Spectrum Controls 1794 User manual

User’s Manual Pub. 0300231-03 Rev. A
1794 Isolated
Universal Input Module
Catalog Number: 1794sc-IF8IU

ii Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
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 Series A and
firmware version 1.0 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.

iii
User's Manual Pub. 0300231-03 Rev. A
Table of Contents
IMPORTANT NOTES ............................................................................................................................................... II
NOTICE .................................................................................................................................................................. II
LIMITED WARRANTY .............................................................................................................................................. II
CHAPTER 1 MODULE OVERVIEW......................................................................................................................... 1-1
SECTION 1.1 GENERAL DESCRIPTION .............................................................................................................................. 1-1
SECTION 1.2 INPUT TYPES AND RANGES.......................................................................................................................... 1-1
SECTION 1.3 DATA FORMATS ....................................................................................................................................... 1-2
SECTION 1.4 FILTER FREQUENCIES ................................................................................................................................ 1-2
SECTION 1.5 HARDWARE FEATURES .............................................................................................................................. 1-2
SECTION 1.6 SYSTEM OVERVIEW ................................................................................................................................... 1-3
1.6.1 Module Power-up ..................................................................................................................................... 1-3
SECTION 1.7 MODULE OPERATION ................................................................................................................................ 1-4
CHAPTER 2 INSTALLATION AND WIRING............................................................................................................. 2-1
SECTION 2.1 COMPLIANCE TO EUROPEAN UNION DIRECTIVES............................................................................................. 2-1
2.1.1 EMC Directive............................................................................................................................................ 2-1
2.1.2 Low Voltage Directive ............................................................................................................................... 2-1
SECTION 2.2 GENERAL CONSIDERATIONS ........................................................................................................................ 2-2
2.2.1 Hazardous Location Considerations.......................................................................................................... 2-2
2.2.2 Prevent Electrostatic Discharge ................................................................................................................ 2-2
2.2.3 Remove Power .......................................................................................................................................... 2-3
2.2.4 Selecting a Location .................................................................................................................................. 2-3
SECTION 2.3 POWER REQUIREMENTS ............................................................................................................................ 2-3
2.3.1 Wiring the Terminal Base Units (1794-TB3G shown)................................................................................ 2-3
SECTION 2.4 INSTALLING THE MODULE........................................................................................................................... 2-5
2.4.1 Mounting the Terminal Base Unit on a DIN Rail ....................................................................................... 2-5
2.4.2 Panel/Wall Mounting ............................................................................................................................... 2-7
2.4.3 Mounting the IF8IU Module on the Terminal Base Unit ........................................................................... 2-9
SECTION 2.5 FIELD WIRING CONNECTIONS.................................................................................................................... 2-10
2.5.1 Field Wiring using a 1794-TB3G and TB3GS Terminal Base.................................................................... 2-10
SECTION 2.6 MODULE INDICATORS.............................................................................................................................. 2-16
CHAPTER 3 CONFIGURING THE 1794SC-IF8IU USING RSLOGIX 5000.................................................................... 3-1
SECTION 3.1 THINGS YOU SHOULD KNOW ...................................................................................................................... 3-1
SECTION 3.2 MODULE MEMORY MAP ........................................................................................................................... 3-1
SECTION 3.3 CONFIGURE GENERIC PROFILE..................................................................................................................... 3-2
3.3.1 Add a Local Ethernet Bridge Module ........................................................................................................ 3-3
3.3.2 Add a Remote Ethernet Flex Adapter........................................................................................................ 3-4
3.3.3 Add the Generic Flex Module .................................................................................................................... 3-6
SECTION 3.4 MODULE CONFIGURATION......................................................................................................................... 3-7
3.4.1 Fault Mode [Word 0 (Bits 2,3,4,5,10,11,12,13)] ....................................................................................... 3-9
3.4.2 Input Type [Words 1 –8 (Bits 0 to 4)] ..................................................................................................... 3-10
3.4.3 Input Filter [Words 1 –8 (Bits 5 to 7) ...................................................................................................... 3-10
3.4.4 Data Format [Words 1 –8 (Bits 8 to 10) ................................................................................................. 3-11
3.4.5 Open Circuit Mode [Words 1 –8 (Bits 12 & 13)]..................................................................................... 3-12
3.4.6 Disable CJC [Words 1 –8 (Bit 14)]........................................................................................................... 3-12
3.4.7 Temperature Units [Words 1 –8 (Bit 15)]............................................................................................... 3-12
3.4.8 Low Alarm Threshold [Words 9,12,15,18,21,24,27,30] .......................................................................... 3-13
3.4.9 High Alarm Threshold [Words 10,13,16,19,22,25,28,31] ....................................................................... 3-13
3.4.10 User Alarm Deadband [Words 11,14,17,20,23,26,29,32]..................................................................... 3-13
3.4.11 Calibration Offset [Words 33 to 40]...................................................................................................... 3-13

