Allen-Bradley MicroLogix 1200 User manual

MicroLogix™ 1200
RTD/Resistance
Input Module
(Catalog Number 1762-IR4)
User Manual

Important User Information
Because of the variety of uses for the products described in this
publication, those responsible for the application and use of these
products must satisfy themselves that all necessary steps have been
taken to assure that each application and use meets all performance
and safety requirements, including any applicable laws, regulations,
codes and standards. In no event will Rockwell Automation be
responsible or liable for indirect or consequential damage resulting
from the use or application of these products.
Any illustrations, charts, sample programs, and layout examples
shown in this publication are intended solely for purposes of
example. Since there are many variables and requirements associated
with any particular installation, Rockwell Automation does not assume
responsibility or liability (to include intellectual property liability) for
actual use based upon the examples shown in this publication.
Allen-Bradley publication SGI-1.1, Safety Guidelines for the
Application, Installation and Maintenance of Solid-State Control
(available from your local Rockwell Automation office), describes
some important differences between solid-state equipment and
electromechanical devices that should be taken into consideration
when applying products such as those described in this publication.
Reproduction of the contents of this copyrighted publication, in whole
or part, without written permission of Rockwell Automation, is
prohibited.
Throughout this publication, notes may be used to make you aware of
safety considerations. The following annotations and their
accompanying statements help you to identify a potential hazard,
avoid a potential hazard, and recognize the consequences of a
potential hazard:
Allen-Bradley, MicroLogix, RSLogix, and RSLinx are trademarks of Rockwell Automation.
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.
IMPORTANT Identifies information that is critical for successful
application and understanding of the product.

1Publication 1762-UM003A-EN-P - February 2003
Table of Contents
Preface
Who Should Use This Manual . . . . . . . . . . . . . . . . . . . . . . P-1
How to Use This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . P-1
Manual Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P-1
Related Documentation . . . . . . . . . . . . . . . . . . . . . . . . P-2
Conventions Used in This Manual . . . . . . . . . . . . . . . . . . . P-2
Rockwell Automation Support . . . . . . . . . . . . . . . . . . . . . . P-3
Your Questions or Comments on the Manual . . . . . . . . P-3
Chapter 1
Overview
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
RTD Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Resistance Device Compatibility . . . . . . . . . . . . . . . . . . 1-5
Hardware Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
General Diagnostic Features . . . . . . . . . . . . . . . . . . . . . 1-6
System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
System Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Module Field Calibration . . . . . . . . . . . . . . . . . . . . . . . 1-8
Chapter 2
Installation and Wiring
Compliance to European Union Directives . . . . . . . . . . . . . 2-1
EMC Directive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Low Voltage Directive . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Hazardous Location Considerations . . . . . . . . . . . . . . . 2-3
Prevent Electrostatic Discharge . . . . . . . . . . . . . . . . . . . 2-3
Remove Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Selecting a Location . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Minimum Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
DIN Rail Mounting. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Panel Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
System Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Field Wiring Connections . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
System Wiring Guidelines. . . . . . . . . . . . . . . . . . . . . . . 2-8
RTD Wiring Considerations . . . . . . . . . . . . . . . . . . . . . 2-9
Wiring the Finger-Safe Terminal Block . . . . . . . . . . . . . 2-10
Wire Size and Terminal Screw Torque . . . . . . . . . . . . . 2-11
Wiring Input Devices to the Module . . . . . . . . . . . . . . . 2-11
Wiring RTDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Wiring Resistance Devices (Potentiometers) . . . . . . . . . 2-14

