Rockwell Automation 1746-NT8 User Manual

SLC 500
Thermocouple/mV
Analog Input
Module

1746-NT8

User Manual

Important User Information

Solid state equipment has operational characteristics differing from those of
electromechanical equipment. Safety Guidelines for the Application,
Installation and Maintenance of Solid State Controls (Publication SGI-1.1
available from your local Rockwell Automation sales office or online at
http://www.ab.com/manuals/gi) describes some important differences
between solid state equipment and hard-wired electromechanical devices.
Because of this difference, and also because of the wide variety of uses for
solid state equipment, all persons responsible for applying this equipment
must satisfy themselves that each intended application of this equipment is
acceptable.

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

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

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

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

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

WARNING

IMPORTANT

ATTENTION

SHOCK HAZARD

BURN HAZARD

Identifies information about practices or circumstances
that can cause an explosion in a hazardous environment,
which may lead to personal injury or death, property
damage, or economic loss.

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

Identifies information about practices or circumstances
that can lead to personal injury or death, property
damage, or economic loss. Attentions help you:

• identify a hazard

• avoid a hazard

• recognize the consequence

Labels may be located on or inside the equipment (e.g.,
drive or motor) to alert people that dangerous voltage may
be present.

Labels may be located on or inside the equipment (e.g.,
drive or motor) to alert people that surfaces may be
dangerous temperatures.

Table of Contents

Preface

Module Overview

Installing And Wiring Your
Module

Who Should Use This Manual . . . . . . . . . . . . . . . . . . . . . . P-1

What This Manual Covers . . . . . . . . . . . . . . . . . . . . . . . . . P-1

Related Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . P-2

Common Techniques Used in this Manual . . . . . . . . . . . . . P-2

Chapter 1

General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Hardware Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Diagnostic LEDs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

System Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Module Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Linear Millivolt Device Compatibility. . . . . . . . . . . . . . . 1-7

Chapter 2

Electrostatic Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Considerations for a Modular System . . . . . . . . . . . . . . 2-2

Fixed I/O Chassis - I/O Module Compatibility . . . . . . . . 2-3

General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Module Installation and Removal . . . . . . . . . . . . . . . . . . . . 2-5

Terminal Block Removal . . . . . . . . . . . . . . . . . . . . . . . 2-6

Wiring Your Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Preparing and Wiring the Cables . . . . . . . . . . . . . . . . . 2-9

Cold-Junction Compensation (CJC) . . . . . . . . . . . . . . . . 2-11

Chapter 3

Considerations Before Using Your
Module

i Publication 1746-UM022B-EN-P - January 2005

Module ID Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Module Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Output Image - Configuration Words . . . . . . . . . . . . . . 3-2

Input Image - Data Words and Status Words. . . . . . . . . 3-3

Channel Filter Frequency Selection . . . . . . . . . . . . . . . . . . 3-3

Channel Cut-Off Frequencyc . . . . . . . . . . . . . . . . . . . . 3-4

Channel Step Response . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Update Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Update Time Calculation Example . . . . . . . . . . . . . . . . 3-8

Channel Turn-On, Turn-Off, and Reconfiguration Times . . . 3-8

Auto-calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

Response to Slot Disabling . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Input Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Output Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Table of Contents ii

Channel Configuration, Data, and
Status

Chapter 4

Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Channel Configuration Procedure . . . . . . . . . . . . . . . . . . . 4-2

Select Channel Enable (Bit 0) . . . . . . . . . . . . . . . . . . . . 4-5

Select Input Types (Bits 1 through 4) . . . . . . . . . . . . . . 4-5

Select Data Format (Bits 5 and 6) . . . . . . . . . . . . . . . . . 4-5

Using Scaled-for-PID and Proportional Counts . . . . . . . 4-6

Effective Resolutions . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

Scaling Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Select Open-Circuit State (Bits 7 and 8). . . . . . . . . . . . . 4-9

