Choose an Auto-synchronization Setting

The setting that you choose for auto-synchronization determines a significant part of your system's behavior. Use the setting that is recommended for your system as follows.
Auto-synchronization Setting
System
Recommended Setting
Logix SIS
Never
IMPORTANT:
If you want to use the Always or Conditional setting, you must consider the impact to safety reaction calculations.
Redundancy
Always
IMPORTANT:
Before you modify your system, verify that the Auto-synchronization setting is correct. This verification helps prevent system errors.
For example, if you update the firmware, verify that this setting is Never or Conditional before disqualifying the secondary chassis. If the Auto-synchronization setting is Always, you cannot properly disqualify your chassis and conduct the update.
The following table describes the synchronization behavior for each setting.
Auto-synchronization Behavior
Setting
Synchronization Behavior
Never
The system remains in the same state, either synchronized or disqualified, until one of these events takes place:
  • A command is issued from the RMCT to either synchronize or disqualify.
  • The controller commands synchronization or disqualification by using an MSG instruction. For this action to occur, Enable User Program Control must be selected.
  • A fault on the primary causes a switchover.
Always
The system automatically synchronizes regularly. If you attempt to disqualify the system by using the Disqualify Secondary command, the resulting disqualification is temporary as the system automatically qualifies and synchronizes again. If the controller disqualifies the system, the resulting disqualification is also temporary.
Conditional
The system behavior depends on the following:
  • If your Auto-synchronization setting is Conditional and your Auto-synchronization state is 'Conditional, Enabled', then the system continually attempts to synchronize.
  • If your Auto-synchronization setting is Conditional and your Auto-synchronization state is 'Conditional, Disabled', then the system does not automatically attempt to synchronize.
To change from 'Conditional, Enabled' to 'Conditional, Disabled', select Disqualify Secondary on the Synchronization tab.
To change from 'Conditional, Disabled' to 'Conditional, Enabled', select Synchronize Secondary on the Synchronization tab.
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