Allen-Bradley 1756-DHRIO Communication Interface Module

The Allen-Bradley 1756-DHRIO is a ControlLogix Data Highway Plus/Remote I/O communication interface module that acts as both a DH+ gateway and a Remote I/O (RIO) scanner, enabling a ControlLogix chassis to exchange data with DH+ networks and remote I/O devices. It provides two DH+ channels (Channel A and Channel B) that can be used to interface with DH+ networks, and it can route messages through as many as four DH+ networks across three chassis. The module is designed to be installed in a ControlLogix chassis alongside other interface modules (for example, an EtherNet module) to facilitate cross-network bridging, and its dual-channel configuration supports flexible DH+ topologies; if both Channel A and Channel B are using DH+, you will not be able to create child modules under the 1756-DHRIO. In addition to bridging DH+ networks, the 1756-DHRIO enables connection to multiple remote I/O adapters, effectively extending ControlLogix reach to legacy DH+ devices. Note that Rockwell Automation announced the discontinuation of the DH+/RIO communications module as of December 31, 2024.