Allen-Bradley 1747-L542 is a SLC 5/04 central processing unit for the SLC 500 modular PLC family, designed to drop into a standard backplane chassis and execute ladder logic in compact automation applications. It combines 12K words of program memory with 32 KB of RAM for data, supporting basic control logic, timers, counters, and sequencing in small to mid-size machines. It provides a Data Highway Plus (DH+) network interface for I/O networking and a built-in RS-232 port for programming and diagnostics. Variants include conformal-coated 1747-L542-CC, and battery backup is supported to preserve memory during power outages.
