National Instruments BridgeVIEW End of Activity 9-2. What is a SubVI?

Chapter 9 Creating VIs

BridgeVIEW User Manual 9-12 © National Instruments Corporation

4. Pop up on the thermometer and ch oose Data Operations»

Description…. Type in the description: Displays simulated

temperature (deg F) measurement. Click on OK.

5. Select Show Help from the Help menu. Place the cursor on Volume

and then on Temp. You can see the descriptions you typed in appear

in the help window.

6. Save and close the VI.

End of Activity 9-2.What is a SubVI?

A subVI is much like a subroutine in text-based programming languages.

It is a VI that is used in the block diagram of another VI.

You can use any VI that has an icon and a connector as a subVI in

another VI. In the block diagram, you select VIs to use as subVIs from

Functions»Select a VI…. Choosing this option produces a file dialog box,

from which you can select any VI in the system. If you open a VI that does

not have an icon and a connector, a blank, square box appears in the calling

VI’s block diagram. You cannot wire to this node.

A subVI is analogous to a subroutine. A subVI node is analogous to a

subroutine call. The subVI node is not the subVI itself, just as a subroutine

call statement in a program is not the subroutine itself. A block diagram that

contains several identical subVI nodes calls the same subVI several times.

The Hierarchy window displays a graphical representation of the calling

hierarchy for all VIs in memory, including type definitions and global

variables. You use the Hierarchy window (Project»Show VI Hierarchy)

to display the dependencies of VIs by providing information on VI callers

and subVIs. This window contains a toolbar that you can use to configure

several types of settings for displayed items. The following illustration

shows an example of the VI hierarchy toolbar.