Spectrum Controls 1756sc-IF8u User Manual

Owner’s Guide 0300191-04 Rev . A

C

ONTROL

U

NIVERSAL

Catalog Number: 1756sc-IF8u

L

OGIX

A

NALOG INPUT

™

M

ODULE

Important Notes

1. Please read all the information in this owner’s guide before installing
the product.

2. The information in this owner's guide applies to hardware version A
and firmware version 2.0 or later.

3. This guide assumes that the reader has a full working knowledge of the
relevant processor.

Notice

The products and services described in this owner's guide are useful in a
wide variety of applications. Therefore, the user and others responsible
for applying the products and services described herein are responsible
for determining their acceptability for each application. While efforts
have been made to provide accurate information within this owner's
guide, Spectrum Controls assumes no responsibility for the accuracy,
completeness, or usefulness of the information herein.

Under no circumstances will Spectrum Controls be responsible or liable
for any damages or losses, including indirect or consequential damages
or losses, arising out of either the use of any information within this
owner's guide or the use of any product or service referenced herein.

No patent liability is assumed by Spectrum Controls with respect to the
use of any of the information, products, circuits, programming, or
services referenced herein.

The information in this owner's guide is subject to change without notice.

Limited Warranty

Spectrum Controls warrants that its products are free from defects in
material and workmanship under normal use and service, as described in
Spectrum Controls literature covering this product, for a period of 1 year.
The obligations of Spectrum Controls under this warranty are limited to
replacing or repairing, at its option, at its factory or facility, any product
which shall, in the applicable period after shipment, be returned to the
Spectrum Controls facility, transportation charges prepaid, and which
after examination is determined, to the satisfaction of Spectrum Controls,
to be thus defective.

This warranty shall not apply to any such equipment which shall have
been repaired or altered except by Spectrum Controls or which shall
have been subject to misuse, neglect, or accident. In no case shall the
liability of Spectrum Controls exceed the purchase price. The
aforementioned provisions do not extend the original warranty period of
any product which has either been repaired or replaced by Spectrum
Controls.

Who Should Use
This Guide

Preface

Read this preface to familiarize yourself with the rest of the owner’s
guide. This preface covers:

• who should use this guide

• what this guide covers

• related Allen-Bradley documents

• terms & abbreviations you should know

Use this guide if you design, install, program, or maintain a control system
that uses Allen-Bradley ControlLogix Controllers.

Y ou should have a basic understanding of ControlLogix products. Y ou
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 Allen-Bradley representative
for the proper training before using these products.

What This Guide
Covers

Related Allen­Bradley Documents

This guide covers the 1756sc-IF8u universal 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.

T able A lists several Allen-Bradley documents that may help you as you
use these products.

Table A. Related Allen-Bradley documents

Allen-Bradley Doc. No. Title Publication Number

1756-P A72, ControlLogix Power Supply Installation

-PB72 Instructions 1756-5.1

1756-A4, ControlLogix Chassis Installation Instructions 1756-5.2

-A7, -A10,

-A13, -A17

vi ControlLogix™ Universal Analog Input Modules

1756 Series ControlLogix Module Installation Instructions
(Each module has separate document for installation) 1756-5.5,

1756-L1, Logix5550 Controller User Manual 1756-6.5.12

-L1M1, -L1M2

1756-DHRIO ControlLogix Data Highway Plus
Communication Interface Module User Manual 1756-6.5.2

1756-ENET ControlLogix Ethernet Communication Interface
Module User Manual 1756-6.5.1

T o obtain a copy of any of the Allen-Bradley documents listed, contact
your local Allen-Bradley office or distributor .

Terms &
Abbreviations You
Should Know

Y ou should understand the following terms and abbreviations before using
this guide.

-5.42

A/D - Refers to analog-to-digital conversion. The conversion produces a
digital value whose magnitude is proportional to the instantaneous
magnitude of an analog input signal.

Attenuation – The reduction in magnitude of a signal as it passes through
a system. The opposite of gain.

