Allen-Bradley 1756-CNB ControlNet Bridge Module

The Allen-Bradley 1756-CNB ControlNet Bridge Module is a ControlLogix interface that connects a ControlNet network to a 1756 backplane, enabling ControlNet devices to communicate with a ControlLogix controller. It provides a dedicated ControlNet bridge within the 1756 I/O architecture, allowing remote I/O on the ControlNet network to be integrated into the ControlLogix system.

On the ControlNet side, the module supports 40–48 connections, giving substantial capacity for bridging multiple I/O points into the ControlLogix rack. The 1756-CNB is designed to route ControlNet messages between the ControlNet devices and the ControlLogix backplane, effectively bridging ControlNet networks with the ControlLogix chassis as described in Rockwell documentation for ControlNet bridging.

• Compatibility: designed for Allen-Bradley ControlLogix controllers supported by the 1756 backplane.
• Connections: 40–48 ControlNet connections on the bridge module.
• Function: bridges ControlNet to the ControlLogix system and routes messages to devices on other networks as part of typical ControlNet bridging configurations.

Note: the 1756-CNB(R) family includes a redundant variant (CNB(R)) for systems requiring fault-tolerant bridges, while the standard 1756-CNB provides the primary ControlNet bridge function within a single-backbone ControlLogix setup.