Select Temperature Units (Bit 9) . . . . . . . . . . . . . . . . . . 4-10

Select Channel Filter Frequency (Bits 10 and 11) . . . . . . 4-10

Unused Bits (Bits 12 through 14) . . . . . . . . . . . . . . . . . 4-11

Select Input Image Type (Bit 15) . . . . . . . . . . . . . . . . . 4-11

Channel Data/Status Word. . . . . . . . . . . . . . . . . . . . . . . . . 4-11

Channel Status Checking . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

Channel Status (Bit 0) . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

Input Type Status (Bits 1 through 4) . . . . . . . . . . . . . . . 4-14

Data Format Type Status (Bits 5 and 6) . . . . . . . . . . . . . 4-14

Open-Circuit Type Status (Bits 7 and 8) . . . . . . . . . . . . 4-14

Temperature Units Type Status (Bit 9). . . . . . . . . . . . . . 4-14

Channel Filter Frequency (Bits 10 and 11). . . . . . . . . . . 4-15

Open-Circuit E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

Under-Range Error (Bit 13). . . . . . . . . . . . . . . . . . . . . . 4-15

Over-Range Error (Bit 14). . . . . . . . . . . . . . . . . . . . . . . 4-15

Channel Error (Bit 15) . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

Programming Examples

Troubleshooting Your Module

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Chapter 5

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Automatic Monitoring Thermocouples and CJC Sensors . . . 5-3

Verifying Configuration Changes . . . . . . . . . . . . . . . . . . . . 5-3

Interfacing to the PID Instruction. . . . . . . . . . . . . . . . . . . . 5-7

Monitoring Channel Status Bits . . . . . . . . . . . . . . . . . . . . . 5-8

Monitoring Channel Status Bits Example . . . . . . . . . . . . 5-9

PLC 5 Example with NT8 in Remote I/O Rack . . . . . . . . . . 5-13

SLC 500 Example with NT8 in Remote I/O Rack. . . . . . . . . 5-15

Chapter 6

Module and Channel Diagnostics. . . . . . . . . . . . . . . . . . . . 6-1

Module Diagnostics at Powerup . . . . . . . . . . . . . . . . . . 6-1

Channel Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

LED Troubleshooting Tables. . . . . . . . . . . . . . . . . . . . . 6-3

Channel-status LEDs (Green) . . . . . . . . . . . . . . . . . . . . 6-4

Open-circuit Detection (Bit 12). . . . . . . . . . . . . . . . . . . 6-4

Maintaining Your Module And
Safety Considerations

Module Specifications

Table of Contents iii

Out-of-Range Detection (Bit 13 for Under Range, Bit 14 for

Over Range) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

Channel Error (Bit 15) . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

Module Status LED (Green) . . . . . . . . . . . . . . . . . . . . . 6-5

Interpreting I/O Error Codes . . . . . . . . . . . . . . . . . . . . . . . 6-5

Chapter 7

Preventive Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Appendix A

Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Physical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2

Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . A-2

Input Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

Overall Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4

Millivolt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4

Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6

Using Grounded Junction,
Ungrounded Junction, and
Exposed Junction Thermocouples

Configuring the 1746-NT8 Module
with RSLogix 500

Appendix B

Thermocouple Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Grounded Junction . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

Ungrounded (Insulated) Junction . . . . . . . . . . . . . . . . . B-2

Exposed Junction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

Grounded Junction . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

Exposed Junction Thermocouples. . . . . . . . . . . . . . . . . B-4

Appendix C

Glossary

Index

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Table of Contents iv

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Summary of Changes

The information below summarizes the changes to this manual since
the last printing. Updates to the manual include using RSLogix 500
instead of APS software.

To help you find new and updated information in this release of the
manual, we have included change bars as shown to the right of this
paragraph.

The table below lists the sections that document new features and
additional or updated information on existing features.

For this information: See

updated data table for initial programming page 5-2

added SLC 500 example with NT8 in
Remote I/O Rack

updated thermocouple graphs page A-8

configuring NT8 with RSLogix 500 page C-1

page 5-15

1 Publication 1746-UM022B-EN-P - January 2005

Summary of Changes 2

Publication 1746-UM022B-EN-P - January 2005

Preface

Read this preface to familiarize yourself with this user manual. This
preface covers:

• who should use this manual

• what this manual provides

• related documents

• common techniques used in this manual

Who Should Use This Manual

What This Manual Covers

Use this manual if you design, install, program, or maintain a control

system that uses SLC 500 controllers.