Channel – Refers to one of eight, small-signal analog input interfaces to
the module’s terminal block. Each channel is configured for connection to
a input device, and has its own configuration and status words.

Chassis – See rack.
CJC - (Cold Junction Compensation) The means by which the module

compensates for the offset voltage error introduced by the temperature at
the junction between the thermocouple lead wire and the input terminal
block (the cold junction).

Common mode rejection ratio (CMRR) - The ratio of a device’s
differential voltage gain to common mode voltage gain. Expressed in dB,
CMRR is a comparative measure of a device’s ability to reject
interference caused by a voltage common to its terminal relative to
ground.

Common mode voltage – The voltage difference between the negative
terminal and analog common during normal differential operation.

Preface vii

Cut-off frequency - The frequency at which the input signal is attenuated
3 dB by the digital filter. Frequency components of the input signal that
are below the cut-off frequency are passed with under 3 dB of attenuation
for low-pass filters.

dB (decibel) – A logarithmic measure of the ratio of two signal levels.
Digital filter - A low-pass mathmatic single order filter applied to the A/D

signal. The digital filter provides high-frequency noise rejection.
Effective resolution – The number of bits in the channel data word that

do not vary due to noise.
Local System - A control system with I/O chassis within several feet of

the processor.
LSB (least significant bit) – The bit that represents the smallest value

within a string of bits.
Mulitplexer – A switching system that allows several input signals to

share a common A/D converter.
Normal mode rejection (differential mode rejection) – A logarithmic

measure, in dB, of a device’ s ability to reject noise signals between or
among circuit signal conductors, but not between the equipment grounding
conductor or signal reference structure and the signal conductors.

Module update time – See channel update time.
Remote system - A control system where the chassis can be located

several thousand feet from the processor chassis. Chassis communication
is via the 1756-DHRIO and 1756-ENET Adapter.

Resolution – The smallest detectable change in a measurement, typically
expressed in engineering units (e.g. 0.15 °C) or as a number of bits. For
example, a 12-bit system has 4096 possible output states. It can therefore
measure 1 part in 4096. See also effective resolution.

RTD (Resistance Temperature Detector) - A temperature sensing
element with 2, 3, 4, lead wires. It uses the basic characteristics that
electrical resistance of metals increases with temperature. When a small
current is applied to the RTD, it creates a voltage that varies with
temperature. This voltage is processed and converted by the RTD module
into a temperature value.

Sampling time - The time required by the A/D converter to sample an
input channel.

viii ControlLogix™ Universal Analog Input Modules

Step response time – The time required for the A/D signal to reach 95%
of its expected, final value, given a full-scale step change in the output
data word.

Tags - Identifiers for configuration, data, and status information found
withing the module. T ags allow the user to modify specific module
attributes and view data and status.

Update time – The time for the module to sample and convert a channel
input signal and make the resulting value available to the ControlLogix
processor.

Table of Contents

Preface v

Module Overview
1

Installing And Wiring
Your Module 9

Who Should Use This Guide ...................................................................................v

What This Guide Covers..........................................................................................v

Related Allen-Bradley Documents ...........................................................................v

T able A. Related Allen-Bradley documents .............................................................v

Terms & Abbreviations You Should Know ............................................................. vi

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

Detailed Specifications ............................................................................................. 2

Hardware Features .................................................................................................... 3

Diagnostic LEDs....................................................................................................... 4

System Overview...................................................................................................... 4

System Operation ..................................................................................................... 5

Module Operation .................................................................................................... 5

Compatibility with Thermocouple, Current, and Millivolt Devices & Cables ......... 6

Electrostatic Damage ................................................................................................ 9

Power Requirements............................................................................................... 10

T able 2.1 Maximum current drawn by the module ................................................. 10

Module Installation and Removal .......................................................................... 10

Figure 2.1 Module insertion into a rack ................................................................ 13

Figure 2.2 T erminal block diagram with keying ..................................................... 14

Wiring Your Module .............................................................................................. 14

Preparing and Wiring the Cables ........................................................................... 15

