Allen-Bradley 1794-OF8IH User manual

Installation Instructions
FLEX I/O Isolated Output HART Analog
Module
Catalog number 1794-OF8IH
Table of Contents
Topic Page
Important User Information 2
Environment and Enclosure 3
Preventing Electrostatic Discharge 3
North American Hazardous Location Approval 4
European Hazardous Location Approval 5
Install the Module 7
Wire the Module 8
Ground the Module9 9
Module Wiring 10
Cyclic HART Input Data 17
Status Indicator 19
Specifications 20
IMPORTANT
This module can only be used with 1794-ACN(R)15 with version 5.1 (or
greater) firmware, or 1794-AENT with version 4.2 (or greater) firmware.
The 1794-AENT currently ships with version 4.1 firmware. For more
information about using this module with 1794-ACN(R)15 with version 5.1
(or greater) firmware, see 1794-RN071.

2FLEX I/O Isolated Output HART Analog Module
Publication 1794-IN120D-EN-P - September 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 Isolated Output HART Analog Module 3
Publication 1794-IN120D-EN-P - September 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 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.
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.
• Store the equipment in appropriate static-safe packaging when not in use.

4FLEX I/O Isolated Output HART Analog Module
Publication 1794-IN120D-EN-P - September 2015
North American Hazardous Location Approval
The following modules are North American Hazardous Location approved:
1794-OF8IH.
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.

FLEX I/O Isolated Output HART Analog Module 5
Publication 1794-IN120D-EN-P - September 2015
European Hazardous Location Approval
European Zone 2 Certification (The following applies when the product bears
the Ex or EEx Marking.)
This equipment is intended for use in potentially explosive atmospheres as defined by
European Union Directive 94/9/EC and 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.
This equipment is intended for use in areas which explosive atmospheres caused by
gases, vapors, mists, or air or dust mixtures are unlikely to occur, or are likely to occur only
infrequently and for short periods. Such locations correspond to Zone 2 classification
according to ATEX directive 1999/92/EC.
See the EC Declaration of Conformity at
http://www.rockwellautomation.com/products/certification for details. The type of
protection used is EX nA IIC T4 Gc according to EN 60079-15.
Compliance with the Essential Health and Safety Requirements has been assured by
compliance with EN 60079-15:2010 and EN 60079-0:2012+A11:2013, reference certificate
number DEMKO 07ATEX0724242X.
ATTENTION: This equipment is not resistant to sunlight or other sources of
UV radiation.
WARNING:
• The system shall be mounted in an ATEX certified enclosure with a
minimum ingress protection rating of at least IP54 as defined in
EN60529 and used in an environment of not more than pollution degree
2.
• This equipment shall be used within its specified ratings defined by
Allen-Bradley.
• Provision shall be made to prevent the rated voltage being exceeded by
the transient disturbances of more than 140% of the peak rated voltage.
• This equipment must be used only with ATEX certified backplanes.
• Secure any external connections that mate to this equipment by using
screws, sliding latches, threaded connectors, or other means provided
with this product.
• Do not disconnect equipment unless power has been removed or the
area is known to be nonhazardous.

6FLEX I/O Isolated Output HART Analog Module
Publication 1794-IN120D-EN-P - September 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. Secure DIN rail to mounting surface approximately every 200 mm
(7.8 in.) and use end-anchors appropriately.
ATTENTION: To reduce susceptibility to noise, power analog modules and
digital modules from separate power supplies.
ATTENTION: Do not exceed a length of 3 m (9.8 ft) for DC power cabling.
ATTENTION: To comply with the CE Low Voltage Directive (LVD), all
connected I/O must be powered from a source compliant with the following:
Safety Extra Low Voltage (SELV) or Protected Extra Low Voltage (PELV).
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.
WARNING: 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.

