Which protocol is recommended to communicate between LabVIEW an the S7-300 PLC?

[Matthias_H]

Hello,

I'd like to communicate between LabVIEW (CompactRIO) and the S7-300 PLC.

Which is the protocol NI recommend to use?

I read, that TCP/IP over OPC and profibus work fine. Maybe MPI or Modbus, too.

But I would favor a cheaper solution like the communication directly over TCP/IP. The problem is in my opinion, that Siemens modified the TCP/IP protocol and the protocol itself is not public. I found an example library at ni.com but this was build by using reverse engineering. And I'm not sure, if such a library would work reliable.

I know this topic is interesting for many people, but I could not find a general recommendation here in the forums.

Regards

[Current_93]

Dear Matt!

I have to say that I did not experience any problems with the code from MarcoPolo5.

Do it !

[AEI_JR]

I have direct experience using the NI OPC servers to talk to Siemens S7-300 PLCs, and it's by far the easiest way I've found to communicate.  There may be 'less expensive' options out of the box, but from purely a development standpoint, it's very fast and easy to get working.