Allen-Bradley 1756-CNBR ControlLogix ControlNet Interface Module

Description

The Allen-Bradley 1756-CNBR ControlLogix ControlNet Interface Module is a redundant ControlNet communication interface designed for use within ControlLogix systems, also referred to as a ControlNet bridge redundancy module. A key upgrade from the non-redundant 1756-CNB model, it features dual ControlNet BNC ports (compared to the 1756-CNB’s single port) plus a shared ControlNet RJ45 port, enabling redundant media support to prevent communication loss if a splitter or relay line fails.

This module works with Logix5550 controllers to manage scheduled data, while bridging unscheduled data between the ControlLogix backplane and ControlNet networks. Technically, it supports up to 64 bidirectional scheduled and unscheduled connections with other ControlNet devices, along with up to 20 buffers for unconnected messages. It is optimized for applications with 40 to 48 Logix communication connections per module at a 5 megabytes per second communication rate, and offers 99 available network nodes. Ideal for critical industrial environments like power, petrochemical, and key production lines where uninterrupted network communication is essential, it provides seamless, millisecond-level failover when paired as redundant hardware, ensuring continuous I/O scanning and controller data exchange.