Siemens PIW

Ok guys iv jumped back into the wonderful world of Siemens

I have a 2 plcs designated as DP masters but connected via a profibus coupler. The coupler has been configured for 5 input words starting and 5 output words with a starting address of 100

A process is moving PIW 102 into a DB, and heres my problem...i cannot figure out is where PIW102 comes from?! I know its from the other plc but i cannot find where it transfers the data.

I found this thread which kind of relates to what im doing but not fully:
http://www.plctalk.net/qanda/showthread.php?t=80210&highlight=siemens+piw

Any help on this will be greatly appreciated!!

Cheers,
Ash

Edit: There are alot of blocks locked in the PLC so it may be that where the data is moved into PQW102/PIW102 is not visible for me. Just looking for some pointers on where to look

You have two plcs communicating across a DP/DP coupler?

PLC1 is reading from PIW102, as you stated. This input address is assigned to the DP/DP coupler, which acts as a profibus slave.

the DP/DP coupler is also a profibus slave to PLC2. The DP/DP coupler needs to have mirrored assignment (inputs become outputs, etc) in the 2nd PLC HW Config, but the input/output addresses can be anywhere.

You need to find what IO address the DP/DP coupler is assigned in the 2nd PLC, and then look for access to that memory space. Note that the DP/DP coupler could have multiple virtual slots (multiple data transfer areas), so you need to make sure that you are looking at the correct IO area.

Thank you for the reply, it was throwing me that the coupler didn't have the same address on the networks (noob!)

All sorted managed to find it (ish even though the block processing it is protected)