ControlLogix Redundancy Systems

In industrial automation, system availability and reliability are paramount. The ControlLogix Redundancy Systems are designed to enhance these aspects by providing a seamless transition to a secondary controller chassis in case of primary chassis failure. This ensures that critical processes continue operating without interruption. This article will guide you through the key features, system requirements, and setup procedures for ControlLogix redundancy systems.

ControlLogix Redundancy Overview

Redundancy in the ControlLogix system enhances system availability by switching control to a secondary controller chassis if a fault occurs in the primary chassis. The switchover can happen due to various scenarios, such as power loss, hardware or firmware failure, major faults in the user program, or loss of communication between the primary chassis and remote modules. The system automatically switches control to maintain continuous operation without manual intervention.

System Requirements

To configure a typical redundant system, the following components are generally required:

• ControlLogix Chassis: Two chassis of the same size.
• ControlLogix Power Supply: Identical power supplies in each chassis.
• ControlLogix Controllers: Use either 1756-L6x or 1756-L7x controllers, ensuring the same catalog number, series, firmware revision, memory size, and slot placement in each chassis.
• ControlNet Communication Modules: Identical modules such as 1756-CN2/B, 1756-CN2R/B, or 1756-CN2RXT in terms of firmware revision, series, slot placement, and module type.
• EtherNet/IP Communication Modules: Identical modules like 1756-EN2T, 1756-EN2TXT, or 1756-EN2TR with matching firmware revision, slot placement, and module type.
• Redundancy Module: Use modules such as 1756-RM2 or 1756-RM2XT, ensuring identical firmware revision and slot placement. For L7x high-performance systems, RM modules must be RM/B with the same series and firmware revision in the chassis.
• Redundancy Module Cable (Fiber-Optic): Appropriate cables like 1756-RMCx with standard length options.

Additionally, ensure to place all I/O in remote chassis or DIN rails, and add at least two nodes to each ControlNet network and the redundant chassis pair.

Building a Redundant System

To build a redundant system, follow these steps:

1. Install a ControlLogix chassis and power supply in both the primary and secondary positions.
2. Add either 1756-L6x or 1756-L7x controllers to each chassis. Ensure both chassis have identical controller models; do not mix different controller models in the same chassis.
3. Add one or more ControlNet or EtherNet/IP communication modules to each chassis.
4. Add a redundancy module to each chassis.
5. Configure the secondary chassis to be identical to the primary chassis.
6. Connect the redundancy modules using the appropriate cables.
7. Add I/O modules to the ControlNet or EtherNet/IP networks as needed.
8. Integrate operator interfaces into the ControlNet or EtherNet/IP networks to manage the system【18:8†source】.

Enhanced vs. Standard Redundancy Systems

There are two types of redundancy systems: enhanced and standard. While they operate in a similar manner, there are key differences in features and supported modules.

Enhanced systems offer additional features such as support for the double-slot 1757-SRM redundancy modules and the use of ControlLogix-XT system components, which standard systems do not support.

Conclusion

Implementing a redundancy system in your ControlLogix setup can significantly improve the reliability and availability of your industrial automation processes. By understanding the system requirements and following the proper steps to build and configure the redundancy system, you can ensure continuous operation and reduce the risk of downtime due to hardware or firmware failures.

For more detailed information, refer to the ControlLogix Enhanced Redundancy System User Manual, publication 1756-UM535.