iv Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
3.4.12 CJC Offset [Words 41 to 48] .................................................................................................................. 3-14
SECTION 3.5 READ INPUT &STATUS DATA.................................................................................................................... 3-14
3.5.1 Input Data [Words 0 to 7] ....................................................................................................................... 3-16
3.5.2 UnderRange Alarms [Word 8 (Bits 0 to 7)] ............................................................................................. 3-16
3.5.3 OverRange Alarm [Word 8 (Bits 8 to 15)] ............................................................................................... 3-16
3.5.4 User Low Alarm [Word 9 (Bits 0 to 7)] .................................................................................................... 3-16
3.5.5 User High Alarm [Word 9 (Bits 8 to 15)] ................................................................................................. 3-16
3.5.6 Open Circuit Alarm [Word 10 (Bits 0 to 7)] ............................................................................................. 3-17
3.5.7 CJC Alarm [Word 10 (Bits 8 & 9)] ............................................................................................................ 3-17
3.5.8 Diagnostics [Word 11 (Bits 0 to 7)] ......................................................................................................... 3-17
APPENDIX A MODULE SPECIFICATIONS...............................................................................................................A-1

v
User's Manual Pub. 0300231-03 Rev. A
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 Allen-Bradley I/O and/or compatible controllers,
such as MicroLogix, CompactLogix, ControlLogix, SLC 500 or PLC 5.
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
1794sc-IF8IU.
Related
Documentation The table below provides a listing of publications that contain important information
about Allen-Bradley PLC systems.
Document Title
Document Number
1794 Flex IO Product Data
1794-2.1
CompactLogix System Overview
1769-SO001A-EN-P
ControlLogix System User Manual
1756-6.5.13-SEP99
ControlNet Modules in Logix5000 Control Systems
User Manual
CNET-UM001C-EN-P
EtherNet/IP Modules in Logix5000 Control Systems
User Manual
ENET-UM001G-EN-P
Allen-Bradley Programmable Controller
Grounding and Wiring Guidelines
1770-4.1
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:
oContacting your local distributor or Rockwell Automation
representative
oVisiting www.theautomationbookstore.com and placing your order
oCalling 1.800.963.9548 (USA/Canada) or 001.330.725.1574
(Outside USA/Canada)

vi Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
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
Bold type identifies headings and sub-headings
Are used to identify critical information to the reader
!
Attention

