Losing the Program in case of Power On/Off


Thread Starter

Mohammad Rezvani


There is a problem with one of my SIEMENS S7-400 PLCs. If I cut the power for more than half an hour, I will lose the application program, So, it must be downloaded again.

It is not happening in case of short time power off/on.
The batteries are OK.
The voltage of power supply also is OK.

Thanks for Help.

If you cut the power for more than 30', your data was lost, I think your memory card have problem. so you need changing another mem. ok.

Steve Myres, PE

Have you asked Siemens about it? What did they say?

Do you have to consciously enable battery backup in the configuration? Is the unit reloading an empty program from an EEPROM, that you could load instead with your application program?