The 1756-CN2R is a high-performance ControlNet bridge module belonging to the Allen-Bradley ControlLogix platform. It is specifically designed to facilitate high-speed, deterministic communication in redundant network topologies. Featuring dual BNC ports, the 1756-CN2R allows for a "bumpless" switchover between media cables, ensuring that critical industrial processes remain online even if one network path is compromised.
Supporting up to 99 nodes and a data rate of 5 Mbps, this module is a cornerstone for Distributed I/O architectures, HMI/SCADA connectivity, and peer-to-peer controller interlocking. Its ability to cover up to 1,000 meters per segment (extendable via repeaters) makes it an ideal solution for large-scale manufacturing facilities and process plants that require time-critical data exchange via the Common Industrial Protocol (CIP).
The 1756-CN2R is engineered for maximum availability and system flexibility:
Redundant Media Support: Dual BNC ports provide two independent paths for ControlNet signals, protecting against cable breaks or connector failures.
High Connection Capacity: Supports up to 128 Logix connections and a total of 131 communication connections, allowing for extensive I/O and messaging tasks.
Maintenance Port: Includes a front-facing USB 1.1 port (12 Mbps) dedicated to local configuration, programming, and firmware updates (not intended for runtime data communication).
Robust Environmentals: Designed for a wide operating temperature range (0 to 60 °C) and high vibration resistance (2G at 10-500Hz), suitable for demanding cabinet environments.
Chassis Versatility: Compatible with all standard 1756 ControlLogix chassis (A4 through A17) and both standard and redundant power supply configurations.
| Feature | Specification Details |
| Model | 1756-CN2R |
| Brand | Allen-Bradley (Rockwell Automation) |
| Module Type | ControlNet Bridge (Redundant) |
| Data Rate | 5 Mbps |
| Nodes (Max) | 99 |
| Logix Connections | 128 |
| Total Connections | 131 |
| Backplane Current | 1300 mA @ 5.1V DC / 3 mA @ 24V DC |
| Power Dissipation | 6.7 Watts (22.9 BTU/hr) |
| Dimensions (HxWxD) | 5.51 x 4.41 x 5.71 in |
| Weight | 0.43 kg (0.94 lbs) |
What cable is required for the 1756-CN2R?
The module requires 1786-RG6 quad-shield RG6 coaxial cable. Proper termination with 75-ohm resistors at the ends of the trunk line is mandatory for network stability.
Can the USB port be used for HMI communication?
No. The USB port is strictly for temporary maintenance tasks, such as configuring the module via RSLinx or flashing firmware. Runtime data communication must occur over the ControlNet BNC ports.
Does this module support "Hot Swapping"?
Yes. Like most 1756 modules, the 1756-CN2R supports Removal and Insertion Under Power (RIUP), allowing you to replace the module without cycling power to the entire chassis.
Redundant Cabling Strategy
To achieve true redundancy, route the two BNC coaxial cables (Channel A and Channel B) through different physical paths or conduits. This minimizes the risk of a single mechanical event (like a forklift accident or fire) severing both communication lines simultaneously.
Network Scheduling
Every ControlNet network containing a 1756-CN2R must be scheduled using RSNetWorx for ControlNet. This software establishes the Network Update Time (NUT) and ensures that deterministic data (Scheduled) and non-critical data (Unscheduled) are prioritized correctly. Failing to "save to the keeper" after making hardware changes will result in I/O communication failures.
Power and Grounding
Ensure the chassis is properly grounded to a low-impedance earth ground. The 1756-CN2R has an isolation voltage of 30V continuous, tested at 500V. Proper grounding is critical for the BNC shields to prevent electromagnetic interference (EMI) from corrupting the 5 Mbps data stream.
Global Express Shipping
Returns & Warranty
Manufacturer: Allen-Bradley
Product No.: 1756-CN2R
Country of origin:United States
Product Type: ControlNet Communication Module
Barcode: 8537101190
Payment: T/T, Western Union
Weight: 250g
Dimensions: 14cm x 13.2cm x 3.5cm
Shipping port: Xiamen
Warranty: 12 months
The 1756-CN2R is a high-performance ControlNet bridge module belonging to the Allen-Bradley ControlLogix platform. It is specifically designed to facilitate high-speed, deterministic communication in redundant network topologies. Featuring dual BNC ports, the 1756-CN2R allows for a "bumpless" switchover between media cables, ensuring that critical industrial processes remain online even if one network path is compromised.
Supporting up to 99 nodes and a data rate of 5 Mbps, this module is a cornerstone for Distributed I/O architectures, HMI/SCADA connectivity, and peer-to-peer controller interlocking. Its ability to cover up to 1,000 meters per segment (extendable via repeaters) makes it an ideal solution for large-scale manufacturing facilities and process plants that require time-critical data exchange via the Common Industrial Protocol (CIP).