User's Manual Pub. 0300231-03 Rev. A
Chapter 1
Module Overview
This chapter describes the 1794sc-IF8IU Isolated Universal input module and explains
how the module reads current, voltage, RTD, resistance and thermocouple/millivolt
analog input data. Included is information about:
General description
Input types and ranges
Data Formats and filter frequencies
Hardware Features
System overview and module operation
Auto-calibration
Section 1.1
General
Description The isolated universal input module supports current, voltage, RTD, resistance,
thermocouple and millivolt type inputs. The module digitally converts and stores analog
data from any combination mentioned above. Each input channel is individually
configured via software for a specific input device, data format, filter frequency, and
provides open-circuit, over-range, under-range detection and indication.
Section 1.2
Input Types
and Ranges The tables below list the input types and their associated ranges.
Input Type
Range
B Type Thermocouple
300 to 1820 ˚C (572 to 3308 ˚F)
C Type Thermocouple
0 to 2315 ˚C (32 to 4199 ˚F)
E Type Thermocouple
-270 to 1000 ˚C (-454 to 1832 ˚F)
J Type Thermocouple
-210 to 1200 ˚C (-346 to 2192 ˚F)
K Type Thermocouple
-270 to 1370 ˚C (-454 to 2498 ˚F)
N Type Thermocouple
-210 to 1300 ˚C (-346 to 2372 ˚F)
R Type Thermocouple
0 to 1768 ˚C (32 to 3214 ˚F)
S Type Thermocouple
0 to 1768 ˚C (32 to 3214 ˚F)
T Type Thermocouple
-270 to 400 ˚C (-270 to 752 ˚F)
100 Ω Pt α 0.385
-200 to 850 ˚C (-328 to 1562 ˚F)
200 Ω Pt α 0.385
-200 to 850 ˚C (-328 to 1562 ˚F)
500 Ω Pt α 0.385
-200 to 850 ˚C (-328 to 1562 ˚F)
1000 Ω Pt α 0.385
-200 to 850 ˚C (-328 to 1562 ˚F)
100 Ω Pt α 0.3916
-200 to 630 ˚C (-328 to 1166 ˚F)
200 Ω Pt α 0.3916
-200 to 630 ˚C (-328 to 1166 ˚F)
500 Ω Pt α 0.3916
-200 to 630 ˚C (-328 to 1166 ˚F)
1000 Ω Pt α 0.3916
-200 to 630 ˚C (-328 to 1166 ˚F)
10 Ω Cu α 0.426
-100 to 260 ˚C (-148 to 500 ˚F)
100 Ω Ni α 0.618
-100 to 260 ˚C (-148 to 500 ˚F)

1-2 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
Input Type
Range
120 Ω Ni α 0.672
-80 to 260 ˚C (-112 to 500 ˚F)
604 Ω NiFe α 0.518
-100 to 200 ˚C (-148 to 392 ˚F)
Resistance
0 to 150 Ω
0 to 1000 Ω
0 to 3000 Ω
Voltage
+/- 50 mV
+/- 100 mV
0 to 5V
1 to 5V
+/- 10V
0 to 10V
Current
4 to 20 mA
0 to 20 mA
Section 1.3
Data Formats For each module the data can be configured for:
Engineering units x 1
Engineering units x 10
Scaled-for-PID
Percent of full-scale
Raw/proportional data
CJC Engineering Units
CJC scaled-for-PID
CJC percent of full range
Section 1.4
Filter
Frequencies The module uses a digital filter that provides high frequency noise rejection for each
input signal. The filter for each channel is programmable allowing you to select from six
different filter frequencies:
4.17 Hz
10 Hz
16.7 Hz
19.6 Hz
62 Hz
470 Hz
Section 1.5
Hardware
Features Each module requires a terminal base unit. Terminal base units are connected together to
form the backplane for the system. Each base unit contains terminals for field
terminations. Field terminations are wired as differential inputs with the exception of

Chapter 1: Module Overview 1-3
User's Manual Pub. 0300231-03 Rev. A
RTD and resistance type inputs. Two cold junction compensation (CJC) sensors can be
added to the terminal base unit to enable accurate readings when using thermocouple
input types. Each CJC sensor compensates for offset voltages introduced into the input
signal as a result of the cold-junction where the thermocouple wires come into contact
with the base unit. Module configuration is accomplished using the controller’s
programming software. In addition, some controllers support configuration via the user
program. In either case, the module configuration is stored in the memory of the
controller. Refer to your controller’s user manual for more information. The illustration
below shows the module’s hardware features.
Item
Description
1
Module Catalog Number
2
Module key-switch position
3
Removable label
4
Power/Status LED
Section 1.6
System
Overview The module communicates to the controller through the base unit bus interface. The
module also receives 5 and 24V dc power through the bus interface.
Note: An external power supply is required for all 2-wire transmitters.
1.6.1 Module Power-up
At power-up, the module performs a check of its internal circuits, memory and basic
functions. 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, it continuously
converts the input data to a digital value within the currently selected data range. Each
time a channel is read by the input module, that data value is tested by the module for an
over-range, under-range, or open-circuit condition. If such a condition is detected, a
unique bit is set in the channel status word. The channel status word is described in the
Input Data File in Chapter 3. Using the module image table, the controller reads the
two’s complement 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 made available to the control program.
Figure 1-1
1
2
3
4

