Allen-Bradley 1756-CNB ControlLogix Communication Module

The Allen-Bradley 1756-CNB ControlLogix Communication Module is a ControlNet Bridge Module that provides a ControlNet interface to a ControlLogix system, residing in a chassis-based Logix backplane and occupying a single slot. It supports 40–48 ControlNet connections, enabling mapping of multiple ControlNet devices to the ControlLogix processor, and is designed for installation in a standard ControlLogix chassis. The module facilitates ControlNet communications at up to 5 Mbps, serving as the gateway between the Logix CPU and the ControlNet network. As of December 31, 2024, Rockwell Automation lists the 1756-CNB as discontinued, with 1756-CN2K provided as its replacement for new designs.