Writing on PLCnext OPC-UA server variables from a C# program

PLCnext Technology & PLCnext Controls
1

Hello, We want to interface an independent external C# program with our PLCnext using OPC-UA. The C# DotNet Core 3.0 program uses the OPCFoundation.netstandard.opc.ua v1.4.3.5.9.31 package for that purpose, ant it is compiled using Riders IDE. From the C# program, we are able to read all the PLCnext OPC-UA published variables, but we fail writing on them: we systematically get the “BadAttributeInvalid” error. We feel this is a problem that can be resolved because we can actually read and write theses variables using UaExpert. But UaExpert also shows this kind error in its “Attribute” windows, as shown in the attached screenshot. Therefore, it seems there is a way for a UPC-UA client to bypass this problem. There is probably also a way to fix this problem on the server side. In both case, we can hardly find any documentation to help us solve this situation. Any idea how to:

                                               * Configure the PLCnext OPC server to fix the issue? or
                                               * Bypass the problem on the C# OPC-UA client side?

Thanks a lot, Frederic Details: Using the latest 2020.0 LTS environment. OPC UA Server configuration:
* Visibility of Variables: Marked
* Certificate: Self signed by controller
* Security policies: All three enabled
* Discovery registration : No
* OPC UA file transfer : Enabled

2

Hi Frederic, I see the same using the Ua Expert and struggling also to find more useful information in the web. I’ll involve one of our Ua dev guys, at least we should be able to explain the meaning of those key.

Hope that this gives us also a clue what’s wrong with the netstandard.opc.ua package… Reg Frank

3

Hi Frank, I finally found a demo code from OPC Foundation that gave me an idea on how to deal with all intricacies of making a simple OPC-UA write operation. https://github.com/OPCFoundation/UA-.NETStandard/blob/master/SampleApplications/Samples/NetCoreComplexClient/Program.cs See function WriteValue() So I successfully wrote a PLCnext OPC-UA variable from my external C# program. Therefore, there is no more emergency for me here. But this does not solved the “BadAttributeInvalid” error as seen in UaExpert. It may have some unknown impacts on my projet. Thanks Frederic