OPC and Real-Time Systems in LabVIEW - Telemark...

UniversityCollegeofSoutheastNorway

http://home.hit.no/~hansha

OPCandReal-TimeSystemsinLabVIEW

Hans-PetterHalvorsen,2016.10.31

ii

PrefaceOPC(OLEforprocesscontrol)isastandardinterfacebetweennumerousdatasources,–suchasprogrammablelogiccontrollers(PLCs),remoteterminalunits(RTUs),andsensorsonafactoryfloor–toHMI/SCADAapplications,applicationtools,anddatabases.WithOPC,yourdevice-sideserverandapplicationsoftwarecancommunicatewithoutyourduplicatingdevicedriverdevelopmentandprovidingsupportforhardwarefeaturechanges.TheOPCFoundationdefinesthestandardsthatallowanyclienttoaccessanyOPC-compatibledevice.

[Figure:www.ni.com]

InstallationRequirements

ThefollowingsoftwareisusedinthisTutorial(youdon’tnecessarilyneedtoinstallall;itdependsifyouareinterestedineverythingorjustpartsofthisTutorial):

• LabVIEW• LabVIEWReal-TimeModule• CompactRIO• NI-DAQmx• NIMeasurement&AutomationExplorer• LabVIEWDataloggingandSupervisoryControlModule

Inaddition,thefollowingsoftwarewillbeneededinthisTutorial:

• NIOPServers(Evaluationversionavailablefromwww.ni.com)• MatrikonOPCSimulationServer(freedownloadfromhttp://matrikon.com/)

iv

TableofContentsPreface......................................................................................................................................ii

InstallationRequirements.....................................................................................................ii

TableofContents.....................................................................................................................iv

1 IntroductiontoLabVIEW...................................................................................................1

1.1 Dataflowprogramming...............................................................................................1

1.2 Graphicalprogramming..............................................................................................2

1.3 Benefits.......................................................................................................................2

1.4 LabVIEWMathScriptRTModule................................................................................3

2 IntroductiontoOPC..........................................................................................................4

2.1 OPCServer..................................................................................................................5

2.1.1 MatrikonOPCServerforSimulation....................................................................7

2.1.2 NIOPCServers.....................................................................................................7

2.2 OPCClient...................................................................................................................7

2.3 Tags.............................................................................................................................8

2.4 WhyDoWeNeedOPCStandards?.............................................................................8

3 IntroductiontoReal-TimeSystems.................................................................................10

3.1 LabVIEWReal-TimeModule.....................................................................................10

4 IntroductiontoEmbeddedSystems................................................................................11

4.1 SomeExamplesofEmbeddedsystems.....................................................................11

4.2 EmbeddedhardwareandReal-TimesystemsfromNationalInstruments...............12

5 Real-TimeVIsinLabVIEW................................................................................................13

5.1 Synchronization........................................................................................................13

5.2 Semaphores..............................................................................................................14

v TableofContents

Tutorial:OPCandReal-TimeSystemsinLabVIEW

QueueOperations...............................................................................................................15

5.3 TimedLoop...............................................................................................................17

6 MultithreadinginLabVIEW.............................................................................................18

6.1 Multitasking..............................................................................................................18

6.2 Multithreading..........................................................................................................18

7 DataSocket......................................................................................................................21

7.1 Architecture..............................................................................................................22

7.2 DataSocketServer.....................................................................................................23

7.3 DataSocketinLabVIEW.............................................................................................23

8 OPCServersfromNationalInstruments.........................................................................25

8.1 NIOPCServers..........................................................................................................25

8.1.1 OPCQuickClient................................................................................................26

8.2 SharedVariableEngine.............................................................................................28

9 MatrikonOPCSimulationServer......................................................................................30

9.1 MatrikonOPCServer.................................................................................................30

9.2 Aliases.......................................................................................................................31

9.3 MatrikonOPCExplorer(Client)................................................................................32

10 UsingOPCfromLabVIEW................................................................................................34

10.1 OPCURL....................................................................................................................34

10.2 ReadOPCData..........................................................................................................35

10.3 WriteOPCData.........................................................................................................36

11 LabVIEWDataloggingandSupervisoryControl...............................................................38

11.1 FunctionsandVIsPalettes........................................................................................39

11.2 DSCModuleControlsPalettes..................................................................................40

11.3 CitadelDatabase.......................................................................................................40

11.4 HistoricalDataViewer..............................................................................................41

vi TableofContents


11.5 DistributedSystemManager....................................................................................41

11.6 SQLServer.................................................................................................................42

Exercises..............................................................................................................................43

11.6.1 Task1:OpenandRuntheExample...................................................................44

11.6.2 Task2:CreatingaNewProjectLibrary..............................................................44

11.6.3 Task3:CreatingaPeriodicI/OServer...............................................................45

11.6.4 Task4:DeployingthePeriodicI/OServer.........................................................50

11.6.5 Task5:CreatingSharedVariables.....................................................................52

11.6.6 Task6:ConfiguringDataLogging......................................................................54

11.6.7 Task7:ConfiguringAlarming.............................................................................55

11.6.8 Task8:EnablingLogging....................................................................................56

11.6.9 Task9:CreatetheLabVIEWapplication............................................................57

11.6.10 Task10:UsetheLabVIEWDSCFunctionsandVIs.........................................60

11.6.11 Task11:ViewingReal-TimeData...................................................................62

11.6.12 Task12:ViewingAlarmsusingtheDistributedSystemManager..................63

12 LabVIEWI/OServer.........................................................................................................65

12.1 ConnectLabVIEWtoOPCTagsbyCreatinganI/OServer........................................65

12.2 CreateSharedVariablesthatConnecttotheOPCTagsthroughtheI/OServer......66

12.3 ViewingSharedVariableswithDistributedSystemManager..................................68

12.4 UsingOPCTagDatainLabVIEW...............................................................................68

13 LabVIEWReal-TimeModule............................................................................................73

13.1 Real-TimeDevelopmentinLabVIEW........................................................................74

14 CompactFieldPoint.........................................................................................................76

14.1 Introduction..............................................................................................................76

14.2 Development............................................................................................................77

15 CompactRIO....................................................................................................................85

vii TableofContents


15.1 Introduction..............................................................................................................85

15.2 Development............................................................................................................85

1

1 IntroductiontoLabVIEWLabVIEW(shortforLaboratoryVirtualInstrumentationEngineeringWorkbench)isaplatformanddevelopmentenvironmentforavisualprogramminglanguagefromNationalInstruments.Thegraphicallanguageisnamed"G".OriginallyreleasedfortheAppleMacintoshin1986,LabVIEWiscommonlyusedfordataacquisition,instrumentcontrol,andindustrialautomationonavarietyofplatformsincludingMicrosoftWindows,variousflavorsofUNIX,Linux,andMacOSX.ThelatestversionofLabVIEWisversionLabVIEW2009,releasedinAugust2009.VisitNationalInstrumentsatwww.ni.com.

Thecodefileshavetheextension“.vi”,whichisanabbreviationfor“VirtualInstrument”.LabVIEWofferslotsofadditionalAdd-OnsandToolkits.

ThispaperispartofaserieswithLabVIEWpapers:

• IntroductiontoLabVIEW• DataAcquisitioninLabVIEW• ControlandSimulationinLabVIEW• LinearAlgebrainLabVIEW• DatabaseCommunicationinLabVIEW• DataloggingandSupervisoryControlinLabVIEW• IntermediateTopicsinLabVIEW• AdvancedTopicsinLabVIEW• Etc.

Eachpapermaybeusedindependentlyofeachother.

1.1 Dataflowprogramming

TheprogramminglanguageusedinLabVIEW,alsoreferredtoasG,isadataflowprogramminglanguage.Executionisdeterminedbythestructureofagraphicalblockdiagram(theLV-sourcecode)onwhichtheprogrammerconnectsdifferentfunction-nodesbydrawingwires.Thesewirespropagatevariablesandanynodecanexecuteassoonasallitsinputdatabecomeavailable.Sincethismightbethecaseformultiplenodessimultaneously,Gisinherentlycapableofparallelexecution.Multi-processingandmulti-threadinghardwareisautomaticallyexploitedbythebuilt-inscheduler,whichmultiplexesmultipleOSthreadsoverthenodesreadyforexecution.

2 IntroductiontoLabVIEW


1.2 Graphicalprogramming

LabVIEWtiesthecreationofuserinterfaces(calledfrontpanels)intothedevelopmentcycle.LabVIEWprograms/subroutinesarecalledvirtualinstruments(VIs).EachVIhasthreecomponents:ablockdiagram,afrontpanel,andaconnectorpanel.ThelastisusedtorepresenttheVIintheblockdiagramsofother,callingVIs.Controlsandindicatorsonthefrontpanelallowanoperatortoinputdataintoorextractdatafromarunningvirtualinstrument.However,thefrontpanelcanalsoserveasaprogrammaticinterface.Thusavirtualinstrumentcaneitherberunasaprogram,withthefrontpanelservingasauserinterface,or,whendroppedasanodeontotheblockdiagram,thefrontpaneldefinestheinputsandoutputsforthegivennodethroughtheconnectorpane.ThisimplieseachVIcanbeeasilytestedbeforebeingembeddedasasubroutineintoalargerprogram.

Thegraphicalapproachalsoallowsnon-programmerstobuildprogramssimplybydragginganddroppingvirtualrepresentationsoflabequipmentwithwhichtheyarealreadyfamiliar.TheLabVIEWprogrammingenvironment,withtheincludedexamplesandthedocumentation,makesitsimpletocreatesmallapplications.Thisisabenefitononeside,butthereisalsoacertaindangerofunderestimatingtheexpertiseneededforgoodquality"G"programming.Forcomplexalgorithmsorlarge-scalecode,itisimportantthattheprogrammerpossessanextensiveknowledgeofthespecialLabVIEWsyntaxandthetopologyofitsmemorymanagement.ThemostadvancedLabVIEWdevelopmentsystemsofferthepossibilityofbuildingstand-aloneapplications.Furthermore,itispossibletocreatedistributedapplications,whichcommunicatebyaclient/serverscheme,andarethereforeeasiertoimplementduetotheinherentlyparallelnatureofG-code.

1.3 BenefitsOnebenefitofLabVIEWoverotherdevelopmentenvironmentsistheextensivesupportforaccessinginstrumentationhardware.Driversandabstractionlayersformanydifferenttypesofinstrumentsandbusesareincludedorareavailableforinclusion.Thesepresentthemselvesasgraphicalnodes.Theabstractionlayersofferstandardsoftwareinterfacestocommunicatewithhardwaredevices.Theprovideddriverinterfacessaveprogramdevelopmenttime.ThesalespitchofNationalInstrumentsis,therefore,thatevenpeoplewithlimitedcodingexperiencecanwriteprogramsanddeploytestsolutionsinareducedtimeframewhencomparedtomoreconventionalorcompetingsystems.Anewhardwaredrivertopology(DAQmxBase),whichconsistsmainlyofG-codedcomponentswithonlyafewregistercallsthroughNIMeasurementHardwareDDK(DriverDevelopmentKit)functions,providesplatformindependenthardwareaccesstonumerousdataacquisitionandinstrumentationdevices.TheDAQmxBasedriverisavailableforLabVIEWonWindows,MacOSXandLinuxplatforms.