FLEX I/O Isolated Output HART Analog Module 7
Publication 1794-IN120D-EN-P - September 2015
Install the Module
Read this for information about how to install the module, which mounts on a 1794-TB3
or 1794-TB3S terminal base.
To install the module on a 1794 terminal base, refer to the figure and complete the
following.
1. Rotate the keyswitch (1) on the terminal base (2) clockwise to position 4 as
required for this type of module.
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.
7
1
2
6
5
3
4
44341

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Publication 1794-IN120D-EN-P - September 2015
2. Make certain the flexbus connector (3) is pushed all the way to the left to connect
with the neighboring terminal base/adapter.
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.
Wire the Module
To connect wiring for 1794-TB3 and 1794-TB3S bases, refer to the tables and figure and
complete the following.
1. Connect individual input wiring to numbered terminals on the 0…15 row A, as
indicated in the table, using Belden 8761 cable for signal wiring.
2. Connect each channel signal return to the associated terminal on row A.
IMPORTANT
You cannot install the module unless the connector is fully extended.
WARNING: 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.
WARNING: 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.
ATTENTION: Connect only one current signal per channel.

FLEX I/O Isolated Output HART Analog Module 9
Publication 1794-IN120D-EN-P - September 2015
3. Connect the +V DC power lead to terminal 34 on the 34…51 row C, and the -V
common/return to terminal 16 on the 16…33 row B.
4. If daisy-chaining 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.
5. If continuing 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.
6. For both 1794-TB3 and 1794-TB3S bases, connect wiring shields to functional
earth ground as near as possible to the module.
Ground the Module
All I/O wiring must use shielded wire. Shields must be terminated external to the module,
such as bus bars and shield-terminating feed-throughs.
ATTENTION: 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.
IN0 IN1 IN2 IN3
8 CH HART ISOLATED ANALOG INPUT
1794-xx8iH
I/O
IN4 IN5 IN6 IN7 PWR
3
44398

10 FLEX I/O Isolated Output HART Analog Module
Publication 1794-IN120D-EN-P - September 2015
Module Wiring
Wire Connections
Channel Signal
Type
Label
Markings
Catalog Numbers
1794-TB3 or 1794-TB3S Terminal
0 Current O0 A-0
Current O0 Ret A-1
1 Current O1 A-2
Current O1 Ret A-3
2 Current O2 A-4
Current O2 Ret A-5
3 Current O3 A-6
Current O3 Ret A-7
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
18 19 20 21 22 23 3324 25 26 27 28 29 30 31 3217
35 36 37 38 47 48 49 5034 51
16
39 40 41 42 43 44 45 46
Row A
Row B
Row C
Row A
Row B
Row C
Actuator
1794-TB3S shown
44552
Label placed at top of wiring area
Actuator Actuator

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Publication 1794-IN120D-EN-P - September 2015
Input Map
4 Current O4 A-8
Current O4 Ret A-9
5 Current O5 A-10
Current O5 Ret A-11
6 Current O6 A-12
Current O6 Ret A-13
7 Current O7 A-14
Current O7 Ret A-15
-V DC
common For catalog numbers 1794-TB3 and 1794-TB3S, terminals B-16…33 are internally connected in the terminal base unit.
+V DC power For catalog numbers 1794-TB3 and 1794-TB3S, terminals C-34…51 are internally
connected in the terminal base unit.
Word Bit
1514131211109876543210
0 F7F6F5F4F3F2F1F0DiagnosticStatus
1 Reserved
2 C7C6C5C4C3C2C1C0Reserved
3 X7X6X5X4X3X2X1X0Reserved
Fn =
Cn =
Xn =
Channel n Wire Fault Alarm for open or short circuit(1)
Channel n HART Current Fault
HART Device Transmitter present
(1) This alarm is disabled in Analog 0…20 mA formats (Formats 0, 1, 3) or if “Wire Fault Detection” is not enabled in
configuration.
0 = False; 1 = True
0 = False; 1 = True
0 = False; 1 = True
Note: Reserved data may not be shown in certain controller software
Wire Connections
Channel Signal
Type
Label
Markings
Catalog Numbers
1794-TB3 or 1794-TB3S Terminal

