Dear Experts, 

 I am new to Siemens equipment, this question is only for my khowledge. 

 Please help me with this issue.

 I am using a CPU315F-2PN/DP with a DI32, a DO32, a DI8/DO8 and an AI 2x12, the connexion with Ethernet works very well.

 I would like to use the MPI connexion with my PG, which I am used to do, but:

- I cannot manage to establish the communication 

- the BF1 led is always ON, even if RUN mode is activated.

I have tried many things, with no result for the moment, BF1 is always ON:

- power OFF and power ON the PLC

- MRES reset

- loading to the PLC with new System data, etc...

- configuring the communication on MPI, etc...

- loading other projects

Would you please have an idea of why the BF1 would always stay ON (MPI/DP problem). Can it be due to software ? or hardware ?

  Thank you very much for your help. 

   Hello everyone, 

 I just want to connect my PG to the PLC using MPI.

 For now, only Ethernet communication is working.

 Enclosed is my HW Configuration.

 What could I do to get rid of this BF1 fault ? I think it must be a hardware issue ?...

 FYI, this BF1 does not cause any SF, and the diagnostic buffer of the CPU does not give any information about this fault.

Other info: No special OB was loaded to the PLC to inhibit the SF fault.

   Thank you for your help.

  Answer found !

My colleagues told me that the MPI/Profibus Interface of this S7-300 is out of order (something burnt inside...). 

So we can only use the Ethernet interface. The problem was indeed a hardware one. As I was thinking... 

My colleagues suspect that the PG might be responsible for sending high intensity current which could damage the MPI Interface, as this happened before with other PLCs...

  Thank you all. 

     Have a good day.