Boolean data type
A Boolean is a primitive data type that can have one of two values: True or False. It is represented by green wires on the block diagram. The Boolean constant can be changed from True 
to False 
by a mouse click.
The Boolean palette provides various functions that can be performed on Boolean values, such as AND, OR, and NOT. Most comparison functions from the Comparison palette return Boolean values.
Controls and Indicators
Boolean controls and indicators are available on the Boolean palette. Some controls can display Boolean text to describe the current state (i.e. ON/OFF).
Mechanical action
Boolean controls have mechanical actions, which control how activation with the mouse affects the value of the control. Mechanical action allows a control to mimic certain physical actuators (e.g. a light switch or an emergency stop button). The six types of mechanic actions are:
| Behavior | Mechanical action | Description |
|---|---|---|
| Switch | when pressed | The value of the control change each time it is clicked. This is similar to a light switch. |
| when released | The value of the control only changes once the mouse button is released within the boundary of the control. | |
| until released | The value of the control changes only so long as the mouse button is held down. When the mouse button is released, the control returns to its default value. | |
| Latch | when pressed | The value of the control is updated when the mouse button is depressed. Once the VI reads the value of the control, it returns to its default value. |
| when released. | The value of the control is updated when the mouse button is released within the boundary of the control. Once the VI reads the value of the control, it returns to its default value. | |
| until released. | The value of the control is updated while the mouse button is held down, or until the VI reads the value, whichever comes first. |
The latch behavior can not be used if the control has a local variable on the block diagram.
History
In LabVIEW 2010 the representation of Boolean constants on the block diagram changed so that only the currently selected value is visible.
| Icon | LabVIEW Versions |
|---|---|
| Boolean True | |
|
Before LabVIEW 2010 |
|
|
Since LabVIEW 2010 |
| Boolean False | |
|
Before LabVIEW 2010 |
|
|
Since LabVIEW 2010 |
This change was suggested by user altenbach on the LabVIEW Idea Exchange on 03.07.2009 and later confirmed to be included in the beta version of LabVIEW 2010 by user Wonger on 23.02.2010.