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现场总线profibus技术问答(FieldbusProfibusTechnologyQ&A)CAMETAninthvolume97PROFIBUSfieldbustechnologyquestionansweringtechnologyontheauthor:Mt.DennisvanBoomaisgeneralmanagerofHollandPROCENTECCorporationManagcr,engagedinPROFIBUStechnologyfor14years・Inadditiontoparticipatingintheworld'smorethan100Largeandmedium-sizedPROFIBUSprojects,andisresponsiblefortroubleshooting,oftenparticipateWithseminars,lecturesandtraining,andwrotealargenumberofPROFIBUSArticle,theactualworkexperiencegainedbysharingwithyou.Willbe2006Someoftheaudience'sskillsduringthePROFIBUSseminarinBeijingandianinMayQucstionsanswered・Question1:whatisthepriceratiobetweentraditionalcablingandPROFIBUScabling?Itiswe11knownthatthewiringcostofPROFIBUSismorethanthecostoftraditionalwiring Moreeconomically,infact,notonlythat,butothercostsassociatedwithitarealsoreducedQuiteafew.Suchas:reducingthecableholder,savingenergy,simplifyingthedocument,Theinterfaceofclarity,reducesthetesttimeandparts,moreeasytoexpandWithchanges,duetomaintenanceintime,greatlyreducingthedowntime,whichisonlythebaseknotSavestructureandinitialcosts;andtherealmeaningofthecostsavingstostartanewMaintenanceandoperationcost・PROFIBUSisagreatchoice,butitneedstogothroughSometrainingisneededtounderstanditsadvantages・Problem2:PROFIBUShowmanyrepeaterscanbeconnectedcontinuously?Somedocumentsmentionthatyoucanconnectupto3repeaters,eveninthepresenceofThefigureisalsomentionedinthestandard,butthisisnotentirelycorrect,Theelectroniccomponentsoftherelaydeterminethemaximum numberofconnectionstheycanconnectAsaresultofregeneration,thedigitswillbecomelargerorsmaller・IfyoustringtogetherTherearemanyrepeaters,andthemessagespassedwillnolongerbeidentifiedThedifferenceistoolargefordigits・TherearealsounlimitednumbersofrepeatersonthemarketSo,firstyouneedtocheckthemanual,anditwillbethereExplainthemaximumnumber,forexample,SIEMENS'srepeateris9,ThePROCENTECofHollandProfiHubisinfinite;thesecondstepisTochangebusparameters,allrepeatershavetimedelays,falseIfyouconnectalotofrelaysinseries,youhavetoDPthemainstationThebusparametersoftheTslotarechangedtogreatervalues,allintherepeatermanualPointoutthenumericalvalue・Question3:allPROFIBUSdevicesonthemarkethavebeencertifiedNo,IthasnotyetimposedavendoronitsPROFIBUSmasterstation Orfromthestationforcertification,butitisrecommendedthatthecertificationbebest,asinmostofthecertificationOnlythecertifiedequipmentwillbeselectedfortheproject・InChina,productionThecertificationofproductsiscarriedoutbyCPCC・Atpresent,onlythemasterstationandtheslavestationcanCertification,andproductssuchasconnectors,cablesandrepeaters,havenotyetbeenmadeCertificationguidelinesavailable・Note:PROFIsafeandPROFINETdevicesmustbecertified.Problem4:troubleshootingandtuningduringinstallationofPROFIBUSWhattoolsdoyouneed?Therearetwotoolsthatareabsolutelyessentia1.Oneisabusanalyzer,SuchasProfiTrace,usedtocheckthequalityoftherules;anotheristochecktheoscilloscope.Checksignalquality.Aslongasyouhavethesetwotools,youcanfind99% Lineerror.Amultimeterisnotusedforsignalanalysis,butonlyfortwopointsConnectionbetween.Question5:whataretheusesoftheoscilloscope?Thequalityofdatacommunicationcanbecheckedbyusingoscillograph・ThroughtheletterTheverificationofalltheproblems,suchasshortcircuit,break,terminaldeletionorwww.cameta・org.cn982006fifthtechnologyandequipmentinexcessofEMCconstruction,electronicinterfaceunqualifiedcanbechecked・Althoughtheuseofoscilloscopesrequiressometimeoftraining,butrelativetothefaultThisisnothingcomparedtotheamountoftimeandexpensesavedduringtheoperationWhatoQuestion6:howmanyDPslavestationscanbeconfiguredinanetwork?Mostpeoplewillanswer126,butthisansweriswrong・fromTheaddressandreservedaddressusedattheterminusare0and126(configurationworker) Blockingthesetwonumbers)thetotalnumberofDPslavestationsindataexchangeis124.Anotherthingtonoteisthatsometimestheaddress2isalsofromthestationSetasideandbeblocked.Question7:youcanprovideuswiththeinstallationofaPROFIBUSDPnetworkAnybasicconsiderations?1.alwaysusethePROFIBUScableandconnector;2.nomorethan32equipmentpersection(includingrepeaters,OLM,andCoupler);3.makesurethatthelengthofeachsegmentcorrespondstothebaudrate;4.ensurethepowersupplyofterminalsateachendofthesegment;5.avoidthebranchline;6.avoidconfusionbetweengroundwireandFireWire（A二green,B二red）;7.measuretheactuallengthofthecableandupdatethedrawing・ Aftertheinstallationiscompleted,theworkdoneshallbeexamined:Isthe1.addresssetcorrect?2.isthereanyshortcircuitorbrokenline?3.canyoucommunicatewiththedevice?Question8:whyistheterminalimportant?Aterminalthatpreventsripplesfrominterferingwithdatacommunications.waveThegreatertherate,thelongerthecable,theterminalismoreimportant,shouldputtheterminaldeviceSet/activatetwoterminalsineachlinesegment・ForPROFIBUSDPItsaysthattheterminalispoweredtoprovideafreetimewhennoonesendsthedataLandtohome;forPROFIBUSPA,theterminalsareoneofresistorsandcapacitorsAcombination・Question9:ifthePROFIBUScableisshortcircuited,itwillappearWhathappened? TheshortcircuitthatoccursinthePROFIBUScablewill,inmostcases,beInterferencewiththedatacommunicationofthissectionwilloccur,butthedevicewillnotbedestroyedBad!UsinganoscilloscopecanbeeasilydetectedandevencheckedMeasurethelengthofthedistancefromtheproblem・IftheenduserwantstocontinueIfyouinstallit,youcanchoosethefollowingsolution:A.installoneRedundantsystems:B.dividestheinstallationintomoresegments,andbetweensegmentsandrelaysTheOLMandProfiHubarecoupled;theC.ensuresthatthecableisinstalledsafelyInthecablebracket.Question1O:PROFIBUSshouldtherebeadistancebetweenthesupplycableandthepowercable?Thereshouldbe.EvenPORFIBUSissubjecttoparallelTheinterferenceofhighvoltagewiresshallalwaysbeatleast10cmbetweencablesSpacing(dependingonthevoltagelevel)・Mostusersmixallof thecablesPlacedinacableholder,whichoftenresultsinerrors・CrossputThereisnoproblemwiththecablebeingplaced,leavingthespacingjustasolution・thisInaddition,propershieldingprotectionmustalsobeprovided!Question11:howshouldthegroundingofthePROFIBUScablebethemostterminal?Degreeofinterferenceprevention?Therearealotofquestionsaboutgrounding・I'dliketocorrectsomeofthemfirstStatementoStandardPROFIBUSDPcableshieldhasresistance(standardcable)Lineabout9,5/km)thisresistorcarriesdatacommunicationsignalsPollutionvoltage(noise)・Whenthecableissinglepointgrounding,thenoisemustIttakesalongwalktogettotheground,sopartofitWillstoponthecable,whichmeansthatthegroundisnotcorrect,especiallywhen Whentheshieldingresistanceusedbythecableisgreater,theproblembecomesworse;Whenpossibletomultipointgrounding,theshieldingresistancewillbecomeverysmall,whichmeansThenoisecaneasilyberemovedfromthecablebythegroundingpoint,butduetoThegroundingpotentialdifferenceisdifferent,andthegroundingcircuitwillalsoappear・InordertoavoidIofferyou3solutionstothisproblem・ThefirstoneisthemostOneeffectisfiber;thesecondiswithanextragroundcableThelineisinstalledwiththePROFIBUScable;thethirdisthroughtherepeaterandTheProfiHubconductscapacitivegrounding.InSeptember2006,ChinaAssociationofmechatronicstechnologyapplicationswillbeheldChinaPROFIBUStechnicalpersonnelcertificationtraining〃・ThiswillbethehighestlevelAtraining,3daysoftrainingwillincludeboththeoreticalandfieldoperations,intheofficialAcertificatewillbeawardedafterpassingtheexamination.Upon completionoftraining,traineeswillreceiveWithregardtoPROFIBUS,DP/PAengineering,installationandtroubleshootingValuableknowledge・IamresponsiblefortrainingandwillshareasmuchaspossiblePassonknowledge・Inthenextissue,thisprintwillanswersomePROFIBUSinstallationandprocessworkersIndustryrelatedissues・Youarewelcometosendyourquestionstotheeditorialdepartment,ThismagazinewillansweryourquestionsinfutuTejournals・・DennisvanBoomaPROCENTECTheNetherlandsDbooma@procentec・comWw.procentec・com
