You can designate which inputs and outputs are required, recommended, and optional to prevent users from forgetting to wire subVI terminals.
For terminal inputs, required means that the block diagram on which you place 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 place 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.
Complete the following steps to set a terminal to required, recommended, or optional.
You can configure LabVIEW to set all new terminals you configure on the connector pane to required instead of recommended. Select Tools»Options»Front Panel and place a checkmark in the Connector pane terminals default to required checkbox. This option also applies to connections made using the Edit»Create SubVI menu item.
You can connect only one control or indicator to a terminal.