Allen-Bradley 1756-EN4TR Ethernet Bridge Module

Allen-Bradley 1756-EN4TR Ethernet Bridge Module is a dual‑port EtherNet/IP bridge that installs in a ControlLogix 1756 chassis to bridge EtherNet/IP networks and route messages to devices on other networks, effectively extending CIP traffic beyond a single network segment. Each of its two RJ45 Ethernet ports supports 10/100/1000 Mbps, enabling high‑speed connections to other EtherNet/IP devices or network infrastructure without consuming backplane I/O bandwidth. The module is designed for substantial network loads, with support for up to 512 TCP connections and up to 256 axes in large automation configurations. It includes a USB interface for local management and, per Rockwell documentation, USB‑to‑backplane and USB‑to‑Ethernet access for configuration and diagnostics. Typical power dissipation is around 6.12 W. Variants in the EN4TR family include EN4TRK (conformal coating for harsh environments) and EN4TRXT, in addition to the standard EN4TR model, all sharing the same bridging role: connecting ControlLogix EtherNet/IP networks to external networks while preserving CIP framing and routing. Use cases include linking plant‑floor networks to enterprise networks, enabling remote devices and HMI systems to exchange messages with the ControlLogix controllers through a dedicated bridge to improve segmentation and reliability.