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The power of LabVIEW lies in the hierarchical nature of the VI. After you create a VI, you can use it on the block diagramof another VI. There is no limit on the number of layers in the hierarchy. Using modular programming helps you manage changesand debug the block diagram quickly.

A VI within another VI is called a subVI. A subVI corresponds to a subroutine in text-based programming languages. When youdouble-click a subVI, a front panel and block diagram appear, rather than a dialog box in which you can configure options. Thefront panel includes controls and indicators that might look familiar. The block diagram includes wires, front panel icons,functions, possibly subVIs, and other LabVIEW objects that also might look familiar.

The upper right corner of the front panel and block diagram displays the icon for the VI. This icon is the same as the iconthat appears when you place the VI on the block diagram.

Icon and connector pane

After you build a front panel and block diagram, build the icon and theconnector pane so you can use the VI as a subVI. Every VI displays an icon, such as the one shown in , in the upper right corner of the front panel and block diagram windows. An icon is a graphicalrepresentation of a VI. It can contain text, images, or a combination of both. If you use a VI as a subVI, the iconidentifies the subVI on the block diagram of the VI. You can double-click the icon to customize or edit it.

You also need to build a connector pane, shown in , to use the VI as a subVI. The connector pane is a set of terminals that correspond to the controls andindicators of that VI, similar to the parameter list of a function call in text-based programming languages. Theconnector pane defines the inputs and outputs you can wire to the VI so you can use it as a subVI. A connector pane receivesdata at its input terminals and passes the data to the block diagram code through the front panel controls and receives theresults at its output terminals from the front panel indicators.

As you create VIs, you might find that you perform a certain operation frequently. Consider using subVIs or loops toperform that operation repetitively. For example, the block diagram in contains two identical operations.

You can create a subVI that performs that operation and call the subVI twice. The example in calls the Temperature VI as a subVI twice on its block diagram and functions the same as the previous blockdiagram.You also can reuse the subVI in other VIs. Refer to Repetition and Loops for more information about using loops to combine common operations.

Refer to the LabVIEW Basics II: Development Course Manual for more information about application development. The following pseudo-code and block diagramsdemonstrate the analogy between subVIs and subroutines.

Function Code Calling Program Code
main {average (point1, point2, pointavg)}
function average (in1, in2, out){ out = (in1 + in2)/2.0;}
SubVI Block Diagram CallingVI Block Diagram

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Labview graphical programming. OpenStax CNX. Apr 09, 2015 Download for free at https://legacy.cnx.org/content/col11408/1.2
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