T erminal Block Layout............................................................................................ 16

Wiring Voltage/Current Inputs the IF8u Module................................................... 17

Wiring RTD or Resistance Sensors to the IF8u Module ....................................... 18

Wiring Thermocouples to the IF8u Module .......................................................... 20

Operation Within the
ControlLogix
System 23

Programming Your
Module 29

Ownership and Connections .................................................................................. 23

Using RSNetW orx and RSLogix 5000..................................................................... 23

Direct Connections ................................................................................................. 24

Module Operation .................................................................................................. 24

Modules in a Local Chassis ................................................................................... 25

Requested Packet Interval (RPI) ............................................................................ 25

Modules in a Remote Chassis................................................................................ 26

Listen-Only Mode .................................................................................................. 27

Multiple Owners of Input Modules ....................................................................... 27

Configuration Changes in an Input Module with Multiple Owners...................... 28

Module Installation ................................................................................................ 29

Adding Your Module to a Project .......................................................................... 29

Configuring module attributes: Configuration Tags .............................................. 34

x ControlLogix™ Universal Analog Input Modules

Configuration, Data,
and Status Tags
37

Send Configuration Data to the Module................................................................ 37

Configuration Tags ................................................................................................. 38

Global Module Settings .......................................................................................... 38

Channel Specific Settings ....................................................................................... 43

Input Tags .............................................................................................................. 50

Fault and Status Reporting Tags ........................................................................... 50

Module Data Tags.................................................................................................. 53

Programming
Examples 55

Initial Programming................................................................................................. 55

Figure 5.1 Sample Ladder Logic ............................................................................ 56

Troubleshooting
61

Using Module Indicators to Troubleshoot............................................................ 61

Using RSLogix 5000 to Troubleshoot Your Module.............................................. 62

Module Configuration Errors ................................................................................. 64

Maintaining Your
Module
And Ensuring Safety
65

Module
Specifications

69

Ther mocouple
Descriptions 7 5

Preventive Maintenance ........................................................................................ 65

Safety Considerations ............................................................................................ 65

Electrical Specifications.......................................................................................... 69

Physical Specifications .......................................................................................... 70

Environmental Specifications................................................................................. 70

Input Specifications ............................................................................................... 70

J Type Thermocouples ........................................................................................... 75

K Type Thermocouples .......................................................................................... 77

T Type Thermocouples .......................................................................................... 79

E Type Thermocouples .......................................................................................... 81

R Type Thermocouples .......................................................................................... 83

S Type Thermocouples .......................................................................................... 84

B Type Thermocouples .......................................................................................... 86

N Type Thermocouples .......................................................................................... 87

References .............................................................................................................. 90

Using Grounded
Junction,
Ungrounded
Junction, and
Exposed Junction
Ther mocouples 97

Programming Your
Module 101

T able of Contents xi

Thermocouple Types .............................................................................................. 97

Grounded Junction ................................................................................................. 98

Ungrounded (Insulated) Junction .......................................................................... 98

Exposed Junction ................................................................................................... 98

Isolation.................................................................................................................. 98

Module Installation .............................................................................................. 101

Adding Your Module to a Project ........................................................................ 101

Declaration of Conformity .................................................................................... 105

xii ControlLogix™ Universal Analog Input Modules

Chapter 1

Module Overview

This chapter describes the universal analog input module and explains how
the ControlLogix controller reads analog input data from the module. Read
this chapter to familiarize yourself further with your universal analog input
module. This chapter covers:

• general description and hardware features

• an overview of system and module operation

General Description

This module is designed exclusively for use in the Allen-Bradley
ControlLogix 1756 I/O rack systems. The module stores digitally
converted thermocouple, RTD, resistance, millivolt (mV), volt (V),
milliamp (mA), and CJC temperature analog data in its image table for
retrieval by all ControlLogix processors.

Following is a list of features available on the IF8u module that allow their
use in a wide variety of applications.