You should have a basic understanding of SLC 500 products. You
should also understand electronic process control and the ladder
program instructions required to generate the electronic signals that
control your application. If you do not, contact your local Rockwell
Automation representative for the proper training before using these
products.

This manual covers the 1746-NT8 thermocouple/millivolt analog input
module. It contains the information you need to install, wire, use, and
maintain these modules. It also provides diagnostic and
troubleshooting help should the need arise.

1 Publication 1746-UM022B-EN-P - January 2005

Preface 2

Related Documentation

The following table lists several Rockwell Automation documents that
may help you as you use these products.

Publication Number

1746-SG001 SLC 500™ Systems Selection Guide

SGI-1.1 Safety Guidlines for the Application, Installation and

1770-4.1 Industrial Automation Wiringing and Grounding Guidelines

1747-UM011 SLC 500 Modular Modular Hardware Style User Manual

1747-6.21 Installation & Operation Manual for Fixed Hardware Style

1747-RM001 SLC 500 Instruction Set Reference Manual

AG-7.1 Allen-Bradley Industrial Automation Glossary

Title

Maintenance of Solid State Controllers

Programmable Controllers

If you would like to:

• view and download the publication, go to Literature Library at

http://www.rockwellautomation.com/literature

• order printed copies, contact your Allen-Bradley Distributor or

Rockwell Automation Sales Office.

Common Techniques Used in this Manual

The following conventions are used throughout this manual:

• Bulleted lists such as this one provide information, not

procedural steps.

• Numbered lists provide sequential steps or hierarchical

information.

• Text in this font indicates words or phrases you should type.

• Key names appear in bold, capital letters within brackets (for

example, [ENTER]).

Publication 1746-UM022B-EN-P - January 2005

Chapter

1

Module Overview

This chapter describes the thermocouple/mV input module and
explains how the SLC 500 processor reads thermocouple or millivolt
analog input data from the module.

Read this chapter to familiarize yourself further with your
thermocouple/mV analog input module. This chapter covers:

• general description and hardware features

• an overview of system and module operation

• block diagram of channel input circuits

General Description

This module mounts into 1746 I/O chassis for use with SLC 500 fixed
and modular systems. The module stores digitally converted
thermocouple/mV analog data in its image table for retrieval by all
fixed and modular SLC 500 processors. The module supports
connections from any combination of up to eight thermocouple/mV
analog sensors.

Input Ranges

The following tables define thermocouple types and associated
temperature ranges and the millivolt analog input signal ranges that
each of the module’s input channels support. To determine the
practical temperature range of your thermocouple, refer to the
specifications in Appendix A.

Thermocouple Temperature Ranges

Type °C Temperature Range °F Temperature Range

J -210°C to +760°C -346°F to +1400°F

K -270°C to +1370°C -454°F to +2498°F

T -270°C to +400°C -454°F to +752°F

B +300°C to +1820°C +572°C to +3308°F

E -270°C to +1000°C -454°F to +1832°F

R 0°C to +1768°C +32 F to +3214°F

1 Publication 1746-UM022B-EN-P - January 2005

1-2 Module Overview

Type °C Temperature Range °F Temperature Range

S 0°C to +1768°C +32°F to +3214°F

N 0°C to +1300°C +32°F to +2372°F

CJC Sensor -25°C to +105°C -13°F to +221 °F

Millivolt Input Ranges

-50 to +50 mV

-100 to +100 mV

(1)

Each input channel is individually configured for a specific input
device, and provides open-circuit, over-range, and under-range
detection and indication.

Hardware Features

The module fits into any single slot for I/O modules in either an SLC
500 modular system or an SLC 500 fixed system expansion chassis
(1746-A2), except the zero slot which is reserved for the processor. It

is a Class 1 module using 8 input words and 8 output words.

