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Exception when browsing KEPServerEX OPC UA server

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06 Jul 2021 15:20 #9904 by support
MyFileName.config.xml is preferred, but functionally, it just needs to be any name that matches the <FilePath> element in the <UAClientEngine> <ConfigurationLocation> in the main config file.

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06 Jul 2021 15:18 #9903 by support
Hello.

1. We are using QuickOPC version 2021.2 (5.61.241.1). Is it OK?

Yes.

2. See the attached config file of our application. Is it OK?

No. The <configSections> part (Point 1 in kb.opclabs.com/OPC_UA_.NET_SDK_Configuration ) is missing.
And, not sure if the positioning is relevant, but I suggest that you place any new stuff just above the final </configuration> closing tag.

3. Where should I place the UAClientEngine.Config_2021-07-05.xml file (after I change the <MaxBufferSize> from 65535 to 65536)?

In the same folder as the program's EXE and its .config file.

3.1. What should be the file name?

It does not matter. It just needs to match the name in the <filePath> element (Point 2 in kb.opclabs.com/OPC_UA_.NET_SDK_Configuration ).

3.2. Is it in the same folder where application exe file is?

Yes

3.3. Should we specify the file name of the above file in our config file (<FilePath>MyApplication.Config.xml</FilePath>)

Yes

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05 Jul 2021 17:55 #9896 by micham
Hi,

One more question:
Should the file UAClientEngine.Config_2021-07-05.xml be:

MyFileName.config.xml
or
MyFileName.xml

?

Thank you.
Michael

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05 Jul 2021 17:50 #9895 by micham
Hi,

Thank you for your answer.

Few questions:

1. We are using QuickOPC version 2021.2 (5.61.241.1). Is it OK?
2. See the attached config file of our application. Is it OK?
3. Where should I place the UAClientEngine.Config_2021-07-05.xml file (after I change the <MaxBufferSize> from 65535 to 65536)?
3.1. What should be the file name?
3.2. Is it in the same folder where application exe file is?
3.3. Should we specify the file name of the above file in our config file (<FilePath>MyApplication.Config.xml</FilePath>)

Thank you.

Michael
Attachments:

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05 Jul 2021 16:08 #9894 by support
The workaround is to create and activate

File Attachment:

File Name: UAClientEn...7-05.xml
File Size:12 KB
a custom OPC UA .NET SDK Configuration, as described here: kb.opclabs.com/OPC_UA_.NET_SDK_Configuration , and in it, change the value under -> from 65535 to 65536. Note that two XML files are involved - one is the standard .NET configuration file for the .EXE that needs to be changed to name the new section; the other is the .NET SDK configuration file which you are probably not deploying yet, so it is a "new" one.

The (yet unchanged) internal SDK configuration file from QuickOPC 2021.2 is attached.

Best regards

File Attachment:

File Name: UAClientEn...7-05.xml
File Size:12 KB
Attachments:

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05 Jul 2021 06:39 #9890 by micham
Hi,

Our customer can't upgrade the OPC server since this is a production environment. You suggested that there are ways to work around. Can you please advise?

Thank you.

Michael

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03 Jul 2021 06:49 #9883 by micham
Hi,
Thank you for your answer!

I have installed KepServer version V6.10.623.0 and it works perfect.

Thank you!

Michael

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02 Jul 2021 17:12 #9880 by support
Hello,
regarding the error "Message size 65536 bytes is too large for buffer of size 65535":

This is a bug in KEPServerEX. It negotiates a message size and then it violates the agreement by sending a larger message. I was able to prove it with KEPServerEX V6.1.655.0, and it works fine with their current version, which is V6.10.623.0. I then searched the Kepware release notes, and it is listed there: On www.kepware.com/en-us/support/release-notes/ , select Product = KEPServerEX and Version = 6.4.321.0 . It has this text under the Release notes:

OPC UA Server Interface
Resolved an issue where the server could send packets that exceeded the ReceiveBufferSize negotiated with the client in the OPC UA TCP Hello message.


(It does not happen with UaExpert because they happened to choose a buffer size that does not trigger the KEPServerEX bug.)
The best and proper resolution is thus to upgrade to latest KEPServerEX version, or at least V6.4.321.0.

If you could not upgrade the KEPServerEX, then there are ways to work around the problem which I can advise. In addition in QuickOPC 2021.3, we will add some mitigations too. There will be no change to QuickOPC 2021.2, because there is no bug to fix - the problem is on the server side.

Best regards

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01 Jul 2021 06:42 #9870 by micham
Thank you!

Michael

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01 Jul 2021 06:08 #9869 by support
Thank you. I was able to reproduce the problem now. It appears that it only happens when encrypted OPC UA connection is in use.

I will investigate and let you know here when I have more information.

Best regards

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