The Allen-Bradley 1756-CN2RK is a ControlNet redundant communication module used in the ControlLogix PLC system from Rockwell Automation. It provides high-speed, deterministic industrial communication over the ControlNet network and supports dual-channel redundancy to improve system availability and fault tolerance.
This module is designed for critical industrial applications where uninterrupted real-time communication between controllers, I/O devices, and distributed systems is required.
It is commonly used in power plants, oil & gas facilities, petrochemical industries, and large-scale automation systems.
Technical Specifications
| Parameter | Details |
|---|---|
| Product Type | ControlNet Redundant Communication Module |
| Model | 1756-CN2RK |
| System Compatibility | Allen-Bradley ControlLogix |
| Network Type | ControlNet |
| Communication Speed | 5 Mbps |
| Channels | 2 (A/B redundant ControlNet ports) |
| Data Transfer | Scheduled & unscheduled messaging |
| Redundancy Support | Yes (dual network paths) |
| Backplane Interface | ControlLogix chassis backplane |
| Power Consumption | ~6 W |
| Max Connections | Up to ~128–131 Logix connections |
| Installation Type | Chassis slot-mounted module |
| Operating Temperature | 0°C to 60°C |
| Protection | Conformal-coated variant available |
The 1756-CN2RK is a redundant ControlNet interface designed to maintain communication continuity in case of network failure.
Physical Dimensions & Weight
- Dimensions (H × W × D): 55 mm × 218 mm × 179 mm
- Weight: ~0.29–0.40 kg
The module is compact and designed for installation in any slot of a ControlLogix chassis.
Function in ControlLogix System
The 1756-CN2RK is used to:
- Provide redundant ControlNet communication paths (A/B networks)
- Enable deterministic real-time data exchange
- Support scheduled I/O and peer-to-peer messaging
- Maintain communication during single-channel failure
- Integrate distributed ControlLogix systems over ControlNet
Recommended Related Models
- Allen-Bradley 1756-CN2 (non-redundant version)
- Allen-Bradley 1756-EN2T Ethernet communication module
- Allen-Bradley 1756-L7x / L8x ControlLogix controllers
- Allen-Bradley 1756-IB16 digital input module
- Allen-Bradley 1756-OB16E digital output module