The module contains a removable terminal block providing
connections for eight thermocouple and/or analog input devices. On
the terminal block are two cold-junction compensation (CJC) sensors
that compensate for the cold junction at ambient temperature. It
should also be noted there are no output channels on the module.
Configure the module with software rather than with jumpers or
switches.

(2)

Publication 1746-UM022B-EN-P - January 2005

IMPORTANT

There is a jumper (JP1) on the circuit board. The
module is shipped with the jumper in the up
position as illustrated below. Do not change the
position of JP1. The jumper is used for test purposes
only.

(1) Output impedance of input device must be less than 100 ohm to meet accuracy specifications.

(2) Requires use of a Block Transfer when used in a remote rack with a 1747-ASB.

Module Overview 1-3

Channel Status
LEDs (green)

Module Status
LEDs (green)

Removable
Terminal Block

CJC Sensors

Cable Tie Slots

INPUT

CHANNEL

014

5
2
123

Door Label

1746-NT8

CJC A+
CJC A­CHL 0+
CHL 0­SHIELD
CHL 1+
CHL 1­CHL 2+
CHL 2­SHIELD
CHL 3+
CHL 3­CHL 4+
CHL 4­SHIELD
CHL 5+
CHL 5­CHL 6+
CHL 6­SHIELD
CHL 7+
CHL 7­CJC B+
CJC B-

Jumper - Do not move

JP1

Self-Locking Tabs

STATUS

MODULE

THERMOCOUPLE/mV

Side Label

CAT

SERIAL NO.

1746 NT4

NT4±xxx x

THERMOCOUPLE/mV INPUT MODULE

SLC 500

SER

FRN

)

CLASS I, GROUPS A, B, C AND D, DIV.2

U

L

FOR HAZ. LOC. A196

LISTED IND. CONT . EQ.

SA

)

OPERA TING

TEMPERA TURE

CODE T3C

THERMOCOUPLE TYPES:

VOLTAGE:

INPUT SIGNAL RANGES

±100mVDC to +100mVDC

±50mVDC to +50mVDC

J, K, T, E, R, S, B, N

MADE IN USAFAC 1M

Hardware Features

Hardware Function

Channel Status LED Indicators Display operating and fault status of

channels 0 to 7

Module Status LED Displays operating and fault status of the

module

Side Label (Nameplate) Provides module information

Removable Terminal Block Provides electrical connection to input

devices

System Overview

Door Label Permits easy terminal identification

Cable Tie Slots Secure and route wiring from module

Self Locking Tabs Secure module in chassis slot

Diagnostic LEDs

The module contains diagnostic LEDs that help you identify the
source of problems that may occur during power-up or during normal
operation. Power-up and channel diagnostics are explained in
Chapter 6, Testing Your Module.

The module communicates with the SLC 500 processor and receives
+5V dc and +24V dc power from the system power supply through
the parallel backplane interface. No external power supply is
required. You may install as many thermocouple modules in the
system as the power supply can support.

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1-4 Module Overview

Each module channel can receive input signals from a thermocouple
or a mV analog input device. You configure each channel to accept
either one. When configured for thermocouple input types, the
module converts analog input voltages into cold-junction
compensated and linearized, digital temperature readings. The
module uses National Institute of Standards and Technology (NIST)
ITS-90 for thermocouple linearization.

When configured for millivolt analog inputs, the module converts
analog values directly into digital counts. The module assumes that
the mV input signal is linear.

System Operation

At power-up, the module checks its internal circuits, memory, and
basic functions. During this time the module status LED remains off. If
the module finds no faults, it turns on its module status LED.

Channel Data Word

Channel Status Word

Therm ocouple or mV
Analog Signals

Thermocou ple

Input

Module

Channel Co nfiguration Word

SL C 5 00

P rocess or

After completing power-up checks, the module waits for valid channel
configuration data from your SLC ladder logic program (channel status
LEDs are off). After channel configuration data is transferred and
channel enable bits are set, the enabled channel status LEDs turn on.
Then the channel continuously converts the thermocouple or millivolt
input to a value within the range you selected for the channel.

