Application-controlling tasks are initiated. Variable values are initialized unless
marked Retain or Cold retain.
To initiate a warm restart, disconnect the power supply for a few seconds.
Following a power failure, the warm restart function will be automatically initiated
on power restoration.
After a power fail, instead of doing a warm restart of the application SIL3
applications are restarted using cold retain marked values saved in the controller
periodically with a cycle time set by the user.
Where is this Cycle time set?
The AC800 OPC Server can be configured to save cold retain values on a cyclic basis. Refer to it's user's guide.
Do not schedule saving of cold retain values too often as it adds some level of stress on the controller, especially if large quantities of the variables are marked with cold retain.
Both cold retain and retain adds to the time needed to swap the application during warm download, i.e. the "Stop Time" increases.
When using redundant AC800 OPC Server, define 2 x desired cycle time on each OPC Server, then add 50% as offset to one of them. This will cause cold retain values to be saved on desired cycle time; split 50/50 over the OPC servers.