolution for the 1756-OF8I module is always 16 bits, regardless of operating mode and operating range.

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

IMPORTANT

The following table lists the resolution for each module’s input/output range and corresponding range capability.

Table 2 - Module Resolution in Various Configuration Selections

Module Mode Available Input/

Vol tag e

1756-IF8I

Curren t

Thermocouple -100…100 mV -101…101 mV

1756-IRT8I

1756-OF8I

(1) These ranges represent the range choices available in the Logix Designer application.

RTD

Vol tag e

Current 0…20 mA 0…21 mA 16.00 0.32 µA

Output Range

-10…10V 0…10V 0…5V

0…20 mA 0…20 mA (sourcing)

1…500 Ω 2…1000 Ω 4…2000 Ω 8…4000 Ω

-10…10V 0…10V 0…5V

(1)

Actual Input/Output Range Capability

-10.5…10.5V 0…10.5V 0…5.25V

0…21 mA 0…21 mA (sourcing)

0…510 Ω 0…1020 Ω 0…2040 Ω 0…4080 Ω

-10.5…10.5V 0…10.5V 0…5.25V

Because these modules must allow for possible calibration inaccuracies, resolution values represent the available Analog-to-Digital or Digital-toAnalog counts over the specified range.

Additionally, RPI and Notch Filter settings affect module resolution on the 1756-IF8I and 1756-IRT8I modules. For more information, see page49

page 68

Number of Bits Across the Theoretical Operating Range

24 bits

16 bits

, respectively.

Number of Bits Across the Actual Range Capability

23.75

22.75

21.75

22.74

23.98 0.01 µV/count

23.98

16.00

Resolution (signal per count)

1.49 µV/count

2.99 nA/count

0.06 mΩ/count

0.12 mΩ/count

0.25 mΩ/count

0.50 mΩ/count

0.32 mV/count

0.16 mV/count

0.08 mV/count

and

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ControlLogix Isolated Analog I/O Module Features Chapter 2

Module Resolution

5,815,117 counts

0 mA 21 mA

4 mA 20 mA

0% in Engineering

Units

100% in Engineering

Units

Module Scaling

Module scaling represents the data returned from the module to the controller.

IMPORTANT

Scaling

When scaling, you choose two points along the module’s operating range and apply low and high values to those points.

For example, if you are using the 1756-IF8I module in Current mode, the module supports a 0…21 mA actual range capability. But your application uses a 4…20 mA transmitter. Scaling lets you configure the module to return data to the controller so that a low signal value of 4 mA returns a low engineering value of 0% and a high signal value of 20 mA returns a high engineering value of 100%.

The returned engineering units value is indicated in the I.Ch[x].Data tag as shown in Ta b l e 3

Figure 3 - Module Resolution Compared to Module Scaling

In choosing two points for the low and high value of your application, you do not limit the range of the module. The module’s range and its resolution remain constant regardless of how you scale it for your application.

The module can operate with values beyond the 4…20 mA range. If an input signal beyond the low and high signals is present at the module, for example, 0 mA, that data is represented in terms of the engineering units set during scaling.

The following table shows example values that can appear based on the example mentioned above.

Table 3 - Current Values Represented in Engineering Units

Current Engineering Units Value Value in I.Ch[x].Data Tag

0.0 mA -25.00% -25.00

4.0 mA 0.0% 0.00

12.0 mA 50.0% 50.0

20.0 mA 100.0% 100.0

21.0 mA 106.25% 106.25

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

Calibration

Calibrated Accuracy

The ControlLogix isolated analog modules are calibrated via the following methods:

• Factory calibration when the modules are built.

• User-executed calibration as described in Chapter 8

ControlLogix Isolated Analog I/O Modules on page 137.

User-executed calibration is optional.

• 1756-IRT8I module only - Channels configured for Thermocouple inputs perform a lead resistance self-calibration when the module power is cycled.

The Calibrated Accuracy specification represents the module’s accuracy when its ambient temperature is the same as the temperature at which the module was calibrated.

The following specifications are related to Calibrated Accuracy:

• Calibrated Accuracy at 25 °C (77 °F)

• Module Error over Full Temperature Range

, Calibrate the

Calibrated Accuracy at 25 °C (77 °F)

This specification matches the temperature at which the module was calibrated in the factory during manufacturing.

The module’s accuracy when operating in 25 °C (77 °F) conditions = 0.05%.

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ControlLogix Isolated Analog I/O Module Features Chapter 2

EXAMPLE

Module Error over Full Temperature Range

The Module Error Over Full Temperature Range specification represents the error that occurs if the module’s ambient temperature changes a total of 60 °C (140 °F), that is, from 0…60 °C (32…140 °F) or 60…0 °C (140…32 °F).

The module accuracy over the full temperature range = 0.1%.

Error Calculated over Hardware Range

RTD and Thermocouple Error Calculations

A ControlLogix isolated analog I/O module’s calibration accuracy at 25 °C (77 °F) is calculated over the full hardware range of the module and is not dependent on the application’s use of the range. The error is the same if you are measuring it across a 10% or 100% portion of a given range.

However, a module’s accuracy at 25 °C (77 °F) is dependent on the hardware range in which the module operates.

When the 1756-IRT8I channel uses the Thermocouple (mV) input type, the input range is -100…100 mV, the module error is 0.2 mV when using 0.1% of range accuracy.

These error values are the same whether you use 10% or 100% of the chosen range.

When you use the 1756-IRT8I module in temperature mode, error calculations are achieved by a two-step process.

1. Calculate the module’s error in ohms or volts.

2. Convert the ohm/volt error to temperature for the specific sensor and at

the correct application temperature.

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

RTD Error

Module error on the 1756-IRT8I module used with an RTD input is defined in ohms. The error is calculated across the entire input range selected, not the available range of a sensor used with the module. For example, if the 1…500 input range is used, the module error is calculated across 510 (actual range = 0…510

Ω).

The error in ohms translates to temperature, but that translation varies because the relationship is non-linear. The most effective way to check 1756-IRT8I module error is to calculate the error in ohms and use that value in a linearization table to check the temperature error.

If the module is calibrated at operating temperature and the operating temperature remains relatively stable, calibration accuracy is better than 0.05% of the full range. This 0.05% value is a worst case value. In other words, with the 1…500

Ω input range selected, the worst case module error is 0.255 Ω.

Finally, you must check an RTD linearization table to determine how the temperature error of 0.510

Ω translates.

For example, if the 1756-IRT8I has a 0.05% (or 0.255

Ω) error and is at a

temperature of 0 °C (32 °F), the temperature error is ±0.65 °C (±1.17 °F) when the Platinum 385 sensor type is used. This same error at a temperature of 200 °C (392 °F) translates to a temperature error of ±0.69 °C (±1.26 °F).

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ControlLogix Isolated Analog I/O Module Features Chapter 2

EXAMPLE

Thermocouple Error

Thermocouple error at 25 °C (77 °F) indicates the module’s accuracy in measuring temperature. This accuracy varies depending on these factors:

• Input range = -100…100 mV.

• Thermocouple sensor type, any of the following: – Typ e B – Typ e C – Typ e D – Typ e E – Typ e J – Type K (default value) – Typ e N – Typ e R – Typ e S – Typ e T – Typ e T XK/ XK ( L)

• Application temperature, that is, the temperature of the physical location

where the thermocouple is being used.

When a 1756-IRT8I module is used with a thermocouple input type in the following conditions, module error at 25 °C (77 °F) is ±3.74 °:

• Connected to a type S thermocouple

• Application temperature of 1200 °C (2192 °F)

In other words, the difference between the temperature the module reports and the actual application temperature can be ±3.74 °.

The module can report an application temperature of 1200 ° C (2192 °F) in this case when the actual temperature can be in the range from

1196.26…1203.74 °C (2185.268…2198.732 °F).

These calculations used a typical error of 0.02% of full scale range.

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

IMPORTANT

Module Error at 25 °C (77

°F)

Ta b l e 4 lists the 1756-IRT8I module error at 25 °C (77 °F) when using a

thermocouple input type.

Table 4 - 1756-IRT8I Module Error At 25 °C (77 °F) with Thermocouple Input Type

Application Temperature

-200 °C (-328 °F) 1.65 1.79 2.06 2.95 4.53 2.86

0 °C (32 °F) 3.46 4.59 0.93 8.51 8.33 0.77 0.89 1.14 1.72 1.16

200 °C (392 °F) 2.65 2.83 0.71 5.09 5.32 0.61 0.81 1.13 1.36 0.85

400 °C (752 °F) 11.08 2.37 2.36 0.62 4.34 4.70 0.56 0.82 1.07 1.21 0.73

600 °C (1112 °F) 7.56 2.37 2.22 0.56 3.96 4.41 0.56 0.77 1.06 1.16

800 °C (1472 °F) 5.89 2.37 2.20 0.51 3.65 4.14 0.57 0.70 1.10 1.15

1000 °C (1832 °F) 4.93 2.37 2.25 3.40 3.90 0.60 0.76 1.15 1.17

1200 °C (2192 °F) 4.35 2.65 2.36 3.23 3.74 0.79 1.23 1.21

1400 °C (2552 °F) 3.99 2.81 2.47 3.18 3.71 1.33

1600 °C (2912 °F) 3.85 3.00 2.63 3.24 3.80

1800 °C (3272 °F) 3.92 3.46 2.85 3.67 4.36

2000 °C (3632 °F) 3.75 3.19

2200 °C (3992 °F) 4.09 3.95

Module Error at 25 °C (77 °F) When Connected to Thermocouple Types

Type B Type C Type D Type TXK/

XK(L)

Type R Type S Type E Type J Type K Type N Type T

When calculating total measurement error, module error at 25 °C (77 °F) is only one factor in deriving the total measurement error budget.

Other factors that impact thermocouple measurement error include the following:

• Thermocouple sensor accuracy/error

• Conditions of thermocouple wire, such as wire length

• Cold junction compensation values

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ControlLogix Isolated Analog I/O Module Features Chapter 2

EXAMPLE

Thermocouple Resolution

Thermocouple resolution indicates the degrees that an application temperature must change before the 1756-IRT8I module connected to a thermocouple module reports a change. Resolution depends on the following factors:

• Application temperature, that is, the temperature of the physical location

where the thermocouple is being used.

For example, when a 1756-IRT8I module is used with a thermocouple input type in the following conditions, module resolution is 0.01 °:

• Input channel is connected to a type K thermocouple

• Application temperature is 400 °C (752 °F)

In other words, the application temperature must change by 0.01 ° or greater for the 1756-IRT8I module used with a thermocouple input to record a change. If the temperature stays in a range from

399.991…400.009 °C (751.984…752.016 °F), the module continues to report an application temperature of 400 °C (752 °F).

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Chapter 2 ControlLogix Isolated Analog I/O Module Features

Ta b l e 5 lists the 1756-IRT8I module resolution when using a thermocouple

input type.

Table 5 - 1756-IRT8I Module Resolution in Degrees C with Thermocouple Input Type

Application Temperature

-200 °C (-328 °F) 0.02 0.02 0.02 0.03 0.04 0.03

0 °C (32 °F) 0.03 0.05 0.01 0.08 0.08 0.01 0.01 0.01 0.02 0.01

200 °C (392 °F) 0.03 0.03 0.01 0.05 0.05 0.01 0.01 0.01 0.01 0.01

400 °C (752 °F) 0.11 0.02 0.02 0.01 0.04 0.05 0.01 0.01 0.01 0.01 0.01

600 °C (1112 °F) 0.07 0.02 0.02 0.01 0.04 0.04 0.01 0.01 0.01 0.01

800 °C (1472 °F) 0.06 0.02 0.02 0.01 0.04 0.04 0.01 0.01 0.01 0.01

1000 °C (1832 °F) 0.05 0.02 0.02 0.03 0.04 0.01 0.01 0.01 0.01

1200 °C (2192 °F) 0.04 0.03 0.02 0.03 0.04 0.01 0.01 0.01

1400 °C (2552 °F) 0.04 0.03 0.02 0.03 0.04 0.01

1600 °C (2912 °F) 0.04 0.03 0.03 0.03 0.04

1800 °C (3272 °F) 0.04 0.03 0.03 0.04 0.04

2000 °C (3632 °F) 0.04 0.03

2200 °C (3992 °F) 0.04 0.04

Module Resolution (in degrees C) When Connected to This Thermocouple Type

Type B Type C Type D Type TXK/

XK(L)

Type R Type S Type E Type J Type K Type N Type T

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Chapter 3

IMPORTANT

1756-IF8I Isolated Analog Input Module

Top ic Pa ge

1756-IF8I Module Features 45

Module Block and Circuit Diagrams 58

Wire the 1756-IF8I Module 61

Fault and Status Reporting 64

The 1756-IF8I module has eight isolated channels. Each channel supports connection to the following input types:

• Current

• Vo l t a g e

1756-IF8I Module Features

The module provides 24-bit resolution and uses differential inputs. Differential input have a greater resistance to the effects of electromagnetic noise and provide improved flexibility with respect to cable length when wiring your module.

Additional features are described in this chapter.

The 1756-IF8I module has the following features:

• Internal Loop Power Source

• Multiple Input Ranges

• Notch Filter

• Underrange/Overrange Detection

• Digital Filter

• Process Alarms

• Rate Alarm

• Sensor Offset

• Wire Off Detection

• Synchronized Sampling

Most of the features available on the 1756-IF8I module are software configurable. For more information on how to configure the module, see

Chapter 7

, Configure ControlLogix Isolated Analog I/O Modules on page 121

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Chapter 3 1756-IF8I Isolated Analog Input Module

Internal Loop Power Source

The 1756-IF8I module offers a software user-configurable selection for an internal loop power source on each channel. You must use the Current input type and enable Source Loop Current to use an internal power source on the channel.

The source is current limited to ~45 mA and lets the module power a two-wire transmitter directly without the need for an external power supply.

A sourcing overcurrent condition typically occurs due to a short between terminals on the module. With this module the short is between terminals IN_x/I/SRC and RTN_x (where x is the channel number).

If a Sourcing overcurrent condition exists, the 1756-IF8I module sets the input to 24 mA, that is, the equivalent engineering unit value. This value indicates a special error condition beyond the normal Overrange value, that is, 21 mA:

• For one second, the overcurrent condition self-corrects if the condition trigger is removed.

• After one second, the condition latches, the channel disables Source Loop Current and continues to send 24 mA with an Overrange indication.

The following are examples of events that unlatch the condition:

– Power is cycled to the module. – The module is reset. – The controller connection to the module is inhibited and

then uninhibited.

– New configuration is downloaded from the controller.

The transmitter varies the current to the analog input in proportion to the process variable being measured. The inclusion of an internal on-board loop power source saves you the expense of extra power supplies and greatly simplifies the interface wiring to field devices. Each channel on the module provides independent, isolated, current-limited power to its current transmitter.

In addition to supplying loop power to two-wire transmitters, the module can also accommodate current transmitters powered by an external supply. The module accommodates two-wire and four-wire transmitters when configured for Current input type and Source Loop Current is disabled.

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1756-IF8I Isolated Analog Input Module Chapter 3

Power Calculations with the 1756-IF8I Module

The module’s 24V backplane current requirements increase when it operates with a Current input type and Source Loop Current mode enabled.

The 1756-IF8I module uses the power provided across the ControlLogix chassis backplane as the source for loop power. Because of the demands placed on that supply, that is, the 1756-IF8I module consumes 10.6 W of backplane power, take special care when calculating the power requirements for modules in the same chassis as a 1756-IF8I module.

For example, when used with the 1756-L75 controller and operating in the Sourcing Loop Current mode, you can place only six 1756-IF8I modules in the chassis before exceeding the wattage capacity of the power supply.

Other Devices in the Wiring Loop

The voltage source on each channel can drive loop impedance of up to approximately 1300 Ω. This lets you include other devices, such as chart recorders and meters, in the current loop.

For more information on wiring the 1756-IF8I module, see page 61

Multiple Input Ranges

The 1756-IF8I module offers multiple input ranges that are dictated by channel configuration choices. The input type selection determines the available ranges.

Input Type Input Range

Current (mA) 0…20 m A

Voltage (V) Any of the following:

To see where to select the input range, see page 127

• -10…10V

• 0…5V

• 0…10V

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Chapter 3 1756-IF8I Isolated Analog Input Module

Notch Filter

The notch filter is a built-in feature of the Analog-to-Digital convertor (ADC) that removes line noise in your application for each channel. The removal of line noise is also known as noise immunity.

The notch filter attenuates the input signal at the specified frequency. That is, the filter reduces the amplitude of the signal with minimal signal distortion.

Choose a notch filter based on what noise frequencies are present in the module's operating environment and any sampling requirements needed for control. The default Notch Filter setting is 60 Hz.

For example, a notch filter is typically set to 60 Hz to filter out 60 Hz AC line noise and its overtones. A 60 Hz notch filter setting attenuates frequencies of 60 Hz, 120 Hz, 180 Hz and so forth.

The following graphic shows 10 Hz notch filter selection and how the noise is dissipated over the entire spectrum but especially at the notch filter setting and its overtones.

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1756-IF8I Isolated Analog Input Module Chapter 3

Relationship between Noise Rejection Level and RPI Setting

The 1756-IF8I module offers two levels of line noise rejection. Each level has a filter associated with it. The module automatically determines which filter is used based on the notch filter setting and RPI rate.

A trade-off exists between sampling speed and level of noise rejection:

• The faster the sampling speed, the less noise rejection. In this case, the module automatically uses a SINC^1 filter.

The SINC^1 filter offers 34 dB noise rejection at the notch filter frequency and its overtones.

• The slower the sampling rate, the better noise rejection. In this case, the module automatically uses a SINC^3 filter.

The SINC^3 filter offers 100 dB noise rejection at the notch filter frequency and its overtones.

The following table lists the available notch filter settings, the minimum RPI rate available with that notch filter setting, and the corresponding noise response.

Notch Filter Setting 5 Hz 10 Hz 15 Hz 20 Hz 50 Hz 60 Hz

Minimum Sample Time (RPI) - SINC^1 Filter

Minimum Sample Time (RPI) - SINC^3 Filter

0…100% Step Response

(2)(3)

Time

-3 dB Frequency

Typical Effective Resolution

(1) The minimum RPI value for the module depends on the channel with the lowest notch filter setting. For example, if three of the channels on a module use a Notch Filter setting of 20 Hz and one channel

uses a Notch Filter setting of 60 Hz, you cannot set the module RPI lower than 50.1 ms.

(2) Using the SINC^3 filter.

(3) Worst case settling time to 100% of step change includes 0…100% step response time plus one RPI sample time. (4) Value represents module performance in Current mode. For the value when the module is used in Voltage mode, include additional 3 ms settling time due to RC time constant of 7500 Ω voltage input

resistor.

(2)

200.1 ms 100.1 ms 66.7 ms 50.1 ms 20.1 ms 16.7 ms 10.1 ms 2.1 ms 1.1 ms 1.0 ms

(1)

600.1 ms 300.1 ms 200.1 ms 150.1 ms 60.1 ms 50.1 ms 30.1 ms 6.1 ms 3.1 ms 1.0 ms

(1)

600 ms + 1RPI

1.3 Hz 2.7 Hz 4.3 Hz 5.1 Hz 13 Hz 15 Hz 26 Hz 128 Hz 258 Hz 1296 Hz

21 bits 20 bits 20 bits 20 bits 20 bits 20 bits 19 bits 18 bits 18 bits 17 bits

300 ms + 1RPI

200 ms + 1RPI

150 ms + 1RPI

60 ms + 1RPI

(Default)

50 ms + 1RPI

100 Hz 500 Hz 1000 Hz 5000 Hz

30 ms + 1RPI

6 ms + 1 RPI 3 ms +

1RPI

(4)

1 ms +

(4)

1RPI

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 49

Chapter 3 1756-IF8I Isolated Analog Input Module

For example, if your application requires a Notch Filter setting of 50 Hz, the module’s minimum RPI rate is 20.1 ms. In this case, sampling speed is more important than noise rejection. The module automatically uses a SINC^1 filter.

If your application requires a Notch Filter setting of 50 Hz and the greater level of noise rejection provided by a SINC^3 filter, the minimum RPI rate is 60.1 ms. The module automatically uses a SINC^3 filter.

The RPI must be > 1/Notch Filter plus some small scan time for the ADC to sample properly. The SINC^3 filter takes 3 times as long and thus requires RPI > 3/Notch plus some small scan time. The module rejects combinations which violate that relationship.

The table below lists the available notch filter settings and the RPI values for the two types of filters.

Notch Filter Fastest RPI for a SINC^1 Filter Fastest RPI for a SINC^3 Filter

5 Hz 200.1 ms 600.1 ms

10 Hz 100.1 ms 300.1 ms

15 Hz 66.7 ms 200.1 ms

20 Hz 50.1 ms 150.1 ms

50 Hz 20.1 ms 60.1 ms

60 Hz (default) 16.7 ms 50.1 ms

100 Hz 10.1 ms 30.1 ms

500 Hz 2.1 ms 6.1 ms

1000 Hz 1.1 ms 3.1 ms

5000 Hz 1.0 ms 1.0 ms

To see where to set the Notch Filter, see page 127

50 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

IMPORTANT

Underrange/Overrange Detection

This feature detects when the isolated input module is operating beyond limits set by the input range. For example, if you are using the 1756-IF8I module in the 0…10V input range and the module voltage increases to 11V, the overrange feature detects this condition.

The following table lists the input ranges of the 1756-IF8I module and the lowest/highest signal available in each range before the module detects an underrange/overrange condition.