Each time the module reads an input channel, the module tests that
data for a fault, i.e. over-range or under-range condition. If open
circuit detection is enabled, the module tests for an open-circuit
condition. If it detects an open-circuit, over-range, or under-range
condition, the module sets a unique bit in the channel status word
and causes the channel status LED to flash.

The SLC processor reads the converted thermocouple or millivolt data
from the module at the end of the program scan, or when
commanded by the ladder program. After the processor and module
determine that the data transfer was made without error, the data can
be used in your ladder program.

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Module Overview 1-5

Module Operation

The module’s input circuitry consists of eight differential analog
inputs, multiplexed into an A/D convertor. The A/D convertor reads
the analog input signals and converts them to a digital value. The
input circuitry also continuously samples the CJC sensors and
compensates for temperature changes at the cold junction (terminal
block).

Module Addressing

The module requires eight words each in the SLC processor’s input
and output image tables. Addresses for the module in slot e are as
follows:

I:e.0-7 thermocouple/mV or status data for channels 0 to 7,
respectively (dependent on bit in configuration word).

O:e.0-7 configuration data for channels 0 to 7, respectively.

See Module Addressing on page 3-2 to see the module’s image table.

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1-6 Module Overview

Block Diagram

ungrounded
thermocouple

Wit hin

12.5V

grounded
thermocouple

Terminal Block Module Circuitry

CJCA Sens or

+

-

+

-

Shield

+

-

+

-

Shield

+

-

Shield

multiplexer

Analog
Ground

Analog to

Digital

Converter

User S elected
Filter F requency

+

-

+

-

Shield

+

-

+

CJCB S ensor

-

Digital

Filter

Digital
Va lue

Publication 1746-UM022B-EN-P - January 2005

IMPORTANT

When using multiple thermocouples, the potential
between any two channels cannot exceed the
channel-to-channel differential voltage (12.5 volts).
For more information, see Appendix B.

Module Overview 1-7

Linear Millivolt Device Compatibility

(1)

A large number of millivolt devices may be used with the 1746-NT8
module. For this reason we do not specify compatibility with any
particular device.

However, millivolt applications often use strain gage bridges. A
resistive voltage divider using fixed resistors is recommended for this
application. The circuit diagram below shows how this connection is
made.

Strain
Gage

Voc

+

variable

fixed

1746-NT8

Channel

Input

Bridge

fixed

+

-

fixed

TIP

The resistors should be selected to ensure that the
differential input voltage is less than or equal to ±100
mV.

(1) Output impedance of input device must be less than 100 ohm to meet accuracy specifications.

Publication 1746-UM022B-EN-P - January 2005

1-8 Module Overview

Publication 1746-UM022B-EN-P - January 2005

Chapter

Installing And Wiring Your Module

Read this chapter to install and wire your module. This chapter
covers:

• avoiding electrostatic damage

• determining power requirements

• installing the module

• wiring signal cables to the module’s terminal block

2

Electrostatic Damage

Electrostatic discharge can damage semiconductor devices inside this
module if you touch backplane connector pins. Guard against
electrostatic damage by observing the following precautions:

ATTENTION

Electrostatically Sensitive Components

• Before handling the module, touch a grounded

object to rid yourself of electrostatic charge.

• Handle the module from the front, away from the

backplane connector. Do not touch backplane
connector pins.

• Keep the module in its static-shield container

when not in use or during shipment.

Failure to observe these precautions can degrade the
module’s performance or cause permanent damage.

1 Publication 1746-UM022B-EN-P - January 2005

2-2 Installing And Wiring Your Module

Power Requirements

The module receives its power through the SLC 500 chassis backplane
from the fixed or modular +5 V dc/+24 V dc chassis power supply.
The maximum current drawn by the module is shown in the table
below.

Maximum Current Drawn by the Module

5Vdc Amps 24Vdc Amps

0.120 0.070

Considerations for a Modular System

Place your module in any slot of an SLC 500 modular, or modular
expansion chassis, except for the left-most slot (slot 0) reserved for
the SLC processor or adapter modules.

