ControlLogix 5590 High Availability Systems

Availability is the percentage of time that a system is functioning and able to perform its mission. High availability is a characteristic of a system that aims to achieve an agreed level of availability for a higher than normal period.
Controller systems can achieve high availability when specific hardware and configuration requirements are met. For general guidelines for high availability systems, including redundant system components, networks, and other hardware and software considerations, see the High Availability Systems Reference Manual, HIGHAV-RM002.
The following types of controller systems use a redundant chassis pair to achieve high availability:
  • ControlLogix®
     redundancy (safety is not enabled on the controller)
  • Logix SIS (safety is enabled on the controller)
For more information, see the ControlLogix 5590 High Availability Systems User Manual, publication 1756-UM901.

ControlLogix Redundancy

ControlLogix®
 redundancy is designed for non-safety applications that require high availability. When redundant controllers are configured for redundancy, the primary controller executes standard tasks and crossloads standard data to the secondary controller.
The redundant controllers can communicate with only standard I/O modules in a remote chassis via concurrent or non-concurrent communication.
ControlLogix 5590 Redundancy
Redundant chassis pair in a high availability architecture.

Logix SIS

Logix SIS is designed for safety applications that require high availability. Logix SIS can achieve up to SIL 2 or SIL 3 safety ratings. When redundant controllers are configured for Logix SIS, logic executes as follows:
  • Both primary and secondary controllers simultaneously execute the safety task and all safety data remains synchronized.
  • Only the primary controller executes standard tasks and crossloads standard data to the secondary controller.
The redundant safety-enabled controllers can communicate with a mix of standard and safety I/O modules in a remote chassis. For safety I/O communication, concurrent communication must be configured between 1756-EN4TR modules in the redundant chassis and the remote safety I/O modules.
ControlLogix 5590 Logix SIS
Redundant chassis pair connected to remote chassis with FLEX 5000 safety I/O.
For information on Logix SIS, see the ControlLogix 5590 High Availability Systems User Manual, publication 1756-UM901.
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.
Normal