PLC's memory

Hello friends
I have one question about memory of Siemens PLCs where PLC program is stored.
We need to switch off a couple of PLCs for a longer time. I wonder what type of memory is used in Siemens PLCs and if there is possibilty to lose program stored in PLC? I know that battery is used but don't know exactly if this has to do with keeping program for weeks and months...

Hello.

Firstly which siemens PLC is it? S5 S7 etc. I have only had limited experience with S5 and i think the PLC program is stored on the EEPROM plugged into the unit. (orange card). Ensure the batteries are changed before you power off and save the program to the EEPROM. Hope this helps if not, i am sure someone will point you in the right direction.

Blue

You can run an S5 without an E/EPROM and rely on the backup battery, but I have run into occasions where the program has been corrupted and the checksum must have passed. I want to get an EPROMMER, but managment is being cheap (or I'm not pressing hard enough).

Take a back-up from the plc and store the back-up. Re-load the plc if necessary when you turn it back on.

Well, it's Siemens S7-300 PLC. We'll do backup but now I know there is chace of loosing program when batteries go down.