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H
HarshNegi1-Visitor
1-Visitor
August 10, 2024
Question

Not able to get tag value from ABB MicroSCADA OPC Server, but able to retrieve tag name and path

  • August 10, 2024
  • 1 reply
  • 1179 views

I am using KepServerEx (version 6.16) OPC DA client to access ABB MicroSCADA OPC server data.

I am able to access OPC tags using the connection parameters. But when trying to read data using the OPC channel, i am getting the BAD vartype error

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If I directly add OPC server to OPC client, and import tags to it from the same server, i am able to read all the values.

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1 reply

R
rajskumar16-Pearl
16-Pearl
August 12, 2024

This is most likely a DCOM issue preventing the client application from connecting and reading the tags. Even if you have tested connectivity to the remote server with the OPC Quick Client, it uses the logged in user's credentials whereas the KEPServerEx service uses the system's credentials on the PC it is running on. Windows security natively blocks this unless the application level access is granted to the connecting client.

Here is a link to our DCOM configuration guide:
https://www.ptc.com/en/support/help/~/-/media/3795FFE124D64FFC8125A9464EC070AE.ashx

In section 4.1.3 of the above document, you will see "OPC Server" below the screenshot, this will be the name of the target OPC server in your installation. I recommend setting DCOM for "OpcEnum" as well. This is what tells the connecting client which servers are available to connect to.

Please verify sections 5 and 7 of the above document are configured correctly on both computers. You may find that you also need to perform section 4.3 on the Client computer as well.

I also recommend you verify that User Account Control (UAC) is disabled (if applicable in your OS).Depending on your operating systems and network configuration, we have several documents available on our website search engines to assist you with configuring DCOM.

https://www.ptc.com/en/support/search/#q=DCOM

If connectivity over OPC DA cannot be established, as a troubleshooting step DCOM permissions may need to be opened to the fullest extent in order for communication to succeed. These recommendations are for troubleshooting purposes ONLY and should not be used in a production environment without review by trained security personnel or a qualified system administrator.

Please take a look at the following article for recommendations:

https://www.ptc.com/en/support/article/CS293793

If you are prompted to log in to view the complete article, you can use your MyKepware login credentials.

BR,

 

H
HarshNegi1-VisitorAuthor
1-Visitor
August 19, 2024

I checked from WinCC OPC client, it is working fine. I am able to access tag values in WinCC. Hence I assume DCOM settings are working fine.

In kepserverex, I am able to browse tags from OPC server. But in runtime not able to read tag values 

R
rajskumar16-Pearl
16-Pearl
August 19, 2024

Do you know how the WinCC OPC Client is running? Is it using the user’s credentials or the system’s credentials? Have you tried performing a synchronous read from Quick Client?

Here are a few things to try:

  1. As a troubleshooting step, DCOM permissions may need to be opened to the fullest extent for communication to succeed.

    These recommendations are for troubleshooting purposes ONLY and should not be used in a production environment without review by trained security personnel or a qualified system administrator.

     

    Please take a look at the following article for recommendations:

     

    https://www.ptc.com/en/support/article/CS293793

     

    If you are prompted to log in to view the complete article, you can use your MyKepware login credentials.

  2. For testing purposes, disable the firewall on both the DA Client and Server and check.

Note-If the issue persists, I would suggest opening a support ticket with us. Please note that configuration or modification of DCOM settings cannot be performed by PTC personnel, but we can walk you through the DCOM settings.



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