Parameters that you can configure for an Express VI from the configuration dialog box are called configurable parameters. Parameters that you can configure for an Express VI from the block diagram are called expandable parameters or expandable terminals. A parameter can be both configurable and expandable, which means you can configure it from both locations. The configuration you specify for an Express VI with the configurable parameters determines the expandable terminals that appear on the block diagram.
Parameters that you set as configurable or expandable must exist both in the source VI and the configuration dialog box VI. In the source VI, edit the block diagram to include a control or constant for each configurable or expandable parameter. If a parameter is both configurable and expandable, or if a parameter is expandable but not configurable, the source VI must contain a corresponding control or indicator for that parameter. If a parameter is configurable but not expandable, the source VI must contain a corresponding constant for that parameter. You must include all expandable terminals on the connector pane of the source VI. You do not need to include configurable parameters on the connector pane.
On the block diagram of the configuration dialog box VI, the Control Data array lists the configurable parameters for the Express VI, and the Terminals to Grow array lists the expandable terminals for the Express VI. Add, remove, or edit elements in these arrays to set the number and type of configurable and expandable parameters you want.
You also can set parameters as configurable or expandable when you use the Express VI Creator wizard to convert a standard VI to an Express VI. The Configurable column on the Convert VI page corresponds to the Control Data array on the block diagram of the configuration dialog box VI. The Expandable column on the Convert VI page corresponds to the Terminals to Grow array.
Before you create an Express VI, use the following table to determine which options work best for each parameter.
| Parameter Options Selected | Result | Effect on Users |
|---|---|---|
| Configurable and Expandable (default) | Adds an element to the Terminals to Grow array. If the parameter is a control, an element is added to the Control Data array and a control to the source VI. | Users need either to configure the control in the configuration dialog box or to wire a value to the Express VI. |
| Configurable | Adds an element to the Control Data array and a constant to the source VI. | Users need to configure the control in the configuration dialog box. |
| Expandable | Adds an element to the Terminals to Grow array and a control/indicator to the source VI. | Users need to wire a value to the Express VI. |
| None | Does not modify either Express VI component. | Users can keep the default value. |
When you run an Express VI, values you specify using expandable terminals take precedence over values you specify using configurable parameters.