3 IntroductiontoLabVIEW


FormoreinformationaboutLabVIEW,visitmyBlog:http://home.hit.no/~hansha/

1.4 LabVIEWMathScriptRTModule

TheLabVIEWMathScriptRTModuleisanadd-onmoduletoLabVIEW.WithLabVIEWMathScriptRTModuleyoucan:

• Deployyourcustom.mfilestoNIreal-timehardware• ReusemanyofyourscriptscreatedwithTheMathWorks,Inc.MATLAB®softwareand

others• Developyour.mfileswithaninteractivecommand-lineinterface• EmbedyourscriptsintoyourLabVIEWapplicationsusingtheMathScriptNode

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2 IntroductiontoOPC[Source:Wikipedia,NationalInstruments]

OLEforProcessControl(OPC),whichstandsforObjectLinkingandEmbedding(OLE)forProcessControl,istheoriginalnameforastandardspecificationdevelopedin1996.Thestandardspecifiesthecommunicationofreal-timeplantdatabetweencontroldevicesfromdifferentmanufacturers.Aftertheinitialrelease,theOPCFoundationwascreatedtomaintainthestandard.OPCFoundation:http://www.opcfoundation.org/.

In1994agroupofvendorsrepresentingabroadspectrumofdisciplinesinindustrialsegmentformedwhatisnowknownastheOPCFoundation.TheOPCFoundationputforththegoalofdevelopingasingleclient/serverspecificationthatwouldallowanyvendortodevelopsoftwareandapplicationsthatcouldsharedatainafast,robustfashion,anddoitinawaythatwouldeliminatetheproprietaryschemesthatforcedthesesamevendorstoduplicatedevelopmentefforts.TheOPCFoundationdevelopedthefirstspecificationcalledDataAccessSpecification1.0athatwasreleasedinearly1996.Usingthisspecification,vendorswereabletoquicklydevelopclientserversoftware.

AmajorgoaloftheOPCFoundationandtheDataAccessspecificationwastoeliminatetheneedofclientapplicationvendor'stodeveloptheirownproprietarysetofcommunicationsdrivers.

WhileOPCoriginallystoodfor“OLEforProcessControl”,theofficialstanceoftheOPCFoundationisthatOPCisnolongeranacronymandthetechnologyissimplyknownas“OPC”.OneofthereasonsbehindthisiswhileOPCisheavilyusedwithintheprocessindustries.

AsofJune,2006,"OPCisaseriesofstandardsspecifications".OPCconsistsofsevencurrentstandardsandtwoemergingstandards.

TheOPCSpecificationwasbasedontheOLE,COM,andDCOMtechnologiesdevelopedbyMicrosoftfortheMicrosoftWindowsoperatingsystemfamily.Thespecificationdefinedastandardsetofobjects,interfacesandmethodsforuseinprocesscontrolandmanufacturingautomationapplicationstofacilitateinteroperability.ThemostcommonOPCspecificationisOPCDataAccess,whichisusedtoreadandwritereal-timedata.WhenvendorsrefertoOPCgenerically,theytypicallymeanOPCDataAccess.

TheOPCspecifications[Wikipedia]:

• OPCDataAccess(DA)

5 IntroductiontoOPC


• OPCAlarmsandEvents• OPCBatch• OPCDataeXchange• OPCHistoricalDataAccess• OPCSecurity• OPCXML-DA• OPCUnifiedArchitecture(UA)

Note!LabVIEWsupportsonlytheOPCDataAccessspecification.

OPCserversprovideamethodformanydifferentsoftwarepackagestoaccessdatafromaprocesscontroldevice,suchasaPLC(ProgrammableLogicController)orDCS(DistributedControlSystem).Traditionally,anytimeapackageneededaccesstodatafromadevice,acustominterface,ordriver,hadtobewritten.ThepurposeofOPCistodefineacommoninterfacethatiswrittenonceandthenreusedbyanybusiness,SCADA,HMI,orcustomsoftwarepackages.

OnceanOPCserveriswrittenforaparticulardevice,itcanbereusedbyanyapplicationthatisabletoactasanOPCclient.OPCserversuseMicrosoft’sOLEtechnology(alsoknownastheComponentObjectModel,orCOM)tocommunicatewithclients.COMtechnologypermitsastandardforreal-timeinformationexchangebetweensoftwareapplicationsandprocesshardwaretobedefined.

2.1 OPCServerThebasicconceptinOPCisthatwehaveanOPCServerandoneormoreOPCClientsthatcommunicatewiththeserverinordertowriteorreaddata.AnOPCserverhasimplementedasetofservices,andtheclientsareusingtheseservices.

Atahighlevel,anOPCserveriscomprisedofseveralobjects:theserver,thegroup,andtheitem.TheOPCserverobjectmaintainsinformationabouttheserverandservesasacontainerforOPCgroupobjects.TheOPCgroupobjectmaintainsinformationaboutitselfandprovidesthemechanismforcontainingandlogicallyorganizingOPCitems.

OPCServer

OPCClient

OPCClient

…

6 IntroductiontoOPC


[Figure:www.ni.com]

TheOPCGroupsprovideawayforclientstoorganizedata.Forexample,thegroupmightrepresentitemsinaparticularoperatordisplayorreport.Datacanbereadandwritten.

TheOPCItemsrepresentconnectionstodatasourceswithintheserver.AnOPCItem,fromthecustominterfaceperspective,isnotaccessibleasanobjectbyanOPCClient.Therefore,thereisnoexternalinterfacedefinedforanOPCItem.AllaccesstoOPCItemsisviaanOPCGroupobjectthatcontainstheOPCitem,orsimplywheretheOPCItemisdefined.AssociatedwitheachitemareaValue,QualityandTimeStamp.

Note!Theitemsarenotthedatasources,theyarejustconnectionstothem.Forexample,thetagsinaDCSsystemexistregardlessofwhetheranOPCclientiscurrentlyaccessingthem.TheOPCItemshouldbethoughtofassimplyspecifyingtheaddressofthedata,notastheactualphysicalsourceofthedatathattheaddressreferences.

AlthoughOPCisprimarilydesignedforaccessingdatafromanetworkedserver,OPCinterfacescanbeusedinmanyplaceswithinanapplication.AtthelowestleveltheycangetrawdatafromthephysicaldevicesintoaSCADAorDCS,orfromtheSCADAorDCSsystemintotheapplication.ThearchitectureanddesignmakesitpossibletoconstructanOPCServerwhichallowsaclientapplicationtoaccessdatafrommanyOPCServersprovidedbymanydifferentOPCvendorsrunningondifferentnodesviaasingleobject.

[Figure:www.ni.com]

7 IntroductiontoOPC


InthisTutorialwewillusesomeOPCServerfortestpurposes:

2.1.1 MatrikonOPCServerforSimulation

MatrikonOPCSimulationisfreefornon-productionuseandcanbedistributedopenly.Itisafullyfunctioningapplicationwithoutrestriction.

MatrikonOPCSimulationServerisafreeutilityusedtohelptestandtroubleshootOPCapplications(clients)andconnections.Testingapplicationson“live”OPCserversmayresultinlossofactualproductiondata.TheMatrikonOPCSimulationServercreatesasimulatedenvironmentsothatintheeventofaproblem,norealprocessdataislost.

MatrikonOPCExplorerisanOPCClientapplicationfortestingandconfiguringOPCconnections.

http://www.matrikonopc.com/downloads/178/index.aspx

2.1.2 NIOPCServers

TheNationalInstrumentsOPCServersprovidesasingleconsistentinterfacetocommunicatewithmultipledevices,savingyoufromlearningnewcommunicationprotocolsorspendingtimeunderstandingnewapplications.ThecombinationofNIOPCServersandLabVIEWprovidesasingleplatformfordeliveringhighperformancemeasurementsandcontroltobothnewandexistingindustrialsystems.NIOPCserversconnectthroughtheOPCclientinLabVIEWDataloggingandSupervisoryControl(DSC)ModuletoenableyoudevelopafullyfledgedHMI/SCADAsystemwithPLCs,PACsandsmartsensors.

Anevaluationversionisavailablehere:http://sine.ni.com/nips/cds/view/p/lang/en/nid/4584

2.2 OPCClientAnOPCClientcanconnecttoOPCServersprovidedbyoneormorevendors.

8 IntroductiontoOPC


[Figure:www.ni.com]

2.3 TagsTagsareusedalotintheprocessindustryandarenormallyassignedtoapieceofinformation.Atagconsistsofanamedescribingasinglepointofinformationsoaprocesssystemcanconsistsofhundredsandeventhousandsoftags.TheOPCserverhasonetagforeachmeasurementpointsandcontrollerpointsintheplantanditistheresponsibilityoftheOPCservertogettheinformationfromthecontrollers.Thisisoneofthereasonsforthecomplexityoftheservers,theyneedtohavedriversforalotofcontrollersandmeasurementsystems.

2.4 WhyDoWeNeedOPCStandards?

Withhundredsofmajorhardwareandsoftwarevendors,youhavethedifficulttaskofmakingsurethatyourclientapplicationcancommunicatewithanydeviceanddriver.BeforeOPC,youhadtowriteseparateclientapplicationcodetocommunicatewitheachdevicebecauseeachdevicedriverusedadifferentAPI.OPCprovidesanindustry-standardinterface-asingleAPI-soclientapplicationscanretrieveprocessvariables,suchastemperature,pressure,flowrate,orposition,andsetcontrolvariables,suchasthecurrentordiscreteoutputonanI/Omodule.

OPCoffersthefollowingbenefits:

• SingleAPIforallOPCserverssothatyoucanreusethecodeforyourclientapplicationwitheachdevice.

• OpportunitytodevelopclientapplicationsindevelopmentenvironmentsthattakeadvantageofCOMandActiveX,suchasMicrosoftVisualBasic,VisualC++,Excel,andInternetExplorer.

9 IntroductiontoOPC


• BrowserthroughwhichyoucanselectOPCitemsavailabletoclients.AnOPCitemisachannelorvariableinareal-worlddevice(normallyanI/Opoint)thatadeviceservermonitorsorcontrols.

• DistributedandremoteaccessthroughDCOM.Youcanaccessdevicesconnectedtoothercomputersonthenetwork.

