Allen-Bradley 1794-OF4I Isolated Analog Output Module

June 11, 2026 • 1 min read • wayne • Science

Product Summary

The 1794-OF4I delivers four isolated analog output channels with configurable voltage and current ranges. It boasts 15-bit DAC resolution, a <25 µs step response, and 0.1% absolute accuracy at 25°C. Factory calibration ensures immediate deployment, while manual calibration options provide flexibility for critical loops. This module is a reliable choice for precise control in demanding industrial environments.

Technical Evaluation: Precision and Performance

The 1794-OF4I uses a digital-to-analog converter with 15 bits plus sign. This resolution enables fine control over output signals. The module achieves an update rate of 2.5 or 5.0 ms for all channels. This speed suits fast-acting process loops. The step response reaches 63% of full scale in under 25 µs. Such quick response minimizes lag in closed-loop systems. Absolute accuracy holds at 0.1% of full scale at 25°C. Voltage channel drift remains at 0.0012% per °C. Current channel drift is 0.0025% per °C. These values guarantee stable output across temperature swings. The module supports multiple output ranges. Users can select ±10VDC, 0-10VDC, ±5VDC, or 0-5VDC for voltage. For current, options include 4-20 mA and 0-20 mA. The output goes to zero until configuration completes. This feature prevents unwanted actuator movements during startup.

The 1794-OF4I also provides galvanic isolation for each channel. Isolation voltage reaches 120V continuous with standard bases and 250V continuous with the 1794-TBN base. This isolation protects sensitive electronics from ground loops. It also safeguards against transient surges. The module withstands continuous overloads of 30V or 32 mA on one channel at a time. Such robustness reduces downtime risks. Operators can rely on this module for high-integrity signal conversion.

Installation Guide: Mounting and Wiring

Mount the 1794-OF4I on a DIN rail or directly onto a sub-panel. Secure it using the integral clip. The module occupies a single slot in the Flex I/O chassis. Connect it to a compatible terminal base unit. Supported bases include 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3T, 1794-TB3TS, and 1794-TBN. Ensure the terminal base provides proper isolation and retention. The module draws 50 mA from the FlexBus at 5VDC. The external power supply requires a nominal 24VDC with a range of 19.2–31.2VDC. This supply powers the output circuits and field wiring. Connect the supply to the correct terminals on the base unit. The module dissipates up to 4.7W at maximum supply voltage.

Wire analog outputs using shielded twisted-pair cables. Keep cable runs away from high-voltage lines. For current outputs, set the resistive load between 0 and 750 ohms. For voltage outputs, the maximum load current is 3 mA. The module is factory calibrated, but users can perform a manual calibration if needed. This process requires a precision multimeter and the appropriate software tool. The module operates in temperatures from 0 to 55°C and withstands vibration up to 5g.