Sir can you help me regarding our Simatic S7 program. Our Siemens OP7 cannot read the program on the Simatic S7. This is about our facility in our wind farm. Once we turn on the power in appears on the screen of OP7 $551 AS NOT POSSIBLE. tnx, regards and good luck.

 

Hello,

What model of S7 are you using?( S7-200, S7-300)??
Did you replace the hardware? S7 or the OP?
Error 551 means that:
"An MPI/PPI connection to the PLC cannot be established using the specified station address."
Check MPI station addresses and wiring."

best regards,
Alin