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3 IntroductiontoReal-TimeSystemsAreal-timesystemmeansacomputerbasedsystemwhereoneormoreoftheapplicationsmustbeabletosynchronizewithaphysicalprocess.Real-timemeansthatthecomputersystemismonitoringthestatesofthephysicalprocessandmustrespondtochangesofoneormoreofthesestateswithinamaximumtime.Areal-timesystemcanthenbeusedformonitoringofdifferentparametersinthephysicalprocessforpresentation,warnings,alarmsituationsandforcontrol.

Areal-timeoperatingsystem(RTOS)isamultitaskingoperatingsystemintendedforreal-timeapplications.Suchapplicationsincludeembeddedsystems(programmablethermostats,householdappliancecontrollers),industrialrobots,spacecraft,andindustrialcontrol.

3.1 LabVIEWReal-TimeModule

TheNationalInstrumentsLabVIEWReal-TimeModuleisanadd-oncomponentfortheLabVIEWDevelopmentSystem.Wheninstalled,thissoftwarecompilesNILabVIEWgraphicalcodeandoptimizesitfortheselectedreal-timetarget.UsingtheLabVIEWReal-TimeModule,youcandevelopanddeployapplicationstoallNIreal-timehardwaretargetsincludingPXI,CompactFieldPoint,FieldPoint,CompactRIO,andstandarddesktopPCs.TheembeddedRTOSforthesetargetsisasinglededicatedkernelthatprovidesmaximumreliabilityforembeddedcode.

[Figure:www.ni.com]

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4 IntroductiontoEmbeddedSystemsAnembeddedsystemisacomputersystemdesignedtoperformoneorafewdedicatedfunctionsoftenwithreal-timecomputingconstraints.Itisembeddedaspartofacompletedeviceoftenincludinghardwareandmechanicalparts.Bycontrast,ageneral-purposecomputer,suchasapersonalcomputer,isdesignedtobeflexibleandtomeetawiderangeofend-userneeds.Embeddedsystemscontrolmanydevicesincommonusetoday.

Embeddedsystemsarecontrolledbyoneormoremainprocessingcoresthatistypicallyeitheramicrocontrolleroradigitalsignalprocessor(DSP).Thekeycharacteristicishoweverbeingdedicatedtohandleaparticulartask,whichmayrequireverypowerfulprocessors.Forexample,airtrafficcontrolsystemsmayusefullybeviewedasembedded,eventhoughtheyinvolvemainframecomputersanddedicatedregionalandnationalnetworksbetweenairportsandradarsites.

Sincetheembeddedsystemisdedicatedtospecifictasks,designengineerscanoptimizeitreducingthesizeandcostoftheproductandincreasingthereliabilityandperformance.

4.1 SomeExamplesofEmbeddedsystems

FujiPXG5PIDController:

12 IntroductiontoEmbeddedSystems


CompactFieldPoint(fromNationalInstruments):

4.2 EmbeddedhardwareandReal-TimesystemsfromNationalInstruments

Embeddedapplicationshaveuniquerequirementssuchasdeterministicbehavior.WithLabVIEWReal-Time,realtimecontrollers,anddataacquisitionhardwarefromNIyoucancreateapplicationswithdeterministic,real-timeperformance.

YoucandevelopanddebugyourapplicationusingLabVIEWgraphicalprogramming,anddownloadtime-criticalapplicationcomponentstorunembeddedonReal-Timehardware.

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5 Real-TimeVIsinLabVIEWAreal-timesystemmeansacomputerbasedsystemwhereoneormoreoftheapplicationsmustbeableto“synchronize”withaphysicalprocess.“Real-time”meansthatthecomputersystemismonitoringthestatesofthephysicalprocessandmustrespondtochangesofoneormoreofthesestateswithinamaximumtime.Areal-timesystemcanthenbeusedformonitoringofdifferentparametersinthephysicalprocessforpresentation,warnings,alarmsituationsandforcontrol.

Areal-timesystemwillveryoftenbeanembeddedsystem,whileanembeddedsystemdoesnotneedtobeareal-timesystem.

Importantfeaturesinsuchreal-timesystemsaresynchronization,semaphores,deadlock,multithreadingandscheduling.InthischapterwewillseehowwecanusethesefeaturesinLabVIEWwhenprogrammingourreal-timesystems.

5.1 SynchronizationTheapplicationsofthereal-timesystemmustruntogetherwiththephysicalprocess,sothereal-timesystemmustbeabletomanagesimultaneity.Thesolutionisoftentorunseveralapplicationsonthecomputersystemorondifferentcomputersinadistributedsystem.Thesesolutionsrequiresomesortofsynchronizationbetweentheapplicationsandbetweentheapplicationsandthephysicalprocess.

Whenseveralapplicationsarerunning“simultaneous”onacomputersystem,theremustalsobesomesynchronizationoftheusageoftheresourcesinthecomputersystem.Resourcescanbebothhardwareandsoftware,likeI/Oglobalvariablesinthesoftware,theCPU,memory,disketc.

LabVIEWoffersdifferentmechanismsforsynchronizationwewilluseinthistask.

BelowweseetheSynchronizationpaletteinLabVIEW:

14 Real-TimeVIsinLabVIEW


Wecan,e.g.,usetheSynchronizationVIsandfunctionstosynchronizetasksexecutinginparallelandtopassdatabetweenparalleltasks.

5.2 Semaphores

Asemaphoreisthesimplestformofsynchronizationandhastwobasicfunctions.Thesefunctionsare:

• Request;thesystemwillmovethetasktowaitqueueifthesemaphoreisalready“occupied”byanothertask.

• Release;releasesasemaphore,thesystemwillmovethe“blocked”tasksfromthewaitqueuetothereadyqueue.

BelowweseetheSemaphorepaletteinLabVIEW:

UsetheSemaphoreVIstolimitthenumberoftasksthatcansimultaneouslyoperateonashared(protected)resource.Aprotectedresourceorcriticalsectionofcodemightincludewritingtoglobalvariablesorcommunicatingwithexternalinstruments.

YoucanusetheSemaphoreVIstosynchronizetwoormoreseparate,paralleltaskssothatonlyonetaskatatimeexecutesacriticalsectionofcodeprotectedbyacommonsemaphore.Inparticular,usetheseVIswhenyouwantcertainVIsorpartsofablockdiagramtowaituntilanotherVIorpartofablockdiagramisfinishedwiththeexecutionofacriticalsection.



Atypicalexamplecouldbewheretoresourceswanttowritetothesamefile,butonlyonecanaccesstofileatatime.WecanusetheSemaphoreVIstosynchronizethisoperation.Theapplicationcouldhave2whileloopsinparallel.Eachwhileloopcanthenwritetothesamefileifyousynchronizetheoperationsusingsemaphores.

QueueOperations

YouwillusetheQueueOperationsfunctionstocreateaqueueforcommunicatingdatabetweensectionsofablockdiagramorfromanotherVI.

TheQueueOperationspaletteinLabVIEW:

Example:

YoutypicallyusetheQueueVIsforexchangeofmessages.E.g.,aSenderactivityshallreadlettersfromthekeyboardandputthemintotheQueue.TheReceiveractivityshallreadthelettersfromtheQueueanddisplaythemonascreeninaStringindicator.TheSenderandtheReceiveractivitycouldoperateatdifferentspeed(delay).BelowweseetheLabVIEWcode:



Wetypeinnsomelettersusingthekeyboard.TheReceiverismuchslower,buttobesuretonotmissanyletters,weuseaQueuetohandlethis.BelowweseetheFrontPanel:



[EndofExample]

5.3 TimedLoop

InLabVIEWwecanalsouse“TimedLoop”structureinsteadofordinaryWhileLoops.

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6 MultithreadinginLabVIEWAmulticoresystemisasingle-processorCPUthatcontainstwoormorecores,witheachcorehousingindependentmicroprocessors.Amulticoremicroprocessorperformsmultiprocessinginasinglephysicalpackage.Multicoresystemssharecomputingresourcesthatareoftenduplicatedinmultiprocessorsystems,suchastheL2cacheandfront-sidebus.

Multicoresystemsprovideperformancethatissimilartomultiprocessorsystemsbutoftenatasignificantlylowercostbecauseamotherboardwithsupportformultipleprocessors,suchasmultipleprocessorsockets,isnotrequired.

6.1 Multitasking

Incomputing,multitaskingisamethodbywhichmultipletasks,alsoknownasprocesses,sharecommonprocessingresourcessuchasaCPU.WithamultitaskingOS,suchasWindowsXP,Vista,etc.,youcansimultaneouslyrunmultipleapplications.MultitaskingreferstotheabilityoftheOStoquicklyswitchbetweeneachcomputingtasktogivetheimpressionthedifferentapplicationsareexecutingmultipleactionssimultaneously.

6.2 Multithreading

Multithreadingextendstheideaofmultitaskingintoapplications,soyoucansubdividespecificoperationswithinasingleapplicationintoindividualthreads.Eachofthethreadscanruninparallel.TheOSdividesprocessingtimenotonlyamongdifferentapplications,butalsoamongeachthreadwithinanapplication.

InamultithreadedNationalInstrumentsLabVIEWprogram,anexampleapplicationmightbedividedintofourthreads-auserinterfacethread,adataacquisitionthread,networkcommunication,andaloggingthread.Youcanprioritizeeachofthesesothattheyoperateindependently.Thus,inmultithreadedapplications,multipletaskscanprogressinparallelwithotherapplicationsthatarerunningonthesystem.

19 MultithreadinginLabVIEW


[Figure:www.ni.com]

MultithreadinginLabVIEW:

LabVIEWautomaticallydivideseachapplicationintomultipleexecutionthreads.ThecomplextasksofthreadmanagementaretransparentlybuiltintotheLabVIEWexecutionsystem.

[Figure:www.ni.com]

Youcanalsousethe“CPUInformation”functioninLabVIEWtofindCPUinformationaboutyourPC.

MultitaskinginLabVIEW:

LabVIEWusespreemptivemultithreadingonOSsthatofferthisfeature.LabVIEWalsousescooperativemultithreading.OSsandprocessorswithpreemptivemultithreadingemploya

20 MultithreadinginLabVIEW


limitednumberofthreads,soincertaincases,thesesystemsreturntousingcooperativemultithreading.

TheexecutionsystempreemptivelymultitasksVIsusingthreads.However,alimitednumberofthreadsareavailable.Forhighlyparallelapplications,theexecutionsystemusescooperativemultitaskingwhenavailablethreadsarebusy.Also,theOShandlespreemptivemultitaskingbetweentheapplicationandothertasks.

