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KNXSYSTEMPRINCIPLESSmarthomeandbuildingsolutions.
Global.
Secure.
Connected.
KNX.
ORGKNXSystemPrinciples|3CONTENTIntroduction4Conventionalsystem5Switchtypes5Buildingfunctions6Conclusions7Whatisthealternative7Bussystem8Components8Working8Tool9Bussystemadvantages12Flexibility12Powerseparatedfromoperation12Optimizedcabling12Individualdevicescanhavemultiplefunctions13KNXspecificadvantages14Productcertification14Savingenergy14Makingcombinations14Decentralizedbussystem154|KNXSystemPrinciplesDuringthelast50years,scienceandtechnologyhavedevelopedinaswiftmanner.
E.
g.
phones,withhighercapacitiesthanthecomputersusedforthelandingonthemoon,arenowconsideredasrathercommon.
Thistechnologicalevolutionalsopropagatedintotheelectricalinstallationsofhousesandbuildings,dealingwithallsortsofapplications,suchaslighting,shuttercontrol,HVAC,aswellassecurityandenergymanagement.
Whilstconventionalswitchingisstillcommonlyusedfortheresidentialsector,therequirementsandhencethecomplexityofthoseconventionalinstallationsescalaterapidly.
Suchfurtherextensionsrequireadditionaldevices,likerelaysandtimersandmostofalladditionalwiring.
Needlesstosaythatcommercialbuildings,suchashotelsandofficesfaceevenhigherrequirementsandcomplexity,inordertoaccommodatetheneedsforeachuser.
Theanswer,inordertorealisealltheseautomatedfunctionswithoutlosingvaluabletimeandinvestinadditionalwiring,isbuildingcontrolwithKNX–TheworldwideSTANDARDforhomeandbuildingcontrol.
BuildingcontrolwithKNXfounditswayintoeveryone'slifeintheyear1990,atwhichactuatorsandsensors,eachprovidedwithamicrochip,areconnectedviaabuscable.
Thesuccessofthisnewtechnologywasdeterminedbythepossibilitytocontroleverything,whichrunsonelectricityinabuildingaswellasitsflexibleandeasyconfiguration.
Reprogramminginsteadofconventionalre-wiringopenedanewdimensionofmanagingelectricalinstallationsofhousesandbuildings,whichallowstoadd,adjust,modify,change,repair,anyroomfunctionwith–inamannerofspeaking–justafewmouseclicks.
EvenintimesofSmartGrids,whereoptimizingtheuseofrenewableenergyhasakeyrole,conven-tionalinstallationsplayandwillalwaysplayanimportantroleforhousesandbuildings.
Thispublica-tionwillbringyouclosertohowKNXincombinationwiththisconventionaltechnology,allowseveryownertomakeaninvestmentinsustainabilityandthefuture.
Withoutanydoubt,thispublicationwillopenyoureyestothefantasticworldofbuildingautoma-tionwithKNXandwillspecificallyteachyouabouttheflexibilityofbuildingautomationwithKNX.
INTRODUCTIONKNXSystemPrinciples|5SwitchtypesLet'shavealookfirstatthethreedifferentconventionalswitchtypesinordertoexplaintheworkingofconventionalsystems.
CONVENTIONALSYSTEMInordertoexplaintheKNXsystemprinciplesweshouldgowaybackintime:beforethe80's.
Backthen,mostelectricalinstallationsinhousesmainlycontrolledlighting,insomelargerbuildingalsoblindswerecontrolledwithconventionalelectricaltechnology.
SimpleswitchSimpleswitcheshave:twojunctions:'a'and'b'twopositions:··closed:junction'a'isconnectedwithjunction'b'··open:junction'a'isnotconnectedwithjunction'b'aabbToggleswitchToggleswitcheshave:threejunctions:'a','b'and'c'twopositions:··left:junction'a'isconnectedwithjunction'b'··right:junction'a'isconnectedwithjunction'c'abcacbCrossswitchCrossswitcheshave:fourjunctions:'a','b','c'and'd'twopositions:··parallel:junction'a'isconnectedwithjunction'c'andjunction'b'withjunction'd'(leftFigure)··crossed:junction'a'isconnectedwithjunction'd'andjunction'b'withjunction'c'(rightFigure)bdcaacdb6|KNXSystemPrinciplesDoubleswitchfunctionT1T2LE1NT1T2E1LeftRightOffLeftLeftOnRightRightOnRightLeftOffSupposethattwoindependentoperatingpointsarerequiredforlampE1.
