Allen-Bradley 1747-L542 SLC 500 Processor Unit

The Allen-Bradley 1747-L542 is a SLC 500 Processor Unit (CPU) for the SLC 5/04 controller, designed to be mounted in an AB 1747 modular rack and serve as the central processing node for ladder logic and sequencing tasks. It provides 32K of memory for program and data and ships with firmware revision number FRN 3. On the communications front, the 1747-L542 includes an RS-232 port for programming and diagnostics and two DH+ (Data Highway Plus) channels (Channel 1 and Channel 2) for device networking. These DH+ ports support short- to medium-distance networking with Allen-Bradley devices in factory automation environments. Typical applications include small to mid-sized machine controls, conveyors, sorters, or other discrete-control tasks where a compact PLC manages I/O within a DH+-based network. The processor is intended for use with the SLC 500 modular I/O backplane, and it contributes to a complete SLC 500 control system built around the 1747 family.