I'm using 312 PLC.

The PLC was working before in oa anither app. And now i can't put new program in it. When i do download then is OK. My program runs the plc.
But after swiching PLC on-off. The old program is in PLC again.
What must i do.

Hi pr2501.

What is the EXACT type # of the CPU ?

312 IFM

312-5AC02-0AB0

Thank you

Hi again.

That CPU is the old style with battery backup and MC flash card.
An MC card is a flash card in the style of a short PCMCIA card.

If there is an MC card in the PLC, then try to use the function "Store user program on memory card".

If there is no MC card, then you need a backup battery.

In a real-world application, you would install both an MC card and a backup battery.

edit:

Scratch that.

The 312 IFM is an odd beast in the Siemens inventory.
It has neither an MC card slot or a battery slot.
It only has internal Flash memory.
So I think you must use the function in STEP7, "store user program on memory card" or the function "Copy RAM to ROM".
The 312 IFM is obsolete, so maybe you should replace it with something else.

"Copy RAM to ROM"

Now is ok.

Thank you