Allen-Bradley 1771-ASB Remote Input Output Adapter Module

The Allen-Bradley 1771-ASB Remote I/O Adapter Module is a slave device that extends a PLC‑5/1771‑Series Remote I/O network by sitting in a Universal I/O chassis and interfacing the supervisor controller with remote input and output modules. It reads and writes data to the attached I/O modules in parallel, enabling coordinated control across distributed racks. In the same remote system, the 1771‑ASB can be mixed with 1771‑ASB/B and 1771‑AS modules, with a maximum baud rate limited to 115.2 kBaud or lower. Each I/O group supported by the adapter provides 16 input bits and 16 output bits, supporting scalable expansion of digital I/O without adding a local processor to every rack. The device connects across the remote I/O subnet to other adapters in the 1771 family, forming a distributed network that links back to the controller and across racks. This configuration is suitable for traditional PLC‑5 and early 1771 I/O systems that require remote expansion of digital input and output, offering parallel data transfers and straightforward addressing within the 1771 Remote I/O topology.