AFDX(ARINC664)协议讲解

GEFanucEmbeddedSystemsAFDX/ARINC664ProtocolTutorialTableofContentsChapter1Overview4TheAntecedents4WhatisAFDX?4OtherAvionicsBuses5ARINC4295MIL-STD-15535Ethernet6ALOHANet6TheALOHAProtocol6EthernetLocalAreaNetworks(BroadcastMedia)6TheEthernetProtocol6EthernetUsingCategory5UTPCopperTwistedPairs6EthernetFrameFormat6Chapter2Ethernet6Full-duplex,SwitchedEthernet7DoingAwaywithContention7ReducingWireRunsandWeight8Chapter3EndSystemsandAvionicsSubsystems9EndSystemsandAvionicsSubsystems9Chapter4AFDXCommunicationsPorts10AFDXCommunicationsPorts10Chapter5VirtualLinks:PacketRoutinginAFDX11VirtualLinks11Chapter6MessageFlows12MessageFlows12Chapter7RedundancyManagement13RedundancyManagement13Chapter8VirtualLinkIsolation14VirtualLinkIsolation14ChoosingtheBAGandLmaxforaVirtualLink15Chapter9VirtualLinkScheduling15VirtualLinkScheduling15Chapter10Jitter16Jitter16Chapter11AFDXMessageStructures17Introduction17ImplicitMessageStructures17ARINC429Labels18Chapter12TheAFDXProtocolStack19TheAFDXProtocolStack19Transmission19Reception20AppendixAAFDXFrameAddressingandHeaderStructures21EthernetAddressing21IPHeaderFormatandAddressing21UDPHeaderFormat22AppendixBReferencedDocuments23ReferenceList23ListofFiguresFigure1AFDXNetwork4Figure2ARINC429CommunicationProtocol5Figure3MIL-STD-1553BusCommunicationProtocol5Figure4ALOHANet6Figure5EthernetLocalAreaNetworks(BroadcastMedia)6Figure6EthernetFrameFormat6Figure7Full-Duplex,SwitchedEthernetExample7Figure8AFDXversusARINC429architecture8Figure9EndSystemsandAvionicsSubsystemsExample9Figure10SamplingPortatReceiver10Figure11QueuingPortatReceiver10Figure12FormatofEthernetDestinationAddressinAFDXNetwork11Figure13PacketRoutingExample11Figure14MessageSenttoPort1bytheAvionicsSubsystem12Figure15EthernetFramewithIPandUDPHeadersandPayloads12Figure16AandBNetworks13Figure17AFDXFrameandSequenceNumber13Figure18ReceiveProcessingofEthernetFrames13Figure19ThreeVirtualLinksCarriedbyaPhysicalLink14Figure20VirtualLinkScheduling15Figure21VirtualLinkScheduling15Figure22RoleofVirtualLinkRegulation16Figure23TwoMessageStructures17Figure24ARINC664MessageStructures18Figure25AFDXTxProtocolStack19Figure26AFDXRxProtocolStack20Figure27EthernetSourceAddressFormat21Figure28IPHeaderFormat21Figure29IPUnicastAddressFormat21Figure30IPMulticastAddressFormat21Figure31UDPHeaderFormat224OneofthereasonsthatAFDXissuchanattractivetech-nologyisthatitisbaseduponEthernet,amaturetechnol-ogythathasbeencontinuallyenhanced,eversinceitsinceptionin1972Infact,thecommercialinvestmentandadvancementsinEthernethavebeenhugecomparedsay,toARINC429,MIL-STD-1553,andotherspecializeddata-communicationstechnologiesAsshowninFigure1,anAFDXsystemcomprisesthefollow-ingcomponents:AvionicsSubsystem:ThetraditionalAvionicsSubsystemsonboardanaircraft,suchastheflightcontrolcom-puter,globalpositioningsystem,tirepressuremonitoringsystem,etcAnAvionicsComputerSystemprovidesacomputationalenvironmentfortheAvionicsSubsystemsEachAvionicsComputerSystemcontainsanembeddedEndSystemthatconnectstheAvionicsSubsystemstoanAFDXInterconnectAFDXEndSystem(EndSystem):Providesan“interface”betweentheAvionicsSubsystemsandtheAFDXIntercon-nectEachAvionicsSubsystemtheEndSysteminterfacetoguaranteeasecureandreliabledatainterchangewithotherAvionicsSubsystemsThisinterfaceexportsanap-plicationprograminterface(API)tothevariousAvionicsSubsystems,enablingthemtocommunicatewitheachotherthroughasimplemessageinterfaceAFDXInterconnect:Afull-duplex,switchedEthernetin-terconnectItgenerallyconsistsofanetworkofswitchesthatforwardEthernetframestotheirappropriatedestina-tionsThisswitchedEthernettechnologyisadeparturefromthetraditionalARINC429unidirectional,point-to-pointtechnologyandtheMIL-STD-1553bustechnologyChapter1OverviewTheAntecedentsMovinginformationbetweenavionicssubsystemsonboardanaircrafthasneverbeenmorecrucial,anditisherethatelectronicdatatransferisplayingagreaterrolethaneverbeforeSinceitsentryintocommercialairplaneserviceontheAirbusA320in1988,theall-electronicfly-by-wiresystemhasgainedsuchpopularitythatitisbecomingtheonlycontrolsystemusedonnewairlinersButthereareahostofothersystems—inertialplatforms,communicationsystems,andthelike—onaircraft,thatdemandhigh-reliability,high-speedcommunications,aswellControlsystemsandavionicsinparticular,relyonhavingcompleteandup-to-datedatadeliveredfromsourcetore-ceiverinatimelyfashionForsafety-criticalsystems,reliablereal-timecommunicationslinksareessentialThatiswhereAFDXcomesinInitiatedbyAirbusintheevolu-tionofitsA380Aircraft,theycoinedtheterm,AFDX,forAvion-icsFull-DupleX,switchedEthernetAFDXbringsanumberofimprovementssuchashigher-speeddatatransfer—andwithregardtothehostairframe—significantlylesswiring,therebyreducingwirerunsandtheattendantweightWhatisAFDX?AvionicsFullDupleXSwitchedEthernet(AFDX)isastandardthatdefinestheelectricalandprotocolspecifications(IEEE8023andARINC664,Part7)fortheexchangeofdatabe-tweenAvionicsSubsystemsOnethousandtimesfasterthanitspredecessor,ARINC429,itbuildsupontheoriginalAFDXconceptsintroducedbyAirbusFigure1.AFDXNetworkControllersActuatorsSensorsCont