The 1756-CN2R is engineered for maximum availability and system flexibility:
Redundant Media Support: Dual BNC ports provide two independent paths for ControlNet signals, protecting against cable breaks or connector failures.
High Connection Capacity: Supports up to 128 Logix connections and a total of 131 communication connections, allowing for extensive I/O and messaging tasks.
Maintenance Port: Includes a front-facing USB 1.1 port (12 Mbps) dedicated to local configuration, programming, and firmware updates (not intended for runtime data communication).
Robust Environmentals: Designed for a wide operating temperature range (0 to 60 °C) and high vibration resistance (2G at 10-500Hz), suitable for demanding cabinet environments.
Chassis Versatility: Compatible with all standard 1756 ControlLogix chassis (A4 through A17) and both standard and redundant power supply configurations.
| Feature | Specification Details |
| Model | 1756-CN2R |
| Brand | Allen-Bradley (Rockwell Automation) |
| Module Type | ControlNet Bridge (Redundant) |
| Data Rate | 5 Mbps |
| Nodes (Max) | 99 |
| Logix Connections | 128 |
| Total Connections | 131 |
| Backplane Current | 1300 mA @ 5.1V DC / 3 mA @ 24V DC |
| Power Dissipation | 6.7 Watts (22.9 BTU/hr) |
| Dimensions (HxWxD) | 5.51 x 4.41 x 5.71 in |
| Weight | 0.43 kg (0.94 lbs) |
What cable is required for the 1756-CN2R?
The module requires 1786-RG6 quad-shield RG6 coaxial cable. Proper termination with 75-ohm resistors at the ends of the trunk line is mandatory for network stability.
Can the USB port be used for HMI communication?
No. The USB port is strictly for temporary maintenance tasks, such as configuring the module via RSLinx or flashing firmware. Runtime data communication must occur over the ControlNet BNC ports.
Does this module support "Hot Swapping"?
Yes. Like most 1756 modules, the 1756-CN2R supports Removal and Insertion Under Power (RIUP), allowing you to replace the module without cycling power to the entire chassis.
Redundant Cabling Strategy
To achieve true redundancy, route the two BNC coaxial cables (Channel A and Channel B) through different physical paths or conduits. This minimizes the risk of a single mechanical event (like a forklift accident or fire) severing both communication lines simultaneously.
Network Scheduling
Every ControlNet network containing a 1756-CN2R must be scheduled using RSNetWorx for ControlNet. This software establishes the Network Update Time (NUT) and ensures that deterministic data (Scheduled) and non-critical data (Unscheduled) are prioritized correctly. Failing to "save to the keeper" after making hardware changes will result in I/O communication failures.
Power and Grounding
Ensure the chassis is properly grounded to a low-impedance earth ground. The 1756-CN2R has an isolation voltage of 30V continuous, tested at 500V. Proper grounding is critical for the BNC shields to prevent electromagnetic interference (EMI) from corrupting the 5 Mbps data stream.
| Product Image | Model Number / Title | Condition | Availability | Action |
|---|---|---|---|---|
|
Allen-Bradley 1756-L85EPXT ControlLogix 5580 Process XT Controller | Original New | In Stock | View Details |
|
Allen-Bradley 1756-L75 ControlLogix 5570 Controller | Original New | In Stock | View Details |
|
Allen-Bradley 1756-L81E ControlLogix 5580 Programmable Automation Controller | Original New | In Stock | View Details |
Global Express Shipping
Returns & Warranty
Orders are processed and delivered Monday-Friday (excluding public holidays).
For full eligibility, restocking fees, and international return details, please view our official Refund & Return Policy .
| Color pattern |
Black
|
| Country of origin |
United States
|
| Power source |
DC Power
|
Replacing a 1756-L73 does not automatically mean upgrading its firmware. This guide compares v19.013, v21.011 and v31.011, focusing on project compatibility, HMI communications, legacy networks and...
Implementa un circuito luminoso XOR con 3 interruttori SPST in LogixPro o RSLogix 500 utilizzando un bit di relè interno. Include tabelle della verità, equazioni booleane e verifica.
Integra Allen-Bradley CompactLogix, Caterpillar ATS e generatori nel DCS DeltaV tramite Modbus RTU. Include i gateway ProSoft MVI69-MCM e Miille DIN266.
L’istruzione ONS si attiva, ma la bobina OTE non rimane mai eccitata in Studio 5000 perché il one-shot è vero solo per una scansione. Usa OTL/OTU oppure una logica di autoritenuta.
Configura i servoazionamenti Allen-Bradley Kinetix 5500 su EtherNet/IP. Include CIP Sync, la temporizzazione IEEE 1588 V2, la selezione degli switch Stratix, la topologia DLR e l’HMI.
Un filtro a media mobile è lo smussatore a finestra scorrevole che la maggior parte degli ingegneri della strumentazione inserisce nei percorsi dei segnali analogici di DCS e PLC. Ecco come funziona...
