OPC UA on plc|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

Hi all,

I would like to design a software to collect the outputs on a PLC and send the inputs to its. I would like to do it on Siemens, Schneider and Rockweel plcs and I guess OPC UA is the best way to do it because OPC UA seems able to work with any plc manufacturers. I started to read OPC UA specifications given by OPC Fundation and I started to understand how can I do this job with an open source OPC UA server and client (using open62541). The first trouble I have is I guess I need to run my OPC UA client on my computer and my OPC UA server on another computer but how the communication between the PLC and the OPC UA server is done ? I don't really understand this part ... Someone could explain me how I need to run both client and server ? And some tips to program it (do you recommend me open62541 or not ? ...) If you have any recommendations about an opensource OPC UA server/client tell me. I prefer in C or C++.

Many thanks for your help,