The Allen-Bradley 1756-CNB is a ControlNet communication bridge module used in the ControlLogix PLC system from Rockwell Automation. It provides an interface between the ControlLogix backplane and the ControlNet industrial network, enabling high-speed, deterministic data exchange between controllers, I/O devices, and distributed control systems.
The module supports scheduled and unscheduled communication and is designed for non-redundant ControlNet applications.
It is widely used in industrial automation systems such as manufacturing plants, oil & gas facilities, power generation, and process control networks.
Technical Specifications
| Parameter | Details |
|---|---|
| Product Type | ControlNet Bridge Module |
| Model | 1756-CNB |
| System Compatibility | Allen-Bradley ControlLogix |
| Network Type | ControlNet |
| Communication Speed | 5 Mbps |
| Channels | 1 ControlNet channel |
| Data Transfer | Scheduled & unscheduled messaging |
| Max Nodes | 99 nodes |
| Max Connections | Up to 64 Logix connections |
| Backplane Interface | ControlLogix chassis backplane |
| Power Consumption | ~5.1 W |
| Current Draw | ~970 mA @ 5.1 V DC |
| Isolation Voltage | 30 V continuous |
| Installation Type | Chassis slot-mounted module |
| Operating Temperature | 0°C to 60°C |
The 1756-CNB functions as a gateway between the ControlLogix processor backplane and the ControlNet network, enabling real-time industrial communication.
Physical Dimensions & Weight
- Dimensions (H × W × D): 145 mm × 32 mm × 135 mm
- Weight: ~0.26–0.57 kg
It is a single-slot module designed for standard ControlLogix chassis installation.
Function in ControlLogix System
The 1756-CNB is used to:
- Bridge ControlLogix controllers to ControlNet networks
- Enable deterministic real-time I/O communication
- Support scheduled and unscheduled messaging
- Connect distributed I/O, drives, and controllers
- Manage ControlNet network traffic for industrial automation
Recommended Related Models
- Allen-Bradley 1756-CN2 ControlNet module
- Allen-Bradley 1756-CN2R redundant ControlNet module
- Allen-Bradley 1756-EN2T Ethernet module
- Allen-Bradley 1756-L7x / L8x ControlLogix controllers
- Allen-Bradley 1756-IB16 / OB16E I/O modules
