Allen-Bradley 1747-L542 SLC 500 DH RS232 Processor

The Allen-Bradley 1747-L542 is a SLC 5/04 CPU for the SLC 500 family, delivering 32K words of user memory (approximately 28K for program and 4K for data) and providing both Data Highway Plus (DH+) networking and an RS-232 serial port for programming and DF1/ASCII communications. It supports up to 4,096 discrete inputs and 4,096 discrete outputs, making it capable of handling compact to mid-size control tasks, and it is commonly programmed with RSLogix 500. Powered from 5 to 24 VDC, this module combines DH+ connectivity with RS-232 to facilitate serial device communication and offline programming in legacy automation setups. Rockwell Automation discontinued the SLC 5/04 32K Controller as of March 31, 2024, so the 1747-L542 is considered a legacy device, though it remains in use in installations that rely on DH+ networking and RS-232 connectivity for control and data exchange.