Thank you.

Thank you very much for so good assistance.
This time "again", you should be able to make it work by including code such as


var target = new EasyDAClient();
target.ClientMode.AllowAsynchronousMethod = false;

The error happens because for whatever reason, from VS debugger the initial "advise" calls for async operations succeeds, giving the impression that async operations would work, but the actual call to the OPC async Write then fails, with the error you reported. The setting listed above will prevent the component from using async operations even when the "advise" call succeeds.

Hello,
if you would be willing to perform a test with special build again, please find the replacement assembly DLL attached to this post. This one is modified to diagnose the occurrence of 0x80040200 error.
OpcLabs.EasyOpcClassic.zip
Thank you, and best regards

Hello,
the change we have discussed is now implemented, and it is in build 5.12.1333.1, available on the public Web site (www.opclabs.com/Downloads/Quic...). I would appreciate if you can download it and let me know how it works for you. The expected behavior is that Reads and Writes will work (and without any additional coding such as setting flags etc.), but Subscriptions may not.
Best regards

I agree with this approach. Please give me several days to prepare a software with a "relaxed" check for callback interfaces, so that the Reads/Writes become possible even when the particular problematic OPC call fails.