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Entry type: FAQ Entry ID: 95854489, Entry date: 07/02/2014

What is the meaning of the TLG-API messages in the trace file of SIMATIC B.Data Acquisition?

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If, for a WinCC connection of B.Data, no values are acquired, you should check the acquisition trace files (...\BData\GUI\mcl\trace\Kernel\tr*.log) for error messages.
There might now and again be messages like "TLG-API: an error has occurred, line xxx" in the trace files.
The list below shows the main error messages that might be displayed, which can help you to clear the errors.


  • TLG-API: an error has occurred, line 433:
    Possible causes:
    A connection has not been established between B.Data Kernel and WinCC; for example, the B.Data Kernel and WinCC are running under different OS users or Tag Logging has not been enable in the WinCC Runtime.
  • TLG-API: an error has occurred, line 801:
    Possible causes:
    The archive name is not in WinCC; for example, the archive has been renamed in B.Data after browsing and creation of the DPs. The kernel is attempting to read out values from an archive that does not exist.
  • TLG-API: an error has occurred, line 809:
    Possible causes:
    The data point is not (or is no longer) in the WinCC archive.
  • TLG-API: an error has occurred, line 447:
    Possible causes:
    The WinCC archive is not available.
  • TLG-API: access to lower-level COM interfaces has failed, line 200:
    Possible causes:
    The B.Data kernel can connect to the WinCC client. But cannot access the archives. One possible reason is that the B.Data kernel is running as a service (= as System Account) and the WinCC client has been started manually and is thus running under the account of the user who is logged in. This can also occur if WinCC has been started automatically as a service.
    Make sure that the users of the WinCC service and the B.Data kernel are identical.
  • TLG-API: an error has occurred, line 443:
    Possible causes:
    The Runtime of the WinCC project has not been started. The WinCC icon at the bottom right must have a green arrow. Start the WinCC Runtime of your project.

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