Ok, i will to start to investigate about this, another question do you know about another dll library that supports many interfaces? 

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Split from Communication Sinumerik with visual Studio.

Dany.sanchez

another question do you know about another dll library that supports many interfaces? 

Another  "famous" but "unofficial" library which supports various types of communication is libnodave.

A "more official" and modern way could be to use OPC-UA protocol, "directly" (for newer CN versions) or using Simatic-NET driver as "gateway" for accessing hardware (for versions that do not natively support OPC-UA).

I think, before identifying the best technical solution, it would be better to define: what exactly is the "CN family" you need to communicate with (840D power line, 840D solution line, and versions) and which variable you need (PLC data, NC data, both?)