Addingasecondsimpleswitchwillnothelphere,becausetheycannotbeoperatedindependently:theybothneedtobeclosedinordertoswitchonthelamp(inanyothercombinationthelampwouldbeswitchedoff).
Thesolutionistousetwoconventionaltoggleswitches.
TheFigureillustratestheworkingofadoubleswitchfunction.
Thesymbols'L'and'N'representtheconventionalmainswires,'T1'and'T2'representtwoconventionaltoggleswitchesand'E1'anelectricalconsumer,inthiscasealamp.
TheTableexplainsthecorrelationbetweentheswitchpositionsandthestatusofthelamp:··IFbothT1andT2areputinthesameposition(eitherboth'left'orboth'right')THENtheelectricalcircuitisclosed,anelectricalcurrentwillflowandhencethelampwillbelit··puttingT1orT2inoppositepositionswillinterrupttheelectricalcurrentandthelampwillnolongerbelitSingleswitchfunctionS1E1LS1E1OpenOffClosedOnThemostbasicfunctiontypeofaconventionalelectricalsystemisthesingleswitchfunction;thisfunctiontypecanswitchanelectricalconsumerfromoneoperatingpointandisbasedonaconventionalsimpleswitch.
TheFigureillustratestheworkingofasingleswitchfunction.
Thesymbols'L'and'N'representtheconventionalmainswires,'S1'representsaconventionalsimpleswitchand'E1'theelectricalconsumer,inthiscasealamp.
TheTableexplainsthecorrelationbetweentheswitchpositionandthestatusofthelamp:··IFS1isclosedTHENtheelectricalcircuitisclosed,anelectricalcurrentwillflowandhencethelampwillbelit··openingS1againwillinterrupttheelectricalcurrentandthelampwillnolongerbelitBuildingfunctionsTheactualconventional(building)functionsarebasedonconven-tionalswitches.
Thisclausegivesanoverviewofsuchconventionalfunctions,frommostbasictillmostcomplex.
KNXSystemPrinciples|7MultipleswitchfunctionLT1C1.
.
.
CnT2NE1C1.
.
.
CncadbcadbSupposethatxindependentoperatingpointsarerequiredforlampE1.
Thesolutionistoaddx-2crossswitchesbetweentwotoggleswitches.
E.
g.
ifx=7,then5crossswitchesneedtobeinstalledbetweentwotoggleswitches(andthelampitselfofcourse).
TheFigureillustratestheworkingofamultipleswitchfunction.
Thesymbols'L'and'N'representtheconventionalmainswires,'T1'and'T2'representtwoconventionaltoggleswitches,'C1.
.
.
Cn'representsnconventionalcrossswitchesand'E1'anelectricalconsumer,inthiscasealamp.
Atableexplainingthecorrelationbetweentheswitchpositionsandthestatusofthelampcan,dependingonthenumbercrossswitchesinstalledbetweenthetwotoggleswitches,becomequitebig.
Suchtablecanhoweverbesummarizedasfollows–thelampwillbelit:··IFbothT1andT2areputinthesameposition(eitherbothleftorbothright)ANDgivenanevennumberofcrossswitchesincrossedposition··IFT1andT2areputinoppositepositionsANDgivenanoddnumberofcrossswitchesincrossedpositionAnychangewillswitchoffthelampagain.
TheTableexplainsthecorrelationbetweentheswitchpositionsandthestatusofthelampforamultipleswitchfunctionwhereonlyonecrossedswitchC1isused(3independentoperatingpoints)andisagoodillustrationforthecomplexityofmultipleswitchfunctions.
T1C1T2E1LeftIILeftOnLeftIIRightOffLeftXLeftOffLeftXRightOnRightIILeftOffRightIIRightOnRightXLeftOnRightXRightOffConclusionsAfirstconclusionisthatthefunctionalitywithinaconventionalsystemishardwired,i.
e.
thecombinationoftheinstalledswitchtypesandespeciallyhowtheseswitchesarewiredtogether,definesthefunