测控技术及仪器论文翻译英文Word下载.docx

测控技术及仪器论文翻译英文Word下载.docx

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完成日期：

2011年3月5日

ExpandingtheFeaturesofaVI

YoucanchooseoneofmanyLabVIEWVItemplatestouseasastartingpoint.However,sometimesyouneedtobuildaVIforwhichatemplateisnotavailable.ThischapterteachesyouhowtobuildandcustomizeaVIwithoutusingatemplate.

BuildingaVIfromaBlankTemplate

Inthefollowingexercises,youwillopenablankVIandaddExpressVIsandstructurestotheblockdiagramtobuildanewVI.YouwillbuildaVIthatgeneratesasignal,reducesthenumberofsamplesinthesignal,anddisplaystheresultingdatainatableonthefrontpanel.Whenyoucompletetheexercises,thefrontpaneloftheVIwilllooksimilartothefrontpanelinFigure3-1.

Youcancompletetheexercisesinapproximately30minutes.

Figure3-1.FrontPanelfortheReduceSamplesVI

OpeningaBlankVI

Ifnotemplateisavailableforthetaskyouwanttocreate,youcanstartwithablankVIandaddExpressVIstoaccomplishthespecifictask.CompletethefollowingstepstoopenablankVI.

1.IntheLabVIEWdialogbox,clickthearrowontheNewbuttonandselectBlankVI

fromtheshortcutmenuorpressthe<

Ctrl-N>

keystoopenablankVI.

Noticethatablankfrontpanelandblockdiagramappear.

NoteYoualsocanopenablankVIbyselectingBlankVIfromtheCreatenewlistin

TheNewdialogboxorbyselectingFile»

NewVIfromthefrontpanelorblock

diagrammenubar.

2.IftheFunctionspaletteisnotvisible,right-clickanyblankspaceontheblockdiagramtobringupthetemporaryversionoftheFunctionspalette.Clickthethumbtack,shownatleft,intheupperleftcorneroftheFunctionspaletteto

placethepaletteonthescreen.

NoteYoucanright-clickonablankspaceontheblockdiagramorthefrontpaneltobringuptheFunctionsorControlspalettes.

AddinganExpressVIthatSimulatesaSignal

CompletethefollowingstepstofindtheExpressVIyouwanttouseandthenaddittotheblockdiagram.

1.IftheContextHelpwindowisnotvisible,pressthe<

Ctrl-H>

keystoopentheContextHelpwindow.YoualsocanpresstheShowContextHelpWindowbutton,shownatleft,toopentheContextHelpwindow.

2.SelecttheInputpaletteontheFunctionspaletteandmovethecursorovertheExpressVIsontheInputpalette.NoticethattheContextHelpwindowdisplaysinformationaboutthefunctionofeachExpressVI.

3.FromtheinformationprovidedintheContextHelpwindow,findtheExpressVIthatcanoutputasinewavesignal.

4.SelecttheExpressVIandplaceitontheblockdiagram.TheConfigureSimulateSignaldialogboxappears.

5.IdlethecursoroverthevariousoptionsintheConfigureSimulateSignaldialogbox,suchasFrequency（Hz）,Amplitude,andSamplespersecond（Hz）.ReadtheinformationthatappearsintheContextHelpwindow.

6.ConfiguretheSimulateSignalExpressVItogenerateasinewavewithafrequencyof10.7andamplitudeof2.

7.NoticehowthesignaldisplayedintheResultPreviewwindowchangestoreflectthe

configuredsinewave.

8.ClosetheConfigureSimulateSignaldialogbox.

9.MovethecursorovertheSimulateSignalExpressVIandreadtheinformationthat

appearsintheContextHelpwindow.NoticethattheContextHelpwindownowdisplaystheconfigurationoftheSimulateSignalExpressVI.

10.SavethisVIasReduceSamples.vitoaneasilyaccessiblelocation.

ModifyingtheSignal

CompletethefollowingstepstousetheLabVIEWHelptosearchfortheExpressVIthatreducesthenumberofsamplesinasignal.

1.SelectHelp»

VI,Function,&

How-ToHelptoopentheLabVIEWHelp.

2.ClicktheSearchtabandtypesamplecompressionintheTypeintheword（s）tosearchfortextbox.

NoticethatthiswordchoicereflectswhatyouwantthisExpressVItodo—compress,orreduce,thenumberofsamplesinasignal.

3.SelecttheSampleCompressionExpressVItopictodisplaythetopicthatdescribestheSampleCompressionExpressVI.

4.AfteryoureadthedescriptionoftheExpressVI,clickthePlaceontheblockdiagram

button,shownatleft,toselecttheExpressVI.

5.Movethecursortotheblockdiagram.

NoticehowLabVIEWattachestheSampleCompressionExpressVItothecursor.

6.PlacetheSampleCompressionExpressVIontheblockdiagramtotherightoftheSimulateSignalExpressVI.

7.ConfiguretheSampleCompressionExpressVItoreducethesignalbyafactorof25usingthemeanofthesevalues.

8.ClosetheConfigureSampleCompressiondialogbox.

9.UsingtheWiringtool,wiretheSineoutputintheSimulateSignalExpressVItotheSignalsinputintheSampleCompressionExpressVI.

CustomizingtheFrontPanel

Inthepreviousexercises,youaddedcontrolsandindicatorstothefrontpanelusingtheControlspalette.Youalsocanaddcontrolsandindicatorsfromtheblockdiagram.Completethefollowingstepstocreatecontrolsandindicators.

