Allen-Bradley 1757-SRM ControlLogix System Redundancy Module

The Allen-Bradley 1757-SRM, also cataloged as the 1757-SRM System Redundancy Module, operates as a dedicated hardware component for controller state synchronization within ControlLogix and ProcessLogix platforms.

Hardware Specifications

Industrial Control & Drive Integration

The 1757-SRM executes synchronous data transfer routines directly tied to the backplane bus communication velocity properties of the local rack. The module establishes a dedicated fiber-optic link to coordinate memory duplication and I/O density scaling states across paired chassis operating on Profinet / EtherNet/IP deterministic networks. Maintaining identical firmware flash compatibility between the primary and secondary processors, network adapters, and the redundancy modules is required to prevent switchover delays, cross-talk faults, or register discrepancies during cross-chassis replication cycles.

Frequently Asked Questions

Q: Does the 1757-SRM support Removal and Insertion Under Power (RIUP)?

A: Yes. The 1757-SRM hardware supports hot-swapping within the ControlLogix chassis framework. However, removal of an active, synchronized module will disrupt the redundancy cross-link and terminate real-time chassis state mirror tracking.

Q: What are the restrictions regarding the synchronization link cable length?

A: The module accommodates dedicated multi-mode fiber-optic cables utilizing SC-type connectors. Verified operation is limited to specific pre-fabricated physical lengths: 1 m, 3 m, 10 m, 50 m, and 100 m options (cataloged under 1757-SRC series).

Field Installation Guidelines

• Mechanical Slot Occupancy: Insert the 1757-SRM into any two adjacent available slots within the primary ControlLogix chassis. Press the module evenly into the backplane connectors until the top and bottom installation latches lock completely into the chassis framework.
• Fiber-Optic Connection and Minimum Bend Radius: Align the SC-type connector plugs with the optical port on the front face of the module. Ensure the multi-mode fiber cable does not exceed the minimum structural bend radius limits to prevent optical attenuation or signal loss at the 1300 nm operating wavelength.
• Hardware Matching Verification: Prior to initializing commissioning, verify that both the primary and secondary redundant chassis contain identical hardware configurations, power supply ratings, and matched module revisions to allow valid system cross-synchronization.