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Frequently Asked Questions (FAQ)

Screens, Dashboard visualization

Screen text widget

Colorizing register values into custom colours

Question: In my screen widget I want the register values have custom colour. I set a color for them, but still 
they are black/white colours (depending on theme)

The register values in the WebHMI are colourized using this rule - it is either default value color, or the color defined in the register STATE. There is a default register value style which overrides text widget styles for values. So, to make your register value of a desired colour, set a STATE for the register with the colour you want.

My WebHMI is slow

There are many reasons why your device may slow down, a “disable function & try” method should be applied to detect the source of this problem.

Below a summary of the possible causes is provided:

Screens / Dashboards
  • Use screens wherever is possible for visualisation, and use dashboards as a part of screens for graphic part, which can not be done with the screens.
  • Avoid using bulky DASHBOARDS (too rich in elements, having heavy-weight pictures , trends with long time window etc. ) , normal dashboard is about tens of KB, not MB!
  • Set appropriate refresh time in the settings.
  • Keep the number of open tabs minimal for the current sessions. If you need multiple tabs, use auto-close session checkbox to prevent unattended access.


  • Avoid using many scripts (like dashboards scripts or upon change value scripts). The better way is using a few big scripts or scripts with libraries instead of a lot of small scripts (each script takes some os environment)
  • Run scripts upon changing value, minimize the number of scripts, running in each scan
  • Minimize “WriteReg” Lua instructions in each scan. It is better to use wrapping function UpdReg(), which writes to register only if value has changed.


  • Group register to read on external device and use group reading.
  • Decrease timeout and tries in external connections if it possible. Use auto-drop&try for not available connections.
  • Organize and set different reading periods for variables.
  • Keep the actual T1 time less than system scan set in the settings. this will give more “room” for OS' background processes.

Writing to log

  • Minimize logging many registers to DB,
  • Set appropriate log speed for the registers.check you don't have many events logged each scan.

Development process

  • Keep the number of registers in the project below 2-3K
  • During development, keep track of the Load Average parameter it should be below 1 (but can have short bursts above this value, which ought to fall soon)
  • Avoid making simultaneous changes at once, like turning OFF-ON many regs, connection, scripts etc. Use save & apply feature of the latest fw. (apply all changes at once, instead of creating a queue for changes..)
  • In the comm. log, you can set TRACE level and see what times each operation takes (each connection, script, communication with device etc.), checking timestamps