Publication 1762-UM003A-EN-P - February 2003
2Table of Contents
Chapter 3
Module Data, Status, and Channel
Configuration
Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Input Image. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Configuration File . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Accessing Input Image File Data . . . . . . . . . . . . . . . . . . . . 3-2
Input Data File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Input Data Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
General Status Flag Bits (S0 to S3) . . . . . . . . . . . . . . . . 3-3
Open-Circuit Flag Bits (OC0 to OC3) . . . . . . . . . . . . . . 3-4
Over-Range Flag Bits (O0 to O3) . . . . . . . . . . . . . . . . . 3-5
Under-Range Flag Bits (U0 to U3). . . . . . . . . . . . . . . . . 3-5
Configuring Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
Configuration Data File . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Enabling or Disabling a Channel (Bit 15) . . . . . . . . . . . 3-9
Selecting Data Format (Bits 12 to 14) . . . . . . . . . . . . . . 3-9
Selecting Input/Sensor Type (Bits 8 to 11) . . . . . . . . . . 3-14
Selecting Temperature Units/Mode (Bit 7). . . . . . . . . . . 3-15
Selecting Open-Circuit Response (Bits 5 and 6) . . . . . . . 3-15
Selecting Cyclic Lead Compensation (Bit 4). . . . . . . . . . 3-16
Selecting Excitation Current (Bit 3) . . . . . . . . . . . . . . . . 3-16
Setting Filter Frequency (Bits 0 to 2) . . . . . . . . . . . . . . . 3-16
Selecting Enable/Disable Cyclic Autocalibration
(Word 4, Bit 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20
Determining Effective Resolution and Range . . . . . . . . . . . 3-20
Determining Module Update Time. . . . . . . . . . . . . . . . . . . 3-27
Effects of Autocalibration on Module Update Time . . . . 3-28
Calculating Module Update Time with Autocalibration
Enabled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29
Effects of Cyclic Lead Wire Compensation on
Module Update Time . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30
Calculating Module Update Time with Cyclic Lead Wire
Compensation Enabled . . . . . . . . . . . . . . . . . . . . . . . . 3-31
Impact of Autocalibration and Lead Wire Compensation
on Module Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-32
Effects of Autocalibration on Accuracy . . . . . . . . . . . . . . . . 3-33
Chapter 4
Diagnostics and Troubleshooting
Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Indicator Lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Activating Devices When Troubleshooting . . . . . . . . . . 4-2
Stand Clear of the Equipment. . . . . . . . . . . . . . . . . . . . 4-2
Program Alteration. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Safety Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Module Operation vs. Channel Operation . . . . . . . . . . . . . 4-2

Publication 1762-UM003A-EN-P - February 2003
Table of Contents 3
Power-up Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Channel Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Invalid Channel Configuration Detection. . . . . . . . . . . . 4-3
Out-of-Range Detection . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Open-Wire or Short-Circuit Detection . . . . . . . . . . . . . . 4-4
Non-critical vs. Critical Module Errors . . . . . . . . . . . . . . . . 4-4
Module Error Definition Table . . . . . . . . . . . . . . . . . . . . . . 4-5
Module Error Field. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Extended Error Information Field . . . . . . . . . . . . . . . . . 4-6
Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Module Inhibit Function . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Contacting Rockwell Automation . . . . . . . . . . . . . . . . . . . . 4-8
Appendix A
Specifications
General Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Input Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
Cable Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4
RTD Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4
Appendix B
Configuring the 1762-IR4 Module
Using RSLogix 500
Module Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
1762-IR4 Configuration File . . . . . . . . . . . . . . . . . . . . . . . . B-1
Configuration Using RSLogix 500 Version 5.50 or Higher . . B-2
Configuration Using RSLogix 500 Version 5.2 or Lower. . . . B-6
Appendix C
Two’s Complement Binary
Numbers
Positive Decimal Values . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
Negative Decimal Values. . . . . . . . . . . . . . . . . . . . . . . . . . C-2
Glossary
Index

Publication 1762-UM003A-EN-P - February 2003
4Table of Contents

1Publication 1762-UM003A-EN-P - February 2003
Preface
Read this preface to familiarize yourself with the rest of the manual.
This preface covers the following topics:
•who should use this manual
•how to use this manual
•related publications
•conventions used in this manual
•Rockwell Automation support
Who Should Use This
Manual
Use this manual if you are responsible for designing, installing,
programming, or troubleshooting control systems that use
MicroLogix 1200 controllers and 1762 Expansion I/O.
How to Use This Manual
As much as possible, we organized this manual to explain, in a
task-by-task manner, how to install, configure, program, operate and
troubleshoot a control system using the 1762-IR4.
Manual Contents
If you want... See
An overview of the RTD/resistance input module Chapter 1
Installation and wiring guidelines Chapter 2
Module addressing, configuration and status information Chapter 3
Information on module diagnostics and troubleshooting Chapter 4
Specifications for the module Appendix A
Information on programming the module using MicroLogix 1200 and
RSLogix 500 Appendix B
Information on understanding two’s complement binary numbers Appendix C
Definitions of terms used in this manual Glossary

Publication 1762-UM003A-EN-P - February 2003
2 Preface
Related Documentation
The table below provides a listing of publications that contain
important information about MicroLogix 1200 systems.
If you would like a manual, you can:
•download a free electronic version from the internet at
www.theautomationbookstore.com
•purchase a printed manual by:
–contacting your local distributor or Rockwell Automation
representative
–visiting www.theautomationbookstore.com and placing your
order
–calling 1.800.963.9548 (USA/Canada) or 001.330.725.1574
(Outside USA/Canada)
Conventions Used in This
Manual
The following conventions are used throughout this manual:
•Bulleted lists (like this one) provide information not procedural
steps.
•Numbered lists provide sequential steps or hierarchical
information.
•Italic type is used for emphasis.
For Read this document Document number
A user manual containing information on how to install,
use and program your MicroLogix 1200 controller MicroLogix™ 1200 User Manual 1762-UM001
An overview of the MicroLogix 1200 System, including
1762 Expansion I/O. MicroLogix™ 1200 Technical Data 1762-TD001
In-depth information on programming and using
MicroLogix 1200 controllers. MicroLogix 1200 Instruction Set Reference Manual 1762-RM001
In-depth information on grounding and wiring
Allen-Bradley programmable controllers. Allen-Bradley Programmable Controller Grounding and Wiring Guidelines 1770-4.1

Publication 1762-UM003A-EN-P - February 2003
Preface 3
Rockwell Automation
Support
Rockwell Automation tests all of our products to ensure that they are
fully operational when shipped from the manufacturing facility.
If you are experiencing installation or startup problems, please review
the troubleshooting information contained in this publication first. If
you need technical assistance to get your module up and running,
please contact Customer Support (see the table below); our trained
technical specialists are available to help.
If the product is not functioning and needs to be returned, contact
your distributor. You must provide a Customer Support case number
to your distributor in order to complete the return process.
Your Questions or Comments on the Manual
If you find a problem with this manual, please notify us. If you have
any suggestions for how this manual could be made more useful to
you, please contact us at the address below:
Rockwell Automation
Automation Control and Information Group
Technical Communication, Dept. A602V
P.O. Box 2086
Milwaukee, WI 53201-2086
Phone United
States/Canada 1.440.646.5800
Outside United
States/Canada You can access the phone number for your country via the Internet:
1. Go to http://support.rockwellautomation.com/
2. Under Contacting Customer Support and Other
Countries, click on Click here
Internet Worldwide Go to http://support.rockwellautomation.com/

Publication 1762-UM003A-EN-P - February 2003
4 Preface

1Publication 1762-UM003A-EN-P - February 2003
Chapter 1
Overview
This chapter describes the four-channel 1762-IR4 RTD/resistance Input
module and explains how the controller reads resistance temperature
detector (RTD) or direct resistance-initiated analog input data from the
module. Included is:
•a general description of hardware features
•an overview of module and system operation
•compatibility
General Description
The 1762-IR4 module supports RTD and direct resistance signal
measurement applications that require up to four channels. The
module digitally converts analog data and then stores the converted
data in its image table.
The module supports connections from any combination of up to four
input devices. Each channel is individually configurable via software
for 2- or 3-wire RTD or direct resistance input devices. Channels are
compatible with 4-wire sensors, but the fourth sense wire is not used.
Two programmable excitation current values (0.5mA and 1.0mA) are
provided, to limit RTD self-heating. When configured for RTD inputs,
the module can convert the RTD readings into linearized digital
temperature readings in °C or °F. When configured for resistance
analog inputs, the module can convert voltages into linearized
resistance values in ohms. The module assumes that the direct
resistance input signal is linear prior to input to the module.
Each channel provides open-circuit (all wires), short-circuit (excitation
and return wires only), and over- and under-range detection and
indication.
IMPORTANT The module accepts input from RTDs with up to 3
wires. If your application requires a 4-wire RTD, one
of the two lead compensation wires is not used, and
the RTD is treated like a 3-wire sensor. The third wire
provides lead wire compensation. See Chapter 2,
Installation and Wiring, for more information.

Publication 1762-UM003A-EN-P - February 2003
1-2 Overview
The following data formats are supported by the module.:
•raw/proportional
•engineering units x 1
•engineering units x 10
•scaled-for-PID
•percent full scale
Available filter frequencies are:
•10 Hz
•50 Hz
•60 Hz
•250 Hz
•500 Hz
•1 kHz
The module uses six input words for data and status bits and five
configuration words. Module configuration is stored in the controller
memory. Normally configuration is done via the controller’s
programming software. In addition, some controllers support
configuration via the user program. Refer to your controller manual
for additional information. See Chapter 3, Module Data, Status, and
Channel Configuration, for details on module configuration.
RTD Compatibility
An RTD consists of a temperature-sensing element connected by two,
three, or four wires that provide input to the module. The following
table lists the RTD types that you can use with the module, including
their temperature range, effective resolution, and repeatability for both
excitation currents, 0.5 and 1.0 mA.

