support wrote: Hello.
the latter event (10010) is clearly the one that is then transformed to the COM "Server execution failed" error. I know that from past experience.

1. Can you please confirm that the first event (10016) *only* appears together with 10010. That is, that it does not appear with your QuickOPC app (e.g. the pre-built demo) that connect to the Cogent server successfuly?

2. Can you try running your app outside of the debugger, to see if it makes any difference? Ideally, starting it outside of Visual Studio, just by double-clicking its EXE. And, even if it still does not connect, is the error message precisely the same, and also the same two event appear in the log?

Thank you

support wrote: Hello,

thanks for the details. I was also thinking that something must be different 0 be it the server descriptor, or the project setting, or the code. But all of that seems to be correct, I agree.

This shifts the focus more to the error itself, and to the server.

First, are you making the tests always under the same user account? Always under the debugger, or sometimes without it? Always with, or always without administator (elevated) privileges?

Second, do you know how is the Cogent server configured to run? Is it a Windows service, or a COM "Local Server" (meaning that it starts and stops depending on how the clients use it).

Third, please start Task Manager, switch it to the Details view/tab, sort processes by name, and look for the process that corresponds to the Cogent server. And, observe what is happening when you do the "passing" test, and what happens when you do the the "failing" test. Is there always a Cogent server process? Does it start and then disappear? Are there sometimes two or more of them? Are there differences between the "passing" and "failing" scenario?

Fourth, please check the Windows event log to see if there are signs of crashes of the server (or some other process), especially around the time of your test(s). Type ""Event Viewer" into the Windows Search box and run it, and look under Windows Logs -> Application (and possibly others).

Thank you

support wrote: Hello,
thank you for the additional information.

I wanted to verify the ServerDescriptor you are using now, but nowhere in the images provided was it sufficiently displayed (it is there, but for the OPC Labs Kit Server, which works); I'd like to see it in the debugger when the exception occurs, with Cogent server. Can you please provide a picture showing the contents of the ServerDescriptor you are actually using?

Some additional questions, just checking/trying to limit the possibilities:
1. is this on 32-bit or 64-bit machine?
2. In the project properties in Visual Studio, is the target set to AnyCPU, or to x86 or x64?
3. can you try to construct the ServerDescriptor simply like this: new ServerDescriptor("", "Cogent.DataHub.1").

Best regards

support wrote: Hello,

I have some questions.

1. What happens when you try to connect using the Connectivity Explorer, but remotely?
2. What happens when you try to connect using your application, but locally?
3. Is the BrowseNodes first thing your application does with the target OPC server (and it fails right away then), or are there other OPC operation done with that target server before the NrowseNodes, and they work well?

Note: I spotted in your code a somewhat unusal handling of "Element" vs. "Descriptor" objects. For example, you seem to be creating ServerElement from various parts first, and then making ServerDescriptor out of it. That is not normally needed. The descriptors contain everything that is needed to reference some entity (such as the OPC server). The elements are outputs from discovery/browsing, and contain additional useful information, that is however not used to actually refer to the desired entity. So, you should probably be creating ServerDescriptor right away. I am mentioning it because there is a danger that by unnecessary complicating the code, you have made some mistake. You can construct the ServerDescriptor e.g. right from UrlString you have (a simple string), or from two strings - machine name, and server's ProgId. Let me know if you need help with that.

Best regards