Spectrum Controls 1794sc-IF8IU User Manual

Install guide

background image


Install Guide



Publication 0100152‐01 Rev. A (1794sc‐IF8IU) December 2008 

Install Guide

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://literature.rockwellautomation.com)
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 Spectrum Controls, 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, Spectrum
Controls, Inc. cannot assume responsibility or liability for actual use
based on the examples and diagrams.

No patent liability is assumed by Spectrum Controls, 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 Spectrum Controls, Inc., is prohibited.

Throughout this manual we use notes to make you aware of safety

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

Identifies information about practices or
circumstances that can lead to personal injury or
death, property damage, or economic loss.
Attentions help you identify a hazard, avoid a
hazard, and recognize the consequence

Environment and Enclosure
This equipment is intended for use in a Pollution
Degree 2 industrial environment, in overvoltage
Category II applications (as defined in IEC publication
60664-1), at altitudes up to 2000 m (6562 ft) without
derating. This equipment is considered Group 1, Class
A industrial equipment according to IEC/CISPR
Publication 11. Without appropriate precautions, there
may be potential difficulties ensuring electromagnetic
compatibility in other environments due to conducted
as well as radiated disturbance. This equipment is
supplied as open-type equipment. It must be mounted
within an enclosure that is suitably designed for those
specific environmental conditions that will be present
and appropriately designed to prevent personal injury
resulting from accessibility to live parts. The enclosure
must have suitable flame-retardant properties to
prevent or minimize the spread of flame, complying
with a flame spread rating of 5VA, V2, V1, V0 (or
equivalent) if non-metallic. The interior of the
enclosure must be accessible only by the use of a tool.
Subsequent sections of this publication may contain
additional information regarding specific enclosure
type ratings that are required to comply with certain
product safety certifications. Besides this publication,
see: • Industrial Automation Wiring and Grounding
Guidelines, for additional installation requirements,
Allen-Bradley publication 1770-4.1. • NEMA Standards
publication 250 and IEC publication 60529, as
applicable, for explanations of the degrees of
protection provided by different types of enclosure.

If you insert or remove the module while backplane
power is on, an electrical arc can occur. This could
cause an explosion in hazardous location installations.
Be sure that power is removed or the area is
nonhazardous before proceeding.

The FLEX I/O system is grounded through the DIN rail
to chassis ground. Use zinc plated yellow-chromate
steel DIN rail to assure proper grounding. The use of
other DIN rail materials (such as aluminum or plastic)
that can corrode, oxidize, or are poor conductors, can
result in improper or intermittent grounding. Secure
the DIN rail to mounting surface approximately every
200 mm and use end-anchors appropriately.

If you connect or disconnect wiring while the field side
power is on, an electrical arc can occur. This could
cause an explosion in hazardous location installations.
Be sure that power is removed or the area is
nonhazardous before proceeding.

Listed only when used with Listed Allen-Bradley Cat.
NO. 1794-TB3(G) terminal base or equivalent. This
device is intended for use with A-B Type 1794 Flex-
I/O programmable controller system.” or equivalent.

Prevent Electrostatic Discharge

This equipment is sensitive to electrostatic discharge,
which can cause internal damage and affect normal
operation. Follow these guidelines when you handle
this equipment:
• Touch a grounded object to discharge potential
• Wear an approved grounding wrist strap.
• Do not touch connectors or pins on component
• Do not touch circuit components inside the

• Use a static-safe workstation, if available.
•Store the equipment in appropriate static-safe
packaging when not in use.

European Hazardous Location Approval

Observe the following additional Zone 2
certification requirements:
• This equipment is not resistant to sunlight or
other sources of UV radiation.
• This equipment must be installed in an
enclosure providing at least IP54 protection
when applied in Class I, Zone 2 environments.
• This equipment shall be used within its
specified ratings defined by Spectrum Controls.
• Provision shall be made to prevent the rated
voltage from being exceeded by transient
disturbances of more than 40% when applied in
Class I, Zone 2 environments

North American Hazardous Location Approval

The following information applies when
operating this equipment in hazardous

Informations sur l’utilisation de cet
équipement en environnements

Products marked “CL I, DIV 2, GP A, B, C, D”
are suitable for use in Class I Division 2 Groups
A, B, C, D, hazardous locations and
nonhazardous locations only. Each product is
supplied with markings on the rating nameplate
indicating the hazardous location temperature
code. When combining products within a system,
the most adverse temperature code (lowest “T”
number) may be used to help determine the
overall temperature code of the system.
Combinations of equipment in your system are
subject to investigation by the local Authority
Having Jurisdiction at the time of installation.

