基于CAN的最大总线长度和节点数求解方法

Apr.2007,Volume4,No.4(SerialNo.29)JournalofCommunicationandComputer,ISSN1548-7709,USA5CAN1a2a1b2b1.a.b.4300702.a.b.43007482C250CANCANCANCANCAN【】1976E-mail:[e-mail].1946197219461.11CANControllerAreaNetwork[1]PCA82C2502(1)PCA82C250ISODIS11898(2)1Mbps(3)(4)SlopeControlRFI(5)(6)(7)(8)(9)1102PCA82C250DGPSCAN62.CANCANDominationRecessive010103VCAN-HVCAN-LCAN[2]VCAN-HVCAN-LVdiff03CAN11CAN/kbps10005002501251005020105/m4013027053062013003300670010000CAN[3]11/2CANCAN[4](1)CAN(2)(3)3.4[5]Vdiff.outRw=ρ×LRdiff4diff.outdiffTdiffVV1n-12Rw(+)+1RR=(1)vVdiffVdiffVCAN-HVCAN-LtCAN7RWRTRdiffn0.5V0.4V0.9V1.0VVth[6]Vdiff.in.req=Vth+Ksm×(Vdiff.out-Vth)(2)Ksm01Vdiff.in.min=Vdiff.out.min2RW.max(1RT.min+nmax-1Rdiff.min)+1≥Vdiff.in.req(3)Rw.max=ρmax×Lmax(3)Lmax≤12×ρmax×(Vdiff.out.minVth.max+Ksm×(Vdiff.out.min-Vth.max)-1)×RT.min×Rdiff.minRdiff.min+RT.min×(nmax-1)(4)nmaxρmaxVdiff.out.min(1.5V)Vth.max(1V)Rdiff.min(20kΩ)RT.min(118Ω)(4)[7]Ksm0.2RW15ΩVdiff.out2VVth0.9VRdiff50kΩRT120ΩKsm0.2RW45Ω2[8]CANRL.minCANPCA82C250RL.min45ΩRW0nmax≤1+Rdiff.min×(1RL.max2RT.min)(5)PCA82C250Rdiff.min20kΩRT118ΩRL45Ω106RT120ΩRL45Ω112[9]2/mKsm=0.2/mKsm=0.2N=32N=64N=100N=32N=64N=100DeviceNetTM200170150230200170DeviceNetTM8006906009408107000.5mm2AWG203603102704203603200.75mm2AWG1855047041064055048059.5m18mCAN4.CANCAN8[1].[M].:,1996.[2].[M].:,1993.[3],.——[N].,1998.[4],,.CAN[M].:,2003.[5]TANGAdrian,ScogginsSophia.[M]..:,1994.[6]M.Serfert.Developinganddistributingnetworkbasedengineeringsolutions.AdvancesinEngineeringSoftware.2000,31:453-465.[7]Communicationatfieldlevelprofibus.SectionB-FESTODIDACTIC,1997.[8]DouglesE.Comer,ComputerNetworksandInternets.PrenticeHall,2000.[9].[M].:,2002.MethodofsolvingthemaximalbuslengthandnumberofnodesbasedonCANRAOZhi-qiang,YANGuo-ping,RUANYou-lin,YENian-yuAbstract:Thispaperselects82C250astheinterfacebetweentheCAN-buscontrollerandphysicallayer,providesdifferentialtransmissionandreceptionthroughCAN-buscontroller,andestablishesnetworkdistributionequivalentcircuitbasedonCAN-bus,andthelargestlengthofbusandthenumberofnodescanbededuced.Thus,itprovidesatheoreticalbasisforvesselmonitoringsystem.Itcanaccuratelyestimatethelengthandthemaximumnumberofnodes,andrapidlydetectandexcludeoperationalfailures,andimprovethesafetyandreliabilityofthesystem.Keywords:CAN-bus;vesselmonitoringsystem;thelengthofbus;thenumberofnodesSusan,Candy