When using the module with a modular system, add the values shown
above to the requirements of all other modules in the SLC to prevent
overloading the chassis power supply. Refer to the SLC 500 Modular
Hardware Style User Manual, publication 1747-UM011.

Publication 1746-UM022B-EN-P - January 2005

Fixed I/O Chassis - I/O Module Compatibility

The following chart depicts the range of current combinations
supported by the fixed I/O expansion chassis. To use it, find the
backplane current draw and operating voltage for both modules being
used in the chassis. These specifications are found in the table
alongside the chart.

Next, plot each of the currents on the chart below. If the point of
intersection falls within the operating region, the combination is valid.
If not, the combination cannot be used in a 2-slot, fixed I/O chassis.

OW16 and

450

400

350

300

250

Current

(mA)

at 5V dc

200

150

100

50

Example: Plot IN16 and NIO4V
IN16 = 0.085 at 5V dc and 0A at 24V dc
NIO4V = 0.055A at 5V dc and 0.115A at 24V dc

1. Add current draws of both modules at 5V dc to get

0.14 A (140 mA).

2. Plot this point on the chart above (140 mA at 5V dc.

3. Add current draws of both modules at 24V dc to get

0.115 A (115 mA).

4. Plot current draw at 24V dc (115 mA at 24V dc).

5. Note the point of intersection on the chart above
(marked x). This combination falls within the valid
operating region for the fixed I/O chassis.

(0, 455)

Valid Operating

Region

x

50 150 200

100

Current (mA) at 24V

OW16 and IA16

(180, 255)

Plotted from

Example

Shown Below

Installing And Wiring Your Module 2-3

Module Current Draw - Power Supply Loading

I/O Module

BAS .150 .040

BASn .150 .125

DCM .360 .000

FI O4I .055 .150

FI O4V .055 .120

HS .300 .000

HSTP 1 .200 .000

IA4 .035 .000

IA8 .050 .000 NR4 .050 .05 0

IA16 .085 .000

IB8 .050 .000

IB16 .085 .000

IB32 .106 .000

IC16 .085 .000

IG16 .140 .000

IH16 .085 .000

IM4 .035 .000

IM8 .050 .000

IM16 .085 .000

IN16 .085 .000

IO4 .030 .025

IO8 .060 .045

IO12 .090 .070

ITB16 .085 .000

ITV16 .085 .000

IV8 .050 .000

IV16 .085 .000

IV32 .106 .000

KE .150 .040

KEn .125

5V 24V I/O Module 5V 24V

NI4 .025 .085

NI8 .200 .100

NIO4I .055 .145

NIO4V .055 .115

NO4I .055 .195

NO4V .055 .145

120

100 55

120 70

.150

N08I
N08V 120 160*

NR8

NT4 .060 .040

NT8

OA16 .370 .00 0

OA8 .185 .000

OAP 12 .370 .000

OB8 .135 .000

OB16 .280 .000

OB16E .135 .000

OB32 .452 .000

OBP8 .135 .000

OBP16 .250 .000

OG16 .180 .00 0

OV8 .135 .000

OV16 .270 .000

OV32 .452 .000

OVP 16 .250 .000

OW16 .170 .180

OW4 .045 .045

OW8 .085 .090

OX8 .085 .090

250*

* w/jumper set to rack, otherwise 0.0 mA.

Important: The 1747-NO4I and 1746-NO4V analog
output modules may require an external power
supply.

Publication 1746-UM022B-EN-P - January 2005

2-4 Installing And Wiring Your Module

When using the BAS or KE module to supply power to a 1747-AIC
Link Coupler, the link coupler draws its power through the module.
The higher current drawn by the AIC at 24V dc is shown in the table
as BASn (BAS networked) and KEn (KE networked). Be sure to use
these current draw values if the application uses the BAS or KE
module in this way.