· Removal and insertion under power (RIUP) - a system feature that

allows you to remove and insert modules while chassis power is applied

· Producer/consumer communications - an intelligent data exchange

between modules and other system devices in which each module
produces data without having been polled

· Rolling timestamp of data - 15 bit module-specific rolling timestamp with

millisecond resolution which indicates when data was sampled/applied.
This timestamp may be used to calculate the interval between channel or
updates

· System timestamp of data - 64 bit system clock places a timestamp on

the transfer of data between the module and its owner controller within
the local chassis

· IEEE 32 bit floating point format

· On-Board Features, such as custom User Scaling, Process Alarms, Rate

Alarms, Digital Filtering, and Under/Overrange Detection

· Automatic Calibration - analog I/O modules may perform autocalibration

on a channel-by-channel or module-wide basis to reduce drift inaccuracies
due to module ambient temperature changes.

· Class I/Division 2, UL, CSA, CE, and FM Agency Certification

2 ControlLogix™ Counter Module

Detailed
Specifications

Input Ranges
The following tables provide compatibility information on the supported

thermocouple types and their associated temperature ranges, the
supported RTD types and their associated temperature ranges, as well as
the millivolt, volt, milliamp and resistance input types supported by the IF8u
module. To determine the practical temperature range of your
thermocouple, refer to the specifications in appendices A and B.

Table 1.1 Thermocouple Temperature Ranges

T ype °C Temperature Range °F Temperature Range
J -210°C to 1200°C -346°F to 2192°F

K -270°C to 1372°C -454°F to 2502°F
T -270°C to 400°C -454°F to 752°F
B 300°C to 1820°C 572°F 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
S 0°C to 1768°C 32°F to 3214°F
N -210°C to 1300°C -346°F to 2372°F
C 0°C to 2315°C 32°F to 4199°F
CJC Sensor 0°C to 90°C 32°F to 194°F

Table 1.2 RTD Temperature Ranges

Type °C Temp Range °F Temp Range
Platinum (385)

100 Ohm -200°C to +850°C -328°F to +1562°F
200 Ohm -200°C to +850°C -328°F to +1562°F
500 Ohm -200°C to +850°C -328°F to +1562°F
1000 Ohm -200°C to +850°C -328°F to +1562°F

Platinum (3916)
100 Ohm -200°C to +630°C -328°F to +1166°F
200 Ohm -200°C to +630°C -328°F to +1166°F
500 Ohm -200°C to +630°C -328°F to +1166°F
1000 Ohm -200°C to +630°C -328°F to +1166°F

Copper (426)
10 O hm -100°C to +260°C -148°F to +500°F

Nickel (618)
120 Ohm -100°C to + 260°C -148°F to +500°F
200 Ohm -100°C to + 260°C -148°F to +500°F
500 Ohm -100°C to + 260°C -148°F to +500°F
1000 Ohm -100°C to + 260°C -148°F to +500°F

Nickel (672)
120 Ohm -80°C to +260°C -112°F to + 500°F

Nickel/Iron (518)
604 Ohm -100°C to +200°C -148°F to +392°F

The digits in parenthisis following the RTD type represent the temperature coef ficient of resistance (alpha, a),
which is defined as the resistance change per Ohm per°°C. For instance, Platinum 385 refers to a platinum RTD
with a = 0.00385 Ohms/Ohm - °C, or simply 0.00385/°°C.

Table 1.3 Millivolt Input Ranges

Stated Actual

-50 to +50 mV (-75 to +75 mV)

-150 to +150 mV (-175 to +175 mV)

0 to +5.0 V (-0.5 to +5.5 V)

1.0 to +5.0 V (0.5 to +5.5 V)

0 to 10.0 V (-0.5 to 10.0 V)

-10.0 to +10.0 V (-10.0 to +10.0 V)

Table 1.4 Current Input Ranges

4 to 20 mA (-3.5 to +21.5mA)
0 to 20 mA (0 to +21.5mA)

Table 1.5 Resistance Input Range

0 to 250 Ohms
0 to 500 Ohms
0 to 1000 Ohms
0 to 2000 Ohms
0 to 3000 Ohms
0 to 4000 Ohms

Chapter 1: Module Overview 3

Hardware Features

All eight input channels are individually configurable for RTD, resistance,
thermocouple, millivolt, volt, or milliamp input types. Each input channel
provides wire-off input, over-range, and under-range detection and
indication, when enabled.