Publication 1762-UM003A-EN-P - February 2003
Overview 1-3
Table 1.1 RTD Specifications
RTD Type(1) Temperature Range Using
0.5 mA Excitation Temperature Range Using 1.0 mA Excitation Maximum Scaled
Resolution
Maximum
Scaled
Repeatability
Copper 426 10ΩNot allowed -100 to 260°C (-148 to 500°F) 0.1°C (0.1°F) ±0.2°C (±0.4°F)
Nickel 618(2) 120Ω-100 to 260°C (-148 to 500°F) -100 to 260°C (-148 to 500°F) 0.1°C (0.1°F) ±0.1°C (±0.2°F)
Nickel 672 120Ω-80 to 260°C (-112 to 500°F) -80 to 260°C (-112 to 500°F) 0.1°C (0.1°F) ±0.1°C (±0.2°F)
Nickel-Iron
518 604Ω-100 to 200°C (-148 to 392°F) -100 to +200°C (-148 to 392°F) 0.1°C (0.1°F) ±0.1°C (±0.2°F)
Platinum 385 100Ω-200 to 850°C (-328 to 1562°F) -200 to 850°C (-328 to 1562°F) 0.1°C (0.1°F) ±0.2°C (±0.4°F)
200Ω-200 to 850°C (-328 to 1562°F) -200 to 850°C (-328 to 1562°F) 0.1°C (0.1°F) ±0.2°C (±0.4°F)
500Ω-200 to 850°C (-328 to 1562°F) -200 to 850°C (-328 to 1562°F) 0.1 °C (0.1 °F) ±0.2°C (±0.4°F)
1000Ω-200 to 850°C (-328 to 1562°F) Not Allowed 0.1°C (0.1°F) ±0.2°C (±0.4°F)
Platinum 3916 100Ω-200C to 630°C (-328 to
1166°F) -200 to 630°C (-328 to 1166°F) 0.1°C (0.1°F) ±0.2°C (±0.4°F)
200Ω-200 to 630°C (-328 to 1166°F) -200 to 630°C (-328 to 1166°F) 0.1°C (0.1°F) ±0.2°C (±0.4°F)
500Ω-200 to 630°C (-328 to 1166°F) -200 to 630°C (-328 to 1166°F) 0.1°C (0.1°F) ±0.2°C (±0.4°F)
1000Ω-200 to 630°C (-328 to 1166°F) Not Allowed 0.1°C (0.1°F) ±0.2°C (±0.4°F)
(1) Digits following the RTD type represent the temperature coefficient of resistance (α) , which is defined as the resistance change per ohm per °C. For instance,
platinum 385 refers to a platinum RTD with α = 0.00385 ohm/ohm -°C, or simply 0.00385/°C.
(2) Actual value at 0°C is 100 Ωper DIN standard.

