1756-RM2 | Allen-Bradley | ControlLogix Enhanced Redundancy Communication Module

Product Description

The 1756-RM2 is a high-performance redundancy module engineered for the Allen-Bradley ControlLogix platform. This enhanced module provides the high-speed data synchronization necessary to maintain a seamless "hot standby" configuration between a primary and secondary controller chassis. In the event of a hardware or software fault in the primary system, the 1756-RM2 (Ser A/B) facilitates an automatic, bumpless switchover to the redundant controller, ensuring zero downtime for critical industrial processes.

Utilizing fiber-optic connectivity, this module supports significantly faster synchronization speeds and higher data throughput (up to 1000 Mbps) compared to legacy redundancy hardware. It is specifically designed to work with Logix 5560 and Logix 5570 controllers, providing a robust backbone for high-availability systems in mission-critical environments such as power plants, water treatment facilities, and continuous chemical processing.

Detailed Technical Specifications

• Model Number: 1756-RM2

• Brand: Allen-Bradley / Rockwell Automation

• Module Type: Enhanced Redundancy Module

• Supported Controllers: ControlLogix 5560 (L6x) and 5570 (L7x) series

• Transmission Speed: 1000 Mbps (1 Gbps)

• Fiber Optic Connector: LC Type (Small Form-factor)

• Optical Cable Type: 8.5/125 micron single-mode fiber-optic cable

• Maximum Link Distance: 10 kilometers (6.2 miles)

• Optical Wavelength: 1310 nm

• Compatible Link Cables: 1756-RMC1 (1m), 1756-RMC3 (3m), 1756-RMC10 (10m)

• Backplane Current: 1.16 A @ 5.1V DC; 3.4 mA @ 24V DC

• Operating Temperature: 0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit)

• Physical Mounting: Single slot in any 1756 ControlLogix Chassis

• Net Weight: 0.31 kg (0.69 lbs)

Industrial Application Scenarios

The 1756-RM2 is a vital component for any "Always-On" automation architecture. It is primarily deployed in safety-instrumented systems (SIS) and complex process control loops where a system failure could lead to significant financial loss or hazardous conditions. By linking two identical chassis, it creates a fault-tolerant environment that preserves I/O status and program variables during a transition.

Professional FAQ

• Can the 1756-RM2 be used with the newer ControlLogix 5580 (L8x) controllers?

  The 1756-RM2 is primarily optimized for L6 and L7 series controllers. For L8 series redundancy, the functionality is often integrated into the processor's firmware via the onboard Ethernet ports, though the RM2 can still be utilized in specific legacy-bridge configurations.

• Is special software required to configure the redundancy?

  Configuration is handled through the Studio 5000 Logix Designer software and the Redundancy Module Tool (RMT), which allows engineers to monitor link status and initiate manual switchovers for maintenance.