21

7 DataSocketDataSocketisatechnologyforsharingdatabetweenapplicationsordifferentdatasources.TheDataSocketcontrolprovidesasimpleinterfacethroughwhichitcaninteractwithOPCservers,suchasNationalInstrumentsFieldPoint,fromanyActiveXcontainer,includingVisualBasicandVisualC++.YoucanconnecttoanOPCserverwithDataSocketusinganOPCURL,whichissimilartotheURLsusedinaWebbrowser.URLsprovideastandardmechanismforreferringtolocations.YoualreadyknowhowtouseURLstolocatethingsontheWeb,andyoucanlocateOPCdataitemswithDataSocketusingasimilarURLmodel:

opc://machine_name/server_name/item_name

WithDataSocket,youcansharelivedatawithoneormoreclientapplicationsonanetworkwithoutworryingaboutdataformatsandnetworkprotocols.YourLabVIEWapplicationscaneasilysharelivedatawithavarietyofclients,includingVisualBasicapplications,Webbrowsers,VisualC++,MicrosoftExcel,LabWindows/CVI,andotherLabVIEWapplications.UsingDataSockettechnology,youcanpublishandreceivedatafromanyapplicationinthesameway,givingyouthepowertoconnectdiverseapplicationseasily.

Manytypicalinstrumentationsolutionsinvolveasinglelocalapplicationforacquisition,logging,analysis,andpresentation.However,becauseoftheriseinpopularityoftheInternetandcompanyintranets,andtheneedtoremotelymonitorandcontrolyourdataacquisition,youoftenneedtoexchangelivedatawithotherapplicationsondifferentcomputersaroundtheworld.DataSocketforLabVIEWsimplifieslivedataexchangebetweendifferentapplicationsononecomputerorbetweencomputersconnectedthroughanetwork.

Althoughavarietyofdifferenttechnologiesexisttodaytosharedatabetweenapplications,includingTCP/IPanddynamicdataexchange(DDE),mostofthesetoolsarenottargetedforlivedatatransfertomultipleclients.WithTCP/IP,youhavetoconvertyourdataintoanunstructuredstreamofbytesinthebroadcastingapplicationandthenparsethestreamofbytesbackintoitsoriginalformatinsubscribingapplications.DataSocket,however,simplifieslivedatatransfer.Itimplementsaneasy-to-use,high-performanceprogramminginterfacethatisdesignedspecificallyforsharingandpublishinglivedatainmeasurementandautomationapplications.Inaddition,DataSocketfeaturesinterapplicationconnectivity,richdatatypes,andsecuritytomakesharingdataeasy.DataSocketisincludedwithLabVIEW.

IfyouarecomfortableprogrammingwithCOM,youcanwriteprogramsusingeithertheOPCCustomAPIorAutomationAPI,dependingontheprogrammingenvironmentinwhichyou

22 DataSocket


aredevelopingyourOPCclient. IfyoudonotwanttoprogramwithCOM,usetheDataSocketcontrol,anActiveXcontrolforsharingdatabetweenapplicationsanddevices.DataSocketoffersthefollowingbenefits:

• SimpleAPI,helpfultodeveloperswhodon'twanttoprogramwithCOM. • AccesstotheOPCservercustominterface,whichenablesyourapplicationstorun

fasterthanapplicationsthataccesstheautomationinterface.DataSocketisnotanextralayerbutratheradirectconnectiontoOPCservers,andDataSocketalwaysaccessesthecustominterface,regardlessoftheActiveXcontainerinwhichyouaredeveloping.

• EasyintegrationwithNationalInstrumentsproductssuchasLabVIEW.

7.1 ArchitectureDataSocketisasingle,unified,end-userapplicationprogramminginterface(API)forconnectingtodatafromanumberofsources–localfiles,filesonFTPorWebservers,anddataitemsonOPCServers.ADataSocketapplicationspecifiesthedatalocationbyusingafamiliarnetworkingstandard,theURL.JustasaWebbrowserusesaURLtoconnecttoaWebpage,aDataSocketapplicationusesaURLtoconnecttodata.Byusinganindustry-standardURL,youcanquicklyandeasilybringdataintoorsharedatafromyourDataSocketapplications.


machine_name[optional]-ComputeronwhichtheOPCserverisinstalled.DataSocketcanaccessOPCserversonothercomputersusingDCOM.Ifthemachinenameisomitted,DataSocketdirectlyconnectstotheOPCserveronthecomputeronwhichitisrunning.

server_name-OPCserver(providedwiththehardware)toconnectto.

item_name-OPCitemonthespecificOPCserver.Anitemisachannelorvariable(normallyanI/Opoint)inareal-worlddevicethatadeviceservermonitorsorcontrols.ExampleFieldPointitem:FP Res\FP-DI-330 @1\Channel 1

UpdateRate=n inmilliseconds[optional]-MaximumrateatwhichtheOPCserverwillindicatethatanitem’svaluehaschanged.Theservershoulduseanupdaterateascloseaspossibletotheraterequestedbytheclient.Ifthisparameterisomitted,thedefaultis100ms.Thefollowingexamplesetstheupdaterateto1000ms:UpdateRate=1000

DeadBand=n in%ofrange[optional]-Percentagechangerequiredbeforetheservernotifiesyourapplicationofavaluechange.Notallserverssupportthisoption.Ifomitted,

23 DataSocket


thisparameterdefaultsto0%.Thefollowingexamplesetsthedeadbandto10%:DeadBand=10

Forexample,thefollowingURLconnectstothesineitemontheNational Instruments OPCDemoserveronthelocalmachine.TheoptionsattheendoftheURLspecifyanupdaterateof1000msandadeadbandof10%.opc:/National Instruments.OPCDemo/sine?UpdateRate=1000&DeadBand=10

7.2 DataSocketServerWiththeDataSocketServer,alightweight,stand-alonecomponent,programsusingDataSocketcanbroadcastlivemeasurementdataathighratesacrosstheInternettomultipleremoteclientsconcurrently.TheseclientapplicationsuseDataSockettosubscribetothelivemeasurementdata.BecausetheDataSocketServerisastand-alonecomponent,itsimplifiesnetwork(TCP/IP)programmingbyautomaticallymanagingconnectionstoclientsandautomaticallyconvertingyourmeasurementdatatoandfromthestreamofbytessentacrossthenetwork.Youdonothavetowritetheparsingcode.AndbecausetheDataSocketServercanrunonanymachineonyournetwork,italsoimprovesperformanceandprovidessecuritybyisolatingtheWebconnectionsfromyouracquisitionapplication.

7.3 DataSocketinLabVIEW

TheDataSocketpaletteinLabVIEW:

DescriptionoftheDataSocketVIsinLabVIEW.

DataSocketSelectURLDisplaysadialogboxfortheusertoselectadatasourceandreturnstheURLtothatdata.

24 DataSocket


DataSocketOpenOpensadataconnectionyouspecifyinURL.

DataSocketReadDequeuesthenextavailabledatavaluefromtheclient-sidebufferassociatedwiththeconnectionyouspecifyinconnectioninandreturnsthedata.

DataSocketWriteWritesdatatotheconnectionyouspecifyinconnectionin.

DataSocketCloseClosesadataconnectionyouspecifyinconnectionid.

25

8 OPCServersfromNationalInstruments

NationalInstrumentsoffersdifferentOPCServers,suchas:

• NIOPCServers• FieldPointOPCServer• VariableEngine• Etc.

IfyoubrowseforOPCserversandOPCItemsonyourcomputeritprobablylookssomethinglikethis:

BelowwegothroughthebasicfunctionalityintheseOPCServers.

8.1 NIOPCServersTheNationalInstrumentsOPCServersprovidesasingleconsistentinterfacetocommunicatewithmultipledevices,savingyoufromlearningnewcommunicationprotocolsorspendingtimeunderstandingnewapplications.ThecombinationofNIOPCServersandLabVIEWprovidesasingleplatformfordeliveringhighperformancemeasurementsandcontroltobothnewandexistingindustrialsystems.NIOPCserversconnectthroughtheOPCclientinLabVIEWDataloggingandSupervisoryControl(DSC)Moduletoenableyoudevelopafull-fledgedHMI/SCADAsystemwithPLCs,PACsandsmartsensors.



NIOPCServersarea32-bitwindowsapplicationthatprovidesameansofbringingdataandinformationfromawiderangeofindustrialdevicesandsystemsintoclientapplicationsonyourwindowsPC.OurOPCServerapplicationenablesthesharingofmanufacturingorproductiondatabetweenavarietyofapplicationsrangingfromhumanmachineinterfacesoftwareanddatahistorians,toolargeMESandERPapplications.

8.1.1 OPCQuickClient

TheOPCQuickClienthasbeendevelopedtoassistinthetestanddevelopmentoftheOPCDataAccess1.0and2.0Servers.TheOPCQuickClientdoesnotfullysupportOPCDA3.0.

TheOPCQuickClientsupportsbothlocalandremoteOPCserverconnections.Remoteconnectionsarehandledthroughtheoperatingsystem'sDCOMinterface.



TostartusingtheOPCQuickClient,dothefollowing:

1. CreateaserverconnectionwhichwillbeusedtoconnecttoanOPCserver. 2. Next,addagrouptotheconnectionwhichcontainsvaryingproperties(suchas

updaterate,deadbandandtimebias). 3. Finally,additemstotheindividualgroups(whichcontainpropertiessuchasaninitial

activestate,datatypeandaccesspath).

AserverconnectionprovidesalinkbetweenanOPCserverandthisclient.Groupsareaddedthroughthisconnection.Tocreateanewserverconnection,clickEdit|NewServerConnection....Alternatively,clicktheNewServertoolbarbutton.

Agroupisusedtoorganizeacollectionofitemswithacommonsetofproperties.Thegroupalsospecifiesthefollowingproperties:groupname,updaterate,timebias,percentdead



band,LanguageID,activestateandthedataconnectiontype.Tocreateanewgroup,clickEdit|NewGroup.Alternatively,clickNewGroupinthetoolbar.

ItemsrepresentdatathatmaybeaccessedviaanOPCserver.Anitemspecifiesthefollowingproperties:ItemID,accesspath,requesteddatatypeandactivestate.TodefineanitemusingtheItemEditordialog,clickEdit|NewItem.Alternatively,clickNewItemonthetoolbar.

8.2 SharedVariableEngine



LabVIEWcontainsanOPCservercalledtheSharedVariableEngine.TheSharedVariableEnginesupportsOPCDataAccess2.xandOPCDataAccess3.0.YoucanpublishdatafromtheSharedVariableEngineusingLabVIEWsharedvariables.

ToconnecttotheSharedVariableEnginefromathird-partyOPCclient,usetheProgIDNationalInstruments.VariableEngine.IftheOPCclientallowsyoutobrowseforOPCservers,youcanlocatetheNationalInstruments.VariableEngineunderOPCversion2.xor3.0,dependingonwhichversionstheclientsupports.

30

9 MatrikonOPCSimulationServerMatrikonOPCSimulationisfreefornon-productionuseandcanbedistributedopenly.Itisafullyfunctioningapplicationwithoutrestriction.

