Many existing plants have an extremely large investment in older “1771” style I/O hardware – and in the solid old PLC-5 controllers. Upgrading to a newer ControlLogix system is often done in stages – so maintaining communication with the existing hardware is usually a necessity.
The 1756-DHRIO module provides a means of connecting the legacy cables (usually known as “blue hose”) to the ControlLogix system.
The “DH” in the module’s catalog number refers to Data Highway Plus – which is the native communication network for the PLC-5 processor family. The “RIO” indicates that the module can also handle Remote Input and Output connections.
Our Boot Camp classes can provide hands-on exercises in using the 1756-DHRIO module for communicating over a Data Highway Plus network – and in working with Remote I/O systems.