Allen-Bradley 1756-CN2R B ControlLogix ControlNet Module

The Allen-Bradley 1756-CN2R B is a rugged ControlNet communication module engineered for industrial automation systems requiring high-speed data exchange and real-time control. Designed to bridge ControlLogix controllers with networked devices, this module delivers consistent performance in applications ranging from assembly lines to process control systems.

• Manufacturer: Allen-Bradley
• Model Number: 1756-CN2R B
• Series: ControlLogix
• Protocol: ControlNet
• Voltage: 24 VDC
• Temp Range: -20°C to 65°C
• Certifications: UL, CE, CSA
• Dimensions: 130 x 30 x 85 mm
• Weight: ~200g
• Network Speed: 5 Mbps
• Isolation: 500 Vrms
• Data Rate: 6,000 msg/sec

Commonly deployed in automotive manufacturing plants and chemical processing facilities, this module forms the backbone of ControlLogix-based networks. For instance, in a bottling line scenario, it synchronizes conveyor belts and filling machines through its 5 Mbps communication speed. We frequently pair it with ControlLogix controllers like the 1756-L71 or 1756-ENBT to build scalable automation architectures. Its -20°C to 65°C operating range makes it particularly suited for outdoor installations like water treatment plants.

What sets this module apart is its dual-port redundancy design – if one network path fails, it automatically switches to the backup without interrupting communication. The 500 Vrms isolation protects against voltage spikes in harsh electrical environments, while the Studio 5000 software integration simplifies troubleshooting. Personally, I’ve found its diagnostic LEDs invaluable for quickly identifying cabling issues during plant shutdowns. The compact 130mm height profile also makes it ideal for control cabinets with space constraints.