The module fits into any single slot for I/O modules in a ControlLogix
modular system. The module has a unique generic profile which may be
configured using your RSLogix 5000 programming software.

The module utilizes one removable terminal block, that provides
connections for the eight input channels. There are two cold-junction
compensation (CJC) sensors that compensate for the cold junction at
ambient temperature rather than at freezing (0°C). There are eight current
sources for supplying the RTD or resistance sensors. The module is
configured through RSLogix 5000 software, defining R TD, resistance,
current or voltage input paths.

4 ControlLogix™ Counter Module

Table 1.6 Hardware Features

Hardware Function
OK LED Displays communication and fault status of the module
Cal LED Displays a fault condition
Side Label (Nameplate) Provides module information
Removable T erminal Block Provides electrical connection to input devices
Door Label Permits easy terminal identification
Self Locking T abs Secure module in chassis slot
Terminal Block Switch Locks the R TB to the module.

Diagnostic LEDs

System Overview

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 diagnostics are explained in Chapter 7, Testing Your
Module.

The module communicates with the ControlLogix processor and receives
+5 Vdc and +24 Vdc power from the system power supply through the
parallel backplane interface. You may install as many universal modules in

the system as the power supply can support. Channels (0 through 7) can
receive input signals from RTDs, resistance sources, thermocouples,
millivolt, volt, or milliamp devices. When configured for thermocouple input
types, the module converts analog input voltages into cold-junction
compensated and linearized, digital temperature readings. The module uses
the National Institute of Standards and T echnology (NIST) linearization
tables based on ITS-90 for thermocouple linearization.

When configured for R TD input types, the module converts the analog
input voltages into digital temperature readings, based on the alpha type,
wire type, and ohms specified. The standards used are the JIS C 1604­1997 for the Pt 385 R TD types, the JIS C 1604-1989 for the Pt 3916 RTD
types, SAMA RC21-4-1966 for the 10. Cu 426 RTD, DIN 43760 Sept.
1987 for the 120. Ni 618 RTD, and MINCO Application Aid #18 May
1990 for the 120. Ni 672 RTD.When configured for millivolt, volt, milliamp,
or resistance analog inputs, the module converts the analog values directly
into floating point values. For those input types, the module assumes that
the input signal is linear prior to input into the module.

Chapter 1: Module Overview 5

Table 1.6 Hardware Features

Hardware Function
OK LED Displays communication and fault status of the module
Cal LED Displays a fault condition
Side Label (Nameplate) Provides module information
Removable T erminal Block Provides electrical connection to input devices
Door Label Permits easy terminal identification
Self Locking T abs Secure module in chassis slot
Terminal Block Switch Locks the R TB to the module.

System Operation

Module Operation

At power-up, the module checks internal circuits, memory , and basic
functions. During this time the Cal LED remains on. If the module does
not find any faults, it turns off the Cal LED. After completing power-up
checks, the module wait for a connection to an owner controller then valid
channel configuration data from your ladder logic program. After channel
configuration data is transferred, and one or more channels are enabled,
the module continuously converts the inputs to floating point data for use in
your ladder program.

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 it detects an
overrange or under-range condition, the module sets a unique bit in the
status tags.

The module’s input circuitry consists of eight differential analog inputs,
multiplexed into an A/D converter. The A/D converter reads the analog
input signals and converts them to floating point values.. The input circuitry
also continuously samples the CJC sensors, if not disabled and
compensates for temperature changes for thermocouples at the cold
junction (terminal block). The sensors must be Spectrum Controls supplied
temperature sensors. The module will not accept other CJC sensor inputs,
and thermocouple inputs will not function properly if incorrect CJC sensors
are used. Two CJC sensors are shipped with each module.

