CAN 总线协议外文翻译.doc

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1、CANBusProtocolIntroductionControllerAreaNetwork(CAN)wasinitiallycreatedbyGermanautomotivesystemsupplierRobertBoschinthemid-1980sforautomotiveapplicationsasamethodforenablingrobustserialcommunication.Thegoalwastomakeautomobilesmorereliable,safeandfuel-effic

2、ientwhiledecreasingwiringharnessweightandcomplexity・Sinceitsinception,theCANprotocolhasgainedwidespreadpopularityinindustrialautomationandautomotive/truckapplications.Othermarketswherenetworkedsolutionscanbringattractivebenefitslikemedicalequipment,testequ

3、ipmentandmobilemachinesarealsostartingtoutilizethebenefitsofCAN.ThegoalofthisapplicationnoteistoexplainsomeofthebasicsofCANandshowthebenefitsofchoosingCANforembeddedsystemsnetworkedapplications.CANOverviewMostnetworkapplicationsfollowalayeredapproachtosyst

4、emimplementation.Thissystemeticapproachenablessinteroperabilitybetweenproductsfromdifferentmanufacturers.AstandardwascreatedbytheInternationalStandardsOrganization(ISO)asatemplatetofollowforthislayeredapproach.ItiscalledtheISOOpenSystemsInterconnection(OSI

5、)NetworkLayeringReferenceModel.TheCANprotocolitselfimplementsmostofthelowertwolayersofthisreferencemodel.ThecommunicationmediumportionofthemodelwaspurposelyleftoutoftheBoschCANspecificationtoenablesystemdesignerstoadaptandoptimizethecommunicationprotocolon

6、multiplemediaformaximumflexibility(twistedpair,singlewire,opticallyisolated,RF,IR,etc.).Withthisflexibility,however,comesthepossibilityofinteroperabilityconcerns.Toeasesomeoftheseconcerns,theInternationalStandardsOrganizationandSocietyofAutomotiveEngineers

7、(SAE)havedefinedsomeprotocolsbasedonCANthatincludetheMediaDependentsInterfacedefinitionsuchthatallofthelowertwolayersarespecified.ISO11898isastandardforhigh-speedapplications,ISO11519isastandardforlow-speedapplications,andJ1939(fromSAE)istargetedfortruckan

8、dbusapplications.Allthreeoftheseprotocolsspecifya5Vdifferentialelectricalbusasthephysicalinterface.TherestofthelayersoftheISO/OSIprotocolstackarelefttobeimplementedbythesystemsoftwaredeveloper.HigherLayerProt