Input Type Range Underrange Threshold Overrange Threshold

Current (mA) 0…20 mA < 3.6 mA

Voltage (V) ±10.00V < -10.50 >10.50

0…10V < 0.00V >10.50

0…5V < 0.00V > 5.25V

(1) Underrange is set at 3.6 mA, but the I:Ch[x].Data tag reports values as low as 0.0 mA.

(2) When used with a Current input type, the module has an inherent deadband. Once latched, an Underrange condition continues

until the signal is greater than 3.8 mA.

(3) When used with a Current input type, the module has an inherent deadband. Once latched, an Overrange condition continues

until the signal is less than 20.75 mA.

(1) (2)

> 21.00 mA

(3)

Be aware that the Disable All Alarms feature, does not disable the underrange/overrange detection feature. The Disable All Alarms feature disables all alarms on the module.

The underrange/overrange detection feature is not an alarm. It is an indicator that channel data has gone beyond the absolute maximum or minimum, respectively, for the channel’s chosen range but does not trigger an alarm.

To disable the underrange/overrange detection feature, you must disable the channel.

To see where to set the Underrange/Overrange detection values, see page 131

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 51

Chapter 3 1756-IF8I Isolated Analog Input Module

Yn = Y

-1

- Y

-1

[Δ t]

t + TA

Yn = Present output, filtered peak voltage (PV)‘

-1

= Previous output, filtered PV

t = Module channel update time (seconds)

TA = Digital filter time constant (seconds) X

= Present input, unfiltered PV

0 0.01 0.5 0.99 Time in Seconds

100%

63%

Amplitude

Unfiltered Input

TA = 0.01 second TA = 0.5 second

TA = 0.99 second

Digital Filter

The digital filter smooths input data noise transients on each input channel. This value specifies the time constant for a digital, first-order lag filter on the input. It is specified in units of milliseconds. A value of 0 (zero) disables the filter.

The digital filter equation is a classic, first order lag equation.

As shown in the following graphic, by using a step input change to illustrate the filter response, you see that 63.2% of the total response is reached when the digital filter time constant elapses. Each additional time constant achieves 63.2% of the remaining response.

To see where to set the Digital Filter, see page 127

52 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

IMPORTANT

Process Alarms

Process alarms alert you when the module has exceeded configured high or low limits for each channel. These are set at four, user-configurable, alarm trigger points:

• High high

• High

• Low

• Low low

You can enable or disable Process Alarms individually via the Output tags for each channel. When a module is added to your Logix Designer application project and tags are created, the Alarms are disabled by default.

Each individual Process Alarm enable tag, that is, O.Ch[x].LLAlarmEn, O.Ch[x].LAlarmEn, O.Ch[x].HAlarmEn and O.Ch[x].HHAlarmEn, is disabled when the module is created. You must enable the tags in the Output Data to allow the individual alarm to trigger.

If a Process Alarm's enable bit is not set, the corresponding Input Process Alarm never triggers. To see where to set the Process Alarms, see page 131

You can latch process alarms. The alarm remains on, even if the condition causing it to occur disappears, until the alarm is unlatched.

You must manually unlatch the alarm. You can unlatch the alarm, by using one of the following methods:

• While the project is online, click the Alarm Configuration tab on the Module. Then click Unlatch to unlatch a specific alarm or Unlatch All to unlatch all alarms.

• Change the module output tag for the alarm that you want to unlatch. For example, the Ch[x].LLAlarmUnlatch tag to unlatch a Low Low Alarm.

For more information on module tags, see Appendix A, Isolated Analog I/O

Module Tag Definitions on page 173.

• Use a CIP Generic message.

For more information how to use a CIP Generic message, see Rockwell Automation Knowledgebase article #63046, How to Reset Latched Status of an Analog Module. You can access the article at:

https://rockwellautomation.custhelp.com/

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 53

Chapter 3 1756-IF8I Isolated Analog Input Module

43153

High high

Low low

Low

High

Alarm Deadbands

High high alarm turns Off. High alarm remains On.

High high alarm turns On. High alarm remains On.

Normal Input Range

Low low alarm turns Off. Low alarm remains On.

High alarm turns Off.

Low low alarm turns On. Low alarm remains On.

Low alarm tur ns Off.Low alarm turns On.

High alarm turns On.

Alarm Deadband

You can configure an alarm deadband to work with these alarms. The deadband lets the process alarm status bit remain set, despite the alarm condition disappearing, as long as the input data remains within the deadband of the process alarm.

The following graphic shows input data that sets each of the four alarms at some point during module operation. In this example, latching is disabled; therefore, each alarm turns Off when the condition that caused it to set ceases to exist.

Figure 4 - Alarm Deadband Alarm Settings

To see where to set the Alarm Deadband, see page 131.

54 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

EXAMPLE

Rate Alarm

The rate alarm triggers if the rate of change between input samples for each channel exceeds the specified trigger point for that channel. The actual rate of

change for the last sample is returned in the Ch[x].RateOfChange input tag of each channel.

If scaling mA to mA, if you configure a channel’s rate alarm to 1.0 mA/s, the rate alarm triggers only if the difference between measured input samples changes at a rate > 1.0 mA/s.

Consider the following conditions:

• The module’s RPI is 100 ms, that is, new data is sampled every 100 ms.

• At input sample 1, the channel measures 5.0 mA.

• At input sample 2, (100 ms later) the channel measures 5.08 mA.

At this sample instance, the rate alarm is not triggered because the rate of change is less than 1.0 mA/s.

The rate of change is 0.8 mA/s [(5.08 mA - 5.0 mA) / (100 ms)].

• At input sample 3 (100 ms later) the channel measures 4.9 mA.

At this sample instance, the rate alarm is triggered because the rate of change is greater than 1.0 mA/s.

The rate of change is 1.8 mA/s. [(4.9 mA - 5.08 mA) / (100 ms)].

At this sample instance, the absolute value of this result is > 1.0 mA/s, so the rate alarm sets. Absolute value is used because rate alarm checks for the magnitude of the rate of change being beyond the trigger point, whether a positive or negative excursion.

To see where to set the Rate Alarm, see page 131

Sensor Offset

The sensor offset compensates for any known error on the sensor or channel to which the sensor is connected. The value is set in signal units and is added to the data value.

For example, if the sensor has an error such that the channel consistently reports current signal values by 0.2 mA lower than actual the value, you set this parameter to 0.2 in channel configuration.

You set this value via a module output tags. That is, tag O.Ch[x].SensorOffset. Where x represents the module channel.

In the example above, the O.Ch[x]SensorOffset tag = 0.2.

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 55

Chapter 3 1756-IF8I Isolated Analog Input Module

IMPORTANT

Wire Off Detection

The 1756-IF8I module alerts you when a wire is disconnected from a channel or the RTB is removed from the module. The following events occur when a wire off condition exists:

• Module Operating in Vo lt ag e M od e – Input data for that channel changes to a specific scaled value

corresponding to the Overrange value.

– The Overrange bit is set in the I:Ch[x].Overrange tag.

• Module Operating in Current Mode – Input data for that channel changes to a specific scaled value

corresponding to the Underrange value.

– The Underrange bit is set in the I:Ch[x].Underrange tag.

• A fault bit is set in the owner-controller that can indicate the presence of a

wire off condition.

Be aware that the Disable All Alarms feature, does not disable the wire off detection feature. The Disable All Alarms feature disables all alarms on the module.

The wire off detection feature is not an alarm. It is an indicator that a wire has been disconnected from the channel but does not trigger an alarm.

To disable the wire off detection feature, you must disable the channel.

Because the module can be used in voltage or current applications, differences exist as to how a wire off condition is detected in voltage or current applications.

Table 6 - 1756-IF8I Module - Wire Off Conditions in Different Applications

Application Configuration Wire Off Condition Cause Resulting Module Behavior

Voltage Applications Either of the following:

• A wire is disconnected from the module.

Current Applications • Input data for that channel changes to the scaled value associated with the underrange signal value of the

• The RTB is disconnected from the module.

• Input data for that channel changes to the scaled value associated with the overrange signal value of the selected operational range.

• The I.Ch[x].Overrange (x=channel number) tag is set to 1.

selected operational range.

• The I.Ch[x].Underrange (x=channel number) tag is set to 1.

56 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

IMPORTANT

Synchronized Sampling

This feature lets you synchronize input sampling across inputs on multiple modules in the same chassis, forcing those inputs to sample simultaneously within approximately 20 μS of each other.

Synchronized Sampling is not limited to input sample across inputs on the same module types.

You can use Synchronized Sampling across inputs on 1756-IF8I modules and 1756-IRT8I modules in the same system.

For example, if you have 12 input devices connected to one 1756-IF8I module and two 1756-IRT8I modules in the same chassis, or different chassis synchronized to the same CIP Sync TimeMaster, use Synchronized Sampling to take a snapshot of the input data available at each input at a single moment in time.

The following conditions must exist to use this feature:

• A 1588 CIP Sync Time Master is configured for the chassis.

• All modules in the set use the same RPI value or values that are multiples

of each other.

• Synchronized Sampling with Other Synchronized Modules is enabled for all input channels in the set.

For these input modules, configuring one channel for Synchronized Sampling synchronizes all eight channels.

While setting the RPI to the same value on all 1756-IF8I modules guarantees that each module samples at the same rate, it does not guarantee that they sample at the same time. When enabled, Synchronized Sampling provides each module a synchronized starting point for its respective input scans. Because the RPI values are the same, the inputs on the modules are sampled at the same rate and the same time.

To see where to enable Synchronized Sampling, see page 127

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 57

Chapter 3 1756-IF8I Isolated Analog Input Module

RIUP

Circuit

DSP

Field Side Backplane Side

1 7 5 6 B A C K P L

A N E

Channels 1…6 (not shown)

Backplane

ASIC

DC-DC

Shutdown

Circuit

System +5V

Isolator

DC-DC

Conver ter

Vref

Signal Conditioning

and A/D Converter

Isolated Power

Channel 0

Channel 7

IN_0/V

IN_0/I/SRC

RTN_0

Isolator

DC-DC

Conver ter

Vref

Signal Conditioning

and A/D Converter

Isolated Power

Nonvolatile

Memory

Status

Indicators

IN_7/V

IN_7/I/SRC

RTN_7

Represents Channel Isolation

Module Block and Circuit Diagrams

The graphics in this section show the 1756-IF8I module’s block diagrams and field-side circuit diagrams.

Figure 5 - 1756-IF8I Module Block Diagram

58 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

RTN-x

1 μA Pullup

0.1 μF

IN_x/V

A/D Converter

7500 Ω

2.5V Vref

IN_x/I/SRC

1000 Ω

55 Ω

0.01 μF0.01 μF

–

1000 Ω

20 Ω

Volt age

Source

0.01 μF

PGA

RTN-x

0.1 μF

IN_x/V

A/D Converter

7500 Ω

IN_x/I/SRC

1000 Ω

55 Ω

4…20 mA Tra ns mi tt er

0.01 μF0.01 μF

1000 Ω

20 Ω

Tra ns mi tt er

Power

0.01 μF

Current Limit

24.9 Ω

25 Ω

i_sense

2.5V Vref

PGA

–

Field-side Circuit Diagrams

The following diagrams show the field-side circuitry for the 1756-IF8I module.

Figure 6 - 1756-IF8I Module Field-side Circuit with Voltage Input

Figure 7 - 1756-IF8I Input Module Field-side Circuit with an Externally-powered Current Input Loop

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 59

Chapter 3 1756-IF8I Isolated Analog Input Module

RTN-x

0.1 μF

IN_x/V

A/D Converter

7500 Ω

IN_x/I/SRC

1000 Ω

55 Ω

4…20 mA Transmitter

0.01 μF0.01 μF

1000 Ω

20 Ω

0.01 μF

Current Limit

24.9 Ω

25 Ω

Current Limit

i_sense

2.5V Vref

PGA

+18V

–

Figure 8 - 1756-IF8I Module Field-side Circuit with the Module Sourcing the Current Input Loop

60 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

IMPORTANT

IN_0/V

IN_0/I/SRC

RTN_0

Not used

IN_2/V

IN_2/I/SRC

RTN_2

Not used

4-wire

Tra ns mi tt er

Shield Ground

IN_4/V

IN_4/I/SRC

RTN_4 Not used

IN_6/V

IN_6/I/SRC

RTN_6

Not used

IN_1/V

IN_1/I/SRC

RTN_1

Not used

IN_3/V

IN_3/I/SRC

RTN_3

Not used

IN_5/V

IN_5/I/SRC

RTN_5 Not used

IN_7/V

IN_7/I/SRC

RTN_7

Not used

24V DC

IMPORTANT: Remember the following:

• If separate power sources are used, do

not exceed the specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Specifications Technical Data, publication

1756-TD002

• Place additional loop devices, for example, s trip chart reco rders, at either ‘A’ location in the current loop.

24V DC

2-wire

Tra ns mi tt er

Shield Ground

–

Wire the 1756-IF8I Module

This section shows how to wire the 1756-IF8I module for current and voltage input types.

Figure 9 - 1756-IF8I Module Wiring Diagram -Current Mode with External Loop Power

In this wiring diagram, an external, user-provided power supply provides 24V DC loop power.

–

019

1112

4131

6151

8171

0291

2212

4232

6252

8272

0392

2313

6353

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 61

Chapter 3 1756-IF8I Isolated Analog Input Module

IMPORTANT

IN_0/V

IN_0/I/SRC

RTN-0

Not used

IN_2/V

IN_2/I/SRC

RTN_2

Not used

Shield Ground

IN_4/V

IN_4/I/SRC

RTN-4

Not used

IN_6/V

IN_6/I/SRC

RTN_6

Not used

IN_1/V

IN_1/I/SRC

RTN-1

Not used

IN_3/V

IN_3/I/SRC

RTN_3

Not used

IN_5/V

IN_5/I/SRC

RTN-5

Not used

IN_7/V

IN_7/I/SRC

RTN_7

Not used

IMPORTANT: Remember the following:

• If separate power sources are used, do

not exceed the specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Specifications Technical Data, publication

1756-TD002

• Place additional loop devices, for example, strip chart recorders, at either ‘A’ location in the current loop.

2-wire

Tra ns mi tt er

Figure 10 - 1756-IF8I Module Wiring Diagram -Current Mode with Internal Loop Power

In this wiring diagram, the module provides 24V DC loop power.

019

1112

4131

6151

8171

0291

2212

4232

6252

8272

0392

2313

6353

62 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IF8I Isolated Analog Input Module Chapter 3

IN_0/V

IN_0/I/SRC

RTN-0

Not used

IN_2/V

IN_2/I/SRC

RTN_2

Not used

User Analog Input Device

Shield Ground

IMPORTANT: If separate power sources are used, do not exceed the specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Spe cifications Technical Data, publication 1756-TD002.

IN_4/V

IN_4/I/SRC

RTN-4 Not used

IN_6/V

IN_6/I/SRC

RTN_6

Not used

IN_1/V

IN_1/I/SRC

RTN-1

Not used

IN_3/V

IN_3/I/SRC

RTN_3

Not used

IN_5/V

IN_5/I/SRC

RTN-5 Not used

IN_7/V

IN_7/I/SRC

RTN_7

Not used

Device

External

Power

Figure 11 - 1756-IF8I Module Wiring Diagram - Voltage Mode

–

019

1112

4131

6151

8171

0291

2212

4232

6252

8272

0392

2313

6353

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 63

Chapter 3 1756-IF8I Isolated Analog Input Module

Fault and Status Reporting

The 1756-IF8I module multicasts fault and status data with channel data to the owner and listening controllers. The data is returned via module tags that you can monitor in your Logix Designer application.

With some exceptions, as noted in the following table, the 1756-IF8I module provides the fault and data status in a channel-centric format.

The following table lists the 1756-IF8I module’s fault and status tags available in the Logix Designer application.

Table 7 - 1756-IF8I Module - Fault and Status Data Tags

Data Type Tag Name Triggering Event That Sets Tag

(1)

Fau lt

Status

Fau lt

Ch[x].Fault The channel data quality is bad.

Ch[x].Underrange The channel data is beneath the absolute minimum for this channel.

Ch[x].Overrange The channel data is above the absolute maximum for this channel.

CIPSyncValid

CIPSyncTimeout

CIPSyncOffsetJump

Ch[x].Uncertain The channel data can be imperfect

Ch[x].LLAlarm The I.Ch[x].Data tag value is less than the C.Ch[x].LLAlarmLimit tag value, the O.Ch[x].LLAlarmEn tag is set and alarms

Ch[x].LAlarm The I.Ch[x].Data tag value is less than the C.Ch[x].LAlarmLimit tag value, the O.Ch[x].LAlarmEn tag is set and alarms

Ch[x].HAlarm The I.Ch[x].Data tag value is greater than the C.Ch[x].HAlarmLimit tag value, the O.Ch[x].HAlarmEn tag is set and

Ch[x].HHAlarm The I.Ch[x].Data tag value is greater than the C.Ch[x].HHAlarmLimit tag value, the O.Ch[x].HHAlarmEn tag is set and

Ch[x].RateAlarm The absolute change between consecutive channel samples exceeds the C.Ch[x].RateAlarmLimit tag value.

Ch[x].CalibrationFault The last attempted Calibration for this channel failed.

Ch[x].Calibrating The channel is currently being calibrated

Ch[x].CalGoodLowRef A valid Low Reference signal has been sampled on this channel.

Ch[x].CalBadLowRef An invalid Low Reference signal has been sampled on this channel.

Ch[x].CalGoodHighRef An valid High Reference signal has been sampled on this channel.

Ch[x].CalBadHighRef An invalid High Reference signal has been sampled on this channel.

Ch[x].CalSuccessful Calibration on this channel is complete and the Calibrating state has been exited.

Ch[x].RateOfChange The change in channel data since last sample in Engineering Units/Second.

Ch[x].Data The channel data in scaled Engineering Units.

Timestamp

RollingTimestamp

(1)

The owner-controller loses its connection to the module.

Indicates whether the module has synchronized to a valid CIP Sync time master on the backplane.

Indicates whether a valid time master on the backplane has timed out.

Indicates a significant jump, that is, 1 ms or greater, in the CST and CIP Sync times sent from the Timemaster to the module. (The Timemaster sends the CST and CIP Sync times to the module every second.)

When a significant jump occurs, this tag value becomes 1 but changes to 0 a second later unless another jump occurred.

are enabled for the channel.

alarms are enabled for the channel.

This alarm only applies to enabled Process alarms.

A 64-bit Timestamp indicating when all 8 channels were last sampled in terms of CIPSync time.

16 bit timestamp that ‘rolls’ from 0…32,767 ms. Compatible with existing PID instruction to automatically calculate sample deltas.

(1) This tag provides module-wide data and affects all channels simultaneously.

64 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

Chapter 4

IMPORTANT

1756-IRT8I Combined Temperature-sensing Isolated Analog Module

Top ic Pa ge

1756-IRT8I Module Features 65

Module Block and Circuit Diagrams 87

Wire the 1756-IRT8I Module 89

Fault and Status Reporting 92

The 1756-IRT8I module has eight isolated channels. Each channel supports connection to the following input types:

• RTD, both 3-wire and 4-wire

• Thermocouple mV devices

1756-IRT8I Module Features

The module provides 24-bit data resolution. Additional features are described in this chapter.

The 1756-IRT8I module has the following features:

• Multiple Input Ranges

• Notch Filter

• Underrange/Overrange Detection

• Digital Filter

• Process Alarms

• Rate Alarm

• Sensor Offset

• 10 Ohm Copper Offset

• Wire Off Detection

• Te mp e ra tu re Un i ts

• Sensor Types

• Thermocouple Wire Length Compensation

• Synchronized Sampling

• Cold Junction Compensation

Most of the features available on the 1756-IRT8I module are software configurable. For more information on how to configure the module, see

Chapter 7

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 65

, Configure ControlLogix Isolated Analog I/O Modules on page 121

Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

Multiple Input Ranges

The 1756-IRT8I module offers multiple input ranges. The input type and sensor type selections determine the available ranges.

The following table describes this module’s input ranges in relation to the sensor type. If a single range is listed in the Input Range column, the programming application automatically selects the range used with the previously listed sensor type.

Table 8 - 1756-IRT8I Module - Channel Input Ranges

Input Type Sensor Type Input Range

RTD

Thermoc ouple

Ohm One of the following:

100 Ω PT 385 1…500 Ω 200 Ω PT 385 2…1000 Ω 500 Ω PT 385 4…2000 Ω 1000 Ω PT 385 8…4000 Ω 100 Ω PT 3916 1…500 Ω 200 Ω PT 3916 2…1000 Ω 500 Ω PT 3916 4…2000 Ω 1000 Ω PT 3916 8…4000 Ω 10 Ω CU 427 1…500 Ω 120 Ω NI 672 1…500 Ω 100 Ω NI 618 1…500 Ω 120 Ω NI 618 1…500 Ω 200 Ω NI 618 2…1000 Ω 500 Ω NI 618 4…2000 Ω

TC Typ e B

TC Typ e C

TC Typ e E

TC Typ e J

TC Typ e K

TC Typ e N

TC Typ e R

TC Typ e S

TC Typ e T

TC Typ e TXK /XK(L )

TC Typ e D

• 1…500 Ω

• 2…1000 Ω

• 4…2000 Ω

• 8…4000 Ω

-100…100 mV

To see where to select the input range, see page 127

66 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

Notch Filter

The notch filter attenuates the input signal at the specified frequency. That is, the filter reduces the amplitude of the signal with minimal signal distortion.

Choose a notch filter based on what noise frequencies are present in the module's operating environment and any sampling requirements needed for control. The default Notch Filter setting is 60 Hz.

