Freelance 2016 the backup picked up right away but all the control reverted back to their default settings
From what I recall, the backup controller appears to pick up right away.
In the instance where I disconnected power from the primary the backup controller looked as though it took over like normal
when I removed the cross over cable, the primary actually rebooted and the control failed over to the backup and looked as though it took over like normal
when I pushed the toggle button, the backup controller looked as though it took over like normal
In all three cases, the backup picked up right away but all the control reverted back to their default settings that are in the CB program. If the valve is set to manual with output 0% in the control builder then after the failover the valve will be found in that state. It looks as though the backup only has the program loaded without the current settings, I didn’t really test this theory, but I found two of our valves changed to their programmed state after fail over.
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Parameters changed by an Operator are sent to the Secondary first, and only when acknowledged from the Secondary will the Primary take it too.
New output variables (Write variables), created by Function blocks in a task, are synchronized at the end of a task's programmes.
Inputs are not synchronized, because the Secondary will read all Inputs after a fail over before starting the execution. An here could be the source of your finding. The reading in of inputs is guarded by a timeout (approx 300ms by default). That timeout prevents that the fail over will stall, because an input device doesn't answer or takes too much time to answer.
If you have a PROFIBUS with a lot of PA devices the cycle time of the bus can become longer than the 300 ms and the Secondary would run into the timeout.
It then would use the initial values for its start of the execution.
You can see that situation has happened based on an additional Alarm in Freelance operation. You would get the normal alarm for fail over that specifies the failover reason, but additionally you would get an alarm that states "start with default values" or "start after read timeout" or something similar.