12 FLEX I/O Isolated Output HART Analog Module
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Output Map
Word Bit
1514131211109876543210
0 R GR R R R R R R DG7 DG6 DG5 DG4 DG3 DG2 DG1 DG0
1 Channel 0 Output Data
2 Channel 1 Output Data
3 Channel 2 Output Data
4 Channel 3 Output Data
5 Channel 4 Output Data
6 Channel 5 Output Data
7 Channel 6 Output Data
8 Channel 7 Output Data
DGn =
GR =
R =
Channel n Digital Output Data. Valid in Digital mode only.
Global reset. Resets all latched wire fault alarms.
Reserved
0 = Output 0 mA(1);
1 = Output 22 mA
0 = Inactive; 1 = Active
(1) When Open Wire Detect is Enabled, 0 = 100 μA on Output
Note: Reserved data may not be shown in certain controller software

FLEX I/O Isolated Output HART Analog Module 13
Publication 1794-IN120D-EN-P - September 2015
Configuration Map
Word Bit
1514131211109876543210
0FTREW
7EW 6EW 5EW 4BOB(1)
(1) Not shown or used in RSLogix 5000.
RREW
3EW 2EW 1EW 0BOA(1)
1 DH7 DH6 DH5 DH4 DH3 DH2 DH1 DH0 Reserved
2 CH 3 Format CH 2 Format CH 1 Format CH 0 Format
3 CH 7 Format CH 6 Format CH 5 Format CH 4 Format
4 CH1 HART Current Ratio L1 AFS1 CH0 HART Current Ratio L0 AFS0
5 CH3 HART Current Ratio L3 AFS3 CH2 HART Current Ratio L2 AFS2
6 CH5 HART Current Ratio L5 AFS5 CH4 HART Current Ratio L4 AFS4
7 CH7 HART Current Ratio L7 AFS7 CH6 HART Current Ratio L6 AFS6
8DF7
DF6 DF5 DF4 DF3 DF2 DF1 DF0 DM7 DM6 DM5 DM4 DM3 DM2 DM1 DM0
9 Channel 0 Analog Fault Value Output Data
10 Channel 1 Analog Fault Value Output Data
11 Channel 2 Analog Fault Value Output Data
12 Channel 3 Analog Fault Value Output Data
13 Channel 4 Analog Fault Value Output Data
14 Channel 5 Analog Fault Value Output Data
15 Channel 6 Analog Fault Value Output Data
16 Channel 7 Analog Fault Value Output Data
17 Reserved C7 C6 C5 C4 C3 C2 C1 C0
Note: Reserved data may not be shown in certain controller software

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Publication 1794-IN120D-EN-P - September 2015
Configuration Map Descriptions
BOA
BOB Byte order group A Byte order group B Byte order group A and B values must match
each other.
Refer to Byte Order table.
FT LocalFaultMode 0 = Outputs set to
safe value on
communication
faults only
1 = Output set to safe
value on any fault
EWn Fault Enable for wire fault
detection on channel n.(1)
(1) Not supported in Analog 0…20 mA formats.
0 = Disable wire
off/lead break
detection
1 = Enable wire
off/lead break
detection(2)
(2) Lead break must be present for 100 ms or more.
CHn HART Current Ratio HART current fault ratio limit on
channel n Valid values are 0, or 5...31 percent of full scale. A value of 0 disables this feature.
Refer to HART Current Ratio table for more
information.
ASFn Channel n Analog Fault Mode
Selection Refer to the Channel Analog Fault Mode Selection table.
Ln Channel n Enable Latching of
wire fault 0 = Unlatched 1 = Latched
DFn Channel n Digital Fault Mode
Selection 0 = Reset (0 mA) 1 = Hold Last State
DMn Channel n Enable Digital Mode 0 = Analog 1 = Digital
Fn Fault Mode Channel n 0 = Local/Remote
faults disabled 1 = Enabled
DHn Disable HART communications
on channel n 0 = HART communications
enabled
1 = HART
communications
disabled
Cn HART CMD 3 Disable 0 = HART CMD 3
communications
enabled
1 = HART CMD 3
communications
disabled
R Reserved
CH n Format Refer to Channel Data Formats table.

