Allen-Bradley 1747-L542 SLC 500 Memory Controller

Allen-Bradley 1747-L542 SLC 500 Memory Controller is a SLC 5/04 CPU processor for the SLC 500 modular PLC family. It provides 32K of total memory for user programs and data and includes two on-board communications ports: RS-232 serial for direct programming and data transfer and a DH+ (Data Highway Plus) port for networked device communication. This controller is used to execute control logic and manage I/O in legacy automation lines, typically interfacing with standard SLC 500 I/O modules and DH+ networks or serial peripherals. It operates with the SLC 500 instruction set and software tools historically used with RSLogix 500, supporting applications that require reliable serial and DH+ connectivity. Common applications include machine and process control on older manufacturing lines, batch operations, and data collection on systems where upgrading to modern PLCs is not feasible. The 1747-L542’s 32K memory capacity supports moderate-sized programs and data tables within the SLC 500 architecture, making it a practical option for maintaining legacy installations that rely on RS-232 and DH+ communication.