Les produits marqués “CL I, DIV 2, GP
A, B, C, D” ne conviennent qu’à une
utilisation en environnements de Classe
I Division 2 Groupes A, B, C, D
dangereux et non dangereux. Chaque
produit est livré avec des marquages sur
sa plaque d’identification qui indiquent le
code de température pour les
environnements dangereux. Lorsque
plusieurs produits sont combinés dans
un système, le code de température le
plus défavorable (code de température
le plus faible) peut être utilisé pour
déterminer le code de température
global du système. Les combinaisons
d’équipements dans le système sont
sujettes à inspection par les autorités
locales qualifiées au moment de


•Do not disconnect
equipment unless power
has been removed or the
area is known to be

•Do not disconnect
connections to this
equipment unless power
has been removed or the
area is known to be
nonhazardous. Secure any
external connections that
mate to this equipment by
using screws, sliding
latches, threaded
connectors, or other means
provided with this product.

•Substitution of
components may impair
suitability for Class I,
Division 2.

•If this product contains
batteries, they must only be
changed in an area known
to be nonhazardous.


•Couper le courant
ou s’assurer que
l’environnement est
classé non
dangereux avant
de débrancher

•Couper le courant
ou s'assurer que
l’environnement est
classé non
dangereux avant
de débrancher les
connecteurs. Fixer
tous les
externes reliés à
cet équipement à
l'aide de vis,
connecteurs filetés
ou autres moyens
fournis avec ce

•La substitution de
composants peut
rendre cet
inadapté à une
utilisation en
environnement de
Classe I, Division

•S’assurer que
l’environnement est
classé non
dangereux avant
de changer les

Install Your IF8IU Input Module

During mounting of all devices, be sure that all
debris (for example, metal chips or wire strands)
is kept from falling into the module. Debris that
falls into the module could cause damage on
power up.

The module mounts on a 1794-TB3G 0r 1794-TB3GS terminal base.
1.Rotate the keyswitch (1) on the terminal base (2) clockwise to position 3

as required for this type of 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 the pins on the bottom of the module are straight so they will
align properly with the connector in the terminal base.

If you remove or insert the module while the
backplane power is on, an electrical arc can
occur. This could cause an explosion in
hazardous location installations. Be sure that
power is removed or the area is

nonhazardous before proceeding.

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 is seated when the latching mechanism (7) is locked into the


Connect Wiring for the 1794-TB3G or 1794-TB3GS Terminal Base
1.Connect individual input wiring and associated signal returns to
numbered terminals on the 0…15 row (A) and the 16…33 row (B) as

indicated in the table.
Use Belden 8761 cable for mV signal wiring, or the appropriate

thermocouple wire for your thermocouples.

2.Signal wiring shields can be connected to terminals 16 or 33 on row (B)

or terminals 40…45 on row (C).
3.Connect the +V dc power lead to terminal 34 on the 34…51 row (C).

Connect the -V dc common (return-) to terminal 35 on the 34…51 row


To reduce susceptibility to noise, power
analog modules and digital modules from
separate power supplies. Do not exceed a
length of 3 m (9.8 ft) for dc power cabling.

Do not daisy-chain power or ground from this
terminal base unit to any ac or dc digital
module terminal base units.

5.If daisy-chaining power to the next terminal base unit, connect a jumper
from terminal 50 (+V dc) on this base unit to +V terminal on the next
terminal base unit.

Connect a jumper from terminal 51 (-V dc common) to the -V dc

common terminal on the next terminal base unit.
6.If using cold junction compensators, make these connections as shown

in the CJC Sensor chart below.

Identify RTD Wire Pairs

If the RTD wires are color-coded, the wires that are the same color are
connected together. If the wires are not color-coded, use an ohmmeter to
determine the pairs as explained below.

How to Connect a 3-wire RTD

If the 3-wire RTD wires are all different colors, use an ohmmeter to
determine which leads are connected together. Either lead of the pair can
be the compensation lead. Attach one lead of the pair to terminal L and
the other to +. Attach the single lead to -.

Refer to the following table.