National Instruments BridgeVIEW 用户手册
Chapter 12
Case and Sequence Structures and the Formula Node
12-4
© National Instruments Corporation
One Button Dialog function (Functions»Time & Dialog)—In this
activity, the function displays a dialog box that contains the message
activity, the function displays a dialog box that contains the message
Error...Negative Number
.
String Constant (Functions»String)—Enter text inside the box with
the Labeling tool.
the Labeling tool.
The VI executes either the TRUE case or the FALSE case. If the
number is greater than or equal to zero, the VI executes the TRUE case
and returns the square root of the number. The FALSE case outputs
–99999.00 and displays a dialog box with the message
number is greater than or equal to zero, the VI executes the TRUE case
and returns the square root of the number. The FALSE case outputs
–99999.00 and displays a dialog box with the message
Error...Negative Number
.
Note
You must define the output tunnel for each case. When you create an output
tunnel in one case, tunnels appear at the same position in all the other cases.
Unwired tunnels appear as white squares.
tunnel in one case, tunnels appear at the same position in all the other cases.
Unwired tunnels appear as white squares.
4.
Return to the front panel and run the VI. Try a number greater than zero
and a number less than zero by changing the value in the digital control
you labeled
and a number less than zero by changing the value in the digital control
you labeled
Number
. Notice that when you change the digital control
to a negative number, BridgeVIEW displays the error message you set
up in the FALSE case of the Case structure.
up in the FALSE case of the Case structure.
5.
Save the VI as
Square Root.vi
in the
BridgeVIEW\Activity
directory.
VI Logic
The block diagram in this activity has the same effect as the following
pseudocode in a text-based language.
pseudocode in a text-based language.
if (Number >= 0) then
Square Root Value = SQRT(Number)
else
Square Root Value = -99999.00
Display Message "Error...Negative Number"
end if
End of Activity 12-1.