Configure this property to define whether this Tag must be written or not automatically when the Value, any Bits (from Bit00 to Bit31), or RawValue properties are modified. If this property is set to True, these changes are sent to the device associated to the I/O Driver. Otherwise, changes are ignored. Default value of this property is True. Example:

Sub Button1_Click()
  ' Disables tag writing
  Set obj = Application.GetObject("Driver1.tag")
  obj.AllowWrite = False
End Sub