Allen-Bradley 1747-L551 SLC 5/05 Processor | High-Performance Controller By wayne No Comments on Allen-Bradley 1747-L551 SLC 5/05 Processor | High-Performance Controller 3 Min Read The Allen-Bradley 1747-L551 SLC 5/05 processor controls up to 4096 I/O points with 16 KB memory and Ethernet communication.