when i was trying to enable audit trial in 800xA V4.1 the write commands from screens are getting 3sec delay.
Enabling the Audit Trail option "AuditEvent_OperatorAction"...
... will add overhead to most OPC write actions.
1. Read current value
2. Write new value
3. Read new value
4. Log the audit event in Event Storage
Depending on your OPC server, target controller and their workload the additional tasks (1, 3 and 4) may take a few seconds.
Below is an example of timing in the OPC traffic during an audited write of one (1) OPC item towards an otherwise idling AC800 OPC server and controller:
Total time to write: ~1.5 seconds
In 800xA version 5.0 step 3) was removed which should make the operation about 1/3 faster than in previous versions.