1794-IF2XOF2I | Allen-Bradley 2-Input/2-Output Isolated Analog Module

The 1794-IF2XOF2I is designed to connect field analog devices—such as sensors, transmitters, and actuators—to an Allen-Bradley control system through the FLEX I/O platform. This specific model is unique in that it:

• Provides two isolated analog inputs and two isolated analog outputs
• Supports voltage or current signals
• Offers channel-to-channel isolation, enhancing signal integrity in noisy environments

Inputs:

• Voltage mode: ±10V DC
• Current mode: 4–20 mA (2-wire or 4-wire devices)

Outputs:

• Voltage output: ±10V DC
• Current output: 4–20 mA

Each channel (input or output) is independently configurable, and isolated from other channels and system power. This isolation helps prevent ground loops and cross-channel interference.

Each channel includes dedicated terminals for input/output signals and return lines. The wiring approach depends on the signal type.

For analog inputs (typical wiring):

• Voltage input: Connect signal to I+ and return to I-
• Current input: Loop through device and return via I-

For analog outputs:

• Voltage output: Connect O+ and O-
• Current output: Connect in series with the load and return path

Important Wiring Notes:

• Use shielded twisted pair cables for all analog signals
• Ground shields at one end only (typically controller side)
• Power external devices with isolated power supplies if possible

For the full terminal layout and wiring diagrams, consult the manual by searching the product number.

You configure and monitor the 1794-IF2XOF2I using:

• Studio 5000 Logix Designer (for ControlLogix/CompactLogix controllers)
• RSLogix 5000 (for older systems)
• Add the module via Add-On Profile (AOP) or via Generic Module with configuration parameters

Key configuration parameters include:

• Input/output range selection (current or voltage)
• Data format (scaled, raw, engineering units)
• Fault behavior (e.g., hold last state or go to zero)
• Output clamping and rate limiting

Tags are automatically created in Logix for each channel, which can be used directly in ladder logic, structured text, or function block programming.

• Input resolution: Typically 16-bit
• Output resolution: Typically 15- or 16-bit depending on mode
• Conversion rate: 10–20 ms per channel, depending on network scan rate and configuration
• Accuracy: ±0.1% to ±0.2% full scale, varies with temp and signal type

Because the module is part of the FLEX I/O family, update timing also depends on:

• The chosen adapter (EtherNet/IP, ControlNet, DeviceNet)
• Network traffic and RPI settings
• Number of modules on the network