Product Overview
The Allen-Bradley 1756-RM2 is a ControlLogix Redundancy Module engineered for high-availability control systems. It enables seamless controller redundancy when paired with another 1756-RM2 module in a second ControlLogix chassis. With synchronization speeds up to 1000 Mbps and controller switchover as fast as 20 ms, this module minimizes downtime in critical processes.
This enhanced redundancy module supports ControlLogix 5560 and 5570 controllers, making it a versatile choice for modernizing or expanding existing automation architectures.
Key Features & Benefits
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High-Speed Synchronization: Achieve up to 1000 Mbps synchronization when using matched 1756-RM2 modules, ensuring rapid data consistency between redundant controllers.
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Fast Switchover: Controller switchover occurs in as little as 20 ms, reducing process interruption during failover events.
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Redundant Fiber Ports: The 1756-RM2 uses redundant fiber-optic connections with no single point of failure, enhancing system reliability.
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Interference-Free Diagnostics: Enhanced safety features provide interference-free diagnostics, simplifying troubleshooting.
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Single-Slot Design: Occupies only one slot in a ControlLogix chassis, preserving space for other modules.
Technical Specifications
| Specification |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number |
1756-RM2 |
| Series |
ControlLogix |
| Module Type |
Enhanced Redundancy Module |
| Connector |
LC Type |
| Cable Type |
8.5/125 micron single-mode fiber-optic cable |
| Connector Cables |
1756-RMC1 (1 m), 1756-RMC3 (3 m), 1756-RMC10 (10 m) |
| Supported Controllers |
Logix 5560 / Logix 5570 |
| Length |
10 kilometers |
| Wavelength |
1310 Newton Meters |
| Transmission |
1000 MB per Second |
| Channels |
1 |
| UPC |
884951800434 |
| Wire Size |
20 AWG |
| Dimensions |
5.51 x 4.41 x 5.71 inches |
| Operating Temperature |
32-140 °F (0-60 °C) |
| Enclosure |
None (Open) |
| Current Draw |
1.16 A @ 5.1V DC; 3.4 mA @ 24V DC |
| Power Dissipation |
6 W max |
| Thermal Dissipation |
21 BTU/hr |
| Weight |
0.64 lbs |
Industry Applications
The 1756-RM2 is ideal for industries where uninterrupted operation is critical, such as:
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Manufacturing: Ensure continuous production lines with automatic failover during controller faults.
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Oil & Gas: Maintain control integrity in remote or hazardous environments where downtime is costly.
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Water Treatment: Provide redundant control for essential processes, ensuring consistent water quality.
With its high-speed synchronization and fast switchover, the 1756-RM2 minimizes the risk of data loss and process interruption, directly contributing to operational efficiency and reduced downtime.
Installation & Setup Guidance
Install the 1756-RM2 in any slot of a ControlLogix chassis. When implementing redundancy, you must use a pair of redundant racks, each with the same controller type and revision. Note that I/O modules, intelligent modules, and Encompass partner modules cannot be installed in the redundant chassis pair; place them in a third or higher-order chassis as needed.
Connect the two 1756-RM2 modules using the appropriate fiber-optic cable (1756-RMC1, 1756-RMC3, or 1756-RMC10) with LC-type connectors. The modules can be up to 10 km apart, but for optimal performance, keep the redundant chassis pair in close proximity.
Maintenance & Reliability
Regularly inspect fiber-optic connections for cleanliness and proper seating. The module's open enclosure allows for adequate airflow, but ensure the chassis environment stays within the specified operating temperature (0-60 °C). Periodically verify synchronization status and diagnostic LEDs to detect potential issues early.
By adhering to these simple maintenance practices, you extend the life of the 1756-RM2 and maintain high system availability, reducing long-term operational costs.
Compatibility & Integration
The 1756-RM2 supports ControlLogix 5560 and 5570 controllers. It also supports up to seven enhanced ControlNet and EtherNet/IP communication modules, allowing seamless integration into existing networks. Use the Redundancy Module Configuration tool (RSLinx 2.59 or later) to configure and monitor the redundant system.
Selection Guide & Purchasing Advice
Before purchasing, verify that your controllers are from the 5560 or 5570 series and that you have the required fiber-optic cables (1756-RMC1, 1756-RMC3, or 1756-RMC10). Ensure your chassis has an available slot, as the 1756-RM2 occupies one slot.
PLC Source PRO offers genuine Allen-Bradley 1756-RM2 modules with reliable availability and competitive pricing. When you order from PLC Source PRO, you get the exact part you need for your redundancy application.