MatrikonOPCSimulationServerisafreeutilityusedtohelptestandtroubleshootOPCapplications(clients)andconnections.Testingapplicationson“live”OPCserversmayresultinlossofactualproductiondata.TheMatrikonOPCSimulationServercreatesasimulatedenvironmentsothatintheeventofaproblem,norealprocessdataislost.


DownloadMatrikonOPCSimulationServerandMatrikonOPCExplorerher:

http://www.matrikonopc.com/downloads/178/index.aspx

Watchthisvideo:http://www.matrikonopc.com/training/opc-multimedia-tutorial/opcda_pop.html

9.1 MatrikonOPCServer

BelowweseetheMatrikonOPCServerforSimulation:

31 MatrikonOPCSimulationServer


ViewTags:

OpentheMatrikonOPCExplorerwhereyoubrowseforavailableItems(Tags).

9.2 AliasesMatrikonOPCServers,includingthisone,providetheabilitytocreateuser-definedaliasesthatcanbeusedinplaceofregularOPCitems.Thisfeatureisparticularlyusefulwhentheitempathforagivenserverisverycomplexordifficulttoremember,forexample:Com1.Radio1.Unit1.41.4.123.Serverscanalsobeconfiguredsothatclientapplicationshaveaccesstoconfiguredaliasesonly,ratherthaneveryavailableitem.

Toinsertanewalias,performthefollowingsteps:

1. OpentheMatrikonOPCServerforSimulationConfigurationwindow.2. ClickontheAliasConfigurationnodeintheCurrentConfigurationpaneltoopenthe

AliasConfigurationpanel.



3. Right-clickyourmouseandselecttheInsertNewAliasoption,orPresstheInsertbuttononthekeyboard,tolaunchtheInsertNewAliaswindow.

4. Fillinanameforthealias,andenteravaliditempath.Theitempathcanbefoundbybrowsingtheserver’saddressspace(usetheellipsisbuttonnexttothisfield).

5. Savethisaliaswhenfinished.ItwillnowbevisibletoOPCclientsundertheConfiguredAliasesheading.

Formoredetailedscalingoptions,pleaseconsulttheMatrikonOPCServerforSimulationUser’sManual.

9.3 MatrikonOPCExplorer(Client)


TheMatrikonOPCExplorerlistsalltheavailableOPCServersintheupperleftcorner.

MatrikonOPCExplorerlistsOPCserversonyourcomputer(localhost)orinthenetwork.



ClickConnectonordertoconnecttotheserver.

34

10 UsingOPCfromLabVIEWYoucanuseLabVIEWasanOPCclientbyconnectingtoanOPCserverthroughaDataSocketconnection.

TheDataSocketpaletteinLabVIEW:

DescriptionoftheDataSocketVIsinLabVIEW:

DataSocketSelectURLDisplaysadialogboxfortheusertoselectadatasourceandreturnstheURLtothatdata.

DataSocketOpenOpensadataconnectionyouspecifyinURL.

DataSocketReadDequeuesthenextavailabledatavaluefromtheclient-sidebufferassociatedwiththeconnectionyouspecifyinconnectioninandreturnsthedata.

DataSocketWriteWritesdatatotheconnectionyouspecifyinconnectionin.

DataSocketCloseClosesadataconnectionyouspecifyinconnectionid.

10.1 OPCURL

AtypicalURLforanOPCItemcouldbe:

opc://localhost/Matrikon.OPC.Simulation/Random.Int4

35 UsingOPCfromLabVIEW


oringeneral:


Youmayusethe“DataSocketSelectURL”VI inordertofindanOPCItem.

Usingthe“DataSocketSelectURL”displaysthe“SelectURL”window:

ThisVIisnicetohavewhenyoudontknowtheexactnameoftheOPCURL.

IfyouknowtheURLinadvanceyouusethe“DataSocketOpen”VI .ThisVIopensadataconnectionyouspecifyintheinputURL.Likethis:

10.2 ReadOPCData

Youuse DataSocketReadinordertogetdatafromaspecificItemintheOPCserver.

Example:



orusingthespecificURLdirectlylikethis:

TheDataSocketReadVIhaveseveraloutputsinadditiontotheValue(data).

AllOPCItemshavethefollowingproperties:

• Value• Timestamp• Status• Quality

10.3 WriteOPCData

Youuse DataSocketWriteinordertowritedatatoaspecificItemintheOPCserver.



Note!InordertowritedatatoanOPCItemitmusthavetheWritepropertyset.

Example:

orusingthespecificURLdirectlylikethis:

38

11 LabVIEWDataloggingandSupervisoryControl

TheLabVIEWDataloggingandSupervisoryControl(DSC)ModuleextendstheLabVIEWgraphicaldevelopmentenvironmentwithadditionalfunctionalityfortherapiddevelopmentofdistributedmeasurement,control,andhigh-channel-countmonitoringapplications.

TheDSCModulealsoenhancestheLabVIEWsharedvariable.UsethesharedvariabletoaccessandpassdataamongseveralVIsinaLabVIEWprojectoracrossanetwork.AsharedvariablecanrepresentavalueoranI/Opoint.WiththeDSCModule,youcanlogdataautomatically;addalarming,scaling,andsecuritytothesharedvariable;andconfigurethesharedvariableprogrammatically.

TheDSCModulealsoprovidestoolsforgraphinghistoricalorreal-timetrends,enhancingthesecurityoffrontpanels,andwritingcustomI/Oservers.YoucanreadorwritetoOLEforProcessControl(OPC)connections,programmablelogiccontrollers(PLC),orcustomI/Oserversthatyouwrite.

TorunapplicationsbuiltwithLabVIEW,theDSCModuleonacomputerwithouttheDSCModuleinstalled,youmustinstallthe“DSCModuleRun-TimeSystem”onthatcomputer.TheDSCModuleRun-TimeSystemcontainscomponentsthatenabletheDSCModulefeaturesinthebuiltapplications.

TheDSCModuleincludesthefollowingcomponents:

• FunctionsandVIsPalettes• DSCModuleControlsPalettes• CitadelDatabase• HistoricalDataViewer • DistributedSystemManager

Thesecomponentsaredescribedinmoredetailbelow.

MostoftheLabVIEWDSCfunctionalityisavailablefromtheToolsmenu(“Tools→DSCModule”).



11.1 FunctionsandVIsPalettes

TheDSCModuleinstallsthefollowingpalettes:

• Alarms&Events• Historical• Tags• SharedVariables• EngineControl• Security

TheDSCModulealsoincludestheHistoricalTrendExpressVIandtheReal-TimeTrendExpressVI.



11.2 DSCModuleControlsPalettes

TheDSCModuleinstallsthefollowingcontrolspalettestohelpyoubuilduserinterfacesthatresembleaplantorsystemandtoviewreal-timedatafromtheplantorsystem:

• 2DControls• 3DControls• Vessels• AlarmControls• TrendControls

TheDSCModulealsoincludestheHistoricalTrendcontrolandtheReal-TimeTrendcontrol.

11.3 CitadelDatabase

TheDSCModulelogssharedvariabledatatotheCitadeldatabase.TheCitadeldatabasestoreshistoricaldata,alarms,andevents.YoucanaccessandviewCitadeldatausingtheHistoricalDataViewerandusingthe“HistoricalVIs”.



11.4 HistoricalDataViewer

UsetheHistoricalDataViewertoviewdatastoredintheCitadeldatabase.Select“Tools→DSCModule→ViewHistorical”DatatolaunchtheMeasurement&AutomationExplorer(MAX).Expandthe“HistoricalData”categorytoselectadatabasethatappearsunder“Citadel5Universe”.YoualsocanusetheCallHDVVItolaunchtheHistoricalDataViewerprogrammatically.

DataLogger:

11.5 DistributedSystemManager



UsetheSharedVariableMonitortoviewthecurrentvalueofasharedvariableanditsstatusandalarmstate.Select“Tools→DistributedSystemManager”tolaunchtheDistributedSystemManager.

11.6 SQLServer

TheDSCModulerequirestheMicrosoftSQLServer2005ExpressEdition(SQLExpress).ThiscomponentisinstalledbydefaultwhenyouinstalltheDSCModule.Duringtheinstallationprocess,theDSCModuleinstallercreatesaninstanceofSQLExpressnamedCITADEL.TopreventunauthorizedaccesstoSQLExpress,theinstalleralsogeneratesapasswordforthedefaultSQLExpressadministratorsa.ThedefaultpasswordisthecomputerID.CompletethefollowingstepstofindthecomputerIDusingtheNILicenseManager.

1. LaunchtheNILicenseManagerbyselecting“Start→AllPrograms→NationalInstruments→NILicenseManager”.

2. ClicktheDisplayComputerInformationbuttononthetoolbar.

TheSQLServerdatabaseisusedforconfigurations,etc.,whiletheCitadeldatabaseisusedforDatalogging.



Exercises

InthefollowingexerciseswewillbuildanapplicationinLabVIEWusingthefunctionalityfromtheLabVIEWDSCModule.

TheTasksareasfollows:

• Task1:OpenandRuntheExample• Task2:CreatingaNewProjectLibrary• Task3:CreatingaPeriodicI/OServer• Task4:DeployingthePeriodicI/OServer• Task5:CreatingSharedVariables



• Task6:ConfiguringDataLogging• Task7:ConfiguringAlarming• Task8:EnablingLogging• Task9:CreatetheLabVIEWApplication• Task10:UsetheLabVIEWDSCFunctionsandVIs• Task11:ViewingReal-TimeData• Task12:ViewingAlarmsusingtheDistributedSystemManager

11.6.1 Task1:OpenandRuntheExample

OpenDSCTankSimulator.vi.TheExampleisavailablefrom:http://home.hit.no/~hansha/

TheexampledoesnotuseanyDSCfunctionalitysofar.InthenextexerciseyouwillcreateaDSCapplicationbasedonthisexample.

11.6.2 Task2:CreatingaNewProjectLibrary

InthisexerciseyouwilllearnhowtocreateanewLabVIEWprojectandaprojectlibrary.Theprojectallowsyoutomanagesharedvariables,projectlibraries,andVIsinonewindow.LabVIEWprojectlibrariesarecollectionsofVIs,typedefinitions,sharedvariables,palettemenufiles,andotherfiles,includingotherprojectlibraries.

CompletethefollowingstepstocreateaLabVIEWprojectlibrary.

• ClicktheEmptyProjectlinkintheGettingStartedwindow.TheProjectExplorerwindowappears.

• Right-clickMyComputerintheProjectExplorerwindowandselectNew→Libraryfromtheshortcutmenu.

• SelectFile→SaveAll.TheNametheProjectdialogboxappears.• Enter“TankSystem”intheFilenametextbox.• ClicktheOKbutton.TheNametheLibrarydialogboxappears.• Enter“TankSystemIOServer”intheFilenametextbox.• ClicktheOKbutton.



