After you build a VI and create its icon and connector pane, you
can use the VI as a subVI. To place a subVI on the block
diagram, select Functions>>All Functions>>Select a VI
. Navigate to the VI you want to use as a subVI and and
double-click to place it on the block diagram.
You also can place an open VI on the block diagram of another
open VI. Use the Positioning tool to click the icon
in the upper right corner of the front panel or block diagram of
the VI you want to use as a subVI and drag the icon to the block
diagram of the other VI.
To display the front panel of a subVI from the calling VI, use
the Operating or Positioning tool to
double-click the subVI on the block diagram. You also can
select Browse>>This VI's SubVIs. To display
the block diagram of a subVI from the calling VI, press the
<Ctrl> key and use the Operating
or Positioning tool to double-click the subVI on
the block diagram.
Any changes you make to a subVI affect only the current instance of the subVI until you save the subVI. When you save the subVI, the changes affect all calls to the subVI, not just the current instance.
In the Context Help window, which you can
access by selecting Help>>Show Context Help
required terminals appear bold, recommended terminals appear
as plain text, and optional terminals appear dimmed. The
labels of optional terminals do not appear if you click the
Hide Optional Terminals and Full Path button in
the Context Help window.
You can designate which inputs and outputs are required, recommended, and optional to prevent users from forgetting to wire subVI terminals.
Right-click a terminal in the connector pane and select
This Connection Is from the shortcut menu. A
checkmark indicates the terminal setting. Select
Required, Recommended, or Optional
.
For terminal inputs, required means that the block diagram on which you placed the subVI will be broken if you do not wire the required inputs. Required is not available for terminal outputs. For terminal inputs and outputs, recommended or optional means that the block diagram on which you placed the subVI can execute if you do not wire the recommended or optional terminals. If you do not wire the terminals, the VI does not generate any warnings.
LabVIEW sets inputs and outputs of VIs you create to
Recommended by default. Set a terminal setting to
required only if the VI must have the input or output to run
properly. Refer to the Read File function located on the
Functions>>All Functions>>File I/O palette for
examples of required, recommended, and optional inputs and
outputs.
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