Hello. Were you able to use FB640 and FB641 blocks with your S7-300 successfully
? I am trying to make it work but I am having some troubles , if you made it possible and you can give some tips it will be great. Right now when I load the block Plc turns to sto p,so Im wondering if the use of thoae blocks is allow on my Plc,Im using a S7-314

Thanks

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Split from How to identify hardware idenfier for CM in STEP 7 V5.5.?.

Hello. Thanks for the quick answer.  The fb Im using I have had downloaded from the same link you gave me. I added to the program OB 121 and the CPU doesnt stop now. But Im still having problems with the fb 640. When I put in the REQ parameter the First Scan byte it shows status 7000 nothing happens. When I put in the REQ input a clock byte that turns on a off after a while shows the status 8280,this is about port configuration,I check that the poet number is ok,what else should I check? I though maybe was a problem with the cable but I disconected it and the same status remains.

Thanks 

Hello. Im using a CPU 314 6ES7-314-1AG14-0AB0 v3.3,with a CP 341.I have downloaded the Modbus Rtu library and added it to step 7 v5.5 from Siemens site,and in the TIA help for this blocks it says that you can use this blocks in a S7-300.

Thanks ,and best regards

PtP instructions for use of ET 200MP / ET 200SP in the distributed peripherals of a S7-300/400 with Step 7 V5.5