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Exception when calling BrowseServers() while subscribed

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29 Apr 2014 15:46 #1908 by mrltk
I am currently in the process of upgrading my main development computer. Once I have my new machine up and running I will install the required Microsoft Debug C++ libs onto my problematic computer. Hopefully it can shed some light on my weird issue.

I will let you know when I am ready to install the extra debuggers.

Talk to you soon,

Tom.

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27 Apr 2014 08:04 #1899 by support
OK, not sure if there is a relation, but it appear on a relatively powerful machine (the one that has most CPUs among those you tested). Unfortunately, I have used one that is pretty similar, too (with no repro).

Regarding the virtual machine: My thinking was that if you could create a VM that shows the problem, it should then behave independently on the host computer - so if you send it to me, I should be able to reproduce the problem as well. Whether you can make this VM simply by creating it on the host computer that has the problem - I am not sure about it, the chances are not big.

Are you willing to install a Debug build of QuickOPC plus Microsoft Debug C++ libs? There is a possibly (but not certainty) that it will show us more details to the problem.

Thank you

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22 Apr 2014 18:01 #1878 by mrltk
My main development computer is running an Intel i7 2670QM processor with 4 cores and 8 threads. It's operating system is Windows 7 pro 64 bit. The SEHException occurs on this computer.

I tested a Windows XP 32 bit computer with is an Intel Core 2 Duo E4400 with 2 cores. The SEHException does not occur on this computer.

I have tested another Windows 7 Professional 64 bit computer. It's CPU is an Intel i5 3470 3.2 4 cores 4 threads. The SEHException does not occur on this computer either.

Finally, I just finished testing on one of my client's computers. Windows 7 Pro x86. Intel Xeon E5405 2.00 GHz with 4 cores. The SEHException does not occur on this computer.

So far, only my development computer seems to cause this odd issue. I can get a virtual machine installed on this computer if required.

Talk to you soon,

Tom.

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19 Apr 2014 13:41 #1876 by support
Hi,

Thank you for additional info. Are there other differences between the two installations? Specifically, as I suspect some kind of threading-related problem, what is the number of cores and logical processors on the two machines?

What you are seeing should not happen with our component, independent of possible problems with any OPC server. I also do not think there is anything "wrong" with your computer or installations.

Unless we find some other way (what about the VMs?), there is one more think that can be done: I can send you a Debug build of the component. The idea is that it has more "checks" inside the code (ASSERTs etc.), and thus it may come with earlier - and more to the point - error message. I do not want to go this way too early, because it is a bit of a hassle - it also requires an installation of Microsoft Visual C++ Debug libraries on your computer. But it can be done.

Best regards

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18 Apr 2014 16:57 #1869 by mrltk
Yesterday I was testing my test program on another machine running Windows XP. I was able to install 3 of the 4 OPC servers I have been testing with. The issue doesn't occur on that XP machine!

So far it's starting to look like my issue is caused by be either something on my machine or the OPC server I was unable to install. The OPC Server in question is an INAT OPC Server TCPIPH1 Version 4.01.27.00. It is the one OPC Server that I need my program to communicate with reliably.

My next step is to rule out the INAT OPC Server as the issue and continue from there. Also, I am going to try a couple more computers with different versions of Windows over the next couple of days to see if I can reproduce the issue.

I will keep you posted with my results.

Again, thank you very much for all of your help.

Tom.

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18 Apr 2014 12:29 #1868 by support
If I could reproduce it here, I will fix it. Isn't your computer a virtual machine, or is there any chance you can turn into a virtual machine, or create a separate VM which has the same problem?

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16 Apr 2014 23:56 #1855 by mrltk
Unfortunately I still am getting the same SEHException when using Version 5.23.1162.1 in the test program. Also, closing the program after the SEHEXception is thrown still causes a System.AccessViolationException as listed in an earlier post.

I made sure to verify I am using the new DLLs.

I've noticed that the SEHException never occurs on the first BrowseServers() call since the program started. BrowseServers() has to be called at least twice for the SEHException to occur.

Could you recommend anything I could possibly try or look at with regards to my computer that may help diagnose my issue?

Thanks again for all your help,

Tom.

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16 Apr 2014 13:43 #1854 by support
I have created more tests, and tried various combinations. I could get a problem in the situation when I expected it (two BrowseServers calls), but in other situations. I have fixed this, and I think it is worth trying on your side. The new build is labeled 5.23.1162.1, and it is now the publicly available build in the Download area on your side. (the same fix will go to version 5.30 but somewhat later).

Can you please download it, rebuild your app, and try again. Please be absolutely sure that you are using this new build then - check the full assembly version, both in GAC (it is there by default), and/or wherever you app is located (if the assemblies are copied alongside the EXE). You can right-click on one of the assembly DLLs, select Properties, and then see the version on the Details tab.

Best regards

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15 Apr 2014 14:03 #1840 by mrltk
Thanks again for looking into this issue.

I am going to install my test program on some more computers around my office to see if I can get the same behavior.

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15 Apr 2014 09:53 #1839 by support
I have tried in SharpDevelop but still could not reproduce it.
The code change I intend to make is not (at least the way I see it) related to the fact that item subscriptions run in parallel with BrowseServers. It has to do with more BrowseServers calls at the same time. But it is a bit more complicated than that, so maybe.

I will create a program (or modify yours) to actually give it a bigger press (invoke all these operations automatically, without user interaction), and run it then for some time. Hopefully it will show the problem, and if so, will fix it. If not, I will just make the one fix I already know that needs to be made, and make a new build available to you.

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