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TwinCAT OPC Server : Optimisations

In case of trouble with OPC-Server performance please check following steps :

1. Minimise OPC-Namespace in TwinCAT-OPC-Server :

  • OPC-Server should provide required variables in his namespace which are requested by an opc-client.

    It makes no sense to provide 700.000 PLC variables in the OPC-namespace but the opc-client just exchange values from 10.000 variables.

    The size of OPC-namespace will cause a longer opc-server-startup-time and will cause a high memory consumption .


    Option 1 :
    Export just part of PLC variables required for OPC :
  • In the TwinCAT PLC programming environment, select "Project"->"Option"->"Symbolconfiguration". Activate "Create Symbol", and use the mouse to select under "Configure Symbolfile..." the areas that you want to export (e.g. POUs and global variables).
  • After compiling the PLC-project the new symbolfile "<yourProjectName>.sym" will be in the same folder as your plc-project.
  • REMARK:
    • Each compiling of the PLC-project will automatically update the symbolfile.
    • The OPC-Server imports structure and array-elements out of *.SYM files.
  • Option 2 :
    Mark PLC-variables in the PLC-code to be relevant for OPC
    This way is based on the TwinCAT export file *.tpy.
    Detailed info

2. OPC-Server : Running as EXE or DLL ?

  • Arguments for working with EXE :
    - One single OPC-client will access data from TwinCAT-OPC-Server
    - The OPC-Client is installed on a different PC , the network has to be crossed via DCOM.
  • Arguments for working with DLL :
    - More than one OPC-Client will communicate with the OPC-Server : Instead one single OPC-Server shares his CPU time to multiple opc-clients, the OPC-Server should work as a DLL : As a result each OPC-Client will have "his personal" instance of the OPC-Server with each opc-server having a separate ADS-communication channel into the ADS-device like the PLC.

3. OPC-Server via DCOM

  • The installation of BECKHOFF OPC-components consist of two parts : The native OPC-Server from Beckhoff and so called "OPC common components" which comes from the OPC-Foundation.

    The installation of BECKHOFF-OPC-products have been redesigned to integrate the official OPC-components and install them in the recommended way.

    Change of installation : 07/2004, new installation for TwinCAT OPC-Server V4.1.0.37