Allen-Bradley FLEX I/O 1794-OB8 User manual

Installation Instructions
FLEX I/O Digital DC Output Modules
Catalog numbers 1794-OB8, 1794-OB8EP, 1794-OB16,
1794-OB16P, 1794-OB32P
Table of Contents
Topic Page
Important User Information 2
Environment and Enclosure 3
Preventing Electrostatic Discharge 3
European Hazardous Location Approval 4
North American Hazardous Location Approval 5
Installing Your Digital Output Module 7
Configuring your 1794-OB8EP Output Module 15
Configuring your 1794-OB8, 1794-OB16, 1794-OB16P, and 1794-OB32 Output Modules 17
Specifications 18

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Publication 1794-IN094C-EN-P - July 2015
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.rockwellautomation.com/literature/) 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: Identifies information about practices or circumstances that can cause an
explosion in a hazardous environment, which may lead to personal injury or death,
property damage, or economic loss.
ATTENTION: Identifies information about practices or circumstances that can lead to
personal injury or death, property damage, or economic loss. Attentions help you
identify a hazard, avoid a hazard, and recognize the consequences.
SHOCK HAZARD: Labels may be on or inside the equipment (for example, drive or
motor) to alert people that dangerous voltage may be present.
BURN HAZARD: Labels may be on or inside the equipment (for example, drive or
motor) to alert people that surfaces may reach dangerous temperatures.
IMPORTANT Identifies information that is critical for successful application and understanding of
the product.

FLEX I/O Digital DC Output Modules 3
Publication 1794-IN094C-EN-P - July 2015
Environment and Enclosure
Preventing Electrostatic Discharge
ATTENTION: 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 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.
In addition to this publication, see:
• Industrial Automation Wiring and Grounding Guidelines, Rockwell
Automation publication 1770-4.1, for additional installation requirements.
• NEMA Standard 250 and IEC 60529, as applicable, for explanations of the
degrees of protection provided by different types of enclosure.
ATTENTION: 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 static.
• Wear an approved grounding wriststrap.
• Do not touch connectors or pins on component boards.
• Do not touch circuit components inside the equipment.
• Use a static-safe workstation, if available.

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Publication 1794-IN094C-EN-P - July 2015
European Hazardous Location Approval
The following modules are European Zone 2 approved: 1794-OB8, 1794-OB8EP,
1794-OB16, 1794-OB16P.
European Zone 2 Certification
This equipment is intended for use in potentially explosive atmospheres as defined by
European Union Directive 94/9/EC.
The LCIE (Laboratoire Central des Industries Electriques) certifies that this equipment has
been found to comply with the Essential Health and Safety Requirements relating to the
design and construction of Category 3 equipment intended for use in potentially explosive
atmospheres, given in Annex II to this Directive. The examination and test results are
recorded in confidential report No. 28 682 010.
Compliance with the Essential Health and Safety Requirements has been assured by
compliance with EN 50021.
IMPORTANT
Observe the following additional Zone 2 certification requirements.
• This equipment is not resistant to sunlight or other sources of UV
radiation.
• The secondary of a current transformer shall not be open-circuited
when applied in Class I, Zone 2 environments.
• Equipment of lesser Enclosure Type Rating 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
Allen-Bradley.
• 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.

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Publication 1794-IN094C-EN-P - July 2015
North American Hazardous Location Approval
The following modules are North American Hazardous Location approved: 1794-OB8,
1794-OB8EP, 1794-OB16, 1794-OB16P.
The following information applies when
operating this equipment in hazardous
locations:
Informations sur l’utilisation de cet
équipement en environnements dangereux:
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
l'installation.
EXPLOSION HAZARD
• Do not disconnect equipment unless power
has been removed or the area is known to be
nonhazardous.
• 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.
RISQUE D’EXPLOSION
• Couper le courant ou s'assurer que
l'environnement est classé non dangereux
avant de débrancher l'équipement.
• Couper le courant ou s'assurer que
l'environnement est classé non dangereux
avant de débrancher les connecteurs.
Fixer tous les connecteurs externes reliés
à cet équipement à l'aide de vis, loquets
coulissants, connecteurs filetés ou autres
moyens fournis avec ce produit.
• La substitution de composants peut
rendre cet équipement inadapté à une
utilisation en environnement de Classe I,
Division 2.
• S'assurer que l'environnement est classé
non dangereux avant de changer les piles.

