Design of Power meter reading circuit based on CC2430 and RS485 bus.docx
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DesignofPowermeterreadingcircuitbasedonCC2430andRS485bus
DesignofPowermeterreadingcircuitbasedonCC2430andRS485bus
Abstract:
Thearticleanalyzecurrentsituationoftheelectricmeterreadingsystem,andgivencircuitoftheremoteautomaticmeterreadingbasedonsingle-chipsystemmodel,andintroducedindetailthekeypartofdataacquisition,dataconcentratorandthemonitoringcentersoftware,hardwareimplementation.ThewiringcomplexityoftheprojecthasbeenreducedbyusingthetechnologyofRS485communicationfordatatransmission,whichhasbeenimprovedthereliabilityofdatacommunicationsystem,andreducedpowerconsumption.Theresultsshowthattheterminalisnormalandreliable.
Keywords:
RS485;Remotemeterreading;microcontroller;dataacquisition;CC2430;
0Introductions
Withthedevelopmentofournationaleconomyandimprovementofpeople'slivinglevel,powermeterreadingmakethepowersupplyenterpriseworkloadincreasesgreatly,manualmeterreadingsystemwidelyadoptedindomestichasbecomeincreasinglydifficulttoadapttothecurrentsituation,atthesametime,residentsofelectricity(gas)servicequalityrequirementsinthecontinuousimprovement.Atpresentourcountrydomesticmeter(gasmeter)readingscanberoughlydividedintothreekinds.Oneisthetraditionalmanualmeterreading,readingtotheusertoreaddata,andthenthedataisinputtothecomputer.Twoisaprepaidmeterreadingpeople,nottotheuser,theuserthroughthebanktransferfeesortobuythecard,ICcardelectricitymanagementdepartment.Threeisthewayofremotemeterreading,monitoringcenterthroughremotecommunicationsystem(suchasthepublictelephonenetwork,datanetwork)automaticaccessmeterdataway.Extensiveuseoftheartificialmeterreadingway,partoftheareastartedremotemeterreadingpilot.Thetraditionalmanualmeterreadingcannotguaranteetheaccuracyofdataandreal-time,wastingalotofmanpowerandtime,andbringsinconveniencetotheusers.Inthissituation,theurgentneedofanewwayofreadingmetertomeetbusinessneeds.Withthedevelopmentofnetwork,informationandcontroltechnology,remotemeterreadingmodeisgraduallyacceptedbythepublic.Remotemeterreadingaccuratedatainrealtime,canprovideeffectivemanagementforpowersupplyenterprise,savingmanpower,avoidarrearsproblem,improvetheautomationlevelandmodernizationlevelpowermanagement,istheartificialmeterreadingwaytowardthedevelopmentofdigitalizationandautomationdirection. Themeterisanimportanttoolofmodernpowersystemmeasurement.TraditionalpowermanagementmanuallyCollectingandsettlementconsistencyispoor,anddifficulttomanagetheproblem.Meterdistributionpoint,awiderangeofcomplexenvironment,automaticmeterreadingsystemhasbeendifficultforpracticaluse;themajorreasonisthelackofpractical,reliable,inexpensivemeansofdatatransferandmeter-readingterminal[1].
Fortheabovereasons,thedesignaninstallationandeasymaintenance,long-termstableandreliable,notonlycancopyreadingtablewithdataandcanmonitortablewiththeoperationalstatusofremotemeterreadingdataterminals,hasbecometheindustry'sproblemstobesolved.Thispaper,anautomaticmeterreadingbasedonZigbeetechnology,remoteautomaticmeterreadingdataterminal,thecommunicationquality,reliable,economicalandpractical,theusercanaccuratelyandtimelyenergymeterdatacopiedfromtheuploadisanidealsolutionprograms.
1Overallframeworkforthedesignofaremoteelectricitymeterreadingsystem
Thesystemisrunning,firstofallbythepowermeter'sRS-485busdatainterfacetransfertothecollector.CollectorinspectiontablesofRS-485dataprocessingorcount,andstoretheresult.CollectionandcentralizedcommunicationusingZigbeewirelesscommunicationmodule,thecollectorisusuallyinthereceivingstate,whenreceivedconcentratoroperatinginstructions,inaccordancewiththeoperationoftheinstructioncontent,thisacquisitionthedatathroughawirelesscommunicationmodulesenttotheconcentrator.Theconcentratorcanbetimedorreal-timeacquisitionunderthejurisdictionoftheDataCollectingandstorage[2].Superiorequipment-thecomputerwhenthecalldataisstoreddatapackagesent.ThehandheldcomputercanreadeachmeterdataandstoredintheSDcard,thestaffwritesdatatotheSDcardandbacktothepowercompanies,powercompaniesthroughthecomputerreadthedataontheSDcardandcalculatetheelectricitybill.TheoverallframeworkofsystemisshowninFigure1.
2Thehardwaredesignofdatacollectionnode
2.1Thedataacquisitionhardwareblockdiagram
ItisasshowninFigure2,dataacquisitionmoduleuseSTC89C54microcontrollerfordataprocessingunitcompatiblewiththeZigbee/theIEEE802.15.4radiofrequency(RF)transceiverchipCC2430designdatatransmissionunitanddataacquisitionunitpatrolallelectricityRS_485bustechnologytable,andconnectLCD128*64andDS1302eachenergymeterenergyconsumptionvalues?
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andtheacquisitiontime[3].TheprogramofdatacollectionterminalgetsdatabytheRS_485bus,andcollectionterminalcommunicatewithdatacenterusingZigbeewirelesssensornetworktechnology,exchangedatabynetworkanddataconcentratortocontrolremoteequipment. 2.2ThecircuitdesignoftransceiverbasedCC2430chip
ThewirelessRFtransceiverchipisselectedbasedonthedesignoflowpowerZigBee/IEEE802.15.42.4GHzradiotransceiverchipCC2430.ShowninFigure3,theCPU4SPIbusinterface,aswellastheotherfourcontrollinesandtheCC2430tocommunicatewiththeCC2430onthecapacitorC10andR3fortheresetcircuit,C5andC6forthepowersupplydecouplingcapacitors,crystalsconstituteacrystaloscillatorcircuitXTALloadcapacitorC7andC8cantoensurethestabilityofthechipoperatesatlowvoltagecrystaloscillatorXTALloadcapacitorCr1andCr2andcrystaloscillatorcircuit[4],theclockfrequency.MicrocontrollerprogrammingcontrolregistersthroughtheSPIinterface,whilethecompletedataexchangewiththeCC2430.
2.3CircuitdesignofMAX485interface
Inordertoachievetheisolationofthebusandmicrocontroller,opticallyisolated,asynchronouscommunicationportofthemicrocontrollerandMAX485,showninFigure4,P30ofSTC89C54,P31,P32,opto-isolatorreceivinginputfromthecontrolsignalisolation[5].Intheoutputcircuitdesign,theR8,andthetransmissionlinematchingresistortoreducethereflectionofthetransmittedsignalonthelineattheendofthe485signaloutputoftheMAX485seriesoftwo20ΩresistorsR9,R10,inordertopreventtheinfluenceduetothefailureofthemachineotherextensionsinthebuscommunicationMAX485circuitAandBoutputsideplusapull-downresistorsR7,R11,andtheA-sidepotentialishigherthantheB-sidepotential,sothatRXDleveltheMAX485busisnotsentduringtheperiod(bussuspension)showedonlyhigh,soyoucanavoidalltransmittersareprohibitedonthebus,itisoftenmistakenlybelievethattheinitialcauseofthecommunicationframeisnotworkingproperly.CanbeachievedthroughtheabovedesignofmicrocontrollerstheMAX485busunderthejurisdictionofeachelectricitymeteringunit,dataacquisition,processing,storage,andcontrolpurposes.
Gridfaultdetectionsystemusingcurrentandvoltagefrominductivesensorscollecttheappropriatenetworktotransmitdata.Selfinductivesensorisanappropriatetestingnotonlytheoutputvalue,andbeabletocarryouttheirworkstatusofnewsensorsonlineassessment.Thisarticlewillbeakeypositionsensordatacollectioninthepowerdistributionnetworkforcollectingtherelevantrangeofcurrent,voltageandotherinformation.Distributioncanbecollectedfromthenetworktrafficdatatheinductivesensorinapowertransmissionpath,thatshowninFigure5. 3Thesoftwareimplementationoftheterminalnode
3.1transportprotocolfordataacquisitionunit
ThedesignofMAX485networkdataacquisitionpartisamulti-functionwatt-hourmetercommunicationprotocol(DL/T645-1997)asremotecontroloftheenergymetercommunicationprotocoltocommunicateacross.Thenetworklinkandtheliftingoftheinformationwillbecollectedterminalissuedframestocontrolthecommunicationbyteformat.Thetable1showsthetransmissiondirectionfromlowtohigh,astartbit,onestopbit,aparitybit,eightdatabits11.
Amongthem,theframestartcharacteris68H:
markedthebeginningofone.DomainaddressA0~A5:
addresslengthupto12decimalnumber,whenreceivedfromthecontrollertoadataaddressfieldshouldrespondtocommand,toobtaincontrolofthebus,thebuswhentheresponseshouldbetoreturncontroltothemaincontroller.CommandcodeC:
andperformtheappropriateaction.ThedatafieldlengthofL:
Listhenumberofbytesofdatafields,thereaddataisnotgreaterthan200,thewritedataisnotgreaterthan50.L=0indicatesthatnodatafield.ThedatafieldDATA:
senddataencryption33H,receivedatareduction33H.ThechecksumCS:
thateachbyteofbinaryarithmetic,andnotmorethan256oftheoverflowvalue.Terminator16H:
identifiestheendofinformation,itsvalueis16H.
Datacollectionterminalnodesandthenumberofwatt-hourmetertoforma485network,astheMAX485networkhost,accordingto(ofDL/T645-1997)communicationprotocol,itsoperationthebasicsendandreceiveflowchartshowninFigure6,Figure7,accordingtotheprocessshowntowriteprograms,youcanachievethenormalcommunicationtheMAX485networkmasterandslave,andcompletionofdatacollectiont