Allen-Bradley 1756-DHRIO Rio Communications Module

The Allen-Bradley 1756-DHRIO is a DH+/RIO bridge module for ControlLogix that enables communication between modern PLCs and legacy DH+ networks or Remote I/O racks on the same chassis. It provides two ports, each independently configurable for DH+ or Remote I/O, and can route messages across up to four networks and three chassis. DH+ data rates supported are 57.6, 115.2, and 230.4 Kbps, with a typical power dissipation of about 4.5 W and current draw of roughly 850 mA at 5.1 V (1.7 mA at 24 V), with isolation rated at 30 V continuous between the backplane and the DHRIO sides. The module occupies a single 1756 backplane slot and is compatible with chassis such as 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17; Rockwell Automation discontinued the ControlLogix DH Plus/RIO communications module as of December 31, 2024.