Younowhaveaprojectcontainingaprojectlibrary.InthefollowingexerciseyouwillusetheprojectlibraryintheprojecttocreateaperiodicI/Oserver.

11.6.3 Task3:CreatingaPeriodicI/OServer

Aserverisanapplicationthatcommunicateswithandmanagesinput/outputdevicessuchasPLCs,remoteinput/outputdevices,remoteSharedVariableEngines,anddataacquisition(DAQ)plug-indevices.Theseserversreadselectedinputitemsandwritetothemondemand.TheDSCModulecanconnecttoanyOPC-compliantserverandtomanythird-partydeviceservers.YoualsocancreatecustomI/Oservers.YouwillbuildaperiodicI/Oserverinthefollowingexercise.TheperiodicI/OserverwillrunasaserviceandpublishNIPublish-SubscribeProtocol(NI-PSP)dataitemstothenetwork.

CompletethefollowingstepstoaddtheperiodicI/Oservertotheproject.

Right-clicktheTankSystemIOServer.lvlibprojectlibraryintheProjectExplorerwindowandselectNew→I/OServerfromtheshortcutmenu.TheCreateNewI/OServerdialogboxappears.



SelectCustomVI–PeriodicfromtheI/OServerTypelistandclicktheContinuebutton.TheConfigureCustomVI–PeriodicI/OServerdialogboxappears.

ClicktheNewbuttontodisplaytheSelectVIstepoftheCustomVI-basedServer–PeriodicWizard.

SelecttheDSCTankSimulator.vi.

ClicktheNextbuttonintheCustomVI-basedServer–PeriodicWizardtoadvancetotheSelectControlsandIndicatorsToPublishstep.



HereyouwillselectControlsandIndicatorsyouwanttopublishassharedvariables.

RemovethecheckmarkfromthestopcheckboxintheControlslist.Youwillpublishtheremainingcontrolsandindicators.

ClicktheNextbuttontoadvancetotheSelectMethodToStopTheServerpage.

SelectStopthefollowingWhileLoopsandPlaceacheckmarkintheWhileLoopcheckbox.

ClicktheNextbuttontoadvancetotheConfigureServerDistributionComponentstep.



LeavethedefaultoptionsandclickNext.

TheServerDistributionComponentpageappears

TheDSCModuledisplaysasummaryofthefilesthattheCustomVI-basedServer–PeriodicWizardwillcreatefromtheServerDistributionComponentpage.ClicktheBuildbutton.ThewizarddisplaystheBuildstatusdialogboxasitcreatesaVItemplatefile,aregistrationVI,andasupportDLLandVIs.



AfterthewizardcreatestheperiodicI/Oserver,theConfigureCustomVI–PeriodicI/OServerdialogboxappearswiththenameoftheperiodicI/Oserverandthedataitemsitcontains.

ClicktheOKbutton.

LabVIEWaddstheperiodicI/OservertotheTankSystemIOServerprojectlibrary.



Right-clicktheCustomVI–Periodic1itemintheProjectExplorerwindowandselectRenamefromtheshortcutmenu.RenametheperiodicI/Oserver“Tank1”.TheProjectExplorerwindowappearsasshownbelow.

11.6.4 Task4:DeployingthePeriodicI/OServer

NowyoumustdeploytheperiodicI/OserversothatthedataitemsintheI/OserverareavailableforuseinotherVIsandacrossthenetwork.InthisexerciseyouwilldeploytheperiodicI/OserverandviewtheI/OserverdataintheSharedVariableMonitor.

Note!TheperiodicI/OserverrunscontinuouslyinthebackgrounduntilyouundeploythelibraryintheProjectExplorerwindowthatcontainstheI/Oserver.

CompletethefollowingstepstodeploytheTank1periodicI/Oserverandviewthedata.

Right-clicktheTankSystemIOServer.lvlibprojectlibraryundertheMyComputeritemandselectDeployAllfromtheshortcutmenutodeploytheprojectlibrary.



ClicktheDonebuttontoclosetheDeploydialogboxwhenthedeploymentiscomplete.

SelectTools→DistributedSystemManager.

ExpandTankSystemIOServer→Tank1intheleftpane.NoticethatthecontrolsandindicatorsoftheI/OserverappearunderTank1.Becauseyouhavedeployedtheprojectlibrary,theI/OserverisrunningandeachcontrolandindicatorisanI/Odataitem.

ClicktheTank1.InputFlowRate[GPM]controlandenteravalueof10andclicktheOKbutton.NoticethatthevaluesofTank1.TankLevel[Gallons]andTank1.TankOutputFlowrate[GPM]beginincreasing.



CloseDistributedSystemManager.TheperiodicI/Oservercontinuestorun.

11.6.5 Task5:CreatingSharedVariables

Inthisexerciseyouwilladdthenetwork-publishedsharedvariablesthatrepresentthedataitemsintheperiodicI/OservertotheTankSystemSharedVariablesprojectlibrary.

CompletethefollowingstepstoaddtheTankSystemSharedVariablesprojectlibrarytotheTankSystemproject.

Right-clickMyComputerintheProjectExplorerwindowandselectNew→Libraryfromtheshortcutmenu.

Right-clickthenewprojectlibraryyoucreatedandselectCreateBoundVariablesfromtheshortcutmenutodisplaytheCreateBoundVariablesdialogbox.



SelectNetworkItems.

ExpandTankSystemIOServer→Tank1intheNetworktree.ThesharedvariablesappearunderTank1.

SelecteachsharedvariablewiththedatatypeDBLandclicktheAddbuttontoaddeachvariabletotheAddedvariableslist.ClicktheOKbutton.TheCreateBoundVariablesdialogboxclosesandthesharedvariablesappearintheMultipleVariableEditorwindow.

ClicktheDonebuttontoclosetheMultipleVariableEditorwindow.

SelectFile→SaveAllintheProjectExplorer.TheNametheLibrarydialogboxappears.

Enter“TankSystemSharedVariables”intheFilenametextbox.ClicktheOKbutton.LabVIEWbindsthesharedvariablesintheTankSystemSharedVariablesprojectlibrarytothecorrespondingitemsonthenetwork.



11.6.6 Task6:ConfiguringDataLogging

Whenyouaddloggingtoasharedvariable,theDSCModulelogssharedvariabledata,includingthesharedvariablevalue,timestamp,whetherthevalueisinanalarmstate,andthequalityofthevalue.TheDSCModulelogsalldatatotheCitadeldatabase.CompletethefollowingstepstoaddloggingfortheTankLevel[Gallons]sharedvariable.

Right-clicktheTankSystemSharedVariables.lvlibprojectlibraryandselectMultipleVariableEditor.



SetthefollowingfortheTankLevel[Gallons]sharedvariableintheMultipleVariableEditor:

11.6.7 Task7:ConfiguringAlarming

Analarmisanabnormalconditiononasharedvariableorauser-definedcondition.Analarmoccursifasharedvariablevaluegoesoutofitsdefinedalarmlimitsorifasharedvariablehasbadstatus.InthisexerciseyouwilladdanalarmfortheTankLevel[Gallons]sharedvariable.



SetthefollowingfortheTankLevel[Gallons]sharedvariableintheMultipleVariableEditor:

11.6.8 Task8:EnablingLogging

CompletethefollowingstepstoenabledataloggingandalarmandeventloggingfortheTankSystemSharedVariablesprojectlibrary.

Right-clicktheTankSystemSharedVariables.lvlibprojectlibraryintheProjectExplorerwindowandselectPropertiesfromtheshortcutmenu.TheProjectLibraryPropertiesdialogboxappears.

SelectDSCSettings:DatabasefromtheCategorylist.VerifythattheoptionsintheDSCSettings:DatabasepageappearsimilartotheFigurebelow.

TheEnableDataLoggingoptionturnsondataloggingfortheprojectlibrary.localhostspecifiesthelocalcomputer.Uselocalhostinsteadofthenameofthecomputertoreduce



thechangesyoumustmakeifyoumovethisprojecttoanothercomputer.TheEnableAlarmsandEventsLoggingoptionturnsoneventloggingfortheprojectlibrary.TheUsethesamedatabaseforalarmsandeventsoptionensuresthattheDSCModulelogsalarmsandeventsforthisprojectlibrarytothesamedatabasethatitlogsdata.

YoucanchangetheDatabasenamethatappearsintheProjectLibraryPropertiesdialogboxtoamoreusefulordescriptivename.

11.6.9 Task9:CreatetheLabVIEWapplication

InthisexerciseyouwillcreateaVItodisplaydataonafrontpanel.Youdonotneedtoaddanycodetotheblockdiagram.CompletethefollowingstepstocreateafrontpaneltodisplaythedataitemsintheperiodicI/Oserver.

Right-clickMyComputerintheProjectExplorerwindowandselectNew→VIfromtheshortcutmenu.AnewVIfrontpanelandblockdiagramappear.

SelecttheTankLevel[Gallons]sharedvariablefromtheTankSystemSharedVariables.lvlibprojectlibraryintheProjectExplorerwindowanddragthesharedvariableontothefrontpanel.Thesharedvariableappearsasanumericcontrol.Noticethetrianglethatappearsnexttothecontrol.Thetriangleindicatesthatthiscontrolhasbeenconfiguredfordatabinding.

Right-clicktheTankLevel[Gallons]controlandselectChangetoIndicatorfromtheshortcutmenu.



Right-clicktheTankLevel[Gallons]indicatorandselectReplace→DSCModule→Vessels→OpenTankfromtheshortcutmenu.

Right-clicktheTankLevel[Gallons]indicatorandselectPropertiesfromtheshortcutmenu.ThePropertiesdialogboxappears.SelecttheDataBindingtabinthePropertiesdialogbox.

PlaceacheckmarkintheBlinkwhileAlarmOncheckboxtoconfigurethecontroltoblinkwhenthewaterlevelreaches75,thedefaultalarmyousetintheConfiguringAlarmingsectionofthisdocument.

FortheInputFlowrate[GPM]sharedvariable:

• SelecttheInputFlowrate[GPM]sharedvariablefromtheTankSystemSharedVariables.lvlibprojectlibraryintheProjectExplorerwindowanddragthesharedvariableontothefrontpanel.

• Right-clicktheInputFlowrate[GPM]controlandselectReplace→NumCtrls→PointerSlide.

FortheTankValve[%]sharedvariable:

• SelecttheTankValve[%]sharedvariablefromtheTankSystemSharedVariables.lvlibprojectlibraryintheProjectExplorerwindowanddragthesharedvariableontothefrontpanel.



• Right-clicktheTankValve[%]controlandselectReplace→NumCtrls→PointerSlide.

SelectFile→SaveAs.TheNametheVIdialogboxappears.Enter“TankSystemHMI”intheFilenametextbox.ClicktheOKbutton.

