I am kinda new to Step 7, but I'm using Step7 5.5 with a S7-400 series CPU and trying to use a CP341 as a Modbus Master. I think I have the hardware all configured OK, including the dongle and uploading the Modbus Master config to the CP module.

I opened thezXX21_04_PtP_Com_MODMA sample project, but haven't got very far. How would I, for example, request the first six registers as 16 bit WORD from slave at address 1 starting at register 40001? I suspect I need to move the address of the slave and registers into one of the DBs, but not sure which. I see several DBs with BSEND and BRCV in the sym name; likeIDB_BSEND,Work DB BSEND,SOURCE_DB.

I guess I just need a push off of square one on how to do this.

Thanks for your help.

As it turns out, the example S7-400 program uses a different CP. I needed to actually open the S7-300 ModMa example and use that in my S7-400 program, since that is the one that actually uses the CP341.

More background info: The CP341 is in a EM200 rack with a 414-5H CPU using it via Profibus.

Thanks to Siemens Support, I've got it working now.