OPC UA node browsing fails if server contains graphical items
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Jakob Rasmussen
on 8 Aug 2018
Commented: altay engtollykhar
on 5 Dec 2019
I have been working through the Siemens Application Example “Virtual Commissioning with SIMATIC and Simulink” (link: https://support.industry.siemens.com/cs/ww/en/view/109749187 ) following the guides in documents “109749187_DIGI_Usecases_...” to use PLCSIM Advanced, OPC UA and Simulink as the test environment. Simulink however, is not able to see the contents of global data blocks in the PLC system. By using a third party OPC UA Client i have verified that the items are available from the PLC server. I have attached a report with more details, which was also sent to Siemens support. Their answer is quoted here:
" The problem lays in the implementation of the OPC UA Client within Matlab. As you already found out the browse is not working properly in the matlab client. The reason is the following: With FW2.5 we introduced the Node "icon" under each type (e.g.DataBlockGlobal) which represents a TIA icon (for visualization purpose in the clients). Since this change some clients need to adapt as they did not completely fullfil the OPC UA foundation spezifications. What happens is (simplified) the follwoing: If a Browse is executed on a type node like DataBlocksGlobal you will get the icon and a so called ContinuationPoint. If a ContinuationPoint is not null a BrowseNext has to be executed on this ContinuationPoint to get the additional nodes. This is not done in the OPC UA Client."
Is there any solution to this problem?
2 Comments
Leonard Classen
on 20 Jun 2019
Edited: Leonard Classen
on 26 Jun 2019
Hello Jakob
I have exactly the same problem!
Did you come up with a solution for that?
Did you find an alternative solution? I do not need to use OPC UA. Currently I am looking into alternative methods to communicate between the PLC and Matlab, eg. TCPIP.
best regards
Leo
Accepted Answer
Stefanie Schwarz
on 25 Jun 2019
As pointed out, ContinuationPoints are currently not supported by OPC Toolbox. Our developers are aware of this issue and they are considering to fix this in one of the future releases. As of now, there are no workarounds to handle this.
We apologize for any inconvenience caused due to this limitation.
2 Comments
Stefanie Schwarz
on 10 Jul 2019
Edited: Stefanie Schwarz
on 10 Jul 2019
This feature is currently not scheduled for a future release.
I encourage every customer who is interested in this feature to submit a Technical Support Request explaining your use case. We will directly forward this to development.
More Answers (1)
Felipe Ravazzi Iaconis
on 11 Jul 2019
Hello,
Browsing of ContinuationPoints is not supported, but you can still access the variables directly:
![direct_read.PNG](https://www.mathworks.com/matlabcentral/answers/uploaded_files/228617/direct_read.png)
So we do actually have a workaround for this. Just download the attachment and replace the file in the application example!
Best regards,
Felipe R.
4 Comments
Felipe Ravazzi Iaconis
on 5 Dec 2019
Hello,
What Matlab and OPC Toolbox versions are you using?
BR
Felipe
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