Allen Bradley 1756-RM2 /A | ControlLogix Redundancy Module

The Allen Bradley 1756-RM2 (Series A) is a high-performance redundancy module designed for the ControlLogix platform. It provides a robust solution for critical applications that require zero-downtime and high availability. By linking two identical ControlLogix chassis via high-speed fiber optic cables, the 1756-RM2 ensures that a “Secondary” chassis is always synchronized with the “Primary” chassis, allowing for an instantaneous and bumpless switchover in the event of a hardware or software failure.

Product Specifications and Datasheet

  • Model Number: 1756-RM2 /A

  • Series: ControlLogix Redundancy

  • Communication Rate: 1000 Mbps (1 Gbps)

  • Fiber Optic Connection: Supports 1756-RMC1, 1756-RMC3, and 1756-RMC10 cables

  • Chassis Compatibility: 1756-A4, -A7, -A10, -A13, -A17 (Standard and XT versions)

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

  • Power Dissipation: 6.0 W

  • Dimensions: Standard single-slot ControlLogix module width

  • Weight: 0.29 kg

  • Country of Origin: USA

Application Areas

  • Continuous Process Control: Oil refineries and chemical plants where a system shutdown could result in significant financial loss or safety hazards.

  • Power Generation: Ensuring the continuous operation of turbine controls and grid synchronization systems.

  • Water/Wastewater: Maintaining critical pumping stations and treatment processes without interruption.

  • Large-Scale Manufacturing: Protecting high-value production lines from controller-related downtime.

Product Instructions for Use

  1. Hardware Installation: Insert one 1756-RM2 module into each of the two redundant chassis. Ideally, the module should be placed in the same slot number in both chassis to maintain symmetry.

  2. Fiber Link: Connect the two modules using a 1756-RMC series fiber optic cable. This dedicated link handles the high-speed data synchronization between the Primary and Secondary controllers.

  3. Firmware Alignment: Ensure that both the 1756-RM2 modules and the Logix5000 controllers in both chassis are running the exact same firmware revision. Redundancy cannot be established if firmware versions are mismatched.

  4. Software Configuration: Use Studio 5000 Logix Designer to enable the Redundancy feature in the Controller Properties. Monitor the module’s front-panel status display to verify that the system has transitioned to the “Synchronized” state.

NEW Allen Bradley 1756-RM2 /A ControlLogix Redundancy Module 1756RM2 (Sealed)

Q&A: Frequently Asked Questions

Q1: How does the 1756-RM2 differ from the older 1756-RM module? A1: The 1756-RM2 offers significantly faster synchronization speeds (1 Gbps vs. 100 Mbps) and supports larger project sizes and more complex I/O configurations with much lower scan time impact.

Q2: Can I use different types of controllers in a redundant pair? A2: No. For the 1756-RM2 to function correctly, both chassis must have identical hardware, including the same controller model (e.g., two 1756-L73 units) and the same communication modules.

Q3: What does the “Series A” designation mean? A3: Series A refers to the initial hardware design. It is fully compatible with the 1756 redundancy ecosystem, though always check the Release Notes for the specific firmware version you plan to use.

Recommended Similar Models

  • 1756-RM: The legacy redundancy module for older ControlLogix systems.

  • 1756-RMC3: A 3-meter fiber optic redundancy cable used to connect two 1756-RM2 modules.

  • 1756-L73: A high-performance ControlLogix controller frequently used in redundant pairs.

  • 1756-EN2TR: A dual-port EtherNet/IP module often used to provide redundant network paths for I/O.

  • 1756-L83E: A newer generation Logix controller with built-in Ethernet that also supports 1756-RM2 redundancy configurations.

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