6 ControlLogix™ Counter Module

Compatibility with
Ther mocouple,
Current, and Millivolt
Devices & Cables

The module is compatible with the following standard types of
thermocouples: B, E, J, K, N, R, S, T and C and extension wire. Refer to
appendices B and C for details. The module is also compatible with a
variety of voltage and current devices with an output of ±50, ±150 mV, 0­5V , 1-5V, 0-10V , ±10V, 0-20mA, and 4-20mA. T o minimize interference
from radiated electrical noise, we recommend twisted-pair and highly
shielded cables such as the following:

Table 1.7 Recommendations to minimize interference from radiated
electrical noise

For This Type of Device We Recommend This Cable (or equivalent)
Thermocouple Type J EIL Corp. J20-5-502
Thermocouple T ype K EIL Corp. K20-5-510
Thermocouple T ype T EIL Corp. T20-5-502

Other Thermocouple T ypes consult with EIL Corp or other manufacturers mV, V , mA devices Belden 8761,
shielded, twisted-pair Compatibility with RTD and Resistance devices and cables

The module is compatible 100. Platinum 385, 200. Platinum 385, 500.
Platinum 385, 1000. Platinum 385, 100. Platinum 3916, 200. Platinum 3916,

500. Platinum 3916, 1000. Platinum 3916, 10. Copper 426, 120. Nickel

618 and 120. Nickel 672 R TD types and resistance inputs, and 3 possible
wire types (2 wire, 3 wire, or 4 wire). Each RTD input individually
supports three input pins on the terminal block: one excitation current
source (EXC+), one sense positive (IN+) and one sense negative (IN-).
Only those pins are connected that are required by the selected R TD or
resistance wire type. For 2, 3, or 4 wire configurations, the module can
support a maximum combined cable length associated with an overall
cable impedance of 25 ohms or less without exceeding its input limitations.
The accuracy specifications provided herein do not include errors
associated with unbalanced cable impedance.

Since the operating principle of the RTD and resistance inputs is based on
the measurement of resistance, take special care in selecting your input
cable. For 2-wire or 3-wire configuration, select a cable that has a
consistent impedance throughout its entire length. For 2-wire
configurations, we recommend that you use Belden #9501 (or

equivalent). For 3-wire configurations, we recommend that you use
Belden #9533 (or equivalent) for short installation runs (less than 100

feet) or use Belden #83503 (or equivalent) for longer runs (greater than
100 feet) and in high humidity environments.

Chapter 1: Module Overview 7

Table 1.8 Cable Specifications

Description Belden #9501 Belden#9533 Belden#83503
For 2-wire RTDs and 3-wire RTDs and 3-wire R TDs and

potentiometers. potentiometers. Short potentiometers.

When used? Long runs less than 100 feet runs greater than 100

8 ControlLogix™ Counter Module

Electrostatic
Damage

Chapter 2

Installing And Wiring Y our 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

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

CAUTION

!

ELECTROSTATICALLY SENSITIVE COMPONENTS

• Before handling the module, touch a grounded
object to rid yourself of electrostatic charge.

• When handling the module, wear an approved wrist strap
grounding device.

• 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 deg rade the
module’s performance or cause permanent dama ge.

10 ControlLogix™ Universal Analog Input Module

Power
Requirements

The module receives its power through the ControlLogix chassis
backplane from the fixed or modular +5 VDC and +24 VDC chassis
power supply . The maximum current drawn by the module is shown in the
table below .

Table 2.1. Maximum current dr awn by the module

5VDC Amps 24VDC Amps

0.230 0.075

Using your module in the ControlLogix System

Place your module in any slot of a ControlLogix modular, or modular
expansion chassis.

Module Installation
and Removal

An analog I/O module translates an analog signal into, or from, a
corresponding digital representation which controllers can easily operate
on for control purposes.

A ControlLogix I/O module mounts in a ControlLogix chassis and uses a
Removable T erminal Block (R TB) to connect all field-side wiring.

