Point.OnChange (method)

Syntax Point.OnChange
Description To request the point's value on change. The next value of the point may be received by calling the GetNext method or function. The current value of the point is returned immediately. Any subsequent GetNext call will block until the point's value changes.
Only one of the OnChange , OnAlarm , OnTimed or OnAlarmAck requests may be activate at a time.
Example Read the point value on change forever. 
Sub main()
   Dim MyPoint as new Point    ' Declare the point object
   MyPoint.Id = "TANK_LEVEL"   ' Set the Id
   MyPoint.OnChange            ' Request the value on change
top :
   MyPoint. GetNext            ' Get the value
   Trace MyPoint.Value         ' trace it to the output window
   goto top                    ' repeat forever
end sub
See also Point.GetNext (method); Point.OnTimed (method); Point.Cancel (method).