I suppose this is a simulated tag in KepWare. They have a weird behavior, at multiple fronts (see e.g.support.softwaretoolbox.com/app/answers/detail/a_id/3047 ) . It seems that each client connection may get its own, independent value. And QuickOPC is creating/disposing of the connections automatically. If you are using Kepware simulated tags, there is nothing I am going to suggest on the client side. Do not use them, in such case. Get a real tag, or a different server.

Hello,
thank you for the details.

I think I know understand what is happening.

Support for Visual Studio designer - including dragging the components from the Toolbox - is only supported for projects targeting .NET Framework (i.e. 4.7.2 to 4.8.1, in current QuickOPC version). But you can use QuickOPC components from .NET 6/7/8 projects as well; it is just that the additional VS Designer is not there. This is documented in the User's Guide.

So, you can either:

1) Create a .NET Framework project instead. In "Create New Project" Wizard, you will select "Windows Forms App (.NET Framework)", instead of just "Windows Forms App". If "Windows Forms App (.NET Framework)" does not appear under the available project templates, you need to go back to Visual Studio Installer and check whether .NET Framework 4.7.2+ support (targeting pack, SDK, ...) is installed in VS.

2) Or, you can keep using your Windows Forms .NET 8.0 project. And simply type in (or copy/paste) the code that works with the QuickOPC components. You need to install the OpcLabs.QuickOPC NuGet package into the project first, but from the picture you provided, it appears that you have already done that. Then, you can e.g. hook a method to a press of a button, and inside the method, place the QuickOPC code (namespace imports will need to go to the top of the file, of course).

Please let me know if this helps.

Best regards

Hello.
It's not quite clear to me what is happening, but I will try to provide some hints and it will possibly take us somewhere.

1. The warning "There was a mismatch between the processor architecture of the project being built "MSIL" ..." is expected, and benign. You can ignore it.

2. The error from the Visual Compiler, however, is for 0xc0000005 (Access Violation), so it is something that should not normally happen.

3. It is not clear, however, why you reporting an error "coming from the compilation of WebApplication1, when the picture attached appear to look like you are actually trying to create a Windows Forms application. What is the problem with the Windows Forms application then? If you get the error about WebApplication1 when just trying to build the Windows Forms project, Unload or remove the projects that you do not want, or create an empty solution and include just your own project in it.

4. Which .NET version are you targeting in your Windows Forms project? (open the project Properties). This is important for determining why the QuickOPC components are disabled.

5. What is the intent of the code you have provided? If you want to get a value of an OPC Item, use the ReadItemValue instead. The current code appears to be getting PropertyId 1, which is the DataType of the item. If that is what you wanted, then use "Dim propertyId As DAPropertyId = DAPropertyIds.DataType" instead.

Best regards

Cannot reproduce. Works for me, i.e. shows a form. The "exit message" you mentioned only appears to me after I exit the form. You can debug to see what is going on.

Note: Discovered an unrelated issue: The almost-final line in Form1_Load is missing a ".ToString ()" and should be
This piece was apparently lost when converting from C# (the same C# example has it correctly).

Regards

Thank you.

As it turns out, the particular build (5.80.82) was not uploaded to nuget.org. Our fault. Please accept my apology.
I have uploaded it now.

Please exit Visual Studio and start again, because I am not sure whether it will pick the changes correctly otherwise.

Best regards