Before you install and use your module you should have already:

· installed and grounded a 1756 chassis and power supply.

· ordered and received an RTB for your application.
Important: RTBs are not included with your module purchase.
Specify Allen Bradley Part Number:
1756-TBCH - 36 position screw terminals

1756-TBS6H - 36 position press terminals

When installing the module in a chassis, it is not necessary to remove the
terminal blocks from the module. However, if the terminal blocks are
removed, use the write-on label located on the side of the terminal blocks
to identify the module location and type.

Chapter 2: Installing And Wiring Y our Module 11

Preventing Electrostatic Discharge

This module is sensitive to electrostatic discharge.

AA

TTENTION:TTENTION:

A

TTENTION:

AA

TTENTION:TTENTION:

circuits or semiconductors if you touch backplane connector

!

pins. Follow these guidelines when you handle the module:

· Touch a grounded object to discharge static potential

· Wear an approved wrist-strap grounding device

· Do not touch the backplane connector or connector pins

· Do not touch circuit components inside the module

· If available, use a static-safe work station

· When not in use, keep the module in its static-shield box

Electrostatic discharge can damage integrated

Removal and Insertion Under Power

These modules are designed to be installed or removed while chassis
power is applied.

AA

TTENTION:TTENTION:

A

TTENTION:

AA

TTENTION:TTENTION:

backplane power is applied, an electrical arc may occur. An

!

electrical arc can cause personal injur y or property damage
by:

· sending an erroneous signal to your system’s field devices

causing unintended machine motion or loss of process
control.

· causing an explosion in a hazardous environment.

Repeated electrical arcing causes excessive wear to contacts
on both the module and its mating connectors. Worn contacts
may create electrical resistance that can affect module
operation.

When you insert or remove a module while

Compliance to European Union Directives

If this product bears the CE marking, it is approved for installation within
the European Union and EEA regions. It has been designed and tested to
meet the following directives.

EMC Directive

This product 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:

12 ControlLogix™ Universal Analog Input Module

EN 61010-1 and EN 61131-2, EN61000-6-2:2001, EN61000-6-4:2001
EN61010-1:2001

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.

For specific information required by , EN61131-2:1994 + A1 1:1996 +
A12:2000, 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 B1 11

This equipment is classified as open equipment and must be installed
(mounted) in an enclosure during operation as a means of providing safety
protection.

CAUTION

POSSIBLE EQUIPMENT OPERATION

!

AA

TTENTION:TTENTION:

A

TTENTION:

AA

TTENTION:TTENTION:
and Insertion Under Power (RIUP). However, when you remove
or insert an RTB with field-side power applied,
macmac

hine motion or loss ofhine motion or loss of

mac

hine motion or loss of

macmac

hine motion or loss ofhine motion or loss of

Exercise extreme caution when using this feature.

WARNING
The 1756sc-IF8U module is to be used only with the Allen-

!

Bradley 1756 ControlLogix System.

The module is designed to support Removal

unintendedunintended

unintended

unintendedunintended

pr pr

pr

pr pr

ocess ocess

ocess

ocess ocess

contrcontr

ol can occurol can occur

contr

ol can occur.

contrcontr

ol can occurol can occur

Chapter 2: Installing And Wiring Y our Module 13

T o insert your module into the rack, follow these steps:

1. Align the circuit board of your module with the card guides at the top
and bottom of the chassis.

Figure 2.1. Module insertion into a rack

2. Key the R TB in positions that correspond to unkeyed module positions.
Insert the wedge-shaped tab on the RTB with the rounded edge first.
Push the tab onto the R TB until it stops.

Keying the Removable Terminal Block

Key the RTB to prevent inadvertently connecting the incorrect RTB to
your module.

When the RTB mounts onto the module, keying positions will match up.
For example, if you place a U-shaped keying band in position #4 on the
module, you cannot place a wedge-shaped tab in #4 on the R TB or your
RTB will not mount on the module.

W e recommend that you use a unique keying pattern for each slot in the
chassis.

