Allen-Bradley 1771-LIA Loop Controller Interface Module

The Allen-Bradley 1771-LIA Loop Controller Interface Module provides a dedicated Data Highway (DH) interface between a PLC-5 processor and up to 15 1771-LC Loop Controllers, enabling scalable loop control in automation systems. Installed in a PLC-5 backplane, the 1771-LIA occupies a single I/O slot and communicates with loop controllers over a twisted-pair Data Highway network at 4,800 bits per second. As the hub between the PLC-5 logic and the loop controllers, it translates control commands into the loop controllers and returns status, diagnostic data, and process feedback, enabling centralized tuning and monitoring of multiple control loops. Key electrical specs include a backplane current load of about 1.3 A, and the module is designed to be compatible with the 1771-LC Loop Controller family, providing a direct, plug-and-play interface for PLC-5 loop-control architectures. Typical applications include process and manufacturing automation where multiple loops—such as temperature, pressure, or flow control—must be coordinated by a PLC-5 system to maintain consistent operations.