Hello,
I’m working with an ABB PM573 PLC and facing an issue. After a power failure, the main program that was previously in memory is no longer executed. Instead, a simple default program runs, where Input 1 controls Output 1.

Surprisingly, when I upload the main program back into the PLC, it runs normally as expected. However, after another power failure, the main program remains in memory but is not executed, and only the simple program runs again.

Can anyone provide insights into why this is happening and how I can ensure the main program is executed after a power failure? Any advice would be greatly appreciated.

 

Is it the same when you do power off the PLC and Power backout ? Please Check any PLC 's parameters is configured to default to Manufacturing in case of Power loss or check battery backup to dynamic ram if it have.