1756-CNB/E ControlNet Bridge Module Overview
The Allen-Bradley 1756-CNB/E is a discontinued ControlNet bridge module for the ControlLogix platform. It connects controllers to a ControlNet network at 5 Mbps. Maintenance engineers value its deterministic messaging and dual-port redundancy. Because the module is discontinued, verify availability with AutoDCSTech before ordering. The recommended replacement is the 1756-CN2.
Technical Specifications of the 1756-CNB/E
- Network: ControlNet at 5 Mbps
- Ports: Dual RG-6 coax
- Node capacity: Up to 99 nodes
- Backplane current: 750 mA at 5V, 10 mA at 24V
- Isolation: 30V
- Operating temperature: 0 to 60 °C
The 30V isolation protects the backplane from transients. The 5 Mbps rate supports deterministic scheduled messaging. Consequently, the module suits time-critical control tasks.
Reliability and Maintenance Perspective
From a maintenance engineer's view, the 1756-CNB/E offers predictable service. The dual coax ports enable redundant cabling. If one segment fails, the other maintains communication. Therefore, downtime risk drops. Inspect coax connectors periodically for corrosion. Also check the chassis power supply for stable 5V and 24V rails. Because the module is discontinued, stock spare units. This practice reduces unplanned outages. The 0 to 60 °C rating suits most control rooms. However, ensure adequate panel ventilation. High temperatures shorten capacitor life. For exact electrical specifications, contact AutoDCSTech.
Integration and Replacement Notes
The module mounts in any 1756 ControlLogix chassis slot. The backplane handles communication with other modules. Configure it in Studio 5000 Logix Designer. ControlNet wiring may require specific coax cables and taps. Confirm cable and gateway compatibility with AutoDCSTech. Since the 1756-CNB/E is discontinued, the 1756-CN2 is the replacement. Verify firmware and chassis compatibility before swapping. The 1756-CN2 may offer different specifications. Always consult official documentation.
Q: What is the input voltage for the 1756-CNB/E?
A: The module draws 750 mA at 5V and 10 mA at 24V from the chassis backplane. It does not have a separate input voltage.
Q: How does the 1756-CNB/E handle isolation?
A: It provides 30V isolation between the ControlNet network and the backplane. This protects against voltage transients.
Q: Is the 1756-CNB/E still available?
A: No, it was discontinued on 2024-12-31. The recommended replacement is the 1756-CN2. Contact AutoDCSTech for availability.
Q: What is the maximum number of nodes on the ControlNet network?
A: The 1756-CNB/E supports up to 99 nodes on a ControlNet network at 5 Mbps.
Availability & Condition at AutoDCSTech
| Part Number | 1756-CNB/E |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
