Chapter 11 Loops and Charts
BridgeVIEW User Manual 11-8 © National Instruments Corporation
a check mark in a dialog box; it becomes highlighted but does not change
until you release the mouse button.
Switch Until Released action—Changes the control value when you click
on the control. It retains the new value until you release the mouse button,
at which time the control reverts to its original value. The action is similar
to that of a doorbell, and is not affected by how often the VI reads the
control.
Latch When Pressed action—Changes the control value when you click on
the control. It retains the new value until the VI reads it once, at which point
the control reverts to its default value. (This action happens regardless of
whether you continue to press the mouse button.) This action is similar to
that of a circuit breaker and is useful for stopping While Loops or having
the VI do something only once each time you set the control.
Latch When Released action—Changes the control value only after you
release the mouse button. When your VI reads the value once, the control
reverts to the old value. This action guarantees at least one new value. As
with Switch When Released, this action is similar to the behavior of buttons
in a dialog box; clicking on this action highlights the button, and releasing
the mouse button latches a reading.
Latch Until Released action—Changes the control value when you click on
the control. It retains the value until your VI reads the value once or until
you release the mouse button, depending on which one occurs last.
Activity 11-3. Change the Mechanical Action of a Boolean Switch
Your objective is to experiment with the different mechanical actions of
Boolean switches.
1. Open the Random Signal.vi, as saved in Activity 11-2, from the
BridgeVIEW\Activity directory. The default value of the Enable
switch is FALSE.
2. Modify the vertical switch so it is used only to stop the VI. Change the
switch so that you do not need to turn on the switch each time you run
the VI.
a. Turn on the vertical switch with the Operating tool.