Product Overview
The Allen-Bradley 1756-CNB is a ControlLogix ControlNet Bridge Module designed to interface a ControlLogix rack with a ControlNet network. It provides adapter functionality for remote I/O, messaging, and bridging between the backplane and ControlNet. With support for up to 99 nodes and 64 connections, this module is ideal for distributed I/O applications and HMI/SCADA integration.
Key Features
- Maximum nodes: 99
- Maximum connections: 64
- ControlNet communication rate: 5 megabits per second
- Input current: 970 mA at 5.1 V DC, 1.7 mA at 24 V DC
- Power dissipation: 5.1 W
- Thermal dissipation: 17.4 BTU/hr
- Slot width: 1
- Weight: 0.57 lb (0.26 kg)
Technical Specifications
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number |
1756-CNB |
| Series |
ControlLogix |
| Module Type |
Bridge Module |
| Maximum Nodes |
99 |
| Maximum Connections |
64 |
| Communication Rate |
5 Mbps |
| Configuration |
Standard |
| Input Current |
970 mA @ 5.1 V DC, 1.7 mA @ 24 V DC |
| Thermal Dissipation |
17.4 BTU/hr |
| Power Dissipation |
5.1 W |
| Slot Width |
1 |
| Weight |
0.57 lb (0.26 kg) |
| UPC |
10612598174079 |
Industry Applications
The 1756-CNB is commonly deployed in manufacturing plants, water treatment facilities, and material handling systems. It enables distributed I/O by connecting remote ControlLogix racks over ControlNet. It also supports HMI and SCADA interfaces, allowing operators to monitor and control processes in real time. For applications requiring 40–48 Logix communication connections per module, the 1756-CNB is a perfect fit.
Installation & Setup
Install the module in any ControlLogix chassis slot. Set the node address switches to a unique address between 01 and 99 before power-up. For redundant control, use identical pairs of modules with the same node address. Ensure proper path information is configured for message routing.
Maintenance & Reliability
Regularly inspect the BNC and RJ-45 connectors for damage or loose connections. The module's front panel displays diagnostic information, including connection status and error counters. Keep the module free from dust and moisture to ensure long-term reliability.
Compatibility & Integration
The 1756-CNB works with ControlNet networks and is compatible with Flex I/O, POINT I/O, SLC and PLC5 ControlNet modules, and ControlNet interface cards. It supports scheduled and unscheduled messaging, produced/consumed tags, and MSG instructions.
Buying Guide
When purchasing a 1756-CNB, verify the part number and ensure it matches your ControlLogix system requirements. Check the node address and connection capacity. For genuine parts and reliable service, choose PLC Source PRO as your supplier.