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Publication 1794-IN094C-EN-P - July 2015
ATTENTION: FLEX I/O™ 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 (for example, aluminum or plastic) that can
corrode, oxidize, or are poor conductors, can result in improper or intermittent
grounding.
WARNING: 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.
Compatibility
The following communication adapters are required to ensure compatibility with
the 1794-IB32:
Remote I/O 1794-ASB series E or later
1794-ASB2 series D or later
ControlNet 1794-ACN15 series C, firmware revision 4.1 or later
1794-ACNR15 series C, firmware revision 4.1 or later
Ethernet 1794-AENT series A, firmware revision 2.4 or later
PROFIBUS 1794-APB series A, version 1.1 of the GSD file
(You can download the GSD file at www.ab.com/networks/gsd.)
ControlLogix Family RSLogix5000 programming software, version 11 or later

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Publication 1794-IN094C-EN-P - July 2015
Installing Your Digital Output Module
The module mounts on a 1794 terminal base.
1. Rotate the keyswitch (1) on the terminal base (2) clockwise to position 2 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.
Description Description
1 Keyswitch 5 Alignment bar
2 Terminal base 6 Groove
3 Flexbus connector 7 Latching mechanism
4 Module
ATTENTION: During mounting of all devices, be sure that all debris (metal
chips, wire strands, etc.) is kept from falling into the module. Debris that falls
into the module could cause damage on power up.
1
2
3
45
6
7

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Publication 1794-IN094C-EN-P - July 2015
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.
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 module.
Connecting Wiring for the 1794-OB8, 1794-OB8EP, 1794-OB16, and
1794-OB16P
1. Connect individual output wiring to numbered terminals on the 0-15 row (A) as
indicated in the table below (1794-OB8 – Terminals 0...7; 1794-OB16 and
1794-OB16P – terminals 0...15; 1794-OB8EP – even numbered terminals
0...14).
2. Connect the associated -V output common to the corresponding terminal on the
16-33 row (B) for each output as indicated in the table below. (Commons are
internally connected together.)
1794-OB8EP – connect associated output common to odd-numbered terminals
on row A or associated terminals on row (B).
3. Connect +V DC power to terminal 34 on the 34-51 row (C).
4. Connect -V DC common to terminal 16 on the 16-33 row (B).
5. If daisychaining power to the next terminal base, connect a jumper from terminal
51 (+V DC) on this base unit to terminal 34 on the next base unit.
6. If continuing -V DC common to the next base unit, connect a jumper from
terminal 33 (common) on this base unit to terminal 16 on the next base unit.
WARNING: 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.

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Publication 1794-IN094C-EN-P - July 2015
Wiring Connections for 1794-OB8, 1794-OB16, and 1794-OB16P
(used with 1794-TB2, 1794-TB3, or 1794-TB3S Terminal Base Unit)
Output(1)
(1) 1794-OB8 – Outputs 0...7; 1794-OB16 and 1794-OB16P – Outputs 0...15
Output Terminal Common Terminal
Output 0 A-0 B-17
Output 1 A-1 B-18
Output 2 A-2 B-19
Output 3 A-3 B-20
Output 4 A-4 B-21
Output 5 A-5 B-22
Output 6 A-6 B-23
Output 7 A-7 B-24
Output 8 A-8 B-25
Output 9 A-9 B-26
Output 10 A-10 B-27
Output 11 A-11 B-28
Output 12 A-12 B-29
Output 13 A-13 B-30
Output 14 A-14 B-31
Output 15 A-15 B-32
+V DC C-34 to C-51 (C-34 and C-51 for 1794-TB2
Common B-16 to B-33

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Wiring Connections for 1794-OB8EP
1794-TB2, 1794-TB3, 1794-TB3S 1794-TBN
Output Output
Terminal
Common
Terminal(1) Output
Terminal
Common
Terminal(2)
Output 0 A-0 A-1/B-17 B-0 C-1
Output 1 A-2 A-3/B-19 B-2 C-3
Output 2 A-4 A-5/B-21 B-4 C-5
Output 3 A-6 A-7/B-23 B-6 C-7
Output 4 A-8 A-9/B-25 B-8 C-9
Output 5 A-10 A-11/B-27 B-10 C-11
Output 6 A-12 A-13/B-29 B-12 C-13
Output 7 A-14 A-15/B-31 B-14 C-15
+V DC C-34 to C-51 (C-34 and C-51 for 1794-TB2, 1794-TBN)
Common B-16 to B-33 (B-16 and B-33 for 1794-TBN)
(1) 1794-TB2, 1794-TB3,1794 -TB3S – A-1, A-3, A-5, A-7, A-9, A-11, A-13, and A-15 are connected together inside the
module to 24V DC common.
(2) 1794-TBN – C-1, C-3, C-5, C-7, C-9, C-11, C-13, and C-15 are connected together inside the module to 24V DC common.