1. Insert the U-shaped band with the longer side near the terminals. Push

the band onto the module until it snaps into place.

14 ControlLogix™ Universal Analog Input Module

Figure 2.2. Terminal block diagram with keying

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

• Peripheral equipment must be suitable for the location in which it is
used.

• Route the field wiring away from any other wiring and 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 120 V 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.

• T o limit the pickup of electrical noise, keep thermocouple, R TD,
millivolt, and milliamp signal wires as far from power and load lines as
possible.

• For improved 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 or RTD manufacturer. Using the incorrect type of
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 at the ControlLogix
chassis. (Refer to IEEE Std. 518, Section 6.4.2.7 or contact your sensor
manufacturer for additional details.)

Preparing and
Wiring the Cables

Chapter 2: Installing And Wiring Y our Module 15

• Keep all unshielded wires as short as possible.

• T o limit overall cable impedance, keep input cables as short as possible.
Locate your I/O chassis as near the RTD or thermocouple sensors as
your application will permit.

• Tighten screw terminals with care. Excessive tightening can strip a
screw . The RTB terminations can accommodate 2.1…0.25 mm2
(14…22 AWG) shielded wire and a torque of 0.5 N•m (4.4 lb•in.).

• Follow system grounding and wiring guidelines found in your
ControlLogix Installation and Operation Manual.

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

Signal Wires

Cable

Drain Wire

(At the module-end of the cable, extract
the drain wire but remove the foil shield.)

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

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 (see figure above):

- 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 grounding lug on the PLC chassis.

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. At the source-end of cables from mV devices:

- remove the drain wire and foil shield

- apply shrink wrap as an option

16 ControlLogix™ Universal Analog Input Module

- connect to mV devices keeping the leads short

Important: If noise persists, try grounding the opposite end of the cable,
instead (Ground one end only.)

Terminal Block
Layout

The following figure shows the general terminal block layout. The input
signal type will determine which pins are used.

Wiring Voltage/
Current Inputs the
IF8u Module

Chapter 2: Installing And Wiring Y our Module 17

V oltage inputs use the terminal block pins labelled IN+ and IN­Current inputs use the terminal block pins labelled IN+ and IN-

Voltage Inputs

EXC+

IN+

IN­iRTN

CABLE SHIELD

Current Inputs

Voltage +

Voltage -

ADD
JUMPER

EXC+

IN+

IN­iRTN

Current +

Current -

CABLE SHIELD

18 ControlLogix™ Universal Analog Input Module

Wiring RTD or
Resistance Sensors
to the IF8u Module

The IF8u module supports two, three, and four wire RTDs or resistance
inputs connected individually to the module as shown in the figure below.

These are:
* 2-wire R TDs, which are composed of 2 RTD lead wires (EXC+ and

IN- with a jumper between EXC+ and IN+)

* 3-wire R TDs, which are composed of a 2 Signal and 1 RTD return lead

wires (EXC+ and IN+ with a the return RTD lead to IN-)

* 4-wire R TDs, which are composed of 2 Signal and 2 RTD return lead

wires (EXC+ and IN+ with a the return RTD lead to IN-) The fourth
lead is not used so wiring is identical to 3 wires RTDs.

* 2- wire Resistance, which is composed of 2 leads (EXC+ and IN- with

a jumper between EXC+ and IN+)

* 3- wire Resistance, which is composed of 3 leads (EXC+ IN+ and

IN-) and the resistance lies between IN+ and IN-

In any RTD sensing system, it is important that the lead and sense wire
resistances are matched as much as possible. The lead lengths, and their
resulting impedances, must be matched and kept small to eliminate the
introduction of connectivity errors. The 3/4-wire R TDs are the most
accurate, with 2-wire R TDs being the most inaccurate. In 2-wire the lead
resistance adds error to the resulting degree reading. With a 1.008mA
current source, 1Ω of lead resistance adds 1.008µV, or 2.82°C error, with
the 100Ω 385 alpha type. T o gain an understanding of how lead
resistance affects RTD readings, the µV/C for each RTD type is listed
below.