1-4 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
Section 1.7
Module
Operation The module measures each analog signal using a dedicated A/D converter for each
channel. The converter reads the signal and converts it as required for the type of input
selected. If thermocouples are being utilized, the module continuously samples each CJC
sensor and compensates for temperature changes at the terminal base cold junction,
between the thermocouple wire and the input terminal. See the block diagram below.
The module is designed to support up to 8 isolated channels of RTD, resistance, voltage,
current, or thermocouple.
Thermocouple measurements utilize two cold junction compensation sensors placed at
two different locations on the terminal base unit. The location of each CJC sensor was
chosen to calculate the overall CJC error accurately for each channel. Thermocouple
support includes types J, K, T, E, R, S, B, N, and C. In thermocouple mode the 1794sc-
IF8IU will measure thermocouple and CJC voltages and convert the results to a
linearized temperature reading.
RTD support includes types Pt 385, Pt 3916, Ni 618, Ni 672, Cu 426, and NiFe 518. In
RTD and resistance mode the module will inject a constant current through the RTD or
resistor, measure the voltage across the resistance and convert to a linearized temperature
or resistance reading. The IFIU supports 2 and 3 wired RTD inputs.
When configured for current or voltage type inputs, the module converts the analog
values directly into digital counts.
1794 FLEX
Terminal Base Unit
ADC
+ FLTR
MUX
MICRO-
CNTRLR
24 VDC
Isolated PWR Supply
1 of 8
8 of 8
8 Channels &
24VDC PWR
Signal
Conditioning
Isolation
Barrier
Backplane
COMMS

User's Manual Pub. 0300231-03 Rev. A
Chapter 2
Installation and Wiring
This chapter will cover:
Compliance to European union directives
General considerations
Power requirements
Installing the module
Field wiring connections
Section 2.1
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.
2.1.1 EMC Directive
The 1794sc-IF8IU 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 61000-6-4EMC –Generic Emission Standard, Part 2 - Industrial
Environment
EN 61000-6-2EMC –Generic Immunity Standard, Part 2 - Industrial
Environment
This product is intended for use in an industrial environment.
2.1.2 Low Voltage Directive
This product is tested to meet Council Directive 2006/99/EC Low Voltage, by applying
the safety requirements of EN 61131-2Programmable Controllers, Part 2 –Equipment
Requirements and Tests. 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

2-2 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
Section 2.2
General
Considerations Flex 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
.
2.2.1 Hazardous Location Considerations
This equipment is suitable for use in Class I, Division 2, Groups A, B, C, D or non-
hazardous locations only. The following WARNING statement applies to use in
hazardous locations.
EXPLOSION HAZARD
Substitution of components may impair suitability for Class I,
Division 2.
Do not replace components or disconnect equipment unless
power has been switched off or the area is known to be non-
hazardous.
Do not connect or disconnect components unless power has
been switched off or the area is known to be non-hazardous.
This product must be installed in an enclosure.
All wiring must comply with N.E.C. article 501-4(b).
2.2.2 Prevent Electrostatic Discharge
Electrostatic discharge can damage integrated circuits or
semiconductors if you touch analog I/O module bus connector pins or
the terminal block on the input module. 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 bus connector or connector pins.
Do not touch circuit components inside the module.
If available, use a static-safe work station.
When it is not in use, keep the module in its static-shield bag.
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.
!
Attention
!
Attention