1.Right-clicktheMeanoutputintheSampleCompressionExpressVIandselectCreate»

NumericIndicatortocreateanumericindicator.

2.Right-clicktheMeanoutputoftheSampleCompressionExpressVIandselectInsertInput/OutputfromtheshortcutmenutoinserttheEnableinput.

3.Right-clicktheEnableinputandselectCreate»

ControltocreatetheEnableswitch.

4.Right-clickthewirelinkingtheSineoutputintheSimulateSignalExpressVItotheSignalsinputintheSignalCompressionExpressVIandselectCreate»

GraphIndicator.

Noticethatyoucancreatecontrolsandindicatorsfromtheblockdiagram.Whenyoureatecontrolsandindicatorsusingthismethod,LabVIEWautomaticallycreatesterminalsthatarelabeledandformattedcorrectly.

5.UsingtheWiringtool,wiretheMeanoutputintheSampleCompressionExpressVItotheSineterminal.NoticethattheMergeSignalsfunctionappears.

6.ArrangetheobjectsontheblockdiagramsothattheyappearsimilartoFigure3-2.

TipYoucanright-clickanywireandselectCleanUpWirefromtheshortcutmenutohaveLabVIEWautomaticallyarrangethewiresforyou.

Figure3-2.BlockDiagramfortheReduceSamplesVI

7.Displaythefrontpanel.

Noticethatthecontrolsandindicatorsyouaddedautomaticallyappearonthefrontpanelwithlabelsthatcorrespondtotheirfunction.

8.SavethisVI.

ConfiguringtheVItoRunContinuouslyUntiltheUserStopsIt

Inthecurrentstate,theVIrunsonce,generatesonesignal,thenstopsexecuting.ToruntheVIuntilaconditionismet,youcanaddaWhileLooptotheblockdiagram.CompletethefollowingstepstoaddaWhileLoop.

1.DisplaythefrontpanelandruntheVI.

NoticehowtheVIrunsonceandthenstops.AlsonoticehowthereisnoSTOPbutton.

2.DisplaytheblockdiagramandselecttheWhileLoopontheExecutionControlpalette.

3.Movethecursortotheupperleftcorneroftheblockdiagram.PlacethetopleftcorneroftheWhileLoophere.

4.ClickanddragthecursordiagonallytoenclosealltheExpressVIsandwires,asshowninFigure3-3.

Figure3-3.PlacingtheWhileLooparoundtheExpressVIs

NoticethattheWhileLoop,shownatleft,appearswithaSTOPbuttonwiredtotheconditionterminal.ThisWhileLoopisconfiguredtostopwhentheuserclickstheSTOPbutton.

5.DisplaythefrontpanelandruntheVI.

NoticethattheVInowrunsuntilyouclicktheSTOPbutton.AWhileLoopexecutesthefunctionsinsidetheloopuntiltheuserpressestheSTOPbutton.

ControllingtheSpeedofExecution

Toplotthepointsonthewaveformgraphmoreslowly,youcanaddatimedelaytotheblockdiagram.CompletethefollowingstepstocontrolthespeedatwhichtheVIexecutes.

1.Ontheblockdiagram,selecttheTimeDelayExpressVIontheExecutionControlpaletteandplaceitinsidetheloop.

2.Type.250intheTimedelay（seconds）textbox.Thistimedelayspecifieshowfasttheloopruns.Witha.250secondtimedelay,theloopiteratesonceeveryquarterofasecond.

3.ClosetheConfigureTimeDelaydialogbox.

4.SavethisVI.

6.ClicktheEnableswitchandnoticethechangeonthegraph.

NoticehowiftheEnableswitchison,thegraphdisplaysthereducedsignal.IftheEnableswitchisoff,thegraphdoesnotdisplaythereducedsignal.

7.ClicktheSTOPbuttontostoptheVI.

UsingaTabletoDisplayData

Completethefollowingstepstodisplayacollectionofmeanvaluesinatableonthefrontpanel.

1.Onthefrontpanel,selecttheExpressTableindicatorontheTextIndicatorspaletteandplaceitonthefrontpaneltotherightofthewaveformgraph.

2.Displaytheblockdiagram.

NoticethattheTableterminalappearswiredtotheBuildTableExpressVIautomatically.

3.IftheBuildTableExpressVIandtheTableterminalarenotselectedalready,clickanopenareaontheblockdiagramtotheleftoftheBuildTableExpressVIandtheTableterminal.DragthecursordiagonallyuntiltheselectionrectangleenclosestheBuildTableExpressVIandtheTableterminal,shownatleft.AmovingdashedoutlinecalledamarqueehighlightstheBuildTableExpressVI,theTableterminal,andthewirejoiningthetwo.

4.DragtheobjectsintotheWhileLooptotherightoftheMeanterminal.

NoticethattheWhileLoopautomaticallyresizestoenclosetheBuildTableExpressVIandtheTabletermial.

5.UsingtheWiringtool,wiretheMeanterminaloftheSampleCompressionExpressVItotheSignalsinputoftheBuildTableExpressVI.

TheblockdiagramshouldappearsimilartoFigure3-4.

Figure3-4.BlockDiagramoftheReduceSamplesVI

6.DisplaythefrontpanelandruntheVI.

7.ClicktheEnableswitch.

Thetabledisplaysthemeanvaluesofevery25sa