Allen-Bradley 1747-DCM Direct Communication Module

The Allen-Bradley 1747-DCM Direct Communication Module is a Remote I/O gateway that links an SLC 500 or PLC-5 supervisory controller to a remote SLC 500 via the RIO link, enabling distributed processing across controllers. Unlike a local I/O scanner, the DCM does not scan the host rack’s I/O; it passes the supervisory data to the distributed SLC processor, effectively bridging two or more control systems over the RIO network. This catalog-numbered module (1747-DCM) is designed to address remote I/O as if it were a single logical rack, simplifying data exchange and coordination in expansion chassis configurations and supervisory architectures that require distributed execution. A conformal-coated variant, 1747-DCM-CC, existed for harsher environments but was discontinued by Rockwell Automation on March 31, 2014. The 1747-DCM is part of the SLC 500/Remote I/O ecosystem, serving as a bridge between supervisory controllers (PLC-5 or SLC 500) and distributed SLC-500 processors over the RIO link.