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Introduction to NA Page Object Events And Actions

Each NA on screen object supports events that enable one or more actions to be performed. Not all events are generated by all objects. 

  • – Press – When you press down
    • – This event will ALWAYS fire as soon as you put your finger on an object
  • – Release – When you release the object
    • – This event will ALWAYS fire when the finger is released from the object OR the object loses focus (e.g. another page pops up) 
  • – Click - When you press and release
    • – This will ONLY fire if the release occurs over the object AND the object still has focus
      – If the user presses then moves away or a window pops up the click event will NOT fire

Double Touch Events

When an object has the Double Touch timer set (zero is default) the first touch of the object does not perform any action, only if a second touch comes within the timer period do the normal events and actions process.


Actions linked to the event are the thing that is to be done when this event occurs for example ‘ClosePage’.

Whilst it is possible to develop all the actions directly in VB, there are a number of standard actions which are built into the system so that in some cases users don’t even need to use VB.

The NA supports the following actions:

  • • CallSubroutine [calls a VB method]
  • • ClearUserAlarmLog [clears the history of alarms]
  • • ClosePage [closes the specified page]
  • • DecreaseVariable [reduce a variable by a specified amount]
  • • EjectSDMemory [eject the SD memory]
  • • EnableInputOperation [re-enable the touch screen]
  • • IncreaseVariable [increase a variable]
  • • InvertVariable [invert a boolean variable]
  • • Logout [log the current user out]
  • • Login [display the login screen]
  • • ResetVariable [set a boolean variable to False]
  • • SaveUserAlarmLogToFile [save the alarm log to a storage device]
  • • SetBrightness [change the brightness of the screen]
  • • SetLanguage [change the current language]
  • • SetVariable [set a variable to a specified value]
  • • ShowDocument [show a document (pdf) full screen or windowed]
  • • ShowPage [show a new page]
  • • ShowPreviousPage [load the previously loaded page]
  • • ShowSystemMenu [display the system menu]
  • • StartDataLogging [start the data logging]
  • • StopDataLogging [stop the data logging]

When an event triggers more than one action, it is important to remember that you cannot guarantee that the order of these will not change, even between rebuilds and modifications. If multiple actions are reliant on each other it is better to put these in sequential VB Code rather than separate events.

See Also:

Introduction to the NA series HMI

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Created 2014-06-30
Modified 2015-04-08
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