Chapter 2: Installation and Wiring 2-3
User's Manual Pub. 0300231-03 Rev. A
2.2.3 Remove Power
Remove power before removing or inserting this module. When you
remove or insert a module with power applied, an electrical arc may
occur. An electrical arc can cause personal injury or property damage
by:
Sending an erroneous signal to your system’s field devices,
causing unintended machine motion
Causing an explosion in a hazardous environment
Electrical arcing causes excessive wear to contacts on both the module
and its mating connector and may lead to premature failure.
2.2.4 Selecting a Location
Reducing Noise
Most applications require installation in an industrial enclosure to reduce the effects of
electrical interference. Analog inputs are highly susceptible to electrical noise. Electrical
noise coupled to the analog inputs will reduce the performance (accuracy) of the module.
Group your modules to minimize adverse effects from radiated electrical noise and heat.
Consider the following conditions when selecting a location for the analog module.
Position the module:
Away from sources of electrical noise such as hard-contact switches, relays, and
AC motor drives
Away from modules which generate significant radiated heat, such as the 1794-
OB32. Refer to the module’s heat dissipation specification.
In addition, route shielded, twisted-pair analog input wiring away from any high voltage
I/O wiring.
Section 2.3
Power
Requirements The module receives power through the bus interface from the +5V dc/+24V dc system
power supply. The maximum current drawn by the module is shown in the table below.
5 VDC
24 VDC
80 mA
240 mA
The wiring of the terminal base unit is determined by the current draw through the
terminal base. Make certain that the current draw does not exceed 10A.
Total current draw through the terminal base unit is limited to 10A.
Separate power connections may be necessary.
Methods of wiring the terminal base units are shown in the illustration below.
2.3.1 Wiring the Terminal Base Units (1794-TB3G shown)
!
Attention
!
Attention

2-4 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
Do not daisy chain power or ground from the terminal base unit to any
ac or dc digital module terminal base unit.
Daisy-chaining
Note: All modules must be frequency or IF8IU modules for this
configuration.
Wiring when total current draw is less than 10A
Individual
Note: Use this configuration if using any “noisy” dc digital I/O modules in
your system.
IF8IU module wiring separate from digital wiring
Wiring when total current draw is greater than 10A
!
Attention
Power
IF8u
Module
IF8u
Module
Frequency Input
Module
24 VDC
Power
Digital Input
Module
IF8u
Module
Digital Input
Module
24 VDC
24 VDC
24 VDC

Chapter 2: Installation and Wiring 2-5
User's Manual Pub. 0300231-03 Rev. A
Combination
Note: All modules powered by the same power supply must be frequency
or IF8IU modules for this configuration.
Total current draw through any base unit must not be greater than
10A
Section 2.4
Installing the
Module Installation of the analog module consists of:
Mounting the terminal base unit
Installing the IF8IU module into the terminal base unit
Installing the connecting wiring to the terminal base unit
If you are installing your module into a terminal base unit that is already installed,
proceed to “Mounting the IF8IU Module on the Terminal Base Unit” on page 2-9.
2.4.1 Mounting the Terminal Base Unit on a DIN Rail
Do not remove or replace a terminal base unit when power is applied.
Interruption of the flexbus can result in unintended operation or
machine motion.
1) Remove the cover plug (if used) in the male connector of the unit to which you
are connecting this terminal base unit.
2) Check to make sure that the 16 pins in the male connector on the adjacent device
are straight and in line so that the mating female connector on this terminal base
unit will mate correctly.
3) Position the terminal base on the 35 x 7.5mm DIN rail A (A-B pt.no. 199-DR1;
!
Attention
24 VDC
24 VDC
Power
Frequency Input
Module
IF8u
Module
Frequency Input
Module

2-6 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
46277-3) at a slight angle with hook B on the left side of the terminal base
hooked into the right side of the unit on the left. Proceed as follows:

Chapter 2: Installation and Wiring 2-7
User's Manual Pub. 0300231-03 Rev. A
4) Repeat the above steps to install the next terminal base.
2.4.2 Panel/Wall Mounting
Installation on a wall or panel consists of:
Laying out the drilling points on the wall or panel
Drilling the pilot holes for the mounting screws
Mounting the adapter mounting plate
Installing the terminal base units and securing them to the wall or panel
If you are installing your module into a terminal base unit that is already installed,
proceed to “Mounting the IF8IU Module on the Terminal Base Unit” on page 2-9.
Use the mounting kit Cat. No. 1794-NM1 for panel/wall mounting.

