Allen-Bradley 1771-0A Output Module

The Allen-Bradley 1771-OA is an eight-point digital output module for the 1771 I/O family, designed to install in a 1771 I/O chassis and provide eight discrete output channels from the backplane. As a single-slot card, it plugs into the chassis and uses the 1771 backplane to switch field devices such as relays and motor starters, enabling direct remote control of loads from a PLC program. Field wiring is typically accomplished via the 1771-WA Field Wiring Arm, which interfaces the eight outputs to the external wiring harness for secure terminations. Rockwell Automation lists the 1771-OA as a discontinued part as of September 29, 2023, so current designs should select a modern replacement in new systems, though the 1771-OA remains documented for existing installations. Eight outputs provide straightforward ladder logic mapping, enabling simple status control of connected devices and clear visibility in the controller's I/O image table.