Product Overview
The Allen-Bradley 1794-OF8IH is a Flex I/O module that functions as an Isolated Output HART Analog Module within the 1794 Flex I/O system. This industrial automation module provides eight (8) single-ended, isolated outputs configurable for 0-20 mA and 4-20 mA with 16-bit resolution. Manufactured by Rockwell Automation, the 1794-OF8IH is designed for precise analog control in demanding process environments.
Technical Specifications
The Allen-Bradley 1794-OF8IH delivers reliable performance with the following key parameters:
| Specification |
Value |
| Manufacturer |
Rockwell Automation |
| Series |
Flex I/O 1794 |
| Part Number |
1794-OF8IH |
| Product Type |
Output Module |
| Number of Outputs |
8 isolated outputs |
| Output Signals |
0-20 mA; 4-20 mA |
| Module Resolution |
16-Bit; Unipolar |
| Conversion Method |
16-bit digital-to-analog converter |
| Conversion Rate |
10 ms |
| Data Format |
Engineering Units; Percent of Full Scale; RAW/Proportional Count |
| Terminal Base |
1794-TB3, 1794-TB3S |
| Calibration |
Factory Calibrated |
| FlexBus Current |
80 mA @ 5V DC |
| Power Dissipation (max) |
5.0 W @ 24V DC |
| Thermal Dissipation (max) |
17.06 BTU/hr @ 24V DC |
| Operating Temperature |
32 to 131 degrees Fahrenheit |
Key Features & Benefits
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HART Capability: The 1794-OF8IH supports pass-through messages with 1 or 2 connections, each handling 8 queues, enabling seamless communication with HART devices.
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Flexible Output Configuration: Each channel can be independently programmed for 0-20 mA or 4-20 mA ranges, accommodating diverse application requirements.
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Diagnostic Alarms: The module detects lead breakages and provides alarms for overrange and underrange current conditions, enhancing system reliability.
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No Jumper or Switch Settings: Simplifies installation and reduces setup errors.
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Internal Power Supply: Operates without an external power supply, drawing power from the FlexBus at 80 mA @ 5V DC.
Industry Applications
The Allen-Bradley 1794-OF8IH is ideal for applications requiring precise analog output control with HART communication. Typical use cases include:
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Process Control: Regulating valve positioners or variable speed drives in chemical and petrochemical plants.
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Oil & Gas: Controlling flow and pressure loops in remote terminal units.
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Water Treatment: Managing chemical dosing pumps and filtration systems.
Installation & Setup
Install the Allen-Bradley 1794-OF8IH onto a compatible terminal base (1794-TB3 or 1794-TB3S). Rotate the keyswitch to position 4 to lock the module securely. The module is factory calibrated, so no manual calibration is required. Ensure the FlexBus current does not exceed 80 mA @ 5V DC and that the ambient temperature remains within 32 to 131 degrees Fahrenheit.
Maintenance & Reliability
The 1794-OF8IH is designed for long-term reliability. Regularly inspect the terminal base connections and verify that the module remains firmly seated. Monitor the ambient temperature to prevent overheating, as the module dissipates up to 5.0 W @ 24V DC. The built-in diagnostic alarms help identify wiring issues early, minimizing downtime.
Compatibility & Integration
This module is part of the Flex I/O 1794 series and integrates seamlessly with Allen-Bradley control systems. It supports pass-through messaging for HART devices, allowing direct communication with smart field instruments. The module works with standard Flex I/O terminal bases and is compatible with various Rockwell Automation controllers that support Flex I/O adapters.
Buying Guide
Before purchasing the Allen-Bradley 1794-OF8IH, verify that your existing system includes a compatible Flex I/O adapter and terminal base. Confirm the required output range (0-20 mA or 4-20 mA) and ensure the ambient temperature meets the operating limits. For genuine parts and reliable service, choose PLC Source PRO as your supplier.