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Byte Order
Channel Analog Fault Mode Selection
HART Current Ratio
Byte Order
Group B Byte Order Group A
Bit 9 Bit 8 Bit 1 Bit 0 Description
0 0 0 0 Little Endian Format (default) — all data entries in true Little Endian
format.
1 0 1 0 Word Swap — word swap only values requiring more than one word,
for example, 32 bit float values.
0 1 0 1 Byte Swap — byte swap all words in data table.
1 1 1 1 Big Endian Format — all data entries in true Big Endian format.
Bits
98
Analog Fault Mode Decimal Value 1 0
Min Scale 0 0 0
Max Scale 1 0 0
Hold Last State 2 1 0
User Specified Data Value 3 1 1
Bits
15 14 13 12 11
HART Current Ratio Limit Decimal Value 7 6 5 4 3
Disabled 0 0 0 0 0 0
Not applicable 1 0 0 0 0 1
Not applicable 2 0 0 0 1 0
Not applicable 3 0 0 0 1 1
Not applicable 4 0 0 1 0 0
5% 5 00101
6% 6 00110

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Channel Data Formats
7% 7 00111
8% 8 01000
9% 9 01001
10% 10 0 1 0 1 0
... ... ... ... ... ... ...
30% 30 1 1 1 1 0
31% 31 1 1 1 1 1
Bits
15 14 13 12
11 10 9 8
7 6 5 4 Signal Range User Range
Format(1)
(1) All other formats are invalid.
3210FormatName LO HI LO HI Resolution
0 0 0 0 0 0...20 mA in
Milliamps 0.00 22.00 0 (0.000 mA) 22000 (22.000 mA) 1.0 μA
1 0 0 0 1 0...20 mA in
% Full Scale 0.00 22.00 0 (0%) 11000 (110.00%) 2.0 μA
3 0 0 1 1 0...20 mA in UINT 0 20.00 0 65535 0.3052 μA
4(2)
(2) HART Communications supported with these data formats only.
0 1 0 0 4...20 mA in
Milliamps 2.00 22.00 2000 (2.000 mA) 22000 (22.000 mA) 1.0 μA
7(2) 0 1 1 1 4...20 mA in UINT 4.00 20.00 0 65535 0.2441 μA
14(2) 1 1 1 0 4...20 mA in
% Full Scale 2.00 22.00 -1250 (-12.50%) 11250 (112.50%) 1.6 μA
Bits
15 14 13 12 11
HART Current Ratio Limit Decimal Value 7 6 5 4 3

FLEX I/O Isolated Output HART Analog Module 17
Publication 1794-IN120D-EN-P - September 2015
Format Values
Cyclic HART Input Data
The HART input data holds the primary variables for the “live” HART device, and other
information gathered during the normal HART scan. Additional “documentary” data is
available through the pass through message interface in the device information tables. Pass
through messages are defined in detail in the User Manual.
HART Input Data
Format Format Name 0.0 mA 2.0 mA 4.0 mA 20.0 mA 22.0 mA
0 0...20 mA in Milliamps 0 2000 4000 20000 22000
1 0...20 mA in % Full Scale 0 1000 2000 10000 11000
3 0...20 mA in UINT 0 6554 13107 65535 65535(1)
4 4...20 mA in Milliamps 2000(1)
(1) These values are under, or over the supported user range, and are clamped at the lowest/highest supported values.
2000 4000 20000 22000
7 4...20 mA in UINT 0(1) 0(1) 0 65535 65535(1)
14 4...20 mA in % Full Scale -1250(1) -1250 0 10000 11250
IMPORTANT
The HART Input Data for a channel may be zeroes if HART communications
is disabled for that channel. For more information on disabling HART
communications, refer to the Disable HART communications and HART
CMD 3 Disable functions in the Configuration Map table.
Word Bit
1514131211109876543210
0 Reserved CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0
(HART CMD 3 Communication Status)
1 Reserved
2 CH0 HART Field Device Status CH0 HART Comm Status
3 Reserved FVA TVA SVA PVA CH0 HART Loop Status
4 CH0 HART Primary Value (IEEE 754-1985 Single-Precision 32-bit floating point)
5

