How to Labview

8/14/2019 How to Labview

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AOE 3054 LabViewProgramming


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Starting LabView Lets begin by

opening LabView From the Start Menu,

Locate and start

LabView 8.2

If this is your first time runningLabView you may get aWindows Security Alert dialog. Ifso, select the Unblock button.

You may also get a Welcometo Labview dialog. In that case

just select the Continue button.


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LabView Programs

To begin a new program(or VI) click the NewBlank VI icon

National Instruments uses

programs that are called VIs.This stands for VirtualInstrument . It considerseach program a tool as onewould use a meter oroscilloscope.


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Programming Environment

The front panel is where we put the controls (buttons,knobs, etc) and indicators (Lights, displays or graphs).

The Block Diagram is where the graphical program will be.

The controls window will also appear which contains objectswhich can be moved to the front panel.

What appears isthe programming environment . It consists of twowindows, theFront Panel andthe Block diagramwindows.


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Select Numeric Control

Clicking this will attach to the pointer a control outline and youcan select where you want it placed on the Front Panel.

Place one in the upper left portion of the panel

Controls Palletshold all kinds offront panel objects.The express palletis the third menu

choice in the popuplist. From it youcan get to thecommonly usedcontrols.


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Rename the control Degrees C

After you drop the control, it highlights the name ready for you to rename it.Just drop the control and start typing the name Degrees C. You canalways go back and double click the name to change it. Changing the nameas you place it will speed up programming time when you are doing largeprograms.


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Rename the control Degrees C

After you drop the control, it highlights the name ready for you to rename it.Just drop the control and start typing the name Degrees C. You canalways go back and double click the name to change it. Changing the nameas you place it will speed up programming time when you are doing largeprograms.


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Observe the Block Diagram

Notice the Block diagram has a terminal for the controlyou just placed on the front panel, and the controls palletchanges to the functions pallet.


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Viewing options

By default Labview displaces objects on theblock diagram as icons. By right clicking onan object you display the object as a smallerblock which makes larger programs easier tosee.

Icon view

Block view

Clicking the tack at the top of theexpress menu will allow you to keepthis menu on the screen when in theblock diagram


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Block Diagram Program Now go to the Block Diagram Page.

Right clicking in LabView is the key to doing mostanything.

From the Diagram a right click will open a similar toolpallet, but specific to block diagram programming.


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Block Diagram-Right Click

Right Click forfunction palletto appear


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Click the tack on theexpress pallet tokeep this pallet onthe screen.


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Functions are grouped into categories. We will see more as we go.

Like the express controls pallet , oneexists forFunctions. Thecommon functionsare accessed fromthis main pallet.


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Search button

Also try the search button on this menu as it allows you to search the vasttoolbox.


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Multiply

And place it near the Degrees C Terminal.


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Add

In the same manner place an addition function on the block diagram.


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Constants

Now hover over the lower terminal on the multiply function and rightclick.


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Constants

Hover over the menu item Create then select Constants.


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Constants

Then enter 1.8 for the constant value. Entering this now will save youhaving to select it again later.


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Wiring

Wiring the vi determines the flow of the data calculations. To wirethe C to F converter, hover over the terminal on the right of theDegrees C Control.

The cursor automatically will switch to the wiring tool that lookslike a spool of wire. If it does not, select Auto from the tools pallet.

Click and hover over the remaining terminal on the multiplyfunction. Then click to set the wire in place. You can also click-drag to connect the terminals.


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Complete Wiring


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Sub-VIs Any VI can be used by another VI.

To transfer the information, we must set up ameans to give the VI data and to get data from it.

Terminals can be assigned to Front Panelobjects.

For inputs , use controls . For outputs , use indicators .


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Add Terminals

Right Click the Icon for the VI in the upper right corner.


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Add Terminals

Select Show Connector.


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Set terminal pattern

Depending on the number of inputs and outputs your VI will use youcan select an appropriate terminal pattern by right clicking on theterminal again.

Our VI has one input and one output so we select the appropriateterminal pattern from the list.


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Add Terminals

Click the terminal onthe left.


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Add Terminals

This control is now associated with the terminal on the left.Whatever you connect to that terminal in another vi will beused as the input data for this vi.


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Add Terminals

For program flow and consistency, always try to put inputs onthe left and outputs on the right.

So, now lets hook up the output.

Click the rightterminal.


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Add Terminals

Then select theindicator as the

output.


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Add Terminals

This indicator is now associated with the terminal on theright. Data from this terminal is sent to the VI using this sub-VI.


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Save The VI From the file menu, select Save

Appropriately name the VI and save in aconvenient location.

Close the VI. Closing the Front panel closes bothwindows.

Closing the block diagram leaves the frontpanel and the VI open.


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Using the sub VIs Open a new Blank

VI from theFile>New menu

On the BlockDiagram, open thefunctions palletand choose awhile loop(appears in theExpress palletunder Exec Cntlgroup).


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Place the While Loop

Click in onecorner

Then click in theother corner.


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Sub-VIs

Add our sub-VI that we created before.

Right Click


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Custom VIs

And Select Custom VIs.


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Place the Sub-VI

Locate the vi inside the while loop and click to place it.

Hover over the terminals on the left and right to see what is available.

Right-Click over theLeft terminal andselect create control.


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Create Control


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Add Indicator

Do the same for the output on the right terminal, exceptselect create Indicator .


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Complete wiring

Switch to the Front Panel.


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Stopping VIs

Preferred Stopbutton.

Use this stop only when nothing else works! The abort button willhalt execution immediately, which might not be good if the code

needs to close com ports or save files before exiting.


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What was learned about LabView? Create new VIs from the beginning.

Use of numeric controls and indicators. Block Diagram Wiring and Data Flow.

Creating and Using Sub-VIs. While loops.

How to Labview

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