Product Overview

The Allen Bradley 1756-CNBR functions as the high-speed communication link between a ControlLogix chassis and a ControlNet network. This 100% Brand New module enables deterministic, repeatable data transfer for mission-critical I/O and peer-to-peer interlocking. By utilizing dual BNC connectors, the 1756-CNBR supports redundant media operation, ensuring the network remains active even if one cable segment fails. It occupies any single slot within a 1756 ControlLogix chassis and provides a dedicated Network Access Port (NAP) for local programming and diagnostics.

Technical Specifications

The 1756-CNBR delivers high-bandwidth performance with low power dissipation for efficient cabinet thermal management.

Engineering Advantages

• Redundant Media Support: The dual BNC ports allow for two separate cable paths. If the primary cable experiences a break or signal degradation, the 1756-CNBR switches seamlessly to the redundant path without interrupting the process control or triggering a system halt.

• Transformer-Coupled Isolation: Integrated transformer isolation protects the internal ControlLogix backplane from ground loops and external electrical surges originating from the ControlNet coaxial network.

• Deterministic I/O Control: Unlike standard Ethernet, the 1756-CNBR uses a scheduled communication protocol. This ensures that critical time-sensitive data arrives at precise intervals, making it ideal for high-speed motion and synchronized interlocking.

• Flexible Slot Placement: The module design supports installation in any available slot within the 1756 chassis. This flexibility allows engineers to optimize internal rack wiring and distribute thermal loads effectively.

FAQs

What is the difference between the 1756-CNB and the 1756-CNBR?

The "R" in 1756-CNBR stands for Redundancy. While the standard 1756-CNB provides a single network connection, the 1756-CNBR features two BNC connectors to support redundant physical media. This architecture prevents a single cable failure from taking down the entire network node.

Can I use standard RG-6 television cable for this module?

No. Allen Bradley requires Quad Shield RG-6 coaxial cable to meet industrial EMI/RFI interference standards. Standard consumer-grade cable lacks the shielding density necessary to maintain 5 Mbps data integrity in electromagnetically dense industrial environments.

Is this 1756-CNBR module Series D compatible with older Series A or B chassis?

Yes. The 1756-CNBR Series D maintains backward compatibility with the standard 1756 ControlLogix chassis line. However, always ensure your RSLogix 5000 or Studio 5000 software includes the correct Add-On Profile (AOP) for the Series D hardware to access all diagnostic features.

Does this unit ship in original factory packaging?

We guarantee this unit is 100% Brand New and arrives in the original Allen Bradley factory packing. It has never been installed or energized, ensuring the full 12-month factory warranty remains intact.