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Different QuickOPC runtime revisions on the same PC

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08 Jul 2021 09:30 #9953 by lamar
Yes, I agree.
Thank you for your efforts.

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08 Jul 2021 09:26 #9951 by support
Hello.
I am unable to reproduce this one in my environment.

I suggest to close it as unresolved, due to low priority.
Thank you for understanding.

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03 Jul 2021 09:25 #9886 by lamar
VMWARE version is 15.5.2 build 15785246
Guest OS is Windows 10 x86 1909 build 18363.418

Well, this became less troublesome for me now, since I know the problem appears only running in a shared folder.
However it still may be interesting for you, as QuickOPC 2019.1 did not do this, therefore it may be a new bug,
optionally producing other undiscovered malfunctions. So please let me know if you have any questions,
and I will try to help you further in debugging on my best.

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03 Jul 2021 09:25 #9885 by lamar
VMWARE version is 15.5.2 build 15785246
Guest OS is Windows 10 x86 1909 build 18363.418

Well, this became less troublesome for me now, since I know the problem appears only running in a shared folder.
However it still may be interesting for you, as QuickOPC 2019.1 did not do this, therefore it may be a new bug,
optionally producing other undiscovered malfunctions. So please let me know if you have any questions,
and I will try to help you further in debugging on my best.

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03 Jul 2021 07:31 #9884 by support
OK, thanks for update.

Please give me some time. I will to reproduce as closely as possible what you are doing. This is somewhat complicated, because in an unlucky coincident, we have recently switched our virtualization from VMWare to VirtualBox, so if the problem depends on the VMWare, I would have to go back to VMWare.

I will also need the precise version of the Windows 10 in the VM guest - taken from the WINVER command.

Thank you

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02 Jul 2021 10:21 #9878 by lamar
Hi, I have made the test with exception handling. Nothing changed. The code is the easiest it can be.
The KB article is very interesting.

var
EasyDAClient: _EasyDAClient;

procedure TForm1.FormCreate(Sender: TObject);
begin
try
EasyDAClient := CoEasyDAClient.Create;
except
on E: EOleException do
begin
ShowMessage(Format('*** Failure: %s', [E.GetBaseException.Message]));
Exit;
end;
end;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
try
Edit1.Text := EasyDAClient.ReadItemValue('', 'Matrikon.OPC.Simulation.1','Random.UInt1');
except
on E: EOleException do
begin
ShowMessage(Format('*** Failure: %s', [E.GetBaseException.Message]));
Exit;
end;
end;
end;

end.

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01 Jul 2021 12:47 - 01 Jul 2021 12:48 #9873 by support
Hello.
Yes please test with the exception handling.

I cannot give complete guarantee that the Delphi examples are correct in terms of proper freeing. We are no Delphi experts here. In fact I recently gave the task of checking whether the freeing is OK in those Delphi examples to an external developer, and I am waiting for his answer.

Earlier, we had written an article on this topic - see kb.opclabs.com/Reference_counting_in_Delphi - but the point is, I am not 100% sure if what is in the article is fully correct. Hopefully it is. The task of the external person is also to make the actual long-running tests, to check if there are memory leaks. It is somewhat complicated because the underlying objects are .NET objects, and it is OK for the .NET object to remain in memory until the garbage collector decides to free it, so what looks like a "momentary" leak does not necessarily mean a "true, permanent" leak.

Regards
Last edit: 01 Jul 2021 12:48 by support.

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30 Jun 2021 17:02 #9864 by lamar
Unfortunately there is nothing revealing in the event log.

Yes, I used the sample code. I did no exception handling in this test.
I found some samples in the "Doc Examples" I will test it that way and will come back with the report.

I see in the examples that you use only create methods.
Why is not there any freeing?
I see FreeAndNil command only in the subscription examples.

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30 Jun 2021 14:48 #9861 by support
Hello,
thanks for the video and the update, it is quite illustrative.

I have 2 more questions:

1. Is there something interesting in Windows application event log, around the time the application unexpectedly exits? : Event Viewer -> Event Viewer (Local) -> Windows Logs -> Application.

2. Guessing from the name of your EXE, it might be made by modifying the ReadAndDisplayExample. Unfortunately, this example has no proper exception handling. Do you have some exception handling in tour code, and if so, can you show the code here? My idea was that with the exception handling, there might be a way to obtain some information about what is happening, if the exception is caught and displayed.

Best regards

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30 Jun 2021 08:01 #9860 by lamar
Correction:
3. QuickOPC is installed with the production installer to the own virtual hard drive of guest and to the default location

Additional info:
I have tested it with a shared folder that have a drive letter assigned. Same result.

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