Get Control Value
- 更新时间2023-02-17
- 阅读时长4分钟
Get Control Value
Retrieves the value of a named control or indicator as variant data.
Use Variant to Data to convert the data to another data type.
reference in
A reference to a VI.
Use Open VI Reference or Static VI Reference to obtain a valid reference for this input.
control name
Label for the control or indicator whose value you want.
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Standard Error Behavior
Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.
| error in does not contain an error | error in contains an error |
|---|---|
| If no error occurred before the node runs, the node begins execution normally.
If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out. | If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out. |
Default: No error
reference out
Unchanged reference to the same VI.
control value
Value of the control or indicator.
error out
Error information.
The node produces this output according to standard error behavior.
Standard Error Behavior
Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.
| error in does not contain an error | error in contains an error |
|---|---|
| If no error occurred before the node runs, the node begins execution normally.
If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out. | If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out. |
Using Get Control Value
This node requires the referenced VI to have a panel. To use this node to retrieve data from an application, make sure you include the panel when you build the application.Verifying Valid Data Values
For optimization purposes, the application does not store data values of controls and indicators for any VI until you display the panel or call this node with a reference to the VI.
The first time you use this node to retrieve data from a referenced VI without first opening the panel, this node returns the default values of the control or indicator rather than the actual values. Thereafter, it returns the actual value.