Dear Experts,

Good day to all,

A client contact me for PU machine with PLC S7 315 CPU having lost program.

On site checked and found NO program inside PLC. This PLC is with 128 k byte MC.

I have original program so tried to download project usingdownload user program to memory card.

Download started but after sometime stop light start blinking and error appeared as follows :

(8404) S7 protocol: The function cannot be performed .

I cannot understand what is this problem.

I tried to download project directly to PLC RAM and it was successfully done but when I tried toCopy RAM to ROM, the same error appeared.

I however started machine by using project download directly to RAM but I need to save the program in MC just in case backup battery fails and machine again looses program.

Kindly advise what this error means and how to solve it.

Thanks in anticipation,

Best Regards.

Fahim Jafry