Chapter 4
Human Machine Interface
4-26
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National Instruments Corporation
alarm state
indicator, and controls the blinking of the
Mixer in Alarm
indicator. Both loops run in parallel until shutdown is TRUE.
Figure 4-3.
Monitor Tag Value and Alarm VI
The
Mixer in Alarm Blinking
attribute and the
alarm state
indicator are updated only when the changed? output of the Read Tag
Alarm VI is TRUE. This example demonstrates how you might use the
changed? output. In this example, it is not important to use the Case
structure because BridgeVIEW indicators update only when the displayed
information actually changes.
If you use a large number of indicators or attribute nodes or more complex
indicators such as tables and graphs, updating the indicator when changed
by using a Case structure in your diagram can improve the display
performance of your VI.