Allen-Bradley 1768-CNBR CompactLogix ControlNet Module

The Allen-Bradley 1768-CNBR serves as the primary 1768-CNBR ControlNet Bridge Module utilized to execute redundant deterministic network communications across CompactLogix 1768 platforms.

Suffix Breakdown & Model Matrix

Hardware Specifications

ControlNet Deterministic Networks and Redundant Media Topology

• ControlNet Deterministic Networks: Delivers deterministic, high-speed 5 Mbps command data transfer supporting up to 48 concurrent CIP connections across 99 nodes on a scheduled ControlNet network segment.
• Redundant Media Topology: Features dual BNC coaxial ports (Channel A and Channel B) to maintain active media redundancy, automatically switching communication channels in the event of a cable break or signal loss.
• Firmware Flash Compatibility: Integrates into Studio 5000 / RSLogix 5000 configuration environments for node address assignment, network scheduling, and firmware updates across the 1768 backplane bus.

Frequently Asked Questions

Q: What is the primary operational difference between the 1768-CNB and 1768-CNBR modules?

A: The 1768-CNBR includes dual BNC connectors to support redundant coaxial media cabling, whereas the 1768-CNB provides a single BNC port for non-redundant media operation.

Q: What type of cabling is required to connect the 1768-CNBR to a ControlNet trunk line?

A: The module requires 75-ohm quad-shield RG-6 coaxial cable terminated with standard BNC connectors and proper 75-ohm end-of-line terminators.

Q: How many concurrent logical connections can the 1768-CNBR maintain?

A: The module supports up to 48 concurrent Logix connections across a maximum of 99 network nodes.

Field Installation Guidelines

• Module Mounting: Seat the module securely into any available slot on the 1768 system chassis to the left of the processor, locking top and bottom retainers.
• Coaxial Cable Connection: Connect Channel A and Channel B quad-shield RG-6 coaxial cables to the respective front BNC connectors. Verify 75-ohm terminators are installed at both physical ends of each trunk line.
• NAP Interface Usage: Use the RJ45 Network Access Port (NAP) strictly for temporary local diagnostics or programming terminal attachment using a compatible network access cable.
• Chassis Grounding: Ensure the 1768 chassis mounting surface or DIN rail maintains a low-impedance connection to cabinet ground to safeguard signal processing circuitry from high-frequency noise.