已阅读5页,还剩12页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
英文原文JournalofSoftwareEngineeringandApplications,2011,4,172-180doi:10.4236/jsea.2011.43019PublishedOnlineMarch2011(http:/www.SciRP.org/journal/jsea)DevelopmentofEquivalentVirtualInstrumentstoPLCFunctionsandNetworksMohammadA.K.Alia,TariqM.Younes,MohammadAbuZalataMechatroncisEngineeringDepartment,FacultyofEngineeringTechnology,Al-BalqaAppliedUniversity,Amman,Jordan.Email:,,ReceivedFebruary20th,2011;revisedMarch5th,2011;acceptedMarch10th,2011.ABSTRACTThisresearchisacontinuationtoourworkwhichwaspublishedin1.EightdifferenttimingVIsaredesignedandtested.TheseincludeON-Delay,OFF-Delay,SingleShot,RetriggerableMonostable,andAccumulativesoftware-basedtimers.Usinghardwareprogrammablecounter/timerchip(DAQ-STC-24bit)andPCIMIO-16E-1DAQboard,anothertwoprecisetimersaredesigned.Attheendofthepaper,forillustrationpurposes,anelectro-pneumaticdrivesystemwasdevelopedandcontrolledutilizingdesignedon-delaytimersVIfunctions.ResultsofexperimentshowcompletecoincidencebetweenthePLC-basedcontrolandVirtualPLC-basedprogramresults.Keywords:PLC,VirtualPLC,LabVIEW,ProgrammableTimers1.IntroductionInourwork“DesignofavirtualPLCusingLabVIEW”wehaveshownhowitispossibletocreateLabVIEWVIswhichrepresentPLCfunctionsandnetworks.WecomparedbetweenPC-basedandPLC-basedcontrolsystems,andcametothefactthatbothsystemsarecontinuouslydevelopinginthesamedirectioninordertoobtainbetterprogrammability,connectivityandcommunicationinterfacing.AtthetimebeingthePC-basedDCSsaresuitedforindustrialapplications.Theyarerobustandtheyeasilyworkinanopenarchitecturemode,whilePLCsareequippedwithspecificMMIsoftwareandpseudo-standardcommutationsoftwarealso.WehaveshownthatinordertoimprovetheprogrammabilityofPACs,wepracticallybroughtthePLCtothecomputerutilizingbythatnumerousadvantagesofcomputerssuchasmultitasking,unlimitedmemory,highspeedandthepossibilityofcreatingunlimitednumberofprogrammableobjectssuchascounters,timers,shiftregistersandothers.Becauseofthelimitedsizeofpreviouswork,wewerenotabletocoverotherimportantVIswhichmaybeusedalsoastheanalogofPLCfunctions.InthispaperweshalldevelopdifferenttypesofprogrammabletimersusingLabVIEWsoftware2andNIDAQboardhardwarealso.TheLabVIEWbasicfunctionsthatprovidetimingonmillisecondlevelarethe“wait”and“waitforNextmsMultiple”VIs.Botharebasedonthesameunderlyingmechanism.MostapplicationsworkcomfortablywithavailableLabVIEWmeasurementsthatresolvemilliseconds,andmanymoreoperatewithsecondresolution3-4.Afewapplicationsdemandsub-millisecondresolutionandresponsetime,whichisproblematicdueprimarilytooperatingsystemandnotaLabVIEWlimitation5.Iftheapplicationrequireshigheraccuracyorresolutionthanthebuilt-intimingfunctionscansupply,thenonewillhavetousesomeadditionalhardware,suchasNI-DAQboardsoranexternalclock6.NI-boardshavetwo24bitcounterchipsandseveralon-boardclocksthatcanbecountedtoproduceaccuratetiming(intervals).WiththeDAQcounter-timerVIs,onecanconfiguretheon-boardversatilehardwareforavarietyoftasksincludingtheaccurategenerationoftimedpulses,countingevents,andthemeasurementofperiodsandfrequencies.Thecounteroutputgeneratesapulsewhenapreprogrammedterminalcount(TC)isreached.Thepulsemaybeusedforsequencingpurposes.Similarhardware-basedtimingmaybeperformedusingwindowsAPIfunction“Queryperformancecounter”.Thisfunctionlooksatahighresolutionsystemhardwarecounterthatrunsatapproximately1.2MHzor0.8microsecondcount.Theactualresolution,onceweaccountforthedelayincallingthefunction,willbeconsiderablyless,butstillfarbetterthanonemillisecond.ConcerningReal-Timeoperatingsystems(RTOS),theyaredesignedtorunasingleprogramwithveryprecisetiming.Theycanallowtorunloopswithnearlythesamethingeachiteration(typicallywithinmicroseconds).TimingforhardRTOSscanbeperformedusingtheDAQcardsinternalclock,givingbetteraccuracythansoftwaretimingfunctions7.Atthetimebeing,somehardwareplatformsfeatureanon-boardFPGA,thatmaybeprogrammedusingLabVIEWFPGAmodule.NIComactRIOandsingle-boardRIOareexamples.ThedefaultclockrateofLabVIEWFPGAis40MHz.GeneralFPGAtimingVIs2maygenerateoneclockperiod.One-shotpulseormeasuretheperiod,pulsewidth,accumulateperiodoveraspecifiednumberofpulsesandcountpulsesoveraspecifiedperiodoftime.NeverthelessFPGAVIsdonotincludereadyOn-delaytimers,OFF-delaytimersandmomostableretriggerabletimerswhichfindextensiveapplicationsinPLCsequentialcontrolprograms.Buildingontheabove,thetargetofthisworkistoillustratethedesignofdifferenttypesoftimingVIsusingLabVIEWsoftwareinordertobeusedasprogrammingelementsinvirtualPLCprograms.2.ON-DelayTimer1)ON-DelayTimer-1Figure1showsthefrontpanelandtheblockdiagramcomponentsofasoftware-basedON-DelayTimer.Theloopiterationisindicatedinseconds.Becausetheloopiterationstartsfromzero,theincrementfunctionisaddedinordertostartitatone.Sincethewaiticonhas100msdelaybetweeneverytwoiterationsafactorof10ismultipliedbytimerpreassignedvalue,inordertomeasurethetimedelayinseconds.Aftertheapplicationofenablesignalittakessomedelaytimeintervalfortheequalfunctiontohaveatruestateattheoutput.Iftheinputsignalisdisabled,thetimeroutputinstantlychangestolowstate.2)ON-DelayTimer-2ThecomponentsoftheVIareshownintheblockdiagram,Figure2.Initiallytheinputsignalisnotenabledandthefalsecaseisactivated.Theoutputofselecticonwillbezero,whichislowerthanthetimerpresetvalue,andasaresultofthattheoutputofthetimerisOFF.Whentheinputsignalisenabledthetruecaseisexecutedandtheselecticonwilloutputthevaluethatcomesformtheoutputofthecasestructure.Theinitialvalueoftheiterationlocalvariableiszero,thenitwillbeincrementedafteradelaycausedbythewaiticon,andthencomparedbytimerpresetvalue.Whentheoutputofthecomparisonfunctionistrue,theoutputofthetimerbecomeshigh.Whentheenableinputsignalbecomeslow,theoutputofthetimerbecomeslowsimultaneously.InthisVI,thecheckingofthecasestructureiscontinuousatascanrateequaltoonemillisecond,whichisacceptedformanyapplications.(a)(b)(c)Figure1.On-delaytimer-1,(a)TheBlockDiagram;(b)TheFrontPanel;(c)Subicon3.OFF-DelayTime1)OFF-DelayTimer-1ThefrontpanelandblockdiagramareshowninFi
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 雄激素及同化激素相关行业项目成效实现方案
- 江苏省苏州市吴中学区横泾中学2023-2024学年中考联考物理试题含解析
- 2023年部编版九年级地理上册期末试卷及答案【下载】
- 氢动力汽车的经济性分析与市场推广策略
- 生态文明建设与绿色金融创新
- 新质生产力在远程教育领域的应用研究
- 2023年人教版九年级语文上册期末模拟题
- 2022-2023年人教版九年级化学上册期末考试题及答案
- 人教版九年级数学下册期中试卷及答案【完整版】
- 2023年八年级化学(上册)期末考试卷及答案
- 2023中国数字化慢病管理市场洞察报告-易观分析
- RS-232串行通信电路图
- 小学英语口语教学研究
- 喷漆技能培训教案(技师学院汽车工程系)-AB版
- 浙教版劳动一年级上项目四-任务一《瓶瓶罐罐做花瓶》-课件
- 中国传统文化-瓷器-(英文)
- 《AutoCAD机械绘图课件》课件-任务四法兰盘零件的绘制
- 有机硅化学课件-硅烷交联剂和硅烷偶联剂
- 网络经济学PPT完整全套教学课件
- 三年级下册心理健康教案-探寻记忆的迷宫-通用版
- 公务摄影拍摄技巧分享
评论
0/150
提交评论