Product Overview
The Allen-Bradley 1756-CNB/B is a single-slot ControlNet Bridge Module that connects a ControlLogix chassis to a ControlNet network. As a Series B unit, it carries one BNC connector for non-redundant media operation and one NAP (RJ-45 8-pin with shield). It handles scheduled and unscheduled I/O data with a Logix5550 controller and bridges data between the ControlLogix backplane and ControlNet.
If your line runs on ControlNet and you need a practical, ready-to-ship bridge, this module keeps racks talking without a redesign.
Technical Specifications
| Specification | Value |
|---|---|
| Series | ControlLogix |
| Module Type | Bridge Module |
| ControlNet Communication Rate | 5 megabits per second |
| Maximum Nodes | 99 |
| Maximum Connections | 64 |
| Input Current | 970 milliamps at 5.1 Volts DC, 1.7 milliamps at 24 Volts DC |
| Power Dissipation | 5.1 Watts |
| Thermal Dissipation | 17.4 BTU per Hour |
| Slot Width | 1 |
| Weight | 0.57 pounds (0.26 kilograms) |
What These Numbers Mean
The 5 Mbps ControlNet rate and 99-node ceiling let you build a deterministic I/O network across a wide plant footprint. With 64 bidirectional connections, the 1756-CNB/B supports a mix of scheduled and unscheduled links. If you need more, add another module in the same chassis on the same network.
Where It Fits
This bridge suits distributed I/O architectures where multiple ControlLogix racks exchange data over ControlNet. It also bridges across networks of different protocols and links HMIs and SCADA systems to the main controller. In oil and gas, that means remote I/O cabinets and operator stations stay synchronized without a full network overhaul.
Compatibility and Integration
The module works with ControlNet devices from Flex I/O, POINT I/O, SLC and PLC5 ControlNet platforms, plus ControlNet interface cards and Encompass partner modules. It supports non-redundant operation as a standalone bridge; identical pairs can be used in a redundant setup with matching node address switches.
Integration Note
Wiring into a ControlNet network may require specific cabling or connection accessories. Confirm the cables and gateways you need with your supplier before commissioning.
Setup and Selection Checklist
Before you order, verify the node address you plan to assign (01 to 99), confirm your rack slot is free, and check whether your application needs scheduled, unscheduled, or mixed connections. Set the node address switches before installation. If you are replacing a failed bridge, match the series and port configuration to your existing setup.
Oil AutoTech provides hands-on technical selection help and fast-dispatch spares for oil, gas and industrial automation. Contact Oil AutoTech today for pricing and availability.
Please verify current lifecycle status and availability with Oil AutoTech before ordering.