For example, a notch filter is typically set to 60 Hz to filter out 60 Hz AC line noise and its overtones. A 60 Hz notch filter setting attenuates frequencies of 60 Hz, 120 Hz, 180 Hz and so forth.

The following graphic shows 10 Hz notch filter selection and how the noise is dissipated over the entire spectrum but especially at the notch filter setting and its overtones.

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

Relationship between Noise Rejection Level and RPI Setting

The 1756-IRT8I module offers two levels of line noise rejection. Each level has a filter associated with it. The module automatically determines which filter is used based on the notch filter setting and RPI rate.

A trade-off exists between sampling speed and level of noise rejection:

• The faster the sampling speed, the less noise rejection. In this case, the module automatically uses a SINC^1 filter.

The SINC^1 filter offers 34 dB noise rejection at the notch filter frequency and its overtones.

• The slower the sampling rate, the better noise rejection. In this case, the module automatically uses a SINC^3 filter.

The SINC^3 filter offers 100 dB noise rejection at the notch filter frequency and its overtones.

The following table lists the available notch filter settings, the minimum RPI rate available with that notch filter setting, and the corresponding noise response.

Notch Setting 5 Hz 10 Hz 15 Hz 20 Hz 50 Hz 60 Hz

Minimum Sample Time (RPI) - SINC^1 Filter

Minimum Sample Time (RPI) - SINC^3 Filter

0…100% Step Response

(2)(3)

Time

-3 dB Frequency

Typical Effective Resolution

uses a Notch Filter setting of 60 Hz, you cannot set the module RPI lower than 50.1 ms.

(2) Using the SINC^3 filter.

(3) Worst case settling time to 100% of step change includes 0…100% step response time plus one RPI sample time.

(4) Measured in ±100 mV range.

(2)

(2) (4)

200.1 ms 100.1 ms 66.7 ms 50.1 ms 20.1 ms 16.7 ms 10.1 ms 2.1 ms 1.1 ms 1.0 ms

(1)

600.1 ms 300.1 ms 200.1 ms 150.1 ms 60.1 ms 50.1 ms 30.1 ms 6.1 ms 3.1 ms 1.0 ms

(1)

600 ms + 1RPI

1.3 Hz 2.7 Hz 4.3 Hz 5.1 Hz 13 Hz 15 Hz 26 Hz 128 Hz 258 Hz 1296 Hz

19 bits 18 bits 18 bits 18 bits 17 bits 17 bits 17 bits 16 bits 15 bits 14 bits

300 ms + 1RPI

200 ms + 1RPI

150 ms + 1RPI

60 ms + 1RPI

(Default)

50 ms + 1RPI

100 Hz 500 Hz 1000 Hz 5000 Hz

30 ms + 1RPI

6 ms + 1 RPI 3 ms + 1RPI 1 ms + 1RPI

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1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

The table below lists the available notch filter settings and the RPI values for the two types of filters.

Notch Filter Fastest Available RPI Fastest RPI for a SINC^3 Filter

5 Hz 200.1 ms 600.1 ms

10 Hz 100.1 ms 300.1 ms

15 Hz 66.7 ms 200.1 ms

20 Hz 50.1 ms 150.1 ms

50 Hz 20.1 ms 60.1 ms

60 Hz (default) 16.7 ms 50.1 ms

100 Hz 10.1 ms 30.1 ms

500 Hz 2.1 ms 6.1 ms

1000 Hz 1.1 ms 3.1 ms

5000 Hz 1.0 ms 1.0 ms

To see where to set the Notch Filter, see page 127

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

IMPORTANT

Underrange/Overrange Detection

This feature detects when a temperature-measuring input module is operating beyond limits set by the input range. For example, if you are using the 1756-IRT8I module in the 2…1000 Ω input range and the module resistance increases to 1050 Ω, the overrange detection detects this condition.

The table lists the input ranges of non-isolated input modules and the lowest/ highest signal available in each range before the module detects an underrange/ overrange condition.

Table 9 - Low and High Signal Limits on Temperature-measuring Input Modules

Input Type Available Range Underrange Threshold Overrange Threshold

RTD 1…500 Ω <

Thermocouple -100…100 mV - 101.00 mV 101.00 mV

0.00 Ω 510.00 Ω 2…1000 Ω < 0.00 Ω 1020.00 Ω 4…2000 Ω < 0.00 Ω 2040.00 Ω 8…4000 Ω <

0.00 Ω 4080.00 Ω

Be aware that the Disable All Alarms feature, does not disable the underrange/overrange detection feature. The Disable All Alarms feature disables all alarms on the module.

To disable the underrange/overrange detection feature, you must disable the channel.

To see where to set the Underrange/Overrange detection values, see page 131

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Yn = Y

-1

- Y

-1

[Δ t]

t + TA

Yn = Present output, filtered peak voltage (PV)‘

-1

= Previous output, filtered PV

Δ t = Module channel update time (seconds)

TA = Digital filter time constant (seconds) X

= Present input, unfiltered PV

0 0.01 0.5 0.99 Time in Seconds

1672

100%

63%

Amplitude

Unfiltered Input

TA = 0.01 s TA = 0.5 s

TA = 0.99 s

Digital Filter

The digital filter smooths input data noise transients on each input channel. This value specifies the time constant for a digital first order lag filter on the input. It is specified in units of milliseconds. A value of 0 disables the filter.

The digital filter equation is a classic first order lag equation.

By using a step input change to illustrate the filter response, you can see that when the digital filter time constant elapses, 63.2% of the total response is reached. Each additional time constant achieves 63.2% of the remaining response.

To see where to set the Digital Filter, see page 127

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

IMPORTANT

Process Alarms

Process alarms alert you when the module has exceeded configured high or low limits for each channel. These are set at four, user-configurable, alarm trigger points:

• High high

• High

• Low

• Low low

If a Process Alarm's enable bit is not set, the corresponding Input Process Alarm never triggers. To see where to set the Process Alarms, see page 131

You can latch process alarms. The alarm remains on, even if the condition causing it to occur disappears, until the alarm is unlatched.

You must manually unlatch the alarm. You can unlatch the alarm, by using one of the following methods:

• While the project is online, click the Alarm Configuration tab on the Module. Then click Unlatch to unlatch a specific alarm or Unlatch All to unlatch all alarms.

• Change the module output tag for the alarm that you want to unlatch. For example, the Ch[x].LLAlarmUnlatch tag to unlatch a Low Low Alarm.

For more information on module tags, see Appendix A, Isolated Analog I/O

Module Tag Definitions on page 173.

• Use a CIP Generic message.

For more information how to use a CIP Generic message, see Rockwell Automation Knowledgebase article #63046, How to Reset Latched Status of an Analog Module. You can access the article at:

https://rockwellautomation.custhelp.com/

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43153

High high

Low low

Low

High

Alarm Deadbands

High high alarm turns Off. High alarm remains On.

High high alarm turns On. High alarm remains On.

Normal Input Range

Low low alarm turns Off. Low alarm remains On.

High alarm turns Off.

Low low alarm turns On. Low alarm remains On.

Low alarm tur ns Off.Low alarm turns On.

High alarm turns On.

Alarm Deadband

Figure 12 - Alarm Deadband Alarm Settings

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 73

To see where to set the Alarm Deadband, see page 131.

Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

EXAMPLE

Rate Alarm

The rate alarm triggers if the rate of change between input samples for each channel exceeds the specified trigger point for that channel. The actual rate of

change for the last sample is returned in the Ch[x].RateOfChange input tag of each channel.

In normal scaling in Celsius, if you configure a channel’s rate alarm to

100.1 °C/s, the rate alarm triggers only if the difference between measured input samples changes at a rate > 100.1 °C/s.

Consider the following conditions:

• The module’s RPI is 100 ms, that is, new data is sampled every 100 ms.

• At input sample #1, the channel measures 355 °C.

• At input sample #2, (100 ms later) the channel measures 363 °C.

At this sample instance, the rate alarm is not triggered because the rate of change is less than 100.1 °C/s.

The rate of change is 80 °C/s [(363 °C- 355 °C) / (100 ms)].

• At input sample #3 (100 ms later) the channel measures 350.3 °C.

At this sample instance, the rate alarm is triggered because the rate of change is greater than 100.1 °C.

The rate of change is 127 °C. [(350.3 °C - 363 °C) / (100 ms)].

At this sample instance, the absolute value of this result is > 100.1 °C, so the rate alarm sets. Absolute value is used because rate alarm checks for the magnitude of the rate of change being beyond the trigger point, whether a positive or negative excursion.

To see where to set the Rate Alarm, see page 131

Sensor Offset

The sensor offset value compensates for any known error on the sensor or channel to which the sensor is connected. The value is set in signal units.

You set this value via a module output tags. That is, tag O.Ch[x].SensorOffset. Where x represents the module channel.

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1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

IMPORTANT

10 Ohm Copper Offset

With this feature, you can compensate for a small offset error in a 10 ohm copper RTD. The channel must be connected to the 10 Ohm CU 427 Sensor Type to use this feature. The offset value is indicated in units of 0.01 Ohms.

You can set the 10 Ohm copper offset in either of the following ways:

• On the Configuration tab of the Module Properties dialog box. In this case, valid values are from -0.99…0.99.

• Directly in the channel’s C.Ch[x].TenOhmOffset tag. In this case, valid values are -99…99

For example, if the resistance of a copper RTD used with a channel is 9.74 Ω at 25 °C, you account for error by setting the 10 Ohm Copper Offset field on the Configuration tab to -0.26 or by setting the C.Ch[x].TenOhmOffset to -26.

To see where to set the 10 Ohm Copper Offset on the Configuration tab, see

page 127

Wire Off Detection

The 1756-IRT8I module alerts you when one or more wires have been disconnected from a channel.

When a wire off condition occurs, the following events occur:

• Input data for the channel changes to a specific scaled value.

• A fault bit is set in the owner-controller indicating the presence of a wire

off condition.

For more information on module behavior when a wire off condition occurs, see

Table 10 on page 76

Be aware that the Disable All Alarms feature, does not disable the wire off detection feature. The Disable All Alarms feature disables all alarms on the module.

The wire off detection feature is not an alarm. It is an indicator that a wire has been disconnected from the channel but does not trigger an alarm.

To disable the wire off detection feature, you must disable the channel.

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

Because these modules can each be used in various applications, differences exist when a wire off condition is detected in each application. The table lists the differences that occur when a wire off condition occurs in various applications.

Table 10 - 1756-IRT8I Module - Wire Off Conditions

Application Configuration Wire Off Condition Cause Resulting Module Behavior

Input Type = RTD Sensor Type = Temperature or

Ohm

When using a 3-wire RTD device and any of the following exists:

• One wire is disconnected from any of the channel’s terminals.

• Wires are disconnected from any combination of terminals: – IN_x(+)/A – IN_x(-)/B – IN_x/RTD C

• All of the wires are disconnected from the channel.

With the 3-wire RTD device, the wire off condition is detected within two seconds of wires getting disconnected.

When using a 4-wire RTD device and any of the following exists:

• A wire is disconnected from only terminal IN_x(-)/B.

• Wires are disconnected from any combination of the channel’s

terminals, that is:

– IN_x(+)/A – IN_x(-)/B – IN_x/RTD C – IN_x/RTD D

IMPORTANT: There is one combination exception that does not

apply.

A wire off condition is not detected when wires are simultaneously disconnected from only IN_x/RTD C and IN_x/ RTD D terminals.

The following occurs:

• Input data for the channel changes to the highest scaled temperature value associated with the selected sensor type.

• The I.Ch[x].Overrange tag is set to 1. x represents the channel number.

If bullet 1, the following occurs:

• Input data for the channel changes to the lowest scaled temperature value associated with the selected sensor type.

• The I.Ch[x].Underrange tag is set to 1. x represents the channel number.

If bullets 2 or 3, the following occurs:

• Input data for the channel changes to the highest scaled temperature value associated with the selected sensor type.

• The

I.Ch[x].Overrange tag is set to 1.

x represents the channel number.

Input Type = Thermocouple Sensor Type = Temperature

Input Type = Thermocouple Sensor Type = mV

• All wires are disconnected from the module.

With the 4-wire RTD device, the wire off condition is detected within five seconds of wires getting disconnected.

A wire is disconnected from the module.

With the Thermocouple input type, the wire off condition is

detected within two seconds of wires getting disconnected.

• Input data for the channel changes to the highest scaled temperature

value associated with the selected sensor type.

• The I.Ch[x].Overrange tag is set to 1. x represents the channel number.

• Input data for the channel changes to the scaled value associated with the overrange signal value.

• The I.Ch[x].Overrange tag is set to 1. x represents the channel number.

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1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

Temperature Units

You can use the following temperature units with your 1756-IRT8I module:

• Celsius

• Kelvin

• Fahrenh eit

• Rankine

Each channel is individually configurable for its temperature units.

To see where to set the Temperature Units, see page 127

Sensor Types

This module supports multiple sensor types with the available selections dictated by the input type configuration.

Table 11 - Available Sensor Types on 1756-IRT8I Module

Input Type Available Sensor Types

RTD 100 Ω PT 385

200 Ω PT 385 500 Ω PT 385 1000 Ω PT 385 100 Ω PT 3916 200 Ω PT 3916 500 Ω PT 3916 1000 Ω PT 3916 10 Ω CU 427 120 Ω NI 672 100 Ω NI 618 120 Ω NI 618 200 Ω NI 618 500 Ω NI 618

Thermocouple B, C, D, E, J, K, N, R, S, T, TXK/XK (L)

To see where to set the Sensor Type, see page 127

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

IMPORTANT

Sensor Type Temperature Limits

Sensor type temperature limits are determined by your choice of Input Type, Sensor Type, and Temperature Units.

For example, you can configure a channel with the following parameters:

• Input Type = RTD (Ohms)

• Sensor Type = 100 Ohm PT 385

• Temperature Units = Celsius

In this case, the Scaling parameters are set as follows:

• Low Signal = -200.0000 °C Low Engineering = -200.0000

When you make the configuration choices listed previously, the Scaling parameters are automatically set on the Configuration tab of the Module

Properties dialog box and cannot be changed in the software.

The Low Signal value equals the Low Engineering value. The High Signal value equals the High Engineering value.

• High Signal = 870.0000 °C High Engineering = 870.0000

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The following table lists temperature range limits on the 1756-IRT8I module.

Table 12 - Temperature Limits for RTD and Thermocouple Sensor Types

Input Type Sensor Type Temperature Range Limits

RTD (Ohms) - 3-wire or 4-wire 100 Ohm PT 385

200 Ohm PT 385 500 Ohm PT 385 1000 Ohm PT 385

100 Ohm PT 3916 20 Ohm PT 3916 500 Ohm PT 3916 1000 Ohm PT 3916

10 Ohm CU 247 -200…260 °C

120 Ohm NI 672 -80…320 °C

100 Ohm NI 618 120 Ohm NI 618 200 Ohm NI 618 500 Ohm NI 618

-200…870 °C

-328…1598 °F 73…1143 °K 132…2058 °R

-200…630 °C

-328…1166 °F 73…903 °K 132…1626 °R

-328…500 °F 73…533 °K 132…960 °R

-112…608 °F 193…593 °K 348…1068 °R

-60…250 °C

-76…482 °F 213…523 °K 384…942 °R

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

Table 12 - Temperature Limits for RTD and Thermocouple Sensor Types

Input Type Sensor Type Temperature Range Limits

Thermoco uple (mV) TC Type B 21…1820 °C

68…3308 °F 293…2093 °K 528…3768 °R

TC Type C 0…2320 °C

32…4208 °F 273…2593 °K 492…4668 °R

TC Type D 0…2320 °C

32…4208 °F 273…2593 °K 492…4668 °R

TC Type E -270…1000 °C

-454…1832 °F 3…1273 °K 6…2292 °R

TC Type J -210…1200 °C

-346…2192 °F 63…1473 °K 114…2652 °R

TC Type K -270…1372 °C

-454…2502 °F 3…1645 °K 6…2961 °R

TC Type N -270…1300 °C

-454…2372 °F 3…1573 °K 6…2832 °R

TC Type R -50…1768 °C

-58…3215 °F 223…2041 °K 402…3674 °R

TC Type S -50…1768 °C

-58…3215 °F 223…2041 °K 402…3674 °R

TC Type T -270…400 °C

-454…752 °F 3…673 °K 6…1212 °R

TC Type TXK/XK (L) -200…800 °C

-328…1472 °F 73…1073 °K 132…1932 °R

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IMPORTANT

Thermocouple Wire Length Compensation

Wires connecting a thermocouple to the 1756-IRT8I module have an intrinsic resistance that can negatively impact the module’s accuracy. The wire length and gauge are directly related to resistance level and, by extension, to impact on the module accuracy. The longer the wire length, the greater the resistance, the greater the possible negative impact on module accuracy.

To avoid increased module error resulting from increased resistance levels, the 1756-IRT8I module can automatically compensate for resistance levels and maintain its accuracy. The module measures the wire resistance and actively compensates for that resistance with each sample.

This functionality works when thermocouple wiring is connected to the module before the module is powered or power is cycled to the module.

Connect wiring to the module before applying or cycling module power.

You can disable compensation by removing the wiring prior to a power cycle and reconnecting the wiring later.

Synchronized Sampling

This feature lets you synchronize input sampling across inputs on multiple modules in the same chassis, forcing those inputs to sample simultaneously within approximately 20 μS of each other.

Synchronized Sampling is not limited to input sample across inputs on the same module types.

You can use Synchronized Sampling across inputs on 1756-IF8I modules and 1756-IRT8I modules in the same system.

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

For example, if you have 12 input devices connected to two 1756-IRT8I modules and one 1756-IF8I module in the same chassis, or different chassis synchronized to the same CIP Sync TimeMaster, use Synchronized Sampling to take a snapshot of the input data available at each input at a single moment in time.

The following conditions must exist to use this feature:

• A 1588 CIP Sync Time Master is configured for the chassis.

• All modules in the set use the same RPI value or values that are multiples

of each other.

• Synchronized Sampling with Other Synchronized Modules is enabled for all input channels in the set.

For these input modules, configuring one channel for Synchronized Sampling synchronizes all eight channels.

While setting the RPI to the same value on all 1756-IRT8I modules guarantees that each module samples at the same rate, it does not guarantee that they sample at the same time.

When enabled, Synchronized Sampling provides each module a synchronized starting point for its respective input scans. Because the RPI values are the same, the inputs on the modules are sampled at the same rate and the same time.

To see where to enable Synchronized Sampling, see page 127

Cold Junction Compensation

When using the 1756-IRT8I module with a thermocouple input type, the channel must account for the thermoelectric effect of a junction of the thermocouple field wires and the screw terminals of an RTB or IFM.

The junction at which temperature is measured is the hot junction. The junction where the thermocouple wire interfaces with copper is the cold junction. The transition from thermocouple wire to copper typically happens either on the module screw terminal itself or at an IFM.

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IMPORTANT

The thermoelectric effect alters the input signal and must be compensated for to measure temperatures accurately. To accurately compensate the input signal from your module, you must use a cold junction compensation (CJC) sensor to account for the increased voltage.

CJC sensors are only required with use of the Thermocouple input type and when channel wiring is connected via an RTB.

If you are using an IFM to connecting wiring to a channel using the Thermocouple input type, you do not need to use CJC sensors.

CJC sensors do not come with the 1756-IRT8I module. You must order CJC sensors, product catalog number 1756-CJC, separately from the 1756-IRT8I module for CJC sensors which attach directly to the module's screw terminals. Catalog number 1756-CJC includes two CJC sensors.

To order CJC sensors, contact your local Allen-Bradley distributor or Rockwell Automation sales representative.

Remember the following when compensating the input signal from your module:

• Cold junction compensation is optional and can be disabled.

• The 1756-IRT8I module uses two channels for cold junction

compensation. When using an RTB, you must connected CJC sensors at RTB terminals 1 and 2 and 35 and 36.

If you use cold junction compensation, you must connect CJC sensors to both channels, that is, terminals 1, 2, 35, and 36.

You cannot use cold junction compensation and connect a CJC sensor to only one channel.

• Differences exist between using an RTB or IFM to connect wiring to the module. They are described in the rest of this section.

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

IMPORTANT

019

1112

4131

6151

8171

0291

2212

4232

6252

8272

0392

2313

6353

White Ends of CJC Sensors

CJC 0

CJC 1

Orange Ends of CJC Sensors

Connecting a CJC via a Removable Terminal Block

When using an RTB, if you choose to connect CJC sensors to your module, you must connect a CJC sensor at the top of the RTB and one at the bottom of the RTB.

Remember the following:

• Connect the white end of the CJC sensor to the even-numbered terminals. For CJ 0, connect the white end to terminal 2. For CJ 1, connect the white end to terminal 36.

• Connect the orange end of the CJC sensor to the odd-numbered terminals. For CJ 0, connect the orange end to terminal 1. For CJ 1, connec t the orange end to terminal 35.

• Two CJC values indicate the temperature of the top and bottom CJC sensor

• CJC sensor temperatures are indicated in degrees Celsius.

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1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

Check Remote

CJ Compensation.

Check Cold

Junction Disable

Connecting a Cold Junction Sensor via an Interface Module

The IFMs use an isothermal bar to maintain a steady temperature at all module terminations. When using the IFM, we recommend that you mount it so that the black anodized aluminum bar is in the horizontal position.

When using an IFM, do not connect a CJC sensor to the module because it is built into the IFM. However, you must enable the Remote CJ Compensation field in the Logix Designer application as shown below.

If you connect a CJS via an IFM, configure the module as shown on the Module Properties Configuration tab.

Cold Junction Disable Option

You can disable cold junction compensation on your 1756-IRT8I module. Check Cold Junction Disable to disable compensation as shown below.

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

IMPORTANT

Type offset value.

Cold Junction Offset Option

The Cold Junction Offset box on the Module Properties Configuration Tab lets you make module-wide adjustments to cold junction compensation values. If you know that your cold junction compensation values are consistently inaccurate by some level, for example, 1.2 °C, type the value into the box to account for this

inaccuracy.

Consider the following before disabling cold junction compensation:

• We recommend that you do not disable the cold junction disable option.

Typically, this option is used only in systems that have no thermoelectric effect, such as test equipment in a controlled lab.

• The Cold Junction Disable box on the Module Properties Configuration tab disables cold junction compensation on all module channels.

Cold Junction temperatures are always reported as Celsius temperature units, and, offset values are always set in Celsius temperature units.

You cannot change the temperature units.

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1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

Isolator

RIUP

Circuit

DC-DC

Conver ter

Vref

DSP

Nonvolatile

Memory

Field Side Backplane Side

Signal Conditioning

and A/D Converter

CJC 0

Isolated Power

1 7 5 6 B A C K P L

A N E

Channels 2…5 (not shown - Same diagrams as channels 1 and 7.)

IN_0/RTD D

IN_0(+)/A

Backplane

ASIC

DC-DC

Shutdown

Circuit

System +5V

ADC CJC

(Channel 0)

IN_0(-)/B

Isolator

DC-DC

Conver ter

Vref

Signal Conditioning

and A/D Converter

Isolated Power

Channel 0

Channel 1

Channel 6

Channel 7

IN_0/RTD C

IN_1/RTD D

IN_1(+)/A IN_1(-)/B

IN_1/RTD C

IN_7/RTD D

IN_7(+)/A IN_7(-)/B

IN_7/RTD C

IN_6/RTD D

IN_6(+)/A IN_6(-)/B

IN_6/RTD C

CJC 1

Isolator

DC-DC

Conver ter

Vref

Signal Conditioning

and A/D Converter

Isolated Power

Isolator

DC-DC

Conver ter

Vref

Signal Conditioning

and A/D Converter

Isolated Power

ADC CJC

(Channel 6)

Status

Indicators

Represents Channel Isolation

Module Block and Circuit Diagrams

The graphics in this section show the 1756-IRT8I module’s block diagrams and field-side circuit diagrams.

Figure 13 - 1756-IRT8I Module Block Diagram

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

0.1 μF

IN_x/RTD D

A/D Converter

IN_x(+)/A

1000 Ω

10 Ω

0.01 μF0.01 μF

1000 Ω

10 Ω

RTD

0.01 μF

IN_x(-)/B

IN_x/RTD C

I exc

600 μA

I exc

600 μA

2.5V Vref

PGA

0.1 μF

IN_x/RTD D

A/D Converter

IN_x(+)/A

1000 Ω

10 Ω

0.01 μF0.01 μF

1000 Ω

10 Ω

RTD

0.01 μF

IN_x(-)/B

IN_x/RTD C

I exc

600 μA

2.5V Vref

PGA

Field-side Circuit Diagrams

The following diagrams show the field-side circuitry for the 1756-IRT8I module.

Figure 14 - 1756-IRT8I Module Field-side with 3-wire RTD Input

Figure 15 - 1756-IRT8I Module Field-side with 4-wire RTD Input

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0.1 μF

IN_x/RTD D

A/D Converter

IN_x(+)/A

1000 Ω

10 Ω

0.01 μF0.01 μF

1000 Ω

10 Ω

0.01 μF

IN_x(-)/B

IN_x/RTD C

2.5V Vref

PGA

019

1112

4131

6151

8171

0291

2212

4232

6252

8272

0392

2313

6353

CJC 0

IN_0(-)/B

IN_0/RTD C IN_1(-)/B

IN_1/RTD C

IN_2(-)/B

IN_2/RTD C

IN_3(-)/B

MPORTANT: Remember the following:

• If separate power sources are used, do

not exceed the specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Specifications Technical Data, publication

1756-TD002

• Terminals 1, 2, 35, and 36 are not used in RTD applications.

• For 2-wire resistor appl ications including calibration, make sure IN_x(-)/B and IN_x/RTD C are shorted together.

IN_3/RTD C

IN_4(-)/B

IN_4/RTD C

IN_5(-)/B

IN_5/RTD C

IN_6(-)/B

IN_6/RTD C

IN_7(-)/B

IN_7/RTD C

CJC 1

CJC 0

IN_0(+)/A

IN_0/RTD D IN_1(+)/A

IN_1/RTD D

IN_2(+)/A

IN_2/RTD D

IN_3(+)/A

IN_3/RTD D

IN_4(+)/A

IN_4/RTD D

IN_5(+)/A

IN_5/RTD D

IN_6(+)/A

IN_6/RTD D

IN_7(+)/A

IN_7/RTD D

CJC1

Shield Ground

3-wire RTD

Figure 16 - 1756-IRT8I Module Field-side Circuit with Thermocouple Input

Wire the 1756-IRT8I Module

The following graphics show wiring examples for the 1756-IRT8I module used with RTD and thermocouple input types.

Figure 17 - 1756-IRT8I Module Wiring Diagram - 3-wire RTD Input

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

CJC 0

IN_0(-)/B

IN_0/RTD C

IN_1(-)/B

IN_1/RTD C

IN_2(-)/B

IN_2/RTD C

IN_3(-)/B

IMPORTANT: Remember the following:

• If separate power sources are used, do not exceed the specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Specifications Technical Data, publication

1756-TD002

• Terminals 1, 2, 35, and 36 are not used in RTD applications.

IN_3/RTD C

IN_4(-)/B

IN_4/RTD C IN_5(-)/B

IN_5/RTD C

IN_6(-)/B

IN_6/RTD C

IN_7(-)/B

IN_7/RTD C

CJC 1

CJC 0

IN_0(+)/A

IN_0/RTD D IN_1(+)/A

IN_1/RTD D

IN_2(+)/A

IN_2/RTD D

IN_3(+)/A

IN_3/RTD D

IN_4(+)/A

IN_4/RTD D

IN_5(+)/A

IN_5/RTD D

IN_6(+)/A

IN_6/RTD D

IN_7(+)/A

IN_7/RTD D

CJC1

Shield Ground

4-wire RTD

Figure 18 - 1756-IRT8I Module Wiring Diagram - 4-wire RTD Input

019

4131

6151

8171

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2212

4232

6252

8272

0392

2313

6353

1112

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1756-IRT8I Combined Temperature-sensing Isolated Analog Module Chapter 4

019

1112

4131

6151

8171

0291

2212

4232

6252

8272

0392

2313

6353

CJC 0

IN_0(-)/B

IN_0/RTD C IN_1(-)/B

IN_1/RTD C

IN_2(-)/B

IN_2/RTD C

IN_3(-)/B

IN_3/RTD C

IN_4(-)/B

IN_4/RTD C

IN_5(-)/B

IN_5/RTD C

IN_6(-)/B

IN_6/RTD C

IN_7(-)/B

IN_7/RTD C

CJC 1

CJC 0

IN_0(+)/A

IN_0/RTD D IN_1(+)/A

IN_1/RTD D

IN_2(+)/A

IN_2/RTD D

IN_3(+)/A

IN_3/RTD D

IN_4(+)/A

IN_4/RTD D

IN_5(+)/A

IN_5/RTD D

IN_6(+)/A

IN_6/RTD D

IN_7(+)/A

IN_7/RTD D

CJC

Cold Junction Sensor

–

mV Source

IMPORTANT: Remember the following:

• Connect the white end of the CJC sensor to the even-

numbered terminal., and connect the orange end of the CJC sensor to the odd-numbered terminals. For CJC 0:

– White end - Connected to terminal number 2

– Orange end - Connected to terminal number 1

For CJC 1:

– White end - Connected to terminal number 36

– Orange end - Connected to terminal number 35

• If separate power sources are used, do not exceed the

specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Specifications Technical Data, publication 1756-TD002

Figure 19 - 1756-IRT8I Module Wiring Diagram - Thermocouple Input

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Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module

Fault and Status Reporting

The 1756-IRT8I module multicasts fault and status data with channel data to the owner and listening controllers. The data is returned via module tags that you can monitor in your Logix Designer application.

With some exceptions, as noted in the following table, the 1756-IRT8I module provides the fault and data status in a channel-centric format.

The following table lists the 1756-IRT8I module’s fault and status tags available in the Logix Designer application.

Table 13 - 1756-IRT8I Module - Fault and Status Data Tags

Data Type Tag Name Triggering Event That Sets Tag

(1)

Fau lt

Status

Fau lt

CJ[x].Underrange The cold junction for the channel is below 0 °C

CJ[x].Overrange The cold junction for the channel is above 86 °C

Ch[x].Fault The channel data quality is bad.

Ch[x].Underrange The channel data is beneath the absolute minimum for this channel.

Ch[x].Overrange The channel data is above the absolute maximum for this channel.

CIPSyncValid

CIPSyncTimeout

CIPSyncOffsetJump

Ch[x].Uncertain The channel data can be imperfect.

Ch[x].LLAlarm The I.Ch[x].Data tag value is less than the C.Ch[x].LLAlarmLimit tag value, the O.Ch[x].LLAlarmEn tag is set and alarms

Ch[x].LAlarm The I.Ch[x].Data tag value is less than the C.Ch[x].LAlarmLimit tag value, the O.Ch[x].LAlarmEn tag is set and alarms

Ch[x].HAlarm The I.Ch[x].Da ta tag value is greater than the C.Ch[x].HAlarmLimit tag value, the O.Ch[x].HAlarmEn tag is set and

Ch[x].HHAlarm The I.Ch[x].Data tag value is greater than the C.Ch[x].HHAlarmLimit tag value, the O.Ch[x].HHAlarmEn tag is set and

Ch[x].RateAlarm The absolute change between consecutive channel samples exceeds the C.Ch[x].RateAlarmLimit tag value.

Ch[x].CalibrationFault The last attempted Calibration for this channel failed.

Ch[x].Calibrating The channel is currently being calibrated.

Ch[x].CalGoodLowRef A valid Low Reference signal has been sampled on this channel.

Ch[x].CalBadLowRef An invalid Low Reference signal has been sampled on this channel.

Ch[x].CalGoodHighRef An valid High Reference signal has been sampled on this channel.

Ch[x].CalBadHighRef An invalid High Reference signal has been sampled on this channel.

Ch[x].CalSuccessful Calibration on this channel is complete and the Calibrating state has been exited.

Ch[x].RateOfChange The change in channel data since last sample in Engineering Units/Second.

Ch[x].Data The channel data in scaled Engineering Units.

Timestamp

RollingTimestamp

(1)

The owner-controller loses its connection to the module.

Indicates whether the module has synchronized to a valid CIP Sync time master on the backplane.

Indicates whether a valid time master on the backplane has timed out.

When a significant jump occurs, this tag value becomes 1 but changes to 0 a second later unless another jump occurred.

are enabled for the channel.

alarms are enabled for the channel.

This alarm only applies to enabled Process alarms.

A 64-bit Timestamp indicating when all 8 channels were last sampled in terms of CIPSync time.

16 bit timestamp that ‘rolls’ from 0…32,767 ms. Compatible with existing PID instruction to automatically calculate sample deltas.

(1) This tag provides module-wide data and affects all channels simultaneously.

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Chapter 5

IMPORTANT

1756-OF8I Isolated Analog Output Module

Top ic Pag e

1756-OF8I Module Features 98

Module Block and Output Circuit Diagrams 98

Drive Different Loads with the 1756-OF8I Module 100

Wire the 1756-OF8I Module 100

Fault and Status Reporting 102

The 1756-OF8I module has eight isolated channels. Each channel supports the following output types:

1756-OF8I Module Features

• Current

• Vo l t a g e

The module provides 16-bit resolution. Additional features are described in this chapter.

The 1756-OF8I module has the following features:

• Multiple Output Ranges

• Channel Offset

• Ramping/Rate Limiting

• Hold for Initialization

• Clamping/Limiting

• Clamp/Limit Alarms

• Data Echo

Most of the features available on the 1756-OF8I module are software configurable. For more information on how to configure the module, see

Chapter 7

, Configure ControlLogix Isolated Analog I/O Modules on page 121.

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Chapter 5 1756-OF8I Isolated Analog Output Module

Multiple Output Ranges

The 1756-OF8I module offers multiple output ranges that are dictated by channel configuration choices. The output type selection determines the available ranges.

Table 14 - Channel Output Ranges

Output Type Output Range

Current (mA) 0…20 m A

Voltage (V) Any of the following:

• -10…10V

• 0…5V

• 0…10V

To see where to select the output range, see page 127

Channel Offset

With this feature, you can compensate for any known error on the sensor or channel to which the sensor is connected. This value is in signal units and is added to the output data.

You can set the channel offset in either of the following ways:

• On the Configuration tab of the Module Properties dialog box.

• Directly in the channel’s C.Ch[x].Offset tag.

For example, if the channel has an error such that it reads 8 mA as 7.8 mA, you account for the error by setting the Channel Offset field on the Configuration tab to 0.2000 or by setting the C.Ch[x].Offset tag to 0.2.

To see where to set the Channel Offset, see page 127

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1756-OF8I Isolated Analog Output Module Chapter 5

Ramping/Rate Limiting

Ramping limits the speed at which an analog output signal can change. This prevents fast transitions in the output from damaging the devices that an output module controls. Ramping is also known as rate limiting.

The table describes the types of ramping that are possible.

Ramping type Description

Run mode ramping When the module is in Run mode, ramping occurs to all new output values at

Ramp to Program mode When the present output value changes to the Program value after a Program

Ramp to Fault mode When the present output value changes to the Fault value after a

The maximum rate of change in outputs is expressed in engineering units per second (Engineering Units/second) and called the maximum ramp rate.

the MaxRampRate.

command is received from the controller.

communication fault occurs.

To see where to set Ramping, see page 133

Hold for Initialization

Hold for Initialization causes outputs to hold present state until the value commanded by the controller matches the value at the output screw terminal within 0.1% of full scale, providing a bumpless transfer.

If Hold for Initialization is selected, outputs hold if there is an occurrence of any of these three conditions:

• Initial connection is established after power up.

• A new connection is established after a communication fault occurs.

• There is a transition to Run mode from Program state.

The I.Ch[x].InHold tag for a channel indicates that the channel is holding.

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Chapter 5 1756-OF8I Isolated Analog Output Module

IMPORTANT

Clamping/Limiting

Clamping limits the output from the analog module to remain within a range configured by the controller, even when the controller commands an output outside that range. This safety feature sets a high clamp and a low clamp.

Once clamps are determined for a module and enabled, any data received from the controller that exceeds those clamps sets an appropriate limit alarm and transitions the output to that limit but not beyond the requested value.

For example, an application can set the high clamp on a module for 8V and the low clamp for -8V. If a controller sends a value corresponding to 9V to the module, the module applies only 8V to its screw terminals.

You can disable or latch clamping alarms on a per channel basis. The alarms are disabled by default.

Clamp values are in engineering units and are not automatically updated when the scaling high and low engineering units are changed.

Failure to update the clamp values can generate a very small output signal that could be misinterpreted as a hardware problem.

For example, a 1756-OF8I module channel that uses a Current (mA) output type with Clamping enabled has the following configuration parameters:

• Scaling values: – High Engineering = 100.0000%

– Low Engineering = 0.0000%

• Clamp Limits: – High Clamp = 100.0000%

– Low Clamp = 0.0000%

If you change the Scaling High Engineering value to 90.0000%, the High Clamp value remains at 100.0000.

You must change the High Clamp value to 90.0000 to make sure the application continues to operate as expected.

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1756-OF8I Isolated Analog Output Module Chapter 5

Clamp/Limit Alarms

This function works directly with clamping. When a module receives a data value from the controller that exceeds clamping limits, it applies signal values to the clamping limit but also sends a status bit to the controller notifying it that the value sent exceeds the clamping limits.

With the previous example, if a module has clamping limits of 8V and -8V but then receives data to apply 9V, only 8V is applied to the screw terminals and the module sends a status bit back to the controller informing it that the 9V value exceeds the module’s clamping limits.

To see where to set clamp and limit alarms, see page 133

Data Echo

Data Echo automatically multicasts channel data values that match the analog value that was sent to the module’s screw terminals at that time.

The 1756-OF8I module returns a status word that represents the value sent to it by the controller. The echoed value is indicated in input tag I.Ch[x].Data and is represented in Engineering Units.

Fault and status data are also sent. This data is sent at the RPI.

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Chapter 5 1756-OF8I Isolated Analog Output Module

RIUP

Circuit

DSP

Field Side Backplane Side

1 7 5 6 B A C K P L A N E

Channels 1…6 (not shown)

Backplane

ASIC

DC-DC

Shutdown

Circuit

System +5V

Isolator

DC-DC

Conver ter

Vref

D/A Converter and

Output Stage

Channel 0

Channel 7

OUT_0/V

OUT_0/I

RTN_0

Isolator

DC-DC

Conver ter

Vref

D/A Converter and

Output Stage

Isolated Power

Nonvolatile

Memory

Status

Indicators

OUT_7/V

OUT_7/I

RTN_7

Isolated Power

Represents Channel Isolation

Module Block and Output Circuit Diagrams

The graphics in this section show the 1756-OF8I module’s block diagrams and input circuit diagrams.

Figure 20 - 1756-OF8I Module Block Diagram

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1756-OF8I Isolated Analog Output Module Chapter 5

RTN-x

OUT_x/V

D/A Converter

OUT_x/I

0.047 μF0.0022 μF

46 Ω

Current

Amplifier

Iout

-13V

Curren t

Output Device

0…1000 Ω

5V Vref

Power

Supply

RTN-x

+13V

OUT_x/V

D/A Converter

Gnd_x

5V Vref

OUT_x/I

4640 Ω

0.047 μF0.0022 μF

21 Ω

Vol tag e

Amplifier

Vou t

Vsens e

-13V

Vol tag e

Output Device

>1000 Ω

Field-side Circuit Diagrams

The following diagrams show the field-side circuitry for the 1756-OF8I module.

Figure 21 - 1756-OF8I Module Field-side Circuit with Current Output

Figure 22 - 1756-OF8I Module Field-side Circuit with Voltage Output

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Chapter 5 1756-OF8I Isolated Analog Output Module

OUT_0/V

OUT_0/I

RTN_0

Not used

OUT_2/V

OUT_2/I

RTN_2

Not used

< 1000  User Analog Output

Device

OUT_4/V

OUT_4/I

RTN_4

Not used

OUT_6/V

OUT_6/I

RTN_6

Not used

OUT_1/V

OUT_1/I

RTN_1

Not used

OUT_3/V

OUT_3/I

RTN_3

Not used

OUT_5/V

OUT_5/I

RTN_5

Not used

OUT_7/V

OUT_7/I

RTN_7

Not used

IMPORTANT: Remember the following:

• If separate power sources are used, do

not exceed the specific isolation voltage. For more information on module specifications, see the 1756 ControlLogix I/O Specifications Technical Data, publication

1756-TD002

• Place additional devices anywhere in the loop.

Drive Different Loads with the 1756-OF8I Module

Wire the 1756-OF8I Module

When the 1756-OF8I module operates with a Current output load, each channel automatically adjusts its output power for 0…1000 ohm loads. The module’s 24V backplane current requirements vary based on load.

For more information the module’s 24V current requirements, see the 1756 ControlLogix I/O Specifications Technical Data, publication 1756-TD002

The following graphic show wiring examples for the 1756-OF8I module with current and voltage output types.

Figure 23 - 1756-OF8I Module Wiring Diagram - Current Output Type

019

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4131

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0291

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Rockwell Automation 1756-OF8I User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

Preface

Studio 5000 Environment

Additional Resources

Before You Begin

Ownership

Configure a Module

Direct Connections

Input Module Operation

Requested Packet Interval (RPI)

Input Modules in a Local Chassis

Input Modules in a Remote Chassis

Triggering Event Tasks

Output Module Operation

Output Modules in a Local Chassis

Output Modules in a Remote Chassis

Listen-only Mode

Common Analog I/O Features

CIP Sync Timestamp of Data

Rolling Timestamp of Data

Floating Point Data Format

Module Resolution

Module Quality Reporting

Calibration

Fault and Status Reporting

Configurable Software

Latching of Alarms

Module Inhibiting

Electronic Keying

Exact Match

Compatible Keying

Disabled Keying

Relationship between Module Resolution and Scaling

Module Resolution

Scaling

Calibration

Calibrated Accuracy

Calibrated Accuracy at 25 °C (77 °F)

Module Error over Full Temperature Range

Error Calculated over Hardware Range

RTD and Thermocouple Error Calculations

RTD Error

Thermocouple Error

Thermocouple Resolution

1756-IF8I Module Features

Internal Loop Power Source

Multiple Input Ranges

Notch Filter

Underrange/Overrange Detection

Digital Filter

Process Alarms

Rate Alarm

Sensor Offset

Wire Off Detection

Synchronized Sampling

Module Block and Circuit Diagrams

Field-side Circuit Diagrams

Wire the 1756-IF8I Module

Fault and Status Reporting

1756-IRT8I Module Features

Multiple Input Ranges

Notch Filter

Underrange/Overrange Detection

Digital Filter

Process Alarms

Rate Alarm

Sensor Offset

10 Ohm Copper Offset

Wire Off Detection

Temperature Units

Sensor Types

Thermocouple Wire Length Compensation

Synchronized Sampling

Cold Junction Compensation

Module Block and Circuit Diagrams

Field-side Circuit Diagrams