PLC

Consult your operation manual. Look for a section detailing error codes.

....or telephone Siemens directly for assistance.

check for some errors in your program, as experienced, there are conflicting blocks added in your program, or some short circuit from your inputs/outputs.

Have you made any modifications to the PLC code or the wiring? Is there a ProfiBus or ASi bus connectd?

No modification made, the entire plant was shutdown for maintanance two weeks ago only for the Plc not running when restarted. There is a profiBus connected.

Hello, if your machine was running properly prior to the shut down then it is very likely that you have lost the program. If you have S7 software then you can go online and look for the error codes and correct. if you do not have the software then you will have to contact the machine manufacturer. In any case check and or replace the battery.

Good Luck!

i agree with dthomas16, this happens when your CPU is at fault (at the very rare occasion) or the memory card. try replacing the CPU and download the back-up program (if you have ) and when the fault still exist, then the problem lies within your inputs/output i.e sensors, vfd's etc.

Do you have the ability to go online? It is, as others said, possibly a case of the battery not maintaining the program. However this would only be the case if you do not have an EEPROM/ memory card installed.

Reset it properly less chance of problem with main program. follow guidelines plc trouble shooting.