tukotech
commented
3 years ago RE: How can I access the value of the specific Node directly? i=2258 or ns=0;i=2258 is the current time.
Console.WriteLine("Read value : {0}", session.ReadValue(new NodeId("i=2258")).Value);
RE: I found an example using NodeId but I struggle to recognize what the NodeId is really? Have you used the OPC DCOM? If yes, similar to a tag. Note that node ID in UA is much more complex and richer. A node can represent a branch (in a node hierarchy) or primitive data like INT or complex data type.
RE: How can I determine the NodeId if I know the structure of the datablock? What would you consider datablock?
RE: Is it something I can find in the OPC Server? The node IDs? Yes, you can for example use UA Expert to browse for NodeIDs
RE: I need to examine a value of the specific Node once a 100ms Note that most servers update the runtime value as defined by the publishing interval (RevisedPublishingInterval response from the server). You can figure this out using UA Expert as well. Reading faster than publishing rate may not help - so test your server. For example DeltaV OPC UA Server (workstation) can do 500ms the fastest.
neustupa
Hi. First of all - I am really new to OPC UA. I browse the Samples and Workshops but I struggle to find the simple way to write to a single node the desired value I want.
For now I was able to build and run a simple OPC UA Client application base entirely on NetCoreConsoleClient example. I can browse all the parts of the data block which I have access to using the
Sessionobject and itsBrowsemethod. Then using theforeachcycle i can loop throughReferenceDescriptionCollection. Then I can access the inner structure of the data block find the Node I want to go in using comparation withDisplayName.Textand using another foreach cycle go inside and so on.My question is: How can I access the value of the specific Node directly? I found an example using NodeId but I struggle to recognize what the NodeId is really? How can I determine the NodeId if I know the structure of the datablock? Is it something I can find in the OPC Server?
My usecase is quite simple: I need to examine a value of the specific Node once a 100ms and if it changes I need to read some more Nodes' values and then write a response using another Node.
I just need a kick to my butt in the right direction. Thank you very much for any help.
Kind regards,
Zdeněk Neustupa