After a power failure, the Automation Server has a designed procedure to restore script programs in to a particular state. This process should be taken in to consideration when designing the system.
EcoStruxure Building Operation
Automation Server loses power and restarts, unsure where script programs will start from once the Automation Server comes back online. Due to the onboard "super cap" saving the database to flash on power loss, are the last script program line and variable values retained for when the Automation Server starts back up?
The Automation Server saves it's current active database to flash before losing power completely, the super cap has enough power for it to do this one last task before the Automation Server loses power completely. See AS Power supply interruption or failure on how this is accomplished.
On startup from power fail, any script Programs in the Automation Server will start scanning at the first program line. Make sure to keep this in mind and write your programs so that the first line sets your control values to the default "safe" value before moving on to further control logic.