18 FLEX I/O Isolated Output HART Analog Module
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HART Input Data Descriptions
6 CH0 HART Secondary Value (IEEE 754-1985 Single-Precision 32-bit floating point)
7
8 CH0 HART Tertiary Value (IEEE 754-1985 Single-Precision 32-bit floating point)
9
10 CH0 HART Fourth (Quaternary) Value (IEEE 754-1985 Single-Precision 32-bit floating point)
11
12 CH0 SV Units Code CH0 PV Units Code
13 CH0 FV Units Code CH0 TV Units Code
14...25 Words 2...13 for channel 1
26...37 Words 2...13 for channel 2
38...49 Words 2...13 for channel 3
50...61 Words 2...13 for channel 4
62...73 Words 2...13 for channel 5
74...85 Words 2...13 for channel 6
86...97 Words 2...13 for channel 7
CHn: HART CMD 3 Communication Status 0 = HART CMD 3
Communication Disabled
or No Error
1 = HART CMD 3
Communication Error
between Adapter and
Module
CHn: HART Comm Status
(HART CMD 3 Response first status byte) Refer to User Manual
Word Bit
1514131211109876543210

FLEX I/O Isolated Output HART Analog Module 19
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Status Indicator
The OK status indicator is bicolor, red, and green. The indicator flashes green for these
reasons:
• The module configuration word is zero (for example, powerup reset condition).
• The 24V DC user power is off.
• The module is in Configuration mode.
The indicator displays red to indicate the module did not pass the initial hardware test.
Recycle power in response to this display.
After powerup, if the status indicator is not flashing green or solid green, recycle module
power to verify a proper reset of the bus interface.
CHn: HART Field Device Status
(HART CMD 3 Response second status byte) Refer to User Manual
CHn HART Loop Status
Bit 0 = HART Enable
Bit 1 = Device Connected
Bit 2 = Response Error
Bit 3 = CMD 48 Update
Bit 4 = HART Loop Tolerance Error
Bit 5 = HART Update
Bit 6 = HART Message
Bit 7 =
0 = Disabled
0 = Not connected
0 = No HART message
failure
0 = CMD 48 not updated
0 = No HART current fault
0 = HART device
information not updated
0 = No new message
1 = Enabled
1 = Connected
1 = Response ended in
error
1 = CMD 48 updated
1 = HART current fault
1 = HART device
information updated since
last read
1 = HART user message
queue has completed a
message
Reserved
PVA — The primary variable for this channel has been acquired.
SVA — The secondary variable for this channel has been acquired.
TVA — The tertiary variable for this channel has been acquired.
FVA — The fourth (quaternary) variable for this channel has been acquired.

20 FLEX I/O Isolated Output HART Analog Module
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Specifications
Specifications – FLEX I/O Isolated Output Analog Module – 1794-OF8IH
Attribute Value
Number of outputs 8 single-ended, isolated
Recommended terminal base unit 1794-TB3, 1794-TB3S
Resolution 16-bits – unipolar
Current 0.305 μA/cnt – unipolar
Data format Engineering Units(3)
Percent of Full Scale
RAW/Proportional Count
Conversion type 16-bits digital to analog converter
Conversion rate 10 ms
Output current terminal 4...20 mA (user configurable)
0...20 mA (user configurable)
0 mA output until product is configured
Settling Time 70 ms, 0...99%
Normal mode rejection ratio – current
terminal >70 dB @ 50/60 Hz (4.17 Hz ADC conversion rate) >65 dB @ 50/60 Hz (10.0 Hz ADC conversion rate)
>75 dB @ 50 Hz (16.7 Hz ADC conversion rate)
>85 dB @ 60 Hz (19.6 Hz ADC conversion rate)
Common mode rejection ratio >60 dB @ 50 Hz
>60 dB @ 60 Hz
Load resistance 0...750 Ωstandard
Load reactance, max 10 μH
Absolute accuracy(1) ± 0.1% full scale @ 25 °C
± 0.35% full scale @ 0...55 °C
Accuracy drift with temperature(1) ± 0.008% / °C
0.0038% full scale / °C
Calibration required Factory calibrated
Maximum overload 30V continuous or 32 mA continuous, one channel at a time
Isolation voltage 120V (continuous), Basic Insulation Type
Type tested @ 1000V AC for 60 s, between User power to
system, channel to system, and channel to channel.
Flexbus current 80 mA @ 5V DC
Power dissipation, max 5.0 W @ 24V DC
Thermal dissipation, max 17.06 BTU/hr @ 24V DC