Allen-Bradley 1756-CNBR ControlNet Redundant Media Bridge Module

The Allen-Bradley 1756-CNBR ControlNet Redundant Media Bridge Module is a ControlLogix interface that provides redundant ControlNet media bridging, designed to keep critical ControlNet communications flowing in harsh industrial environments. Installed in a 1756 chassis backplane, the CNBR acts as a bridge between ControlNet devices across dual media paths and supports a network of 40 to 48 connections, making it suitable for mid- to large-scale ControlNet installations. In high-availability applications, such as assembly lines, packaging, and automated material handling, this module helps maintain real-time I/O update rates by automatically switching traffic to the healthy media path if the primary channel experiences a fault. The CNBR is used alongside compatible ControlNet scanners and adapters within a redundant architecture to preserve device data exchanges, alarms, and control signals across the ControlNet network while the ControlLogix controller manages the system. Its redundant media capability differentiates it from non-redundant CNB modules, enabling continued operation during media outages and supporting robust, continuous operation in production environments that demand uptime. This module is part of Rockwell Automation’s ControlNet bridge offerings for ControlLogix systems and is documented in the 1756-CNBR cutsheet and related ControlNet configuration literature.