Allen-Bradley 1747-L542 SLC 500 PLC Processor

The Allen-Bradley 1747-L542 is a SLC 500 Series CPU (SLC 5/04) processor module designed for seven-slot SLC 500 backplanes to support mid-range control tasks. It provides 32K words of memory for program and data and includes RS-232 serial communications plus DH+ (Data Highway Plus) for legacy device networking, enabling programming access and field connections without additional gateways. In typical installations it serves to upgrade or replace older SLC 500 controllers in applications such as packaging lines, conveyors, and simple automated machines, coordinating logic, timing, and I/O across compatible 1747-series I/O modules within the seven-slot chassis. The module’s real-time processing supports ladder logic-style control and deterministic scan cycles, with standard RS-232 and DH+ ports facilitating local programming, diagnostics, and networked communication with peripheral devices. As part of the SLC 500 family, it integrates with Rockwell Automation peripherals and uses the 1747 backplane architecture to manage a mix of discrete and analog I/O in compact automation systems.