General Considerations

Most applications require installation in an industrial enclosure to
reduce the effects of electrical interference. Thermocouple inputs are
highly susceptible to electrical noises due to the small amplitudes of
their signal (microvolt/°C).

Group your modules to minimize adverse effects from radiated
electrical noise and heat. Consider the following conditions when
selecting a slot for the thermocouple module. Position the module:

• in a slot away from sources of electrical noise such as recontact

switches, relays, and AC motor drives

• away from modules which generate significant radiated heat,

such as the 32-point I/O modules

In addition, route shielded twisted pair thermocouple or millivolt
input wiring away from any high voltage I/O wiring.

Remember that in a modular system, the processor or communications
adapter always occupies the first slot of the chassis.

Publication 1746-UM022B-EN-P - January 2005

Module Installation and Removal

ATTENTION

Installing And Wiring Your Module 2-5

Possible Equipment Operation

Before installing or removing your module, always
disconnect power from the SLC 500 system and from
any other source to the module (in other words, do
not ’hot swap’ your module), and disconnect any
devices wired to the module.

Failure to observe this precaution can cause
unintended equipment operation and damage.

Top and Bottom
Module Release(s)

Card Guide

To insert your module into the chassis, follow these steps:

1. Before installing the module, connect the ground wire to TB1.

See the figure on page 2-10.

2. Align the circuit board of your module with the card guides at

the top and bottom of the chassis.

3. Slide your module into the chassis until both top and bottom

retaining clips are secure. Apply firm even pressure on your
module to attach it to its backplane connector. Never force your
module into the slot.

Publication 1746-UM022B-EN-P - January 2005

2-6 Installing And Wiring Your Module

4. Cover all unused slots with the Card Slot Filler, Allen-Bradley

part number 1746-N2.

Terminal Block Removal

To remove the terminal block:

1. Loosen the two terminal block release screws. To avoid cracking

the terminal block, alternate between screws as you remove
them.

2. Using a screwdriver or needle-nose pliers, carefully pry the

terminal block loose. When removing or installing the terminal
block be careful not to damage the CJC sensors.

Publication 1746-UM022B-EN-P - January 2005

Terminal block diagram with CJC sensors

CJC Sensors

Recomm ended Torque:
wiring screws: 0.25 Nm (2.2 in-lb)
release scre ws: 0.25 Nm (2.2 in-lb)

Installing And Wiring Your Module 2-7

Terminal Block
Release Screws

ATTENTION

CJC Sensors

Terminal Block
Release Screws

Possible Equipment Operation

Before wiring your module, always disconnect
power from the SLC 500 system and from any other
source to the module.

Failure to observe this precaution can cause
unintended equipment operation and damage.

Publication 1746-UM022B-EN-P - January 2005

2-8 Installing And Wiring Your Module

Wiring Your Module

Follow these guidelines to wire your input signal cables:

• Power, input, and output (I/O) wiring must be in accordance

with Class 1, Division 2 wiring methods [Article 501-4(b) of the
National Electrical Code, NFPA 70] and in accordance with the
authority having jurisdiction.

• Route thermocouple and millivolt signal wires as far as possible

from sources of electrical noise, such as motors, transformers,
contactors, and ac devices. As a general rule, allow at least 6 in.
(about 15.2 cm) of separation for every 120V ac of power.

• Routing the field wiring in a grounded conduit can reduce

electrical noise further.

• If the field wiring must cross ac or power cables, ensure that

they cross at right angles.

• For high immunity to electrical noise, use Belden™ 8761

(shielded, twisted pair) or equivalent wire for millivolt sensors;
or use shielded, twisted pair thermocouple extension lead wire
specified by the thermocouple manufacturer. Using the incorrect
type of convention thermocouple extension wire or not
following the correct polarity may cause invalid readings.

• Ground the shield drain wire at only one end of the cable. The

preferred location is at the shield connections on the terminal
block. (Refer to IEEE Std. 518, Section 6.4.2.7 or contact your
sensor manufacturer for additional details.)

• Keep all unshielded wires as short as possible.

