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How much memory do I need to allocate for WebVis concurrent users?

This explanation of operation is version dependent, there will be a slight change in behavior starting with 3.5.10. Starting with that version Codesys will use this memory configuration only as initial memory. That way the project can support more visualization clients simultaneously without having to worry about memory configuration.

The settings for Max Memory and Memory per client are in the Visualization Manager Properties. I have included an image at the bottom of this page that shows the screen.

Now to the explanation of the current operation in versions prior to the 3.5.10 release:

  • All memory size units are in bytes
  • "Size of memory for visualization" is an amount of memory (as part of IEC-data) that will be distributed dynamically to the visualization
  • As a rule of thumb we can say that the number of possible clients ~= "Size of memory for visualization"/ ("Size of paintbuffer (per client)" * ~1.5)
  • The 1.5 multiplier depends on the types of visualization elements used in the visualization and could be bigger or smaller.
  • This memory is used for supporting client local states (ie. different toplevel visualizations, different selection within frames/tabcontrols, different scrollpositions etc.) and all such client depending data is allocated within that memory
  • There is no a limit on the the buffer size. It is only limited by the available memory for IEC applications on the PLC.
  • Usually it should be no problem to quickly test the necessary number of clients and increase the "Size of memory for visualization" until they can all connect simultaneously.