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I can't control the execution time of my M580 hot standby user application, and would have liked to set MAST in cyclic mode. How can I do

Cyclic MAST is not supported by the M580 hot standby CPUs in order to improve stability of the system compared to Quantum / Premium.
Set the MAST period to a value that is slightly higher than the typical execution time.
If your application exceeds this value, an "overrun" condition is detected. This condition is not a problem; the system is designed to manage it and will not be jeopardized (Primary / Standby), as long as the program is not permanently in overrun.
Check that there is a margin between the maximum actual execution time and the MAST watchdog value. If not, the watchdog may spuriously be triggered
Make sure the program is not permanently in overrun. If it is, certain operations will be difficult or impossible to execute:
- transfert project from Primary to standby PLC
- application backup
- Read/Write SD card
- Reconfiguration of a module on local rack, after a hot-swap
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