IEEE-1588标准基础教程(英语)

IEEE-1588StandardforaPrecisionClockSynchronizationProtocolforNetworkedMeasurementandControlSystems-ATutorial-JohnEidsonOctober10,[e-mail]©Copyright2005AgilentTechnologies,IncOutline1.Generaloverviewofthetechnologyandapplications2.Guidetothestandard-adetailedanalysisofthemajorclauses3.IEEE1588interoperability/conformancetopics4.ImplementationtopicsTutorialonIEEE1588October10,2005Page2GeneralOverviewoftheTechnologya.Purposeb.StatusandactivitiessurroundingIEEE1588c.ComparisontootherprotocolsTutorialonIEEE1588October10,2005Page3ThePurposeofIEEE1588IEEE1588isaprotocoldesignedtosynchronizereal-timeclocksinthenodesofadistributedsystemthatcommunicateusinganetwork.NETWORKTutorialonIEEE1588October10,2005Page4TheStatusofIEEE1588•ApprovedbytheIEEE-SAReviewCommitteeonSeptember12,2002•PublishedasIEEE1588-2002onNovember8,2002•AvailablefromtheIEEE•ApprovedasIECstandardIEC61588onMay21,2004•Productsandinstallationsstartedappearinginlate2003•ConferencesonIEEE1588heldin2003,2004,2005•P1588committeeinprocessofextendingthestandard-targetcompletioninlate2006•Currentinformationmaybefoundat(continued)IEEE1588NTPGPSTTPSERCOSLatencycorrectionYesYesYesConfiguredNoNoConfiguredYesEveryTDMAcycle,~msProtocolspecifiessecurityNo(V2mayincludesecurity)YesNoNoAdministrationSelforganizingConfiguredN/AConfiguredHardware?ForhighestaccuracyNoRFreceiverandprocessorYesUpdateinterval~2secondsVaries,nominallyseconds~1secondEveryTDMAcycle,~msTutorialonIEEE1588October10,2005Page7ComparisontoOtherProtocols(summary)IEEE1588:Targetisgroupsofrelativelystablecomponents,locallynetworked(afewsubnets),cooperatingonasetofwelldefinedtasks.NTP:(NetworkTimeProtocol,RFC1305).TargetisautonomoussystemswidelydispersedontheInternet.GPS:(SatellitebasedGlobalPositioningSystemoftheUSDepartmentofDefense):Targetisautonomous,widelydispersedsystems.TTP(),SERCOS(IEC61491):Targetistightlyintegrated,usuallybusorspecializedTDMAnetworkbasedclosedsystems.TutorialonIEEE1588October10,2005Page8GuidetotheStandard-(Adetailedanalysisofthemajorclausesofversion1)a.Overviewandgoalsofthestandardb.Synchronizationmessagesandmethodologyc.Selectionofmasterclocksd.Statemachineandeventse.Timingconsiderationsf.ManagementmessagesTutorialonIEEE1588October10,2005Page9ObjectivesofIEEE1588•Sub-microsecondsynchronizationofreal-timeclocksincomponentsofanetworkeddistributedmeasurementandcontrolsystem*•Intendedforrelativelylocalizedsystemstypicalofindustrialautomationandtestandmeasurementenvironments.*•Applicabletolocalareanetworkssupportingmulticastcommunications(includingbutnotlimitedtoEthernet)*indicatesobjectivesthatmaybeextendedinversion2TutorialonIEEE1588October10,2005Page10ObjectivesofIEEE1588(continued)•Simple,administrationfreeinstallation•Supportheterogeneoussystemsofclockswithvaryingprecision,resolutionandstability•Minimalresourcerequirementsonnetworksandhostcomponents.TutorialonIEEE1588October10,2005Page11TheIEEE1588StandardDefines:•Descriptorscharacterizingaclock•Thestatesofaclockandtheallowedstatetransitions•IEEE1588networkmessages,fields,andsemantics•Datasetsmaintainedbyeachclock•ActionsandtimingforallIEEE1588networkandinternaleventsTutorialonIEEE1588October10,2005Page12•Criticalphysicalspecifications•Asuiteofmessagesformonitoringthesystem•SpecificationsforanEthernetbasedimplementation•Conformancerequirements•ImplementationsuggestionsTutorialonIEEE1588October10,2005Page13OverviewoftheIEEE1588StandardClausePurposeAnnexPurpose1ScopeAUserInformation2StandardsReferencesBTimeScales3DefinitionsCSubdomainMaps4NotationConventionDEthernetUDP/IPImplementation5DatatypesEBibliography6ProtocolOverview7Protocol8MessageSpecifications9ConformanceTutorialonIEEE1588October10,2005Page14WARNINGTheIEEEhasratherstrictrulesoninterpretingIEEEStandards.Noindividualororganizationcanissueofficialinterpretationsorprovidedefinitiveanswerstoquestionsofinterpretation.ThismustbedonebyanIEEEauthorizedcommittee.Eventhiscommitteecannotextend,correct,orchangethestandard-thismustbedonebyballot.However-Wecanlearnfromandshareourcollectiveexperience.TutorialonIEEE1588October10,2005Page15Clause6:PTPClockSynchronizationModelQUESTION:Howdowetakeacollectionofclocks,messagetypes,clockproperties,networks,etc.andproduceaconsistenttimebaseinalltheparticipatingclocks?MESSAGETYPESSyncDelay_ReqFollow_UpDelay_RespManagementCLOCKPROPERTIESUUIDStratumIdentifierStateVariance….NETWORKCOMMUNICATIONFORMS:Ethernet(UDP/IP),DeviceNet,L2E