Product Overview
1756-CNBR from Allen‑Bradley / Rockwell Automation is a ControlLogix ControlNet Redundant Media Bridge Module. It delivers high‑speed 5 Mbps communication for scheduled and unscheduled data. The dual ControlNet ports support both simplex and redundant media, ensuring continuous operation even if a trunk line fails. This module manages 40‑48 Logix connections (64 max) and connects up to 99 nodes. It is the ideal choice for critical control networks that demand reliability and deterministic performance.
Key features include a built‑in NAP (RJ45) for local programming, backplane power with low current draw (970 mA @5.1V, 1.7 mA @24V), and open‑type enclosure rated for 0‑60 °C operation. The 1756‑CNBR fits any single slot in standard ControlLogix chassis and works with redundant power supplies.
Technical Specifications
| Brand | Allen‑Bradley / Rockwell Automation |
| Model | 1756‑CNBR |
| Series | ControlLogix |
| Type | ControlNet Redundant Bridge Module |
| Communication Rate | 5 Mbps |
| Ports | 2 x ControlNet (BNC) + 1 x NAP (RJ45) |
| Connections (Logix) | 40‑48 (max 64) |
| Max Nodes | 99 |
| Backplane Current | 970 mA @5.1 VDC / 1.7 mA @24 VDC |
| Power Dissipation | 5.5 W (17.4 BTU/hr) |
| Isolation Voltage | 30 V continuous |
| Operating Temperature | 0‑60 °C (32‑140 °F) |
| Cable | 1786‑RG6 quad shield RG6 coaxial |
| Dimensions | 5.51 x 4.41 x 5.71 in (140 x 112 x 145 mm) |
| Weight | 0.64 lbs (0.293 kg) |
| Slot Width | 1 |
Compatibility & Installation
- Compatible chassis: 1756‑A4, ‑A7, ‑A10, ‑A13, ‑A17
- Standard power supplies: 1756‑PA72/C, ‑PA75/B, ‑PB72/C, ‑PB75/B, ‑PC75/B, ‑PH75/B
- Redundant power supplies: 1756‑PA75R, ‑PB75R, ‑PSCA2
- Installation: single slot, any available slot in the chassis
- Use ControlNet taps to connect to trunk cable – verify tap labels to avoid reversed connections
- Programming via NAP port with standard RJ45 cable
Diagnostics & Maintenance
- LED indicators for network status, module health, and redundant media activity
- Automatic fault detection and reporting via Logix controller
- Easy troubleshooting with RSNetWorx for ControlNet configuration
- Hot‑swappable – replace without powering down the chassis
Typical Applications
- Distributed I/O architectures with remote chassis
- High‑availability control systems requiring redundant media
- Communication bridge between ControlLogix and Modicon Quantum networks
- Critical process automation in oil & gas, water treatment, and power generation
Why Buy From Oiltech Controls?
- 15+ years in industrial automation spare parts
- Global shipment with FedEx, UPS, DHL
- Tested surplus / refurbished options – verified before shipping
- 12‑month warranty on all products
- Technical verification of every unit prior to dispatch
- Expert support for obsolete control systems
FAQ
Q: Can I use this module in a non‑redundant network?
Yes, the 1756‑CNBR works in simplex (single‑cable) mode and also supports redundant media.
Q: How many connections does it support?
It handles 40‑48 scheduled/unscheduled Logix connections, with a maximum of 64 total.
Q: Is it hot‑swappable?
Yes, you can replace it while the system is running.
Q: What cable type is required?
Use 1786‑RG6 quad shield RG6 coaxial cable with appropriate taps.
Shipping & Certifications
- Shipping: FedEx, UPS, DHL – worldwide delivery
- Certifications: UL, CSA, CE (Rockwell standard)
- Package includes: 1756‑CNBR module, installation instructions (no cables included)
For inquiries: info@oiltechcontrols.com | +86 158 8020 0923 (WhatsApp)
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