使用UA-.NET调用OPC-UA方法

Question

I am trying to call an OPC-UA method "ReadVar" from a SINUMERIK 840d, by using the Open OPC-UA.NET implementation at https://github.com/OPCFoundation/UA-.NET

I have limited knowledge about how to use this stack implementation and wonder if somebody has a lightweight example of how to use it to connect to the OPC-UA server and call the method from C# code?

I have tried with the Unified Automation trial binary client to test to call this method and it works perfectly. I also would wonder what is the key benefits (except for obvious ones with support etc) of buying a commercial OPC-UA SDK rather than using the above mentioned open source version.

Answer 1

You have to know the node id of the method, the node id of the "object" of the method, and its arguments. Using the example provided in the OPC-UA .Net you can execute classic "hello world" :-)

IList<object> val = session.Call(  
  // I know that this node holds the method I like to use
  new NodeId("Methods", 2), 
  // and I know this node is "hello" method 
  new NodeId("Methods_Hello", 2), 
  "world");

Console.WriteLine(val[0]);