2-8 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
To install the mounting plate on a wall or panel:
1) Lay out the required points on the wall/panel as shown in the drilling dimension
drawing.
Drilling Dimensions for Panel/Wall Mounting of Flex IO
2) Drill the necessary holes for the #6 self-tapping mounting screws.
3) Mount the mounting plate (1) for the adapter module using two#6 self-tapping
screws (18 included for mounting up to 8 modules and the adapter).
Make certain that the mounting plate is properly grounded to the
panel. Refer to “Industrial Automation Wiring and Grounding
Guidelines,” publication1770-4.1.
4) Hold the adapter (2) at a slight angle and engage the top of the mounting plate in
the indention on the rear of the adapter module.
5) Press the adapter down flush with the panel until the locking lever locks.
6) Position the terminal base unit up against the adapter and push the female bus
connector into the adapter.
7) Secure to the wall with two #6 self-tapping screws.
8) Repeat for each remaining terminal base unit.
!
Attention

Chapter 2: Installation and Wiring 2-9
User's Manual Pub. 0300231-03 Rev. A
Note: The adapter is capable of addressing eight modules. Do not exceed a
maximum of eight terminal base units in your system.
2.4.3 Mounting the IF8IU Module on the Terminal Base Unit
The IF8IU isolated input module mounts on a 1794-TB3G or TB3GS terminal base unit.
1) Rotate the key-switch (1) on the terminal base unit (2) clockwise to position 3 as
required for the IF8IU module.
2) Make certain the flexbus connector (3) is pushed all the way to the left to
connect with the neighboring terminal base/adapter. You cannot install the
module unless the connector is fully extended.
3) Make sure that the pins on the bottom of the module are straight so they will
align properly with the connector in the terminal base unit.
This module is UL listed only when used with listed Allen-Bradley
catalog numbers 1794-TB3G or TB3GS terminal base units.
Remove field-side power before removing or inserting the module.
This module is designed so you can remove and insert it under
backplane power. When you remove or insert a module with field-side
power applied, an electrical arc may occur. An electrical arc can cause
personal injury or property damage by:
sending an erroneous signal to your system’s field devices
causing unintended machine motion
causing an explosion in a hazardous environment
Repeated electrical arcing causes excessive wear to contacts on both
the module and its mating connector. Worn contacts may create
electrical resistance.
4) Position the module (4) with its alignment bar (5) aligned with the groove (6) on
the terminal base.
5) Press firmly and evenly to seat the module in the terminal base unit. The module
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2-10 Flex™ IO Isolated Universal Input Module
User's Manual Pub. 0300231-03 Rev. A
is seated when the latching mechanism (7) is locked into the module.
6) Repeat the above steps to install the next module in its terminal base unit.
Section 2.5
Field Wiring
Connections Wiring to the IF8IU module is made through the terminal base unit on which the module
mounts. Compatible terminal base units are:
Module
1794-TB3G
1794-TB3GS
1794sc-IF8IU
Yes
Yes
2.5.1 Field Wiring using a 1794-TB3G and TB3GS Terminal Base
1) Connect the individual signal wiring to numbered terminals on the 0–15 row (A)
and 17–32 row (B) on the terminal base unit. Connect the input devices as
shown in the wiring table on page 2-11 .
2) Terminate shields: to terminals 16 or 33 on row B, or 40 through 45 on row C.
3) Connect +24V dc to terminal 34 on the 34-51 row (C), and 24V common to
terminal 35 on the 34-51 row (C).
To reduce susceptibility to noise, power IF8IU modules and digital
modules from separate power supplies. Do not exceed a length of 33ft
(10m) for dc power cabling.
4) If daisy chaining the +24V dc power to the next base unit, connect a jumper
from terminal 50 (+24V) on this base unit to terminal 34 and from terminal 51
(24V dc common) to terminal 35 on the next base unit.
Do not daisy chain power or ground from the IF8IU terminal base unit
to any ac or dc digital module terminal base unit.
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