Allen-Bradley 1771-ASB Remote IO Adapter Module

The Allen-Bradley 1771-ASB Remote I/O Adapter Module is a dedicated slave device that extends PLC-5 era systems with remote I/O by residing in a Universal I/O Chassis and connecting to a remote I/O subnet. It is designed to interface PLC-2, PLC-3, and PLC-5 controllers with distributed input/output, enabling I/O modules to be placed near field devices. As part of the 1771-ASB family, this module lets the PLC read inputs and control outputs across a remote rack network, simplifying the expansion of automation architectures in legacy plants. In typical applications, it serves as the link between a PLC-5 controller and remote I/O racks, organizing distributed I/O across the factory floor. The module’s role is strictly as a networked I/O interface within the Allen-Bradley legacy ecosystem, and it should be paired with a compatible Universal I/O chassis and the appropriate PLC configuration. Common use cases include retrofitting existing PLC-5 installations to add remote I/O points without changing the controller, or expanding I/O in plants still operating PLC-2/PLC-3/PLC-5 networks.