Allen-Bradley 1794-OF8IH Flex I/O Isolated Analog Output HART Module

Product Overview

When process control demands high accuracy and isolation, the Allen-Bradley 1794-OF8IH delivers. This Flex I/O isolated analog output HART module from Rockwell Automation provides eight isolated outputs configurable for 0-20 mA or 4-20 mA signals. With 16-bit unipolar resolution, it ensures precise current control for valves, actuators, and transmitters. The module integrates seamlessly into the 1794 Flex I/O system, reducing wiring costs and simplifying maintenance. By supporting HART pass-through messages, it enables remote diagnostics and configuration, cutting downtime and service expenses.

Technical Specifications

The 1794-OF8IH offers eight isolated analog outputs with 16-bit resolution. Its digital-to-analog converter achieves a conversion rate of 10 ms, allowing fast updates for dynamic processes. Data formats include Engineering Units, Percent of Full Scale, and RAW/Proportional Count, giving flexibility for various control strategies. The module draws 80 mA at 5V DC from the FlexBus, so no external power supply is needed—reducing installation costs. Maximum power dissipation is 5.0 W at 24V DC, and thermal dissipation reaches 17.06 BTU/hr at 24V DC, ensuring efficient heat management in crowded cabinets. Factory calibration guarantees accuracy out of the box, eliminating calibration labor expenses.

Industry Applications

In oil and gas refineries, the 1794-OF8IH controls valve positioners with 4-20 mA HART signals, enabling remote calibration and fault detection. This reduces field visits and maintenance costs. In water treatment plants, its isolated outputs protect PLCs from ground loops, improving system reliability and lowering repair expenses. For chemical batch processing, the 0-20 mA range supports precise dosing pumps, while the 16-bit resolution minimizes material waste—directly improving ROI.

Installation & Setup Guidance

Mount the 1794-OF8IH on a 1794-TB3 or 1794-TB3S terminal base. Rotate the keyswitch to position 4 to lock the module securely. Use terminal bases that match your wiring requirements; the module supports pass-through messages with 1 or 2 connections and 8 queues per connection. No external power supply is needed—the FlexBus provides 80 mA at 5V DC. Ensure ambient temperature stays between 32 and 131 degrees Fahrenheit for reliable operation. Proper installation reduces commissioning time and avoids costly rework.

Maintenance & Reliability

The 1794-OF8IH includes overrange and underrange alarms and lead breakage detection, helping operators spot issues early. Routine inspection of terminal base connections and environmental conditions extends module life. With no moving parts and factory calibration, long-term reliability is high, reducing replacement frequency and total cost of ownership. For HART-enabled devices, periodic verification of communication status via pass-through messages can prevent unexpected failures.

Selection Guide & Purchasing Advice

Before purchasing, verify that your system uses a 1794 Flex I/O rack and that the terminal base (1794-TB3 or 1794-TB3S) is available. Confirm compatibility with your controller and HART host. The 1794-OF8IH is factory calibrated and ready to use. For current lifecycle status and availability, contact BluePLC Industrial—a trusted supplier of industrial automation parts. We offer fast shipping and expert support to help you maximize your investment.

For complete technical specifications for the 1794-OF8IH, please contact BluePLC Industrial.