• Excessive tightening can strip a screw. Tighten screws to 0.25

Nm (2.2 in-lb) or less, based on UL 1059, CSA C22.2 No. 158,
VDE 0110B 2.79 standards.

• Follow system grounding and wiring guidelines found in your

SLC 500 Modular Hardware Style User Manual, publication
1747-UM011 or 1747-SLC 500 Fixed Hardware Style User
Manual, publication 1747-6.21.

Publication 1746-UM022B-EN-P - January 2005

Installing And Wiring Your Module 2-9

Preparing and Wiring the Cables

To prepare and connect cable leads and drain wires, follow these
steps:

Cable

Signal Wires

(Remove foil shield and drain wire
from sensor end of the cable.)

Drain Wire

Signal Wires

1. At each end of the cable, strip some casing to expose individual

wires.

2. Trim signal wires to 5-inch lengths beyond the cable casing.

Strip about 3/16 inch (4.76 mm) of insulation to expose the ends
of the wires.

3. At the module end of the cables:

• extract the drain wire and signal wires

• remove the foil shield

• bundle the input cables with a cable strap

4. Connect pairs of drain wires together:

• Channels 0 and 1

• Channels 2 and 3

• Channels 4 and 5

• Channels 6 and 7

Keep drain wires as short as possible.

5. Connect the drain wires to the shield inputs of the terminal

block if appropriate for thermocouple used.

• Channel 0 and 1 drain wires to pin 5

• Channel 2 and 3 drain wires to pin 10

• Channel 4 and 5 drain wires to pin 15

• Channel 6 and 7 drain wires to pin 20

Publication 1746-UM022B-EN-P - January 2005

2-10 Installing And Wiring Your Module

6. Connect the signal wires of each channel to the terminal block.

IMPORTANT

Only after verifying that your connections are
correct for each channel, trim the lengths to keep
them short. Avoid cutting leads too short.

7. Connect TB1 chassis ground connector to the nearest chassis

mounting bolt with 14 gauge wire. (Looking at the face of the
module, TB1 is near the lower part of the terminal block on the
primary side of the PCB.)

TB1

Connect ground wire to TB1
before installing module.

8. At the sensor end of cables from thermocouple/mV devices:

• remove the drain wire and foil shield

• apply shrink wrap as an option

• connect to mV devices keeping the leads short.

IMPORTANT

If noise persists, try grounding the opposite end
of the cable. Ground one end only.

Publication 1746-UM022B-EN-P - January 2005

Terminal Block Diagram with Input Cable

Thermocouple or mV Ca ble

Recommended Torque :
TB 1 0.3 to 0.5 Nm (2.5 to 4.5 in-lb)

Installing And Wiring Your Module 2-11

CJC A+

CJC A­Channel 0+

Channel 0-

Shield for CH0 and CH 1

Channel 1+

Channel 1-

Channel 2+
Channel 2-

Shield for CH2 and CH 3

Channel 3+

Channel 3­Channel 4+

Channel 4­Shield for CH4 and CH 5

Channel 5+
Channel 5-

Channel 6+

Channel 6-

Shield for CH6 and CH 7

Channel 7+

Channel 7-

CJC B +

CJC B -

TB1

The module also has a ground terminal TB1, which should be
grounded to a chassis mounting bolt with 14-gauge wire.

Cold-Junction Compensation (CJC)

ATTENTION

To obtain accurate readings from each of the channels, the
cold-junction temperature (temperature at the module’s terminal
junction between the thermocouple wire and the input channel) must
be compensated for. Two cold-junction compensating sensors have
been integrated in the removable terminal block. They must remain
installed.

Possible Equipment Operation

Do not remove or loosen the cold-junction
compensating temperature transducers located on
the terminal block. Both CJCs are required to ensure
accurate thermocouple input readings at each
channel. The module will not operate in
thermocouple mode if a CJC is not connected.

Failure to observe this precaution can cause
unintended equipment operation and damage.

Publication 1746-UM022B-EN-P - January 2005

2-12 Installing And Wiring Your Module

Publication 1746-UM022B-EN-P - January 2005