Qualification and Synchronization

When a redundant chassis pair starts, the qualification process begins to verify that both chassis have the correct modules and firmware.
After qualification completes, the synchronization process can begin. During synchronization, the system verifies the following:
  • The redundancy modules are connected
  • The redundant chassis continues to meet qualification requirements
  • The partner communication modules can communicate to each other over the
    EtherNet/IP™
     network
The following data is then synchronized, or crossloaded, between the redundant controllers:
  • Updated tag values
  • Forced values
  • Online edits
  • Other project information
NOTE: If Front Port Crossload mode is enabled on the controller and the link between the embedded Ethernet ports is down while the secondary chassis is disqualified or synchronizing, then qualification fails on the first attempt. After the link connection is restored, qualification should succeed upon the second attempt.

Logix SIS Qualification

If the controller is configured for Logix SIS, the qualification process also verifies that a safety application exists in the primary controller in a safety-protected state. The primary controller transfers the safety application and safety signature, if one exists, to the secondary controller.
IMPORTANT:
During qualification, the safety function is temporarily muted. For muting time, see Safety Function Muting.
IMPORTANT:
The qualification process can end for the following reasons:
  • If a safety partner module is installed in either chassis. Safety partner modules are not supported in Logix SIS.
  • If the system cannot validate the safety signature of a safety application in the secondary controller.
  • If the safety function is muted for more than the safety function muting time. In this case, the primary controller resumes the safety function alone.

Possible Communication Delays During Qualification

Some communication delays can occur during qualification. The existence and duration of these delays depend on these factors:
  • Quantity and types of tags on scan in
    FactoryTalk® Linx
     software
  • Client screen and tag update rates, such as in
    FactoryTalk® Live Data
     /
    FactoryTalk®
     Historian
  • Number of data subscribers, such as
    FactoryTalk®
     Alarms and Events and
    FactoryTalk®
     Batch
  • Size of the redundant controller application
  • Network traffic

Timing of Synchronization

Depending on your system configuration, synchronization takes place at the end of each program that is run within the controller project or at other intervals that you specify.
If safety is enabled, the primary and secondary controllers execute the safety task simultaneously and synchronize at the beginning and end of the safety task. As a result, safety data remains synchronized between the controllers.

Synchronization without a Controller Project

To synchronize redundant controllers without a controller project, both controllers must have the same IP mode setting. If there is an IP mode mismatch between the controllers, synchronization fails and the following entry is created in the event log: EVENT_ID_DISQUAL_COMM_PORT_MODE_MISMATCH
IMPORTANT:
To enable the controllers to synchronize after a disqualification caused by mismatching IP modes, you can take the following actions:
  • Download a blank project with the intended IP mode to each controller and perform a Stage 1 reset. The controllers retain the network settings for the front Ethernet port.
  • Perform a Stage 2 reset on each controller. The controllers reset to factory settings, including firmware and all network settings.
For more information about performing a Stage 1 reset, refer to the ControlLogix 5590 Controllers User Manual, publication 1756-UM900.

Synchronization and Fiber Channels

If a fiber channel between partnered redundancy modules fails or is undergoing repair, synchronization is preserved:
  • The repair of a fiber channel can be performed online while the redundant chassis pair is running and synchronized. To aid online repairs, the fiber cable connections and SFP transceiver can be removed and inserted under power.
  • A redundant channel is not required for synchronization. You can synchronize the redundant chassis pair with one channel connected. The redundant channel can be installed later while the chassis is running synchronized. If the channel was disabled, the redundant chassis pair must be disqualified to enable the channel. See Disable or Re-enable SFP Fiber Ports.
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