The Allen-Bradley 1747-L551 is a SLC 5/05 CPU for the SLC 500 family, delivering 16K of memory on‑board for ladder logic programs and data. It features a built‑in 10 Mbps Ethernet port (10Base‑T) for LAN connectivity and a DB9 RS‑232 serial port (Channel 0) supporting DF1, DH‑485, or ASCII communications. An optional EtherNet/IP adapter (1747‑AENTR) can be added to enable EtherNet/IP networking, while the Series C hardware design integrates the Ethernet interface directly on the processor. This CPU is designed for compact control installations and is commonly programmed with RSLogix 500 for use with SLC 500 panels and related HMI interfaces.
