Allen-Bradley 1771-ALX PLC5 Local IO Adapter Module

The Allen-Bradley 1771-ALX PLC-5 Local I/O Adapter Module is a PLC-5 local I/O interface that installs in the leftmost slot of a 1771 I/O chassis to bridge the processor with local I/O racks on the PLC-5 backplane. It enables you to disconnect a rack from the bus without interrupting the rest of the system, allowing maintenance, wiring changes, or expansion without shutting down the entire PLC-5 network. This Extended Local I/O adapter is compatible with Series A or Series B 1771 I/O chassis and is intended for use with PLC-5/40L or PLC-5/60L controllers. Electrical requirements specify a 5 V backplane supply with up to 1.2 A drawn from the leftmost slot, supporting stable operation for attached I/O modules. Environmental limits cover 0 to 60 C operational temperature, -40 to 85 C storage, and 5 to 95% relative humidity (non-condensing). The 1771-ALX is commonly used in PLC-5 installations to facilitate modular I/O maintenance and scalable rack configurations, serving as a key piece of the PLC-5 Local I/O topology by isolating a rack while keeping other racks on the local bus active.