Allen-Bradley 1756-CNB ControlNet Interface Module

The Allen-Bradley 1756-CNB is a ControlNet Bridge Module that provides a dedicated ControlNet interface for a ControlLogix chassis, enabling a Controller to communicate with a ControlNet network. It uses a single ControlNet BNC port to link the 1756 backplane to the ControlNet, and the hardware is sized to support 40–48 devices on the ControlNet segment, which informs network topology planning and device addressing. As a non-redundant interface, the 1756-CNB plugs into a 1756 ControlLogix rack and handles the bridging of ControlNet traffic between PLC logic, inputs, and I/O devices on the network. If redundancy is needed, Rockwell offers a redundant version, the 1756-CNBR, with similar connection capacity, designed to maintain communication in the event of a network path failure. This module is used in automation architectures that require integrating existing ControlNet I/O and devices with modern ControlLogix controllers, allowing data exchange and control signals across both networks.