Publication 1762-UM003A-EN-P - February 2003
1-4 Overview
The tables below provide specifications for RTD accuracy and
temperature drift.
Table 1.2 RTD Accuracy and Temperature Drift
RTD Type Maximum Scaled Accuracy
(25°C with Calibration) Maximum Scaled Accuracy (0 to 55°C with Calibration) Maximum Temperature Drift (from 25°C without
Calibration)
Copper 426 10Ω±0.6°C (1.08°F) ±1.1°C (1.98°F) ±0.032°C/°C (0.032°F/°F)
Nickel 618 120Ω±0.2°C (±0.36°F) ±0.4°C (±0.72°F) ±0.012°C/°C (±0.012°F/°F)
Nickel 672 120Ω±0.2°C (±0.36°F) ±0.4°C (±0.72°F) ±0.012°C/°C (±0.012°F/°F)
Nickel-Iron 518 604Ω±0.3°C (±0.54°F) ±0.5°C (±0.9°F) ±0.015°C/°C (±0.015°F/°F)
Platinum 385 100Ω±0.5°C (±0.9°F) ±0.9°C (±1.62°F) ±0.026°C/°C (±0.026°F/°F)
200Ω±0.5°C (±0.9°F) ±0.9°C (±1.62°F) ±0.026°C/°C (±0.026°F/°F)
500Ω±0.5°C (±0.9°F) ±0.9°C (±1.62°F) ±0.026°C/°C (±0.026°F/°F)
1000Ω±0.5°C (±0.9°F) ±0.9°C (±1.62°F) ±0.026°C/°C (±0.026°F/°F)
Platinum 3916 100Ω±0.4°C (±0.72°F) ±0.8°C (±1.44°F) ±0.023°C/°C (±0.023°F/°F)
200Ω±0.4°C (±0.72°F) ±0.8°C (±1.44°F) ±0.023°C/°C (±0.023°F/°F)
500Ω±0.4°C (±0.72°F) ±0.8°C (±1.44°F) ±0.023°C/°C (±0.023°F/°F)
1000Ω±0.4°C (±0.72°F) ±0.8°C (±1.44°F) ±0.023°C/°C (±0.023°F/°F)
IMPORTANT Using Table 1.2 to Calculate Module Accuracy:
For example, when you are using any platinum (385)
RTDs with 0.5 mA excitation current, the module’s
accuracy is:
•±0.5°C (0.9°F) after you apply power to the
module or perform an autocalibration at 25°C
(77°F) ambient, with module operating
temperature at 25°C (77°F).
•±[0.5°C (0.9°F) ± DT x 0.026 deg./°C
(0.026 deg./°F)] after you apply power to the
module or perform an autocalibration at 25°C
(77°F) ambient, with module operating
temperature between 0 (32°F) and 55°C (131°F).
DT is the temperature difference between the
actual module operating temperature and 25°C
(77°F). The value 0.026 deg./°C (0.026 deg./°F) is
the temperature drift shown in the table above.
•±0.9°C after you apply power to the module or
perform an autocalibration at 55°C (131°F)
ambient, with module operating temperature at
55°C (131°F).

Publication 1762-UM003A-EN-P - February 2003
Overview 1-5
Resistance Device Compatibility
The following table lists the specifications for the resistance devices
that you can use with the module.
Table 1.3 Resistance Device Specifications
Resistance
Device
Type
Resistance Range
(0.5 mA Excitation) Resistance Range (1.0 mA Excitation) Accuracy(1) Temperature Drift Resolution Repeatability
150Ω0 to 150Ω0 to 150Ω±0.15Ω±0.007Ω/°C
(±0.012Ω/°F) 0.01Ω±0.04Ω
500Ω0 to 500Ω0 to 500Ω±0.5Ω±0.023Ω/°C
(±0.041Ω/°F) 0.1Ω±0.2Ω
1000Ω0 to 1000Ω0 to 1000Ω±1.0Ω±0.043Ω/°C
(±0.077Ω/°F) 0.1Ω±0.2Ω
3000Ω0 to 3000ΩNot allowed ±1.5Ω±0.072Ω/°C
(±0.130Ω/°F) 0.1Ω±0.2Ω
(1) Accuracy values are based on the assumption that the module has been calibrated to the temperature range of 0 to 55°C (32 to 131°F).

Publication 1762-UM003A-EN-P - February 2003
1-6 Overview
Hardware Features
The RTD/resistance module provides connections for four 3-wire
inputs for any combination of RTD and resistance input devices.
Channels are wired as differential inputs. The illustration below shows
the hardware features of the module.
General Diagnostic Features
A single diagnostic LED helps you identify the source of problems that
may occur during power-up or during normal channel operation. The
LED indicates both status and power. See Chapter 4, Diagnostics and
Troubleshooting, for details on power-up and channel diagnostics.
9
3
5
2
1b
1a
7
6
4
8
6
1a
1b
2
Item Description
1a upper panel mounting tab
1b lower panel mounting tab
2 power diagnostic LED
3 module door with terminal identification label
4 bus connector with male pins
5 bus connector cover
6 flat ribbon cable with bus connector (female)
7 terminal block
8 DIN rail latch
9 pull loop

Publication 1762-UM003A-EN-P - February 2003
Overview 1-7
System Overview
The modules communicate to the local controller or communication
adapter through the 1762 bus interface. The modules also receive 5
and 24V dc power through the bus interface.
System Operation
At power-up, the module performs a check of its internal circuits,
memory, and basic functions. During this time, the module status LED
remains off. If no faults are found during power-up diagnostics, the
module status LED is turned on.
After power-up checks are complete, the module waits for valid
channel configuration data. If an invalid configuration is detected, the
module generates a configuration error. Once a channel is properly
configured and enabled, the module continuously converts the RTD
or resistance input to a value within the range selected for that
channel.
Each time the module reads an input channel, it tests the data for a
fault (over- or under-range, short-circuit, or open-circuit condition). If
it detects a fault, the module sets a unique bit in the channel status
word. See Input Data File on page 3-3.
Using the module image table, the controller reads the two’s
compliment binary converted input data from the module. This
typically occurs at the end of the program scan or when commanded
by the control program. If the controller and the module determine
that the data transfer has been made without error, the data is used in
the control program.