ClicktheRunContinuouslybuttontoruntheVI.TheVIshouldfunctioninthesamewayastheexampleyouraninthefirstexercise.

BelowwesewthefinalProjectExplorer:

Belowweseethefinalapplication:



11.6.10 Task10:UsetheLabVIEWDSCFunctionsandVIs

InthistaskyouwillusetheLabVIEWDSCFunctionsandVIspalette.

ReadHistoricalData:

BlockDiagram:

FrontPanel:



ReadAlarmData:

BlockDiagram:

FrontPanel:



11.6.11 Task11:ViewingReal-TimeData

YoucanusetheDSCModuletoviewlivedata.TheReal-TimeTrendExpressVIdisplayslivedatafromasharedvariableonanXYgraph.InthefollowingexerciseyouwilladdtheabilitytoviewlivedatatotheTankSystemVI.

PlacetheReal-TimeTrendExpressVI,availableontheDSCModulepalette,ontheblockdiagram.TheConfigureReal-TimeTrenddialogboxappears.

SelecttheTankLevel[Gallons]sharedvariableandselectAdd.

Placeawaveformchartonthefrontpanel.WirethetrenddataoutputoftheReal-TimeTrendExpressVItothewaveformchartontheblockdiagram.PlaceaWhileLooparoundthewaveformchartandExpressReal-TimeTrendcontrol.RuntheVI.



FrontPanel

11.6.12 Task12:ViewingAlarmsusingtheDistributedSystemManager

OpentheDistributedSystemManagerfromTools→DistributedSystemManager.



65

12 LabVIEWI/OServer

12.1 ConnectLabVIEWtoOPCTagsbyCreatinganI/OServer

Inthissection,createaLabVIEWinterfacetotheOPCtagscalledanI/OServer.TheI/OServerautomaticallyupdatesLabVIEWwiththecurrenttagvaluesatarateyouspecify.

IntheGettingStartedwindowofLabVIEW,click“File→NewProject”.ThisopensanewLabVIEWProject.

IftheContextHelpwindowisnotvisible,press“Ctrl+H”todisplaythewindow.Keepthiswindowopenforhelpfulinformationaboutitemsunderyourcursor.

IntheLabVIEWProjectwindow,right-clickMyComputerandselect“New→I/OServer”,asshownintheFigurebelow.

66 LabVIEWI/OServer


SelectOPCClientinthe“CreateNewI/OServer”windowandclickContinue.

Choose“NationalInstruments.NIOPCServers”fromtheRegisteredOPCserversfieldandsetUpdaterate(ms)to100.ThiscreatesaconnectionfromLabVIEWtotheOPCtags,whichupdatesevery100ms.

SelectOK.AlibraryisautomaticallycreatedinyourprojectexplorerwindowtomanagetheI/OServer.

Savetheprojectas“OPCDemoProject”andthelibraryas“OPCDemoLibrary”byselecting“File→SaveAll”fromtheprojectexplorerwindow.

12.2 CreateSharedVariablesthatConnecttotheOPCTagsthroughtheI/OServer

67 LabVIEWI/OServer


Inthissection,createsharedvariables,whichareboundtotheOPCtags,givingyounativeaccessinLabVIEWtoOPCdata.Withthesharedvariable,youcansharedataacrossLabVIEWapplicationsonasinglecomputeroracrossthenetwork.

CreatenewsharedvariablesthatareboundtotheOPCtags.

IntheLabVIEWProjectwindow,right-clickMyComputerandselect“New→Library”.Thiscreatesanewlibraryforthesharedvariables,whichareusedtoconnecttothePLCs’OPCtags.

Right-clickthenewlycreatedlibraryandselect“CreateBoundVariables…”.

IntheCreateBoundVariableswindow,selecttheOPCtagstobindthesharedvariablestobybrowsingdowntothesimulatedsinedatafromtheOPCserverasshownintheFigurebelow.

SelectallthesineitemsandclickAddandOK.ThiscreatessharedvariablesthatareboundtotheOPCtagsandloadsthemintotheMultipleVariableEditor.

IntheMultipleVariableEditor,selectDone.Thisaddsthenewsharedvariablestothelibrarythatwascreatedearlier.

Note!TheLabVIEWDSCModuleenhancessharedvariablesbyaddingtheabilitytologdata,alarms,andeventsdirectlytoadatabasewithouteverwritingaLabVIEWapplication.

Savethenewlibraryas“OPCItems.lvlib”intheprojectexplorerwindowbyright-clickingthelibraryandselectingSaveAs.

68 LabVIEWI/OServer


Deploythesharedvariablesbyright-clickingthe“OPCItems”libraryandselectingDeploy.Thispublishesthesharedvariables,makingthemavailableonthenetworktoothercomputers,OPCclients,andtheLabVIEWReal-TimePAC.

YounowhaveaccesstoOPCdatanativelyinLabVIEWthroughthesharedvariables.

12.3 ViewingSharedVariableswithDistributedSystemManager

FromtheProjectExplorerwindow,select“Tools→DistributedSystemManager”.Thisopensawindowthatyoucanusetomanageyoursharedvariablesinvariousways(view,deploy,undeploy,etc.).

IntheTreepaneoftheVariableManager,expandthe“localhost”itemunderthe“MySystems”category.Right-clickthe“OPCItems”library,andselect“WatchList”todisplaythesharedvariables,whichareboundtothePLCs’OPCtags.

Thesharedvariableswillbeupdatingwiththesimulatedsinedata.

12.4 UsingOPCTagDatainLabVIEW

Fromtheprojectexplorer,right-clickMyComputerandselect“New→VI”.ThiscreatesanewvirtualinstrumentorVI.AVIisusedtocreateauserinterfaceandexecutablegraphicalcode.

Bydefault,youseetheFrontPanel,whichistheuserinterfaceoftheVI.Select“View→ControlsPalette”orright-clickanywhereontheFrontPaneltobringuptheControlspalette.

SelectawaveformchartfromtheControlspalettebyselecting“Express→GraphIndicators→Chart”,andplaceitontheFrontPanel,asshownintheFigurebelow.

69 LabVIEWI/OServer


IntheVI,select“Window→ShowBlockDiagram”orpressCtrl+EtoshowtheBlockDiagram.TheBlockDiagramiswhereyoubuildthebehaviorofyourapplication.NoticetheiconontheBlockDiagram,whichrepresentsthechartontheFrontPanel.Bypassingdataintothisterminal,youcandisplayitinthechartontheFrontPanel.

Intheprojectexplorer,expandthe“OPCItems”libraryandselecttheSine1sharedvariable.

DraganddroptheSine1sharedvariablefromtheprojectexplorertotheBlockDiagramoftheVI.ThesharedvariableactsasasourceofdatatootherterminalsontheBlockDiagram.

70 LabVIEWI/OServer


Select“View→ToolsPalette”orpressShift+right-clicktoshowtheToolspalette,whichcontainsvarioustoolsforbuildingtheBlockDiagram.BydefaultyouusetheAutomaticToolSelectiontool,whichselectstheappropriatetoolbasedonthelocationofthecursor.

SelecttheConnectWiretoolasshownintheFigurebelow.ThistoolisusedtowireterminalstogetherontheBlockDiagram.

UsetheConnectWiretooltowiretheSine1sharedvariabletothewaveformchartbyclickingontheSine1sharedvariableandthenonthewaveformchart,asshownintheFigurebelow.

NowdataflowsfromthesharedvariabletothewaveformchartwhentheVIisrunning.

OpentheFunctionspalettebyselecting“View→FunctionsPalette”orright-clickinganywhereontheBlockDiagram.TheFunctionspalettecontainshundredsofanalysisfunctions,controlfunctions,andstructuresforgraphicalprogramming.

SelectawhileloopfromtheFunctionspalettebynavigatingto“Express→ExecutionControl→WhileLoop”.Thisallowsyoutowrapawhilelooparoundasectionofcode.

ThewhileloopcausesthecodewithinittoexecutecontinuouslyuntilstoppedbytheuseroradditionallogicintheVI.

71 LabVIEWI/OServer


Atimedloop,whichisanadvancedwhileloop,containsadditionalconfigurationoptionsfortimingandexecutioncontrol.Convertthewhileloopintoatimedloopbyright-clickingthewhileloopandselectingReplacewithTimedLoop.

Toconfigurethetimedloop,double-clickthetimedloopinputnode

IntheLoopTimingAttributesfield,setPeriodto100msandclickOK.Thisconfiguresthetimedlooptoexecutethecontainedcodeevery100ms.

ClicktheRunbuttononthetoolbartoexecutetheVI.

ClickCloseontheDeploy…windowoncethedeploymentcompletes.Whentheapplicationbeginsexecuting,youseetheSine1sinewavedisplayedonthewaveformchart.

72 LabVIEWI/OServer


Congratulations!YousuccessfullyaccessedPLCdatainyourLabVIEWapplication,soyoucanincorporatepowerfulanalysisandcontrolfunctionsinyoursolution.

73

13 LabVIEWReal-TimeModuleTheNationalInstrumentsLabVIEWReal-TimeModuleextendstheLabVIEWdevelopmentenvironmenttodeliverdeterministic,real-timeperformance.Developyourapplicationonahostcomputerusinggraphicalprogrammingandthendownloadtheapplicationtorunonanindependenthardwaretargetwithareal-timeOS(RTOS).

TheNationalInstrumentsLabVIEWReal-TimeModuleisanadd-oncomponentfortheLabVIEWDevelopmentSystem.Wheninstalled,thissoftwarecompilesNILabVIEWgraphicalcodeandoptimizesitfortheselectedreal-timetarget.UsingtheLabVIEWReal-TimeModule,youcandevelopanddeployapplicationstoallNIreal-timehardwaretargetsincludingPXI,CompactFieldPoint,FieldPoint,CompactRIO,andstandarddesktopPCs.TheembeddedRTOS(Real-TimeOperatingSystem)forthesetargetsisasinglededicatedkernelthatprovidesmaximumreliabilityforembeddedcode.

[Figure:www.ni.com]

WiththeLabVIEWProfessionalDevelopmentSystemandLabVIEWReal-TimeModule,youcancreateastand-aloneexecutableanddownloadittoahardwaretargetwithonesimplestep.Youcanpermanentlyembedthecodeonthenonvolatilememoryofthereal-timesystemsoitstartsautomaticallywhenthesystembootsforautonomousfieldapplications.

EachhardwaretargetcontainsanembeddedprocessorrunninganRTOS.TheLabVIEWReal-TimeModuleembedscompiledcodeonthehardwaretargetandrunsitindependentlyofthehostcomputer.Assigntheappropriateexecutionprioritytoeachreal-timetask.TheembeddedRTOSthenusesacombinationofround-robinandpreemptiveschedulingtoensuredeterministicexecutionofyourtime-criticaltasks.

74 LabVIEWReal-TimeModule


13.1 Real-TimeDevelopmentinLabVIEW

Developingreal-timeprogramsinLabVIEWisnearlyidenticaltodevelopingstandardLabVIEWapplicationsforyourPC.Whendevelopingreal-time(RT)programsinLabVIEW,youdeveloponahostWindowscomputer,andthendownloadandrunthemonareal-timehardwaretarget.

[Figure:www.ni.com]

Whendevelopingreal-timeapplicationsinLabVIEW,youusetheLabVIEWProjectExplorertoorganizeyourprograms(VIs)andcategorizethembythehardwareplatformthattheywillrunon.Notethatyoudevelopyourcodeonageneral-purposeWindowscomputer,andthenconnecttoyourreal-timehardwareusingEthernet.

TotestyourLabVIEWReal-Timeprogramonyourhardwareplatform,simplyclickontherunarrowandyourapplicationwillautomaticallybetransferredtoyourreal-timehardwareviaEthernetandbeginrunning.YoucanusestandardNIdebuggingtoolssuchashighlight

75 LabVIEWReal-TimeModule


execution,singlestepping,andbreakpointsfromyourdevelopmentsystemeventhoughyourreal-timeprogramisactuallyrunningonaseparatesystem.

Whenyouhavefinalizedyourreal-timeprogram,youcanbuildanEXEinLabVIEWanddownloadittoyourreal-timehardwareasastartupapplication.Afterrebootingyourreal-timehardware,yourprogramwillautomaticallyruninareliable,stand-alonefashion.

YoustartanewReal-TimeProjectfromyourGettingStartedwindow.

Selecteither“Real-TimeProject”intheNewgrouporselect“Real-TimeProject”intheTargetsselectorandthen“Go”.

TheReal-TimeprojectisalsoavailablefromtheToolsmenu.

76

14 CompactFieldPoint

14.1 Introduction

CompactFieldPointisaneasy-to-use,highlyexpandableindustrialcontrolandmeasurementsystemcomposedofruggedanddependableI/Omodulesandintelligentcommunicationinterfaces.DownloadyourNILabVIEWapplicationontotheembeddedreal-timecontrollerforstand-alonedatalogging,monitoring,andadvancedcontrol.Plus,connecttovirtuallyanysensortypewiththewidevarietyofI/Omodules,suchasthermocouples,resistancetemperaturedetectors(RTDs),straingages,4-20mAsensors,andavarietyofdigitalsignalsfrom5-30VDCand0-250VAC.TheCompactFieldPointI/Omodulesfilter,calibrate,andscalerawsensorsignalstoengineeringunitsandperformself-diagnosticstolookforproblems,suchasanopenthermocouple.

WithCompactFieldPointyoucan:

• Deployreal-timeembeddedcontrollersforstand-alonedatalogging,advancedanalysis,andprocesscontrol.

• AccessI/Opointsnearbyormilesawayonthenetworkusingthesamesimplereadandwritesoftwareframework.

• Connectvirtuallyanysensordirectlytothewidevarietyofhigh-accuracyanaloganddiscreteI/Omodules.

• DownloadyourNILabVIEWapplicationtotheembeddedcontrollerforreliable,stand-aloneoperation.



CompactFieldPointisveryeasytouseandcanhelpyouquicklybeginperformingindustrialcontrolandmeasurement.Gettingstartedisasimplethree-stepprocess:

1. Installthehardware2. Configurethecontroller3. ReadorwritetheI/Ochannels

TightintegrationbetweentheLabVIEWsoftwareenvironmentandreal-timehardwaretargets,suchasCompactFieldPoint,makeyourcontroldevelopmentprocessquickandeasy.Youcantakeadvantageofpowerfulgraphicaldevelopmentusingindustry-standardLabVIEWtorapidlyimplementyourcontrolsystem.

1. First,developtheprogramonaWindowshostcomputerusinggraphicalprogrammingblocks.

2. Next,downloadtheapplicationtoanembeddedcontrollersuchtheNIcFP-2000/cFP-2220.

3. Finally,deployyourapplicationfordependablelong-termexecutionthatperformsreliablybothwithandwithoutanetworkconnection.Onceyourapplicationisdeployed,youcanaccesstheembeddedapplicationthroughanyWebbrowserbyconnectingtotheembeddedWebserverofthereal-timeCompactFieldPointcontroller.

14.2 Development

InordertoconfigureanduseyourCompactFieldPointyouneedtodothefollowingsteps.

Step1:ConnecttheCompactFieldPointtoyourPC

ConnectyourCompactFieldPointsystemtoyourPCusinganEthernetcross-overcable.IfyouuseaSwitchorHubyoumayuseastandardEthernetcable.

Step2:InstallandConfiguretheCompactFieldPoint

YouusetheMeasurement&AutomationExplorer(MAX)toconfigureyourCompactFieldPointsystem.

Goto“RemoteSystems”.Thesystemshouldnowbeautomaticallydetected.



YoumayneedtoconfiguretheIPsettings.

Step3:FindyourDevices

ClickonyourCompactFieldPointnodeandright-clickandselect“FindDevices”.

AllyourCompactFieldPointmodules(controller,I/modules)shouldnowappear.



InourcasewehaveacFP-2000controllerandacFP-AIO-610I/Omodule.

Step4:StartanEmptyProjectinLabVIEW

StartLabVIEWandselect“EmptyProject”intheGettingStartedwindow.

Right-clickontheProjectnodeandselect“TargetsandDevices…”



SelectyourCompactFieldPointdevicefromthelist(Real-TimeFieldPoint):

WhenyouclickOK,allyourmoduleswillbeautomaticallyinsertedintoyourProject.



IfyouclickonyourI/Omodule,youwillseeallyourI/Ochannelsforthatmodule:

Step5:CreateyourVI

Right-clickonyourcontrollerandselectNew→VI



GotoyourI/Omoduleintheprojecttreeandselectyourchannel,e.g.,Input0.DragthechanneltoyourBlockDiagramandthecodeforthatchannelwillbeautomaticallycreated.

Step6:FinishyourProgram

Finishyourprogram,e.g.,readInput0andplotthevaluesinaChart.

BlockDiagram:



HereareyourProjectExplorerandtheFrontDiagram:

Step6:Deployment

ClicktheRunbuttontostarttestanddeployyourprogram.LabVIEWthenautomaticallystarttocheckyourcouldanddownloadittothecontroller.



Step6:Finish

Yoursystemshouldnowbereadytouse.

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15 CompactRIO

15.1 Introduction

CompactRIO(cRIO)isarealtimeindustrialcontrollermadebyNationalInstruments.TheCompactRIOisacombinationofaRealTimeController,reconfigurableIOModules(RIO),FPGAModuleandanEthernetexpansionchassis.

BelowweseeaCompactRIOsystem:

YoudevelopyourCompactRIOsoftwareonyourcomputerusingLabVIEWthenyoudownloadyourcodetothesystem.TheLabVIEWReal-TimeModuleisusedforthis.

IfyouwanttousetheFPGA,youneedtoinstalltheLabVIEWFPGAModule

15.2 Development

TightintegrationbetweentheLabVIEWsoftwareenvironmentandreal-timehardwaretargets,suchasCompactRIO,makeyourcontroldevelopmentprocessquickandeasy.Youcantakeadvantageofpowerfulgraphicaldevelopmentusingindustry-standardLabVIEWtorapidlyimplementyourcontrolsystem.

1. First,developtheprogramonaWindowshostcomputerusinggraphicalprogrammingblocks.

2. Next,downloadtheapplicationtoanembeddedcontrollersuchtheNIcFP-2000/cFP-2220.

3. Finally,deployyourapplicationfordependablelong-termexecutionthatperformsreliablybothwithandwithoutanetworkconnection.Onceyourapplicationis

86 CompactRIO


deployed,youcanaccesstheembeddedapplicationthroughanyWebbrowserbyconnectingtotheembeddedWebserverofthereal-timeCompactRIOcontroller.

InordertoconfigureanduseyourCompactRIOyouneedtodothefollowingsteps.

Step1:ConnecttheCompactRIOtoyourPC

ConnectyourCompactRIOsystemtoyourPCusinganEthernetcable.

Step2:InstallandConfiguretheCompactRIO

YouusetheMeasurement&AutomationExplorer(MAX)toconfigureyourCompactRIOsystem.

Goto“RemoteSystems”.Thesystemshouldnowbeautomaticallydetected.

YoumayneedtoconfiguretheIPsettings,etc.(NetworkSettings).

87 CompactRIO


Step3:FindyourDevices

AllyourCompactRIOmodules(controller,I/modules)shouldnowappearunderDevicesandInterfaces.

InourcasewehaveaNIcRIO-9074controller,aNI9263AnalogOutI/OmoduleandaNI9201AnalogInI/Omodule.

Step4:InstallSoftware

YouonlydothisoncewhenyouusetheCompactRIOforthefirsttimeoryouwanttoaddorupgradetheexistingsoftware.

88 CompactRIO


Ifyouselectcustominstallation,youmightgetawarninglikethis:

Justdiscardit!

Step5:StartanewProjectinLabVIEW

StartLabVIEWandselect“Real-TimeProject”intheGettingStartedwindow.

89 CompactRIO


Right-clickontheProjectnodeandselect“TargetsandDevices…”

90 CompactRIO


SelectyourCompactRIOdevicefromthelist(Real-TimeCompactRIO).

WhenyouclickOK,allyourmoduleswillbeautomaticallyinsertedintoyourProject.

91 CompactRIO


YouwillnowseeallyourI/OmodulesthatyouhaveandyouwillseeallyourI/Ochannelsforthesemodules.

Step6:CreateyourVI

Right-clickonyourcontrollerandselectNew→VI

GotoyourI/Omoduleintheprojecttreeandselectyourchannel,e.g.,Input0.DragthechanneltoyourBlockDiagramandthecodeforthatchannelwillbeautomaticallycreated.

BelowweseeasimpleexamplewithoneAnalogInandoneAnalogOut:

92 CompactRIO


TheFrontPanel:

Inthissimpleexamplewehaveusedasimpleloop-backtest,meaningwehaveconnectedAO0(AnalogOut,Chanel0)andAI0(AnalogIn,Chanel0)together,asshownbelow.Thismeanswhenwewrite4VtotheAO0,weshouldreceive4VonAI0.

93 CompactRIO


Step7:Deployment

ClicktheRunbuttontostarttestanddeployyourprogram.LabVIEWthenautomaticallystarttocheckyourcodeanddownloadittothecontroller.

Step8:Finish

Yoursystemshouldnowbereadytouse.

Hans-PetterHalvorsen,M.Sc.

E-mail:[email protected]

Blog:http://home.hit.no/~hansha/

UniversityCollegeofSoutheastNorway

www.usn.no

Date post:	26-Mar-2018
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