Design of Power meter reading circuit based on CC2430 and RS485 bus.docx

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?

?

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