Publication 1762-UM003A-EN-P - February 2003
1-8 Overview
Module Operation
As shown in the block diagram below, each input channel of the
module consists of an RTD/resistance connection that accepts
excitation current; a sense connection that detects lead wire
resistance; and a return connection. The signals are multiplexed to an
A/D converter that reads the RTD or resistance value and the lead
wire resistance.
From the readings taken by the converter, the module returns an
accurate temperature or resistance to the controller user program
through the microprocessor. The module uses two bidirectional serial
ports for communication, each using an optocoupler for isolation. A
third optocoupler is used to reset the microprocessor if the module
detects a loss of communication.
Module Field Calibration
The input module performs autocalibration when a channel is initially
enabled. Autocalibration compensates for offset and gain drift of the
A/D converter caused by temperature change within the module. An
internal, high-precision, low drift voltage and system ground reference
is used for this purpose. In addition, you can program the module to
perform a calibration cycle once every 5 minutes. See Selecting
Enable/Disable Cyclic Autocalibration (Word 4, Bit 0) on page 3-20 for
information on configuring the module to perform periodic
calibration.
Input
EXC
SENSE
RTN
Multiplexer
Current
Source
A/D
Converter MCU ASIC
BUS
Isolation
Power Supply
Terminal
Opto-coupler
+24V dc
S-GND
+15V
+5V
A-GND
-15V

1Publication 1762-UM003A-EN-P - February 2003
Chapter 2
Installation and Wiring
This chapter tells you how to:
•determine the power requirements for the modules
•avoid electrostatic damage
•install the module
•wire the module’s terminal block
•wire input devices
Compliance to European
Union Directives
This product is approved for installation within the European Union
and EEA regions. It has been designed and tested to meet the
following directives.
EMC Directive
The 1762-IR4 module is tested to meet Council Directive 89/336/EEC
Electromagnetic Compatibility (EMC) and the following standards, in
whole or in part, documented in a technical construction file:
•EN 50081-2
EMC – Generic Emission Standard, Part 2 - Industrial
Environment
•EN 50082-2
EMC – Generic Immunity Standard, Part 2 - Industrial
Environment
This product is intended for use in an industrial environment.
Low Voltage Directive
This product is tested to meet Council Directive 73/23/EEC Low
Voltage, by applying the safety requirements of EN 61131-2
Programmable Controllers, Part 2 – Equipment Requirements and
Tests.

Publication 1762-UM003A-EN-P - February 2003
2-2 Installation and Wiring
For specific information required by EN61131-2, see the appropriate
sections in this publication, as well as the following Allen-Bradley
publications:
•Industrial Automation, Wiring and Grounding Guidelines for
Noise Immunity, publication 1770-4.1
•Automation Systems Catalog, publication B113
Power Requirements
The module receives +5V dc and 24V dc power from the system
power supply through the bus interface.
The maximum current drawn by the module is shown in the table
below.
General Considerations
1762 I/O is suitable for use in an industrial environment when
installed in accordance with these instructions. Specifically, this
equipment is intended for use in clean, dry environments (Pollution
degree 2(1)) and to circuits not exceeding Over Voltage Category II(2)
(IEC 60664-1).(3)
5V dc 24V dc
40 mA 50 mA
TIP When you configure your system, ensure that the
total current draw of all the modules does not
exceed the maximum current output of the system
power supply.
(1) Pollution Degree 2 is an environment where, normally, only non-conductive pollution occurs except that
occasionally a temporary conductivity caused by condensation shall be expected.
(2) Over Voltage Category II is the load level section of the electrical distribution system. At this level transient
voltages are controlled and do not exceed the impulse voltage capability of the product’s insulation.
(3) Pollution Degree 2 and Over Voltage Category II are International Electrotechnical Commission (IEC)
designations.