Allen-Bradley 1785-BCM Back-Up Communication Module

Allen-Bradley 1785-BCM Back-Up Communication Module is a PLC-5 backup communications card designed to provide failover protection for Data Highway Plus (DH+) and Remote I/O (RIO) networks. The module offers one High-Speed Serial Link (HSSL) interface and two DH+/RIO interfaces, enabling a primary/backup BCM pair to synchronize I/O, status, and data tables and switch over without disrupting remote I/O operations. It coordinates with compatible PLC-5 processors to maintain continuous communication with remote I/O and to protect critical control paths; note that the PLC-5 backup system does not back up local I/O modules in the processor rack. The 1785-BCM is a legacy hardware solution for high-availability automation networks that rely on DH+ and RIO communications.