第2章-Introduction-to-DDC

§2IntroductiontoDDCBuildingAutomationSystemLecturer:DouLiqianStructureofthecourse•2IntroductiontoDDC2.1WhatisDDC2.2ControlModeofDDC2.3hardwareandsoftwareofDDC2.4SystemArchitecturesofDDC2.5AdvantageofDDCIntroductiontoDDC2.1WhatisDDC1WhatisDDCDCSandDDCmicroprocessorbasedBASusingLAN2.1WhatisDDC1WhatisDDCDDC(DirectDigitalControl)直接数字控制Thecontrolloopconsistsofthreemaincomponents:asensor,acontrollerandacontrolleddevice.Thesethreecomponentsorfunctionsinteracttocontrolamedium.2.1WhatisDDC1WhatisDDCDDC(DirectDigitalControl)直接数字控制sensorsareusedtomeasuretemperature,pressure,relativehumidity,airflowstate.Othervariablesmayalsobemeasuredthatimpactthecontrollerlogic.Thecontrollerprocessesdatathatisinputfromthesensor,appliesthelogicofcontrolandcausesanoutputactiontobegenerated.Acontrolleddeviceisadevicethatrespondstothesignalfromthecontroller,orthecontrollogic,andchangetheconditionofthecontrolledmedium.Thesedevicesincludevalveoperators,damperoperators,electricrelays,fans,pumps,compressors.2.1WhatisDDC1WhatisDDCDirectDigitalControl(DDC)enteredtheHVACindustryinthelate1980’s.DDCutilizesaprogrammablemicroprocessor可编程微处理器astheprimarycontroller.TheHVACsystemvariable(temperature)ismeasuredbyelectronicsensors电子传感器.Thecontrolfunctionsareperformedbyamicroprocessorwhichtransmitsancontrolsignaldirectlytothecontrolleddevice(damperorvalveactuator).DDCisaformofclosed-loopcontrol.Theterm“Direct”meansthemicroprocessorisdirectlyinthecontrolloopandtheterm“Digital”meanscontrolisaccomplishedbythedigitalelectronicsofthemicroprocessor.2.1WhatisDDC1WhatisDDC所谓直接数字控制是以微处理器为基础，不直接借助模拟仪表而将系统中的传感器或变送器的输出信号直接输入至微型计算机中，经微机预先编制的程序运算处理后直接驱动执行器的控制方式，简称DDC。基本组成包括：微处理器（数字控制器）、传感器、执行机构、过程通道（模拟输入、模拟输出、数字输入、数字输出），通信接口（RS232、485、网络接口）、A/D、D/A转换器、人机接口。软件组成：系统软件、应用软件、管理软件、组态软件等2.1WhatisDDC1WhatisDDC2.1WhatisDDC2Digitalcontroller1Buildingautomationsystem(BAS)isprincipallyintegratedprocessor-basedsystems.2ABASoutstationisactuallyadigitalcontrollerthatislinkedintotheentireBASviaanetwork.3Thedigitalcontrollerisdesignedtobesuitablefordataacquisition,controlandcommunicationandotherfunctions.4Besidesthedigitalcontroller,thereareotherfourtypicaltypesofcontroller,includingmechanicalcontroller,pneumaticcontroller,electricalcontrollerandelectroniccontroller.2.1WhatisDDC2Digitalcontroller(1)Dataformusedincomputersdecimalform十进制hexadecimalform十六进制binaryform二进制amachineneedstorecognisetwostates:on/offorhigh/low.Thesebinarystatesareusuallydesignatedas0and1forrecordingpurposes.Differentvoltageisoftenusedtocodethesetwostates.Itisareliablewayfordigitalcomputerstohandleinformation,anditisparticularlysuitedtodigitalelectroniccircuitdesign.2.12.1WhatisDDC2DigitalcontrollerFigure2.1showsthe0and1codedasvoltagepulses.Inthecaseofa1,thelinevoltageinthecommunicationcableisraisedasrapidlyaspossiblefromzerotoacertainsteady-statevalueandremainsconstantatthatvalueforaspecifictime.A0isrepresentedbylackofsuchapulse(zerovolts).2.12.1WhatisDDC2Digitalcontrollerdecimalformhexadecimalformbinaryform2.1WhatisDDC2Digitalcontroller(2)MicroprocessorThemicroprocessororcentralprocessingunit(CPU)istheprincipalcomponentbothoftheconventionalmicrocomputerandtheBAScontrolstation.Itisamicro-electronicchipproducedbylarge-scaleintegratedcircuit(LSIC)manufacturingtechniquesonasmallchipofsilicon,anditisthe‘brains’ofamicrocomputer.MorerecentmicroprocessorsareVLSI(verylargescaleintegrated)chipsandarecorrespondinglymorepowerful.Theactualmicroprocessorchipisoftencontainedinapackagewithanumberofpins,likelegs,connectingthechiptothemotherboard.2.1WhatisDDC2Digitalcontroller研华BAS-3000系列以太网DDCComfortPoint系统VAV控制器2.1WhatisDDC2Digitalcontroller(2)MicroprocessorAsimplifiedschematicdiagramofamicroprocessorisshowninFigure2.2.Themicroprocessorhasseveralbasiccomponents:temporarymemoryorregisters,thearithmeticlogicunit(ALU).thecontrolunit寄存器+算术逻辑单元+控制单元2.1WhatisDDC2DigitalcontrollerThetemporarystoreisasmallmemory,composedofanumberofregisters,whichwillholdboththedataandtheimmediatelyrequiredprograminstructionsfortheALUandcontrolunittoworkonThearithmeticlogicunitistheoperationalunit.Itperformscalculations,suchasadditionandmultiplication,aswellaslogicaldecision-makingprocessessuchasselectingandcomparingdata.Thecontrolunitcontrolstheoperationsofthemicroprocessorandotherassociatedchips,suchasmemorychips.Thisunitcoordinatesallthefunctionsofamicrocomputer,andinterpretstheinstructionsinaprogramtoperformthecontrolfunctionsnecessarytorunthatprogram.2.1WhatisDDC2Digitalcontroller(2)Microprocessor2.1WhatisDDC2Digitalcontroller(2)ThemicrocomputerstructureandbusesFigure2.3illustratesthemainessentialcomponentsandtheinterconnectionsofthemicrocomputerandoutstation.Thecentralpartconsistsofthreecomponents:themicroprocessor(CPU),thememory,andinputandoutput(I/O)units.Alltheoperationsareperformedviathreebuses:databus,addressbusandcontrolbus(busisanabbreviationofbus).2.1WhatisDDC2DigitalcontrollerFigure2.4illustrateshowthemicroprocessorchipofacontrolstationisconnectedtothememoryunitandtheinputandoutputunits.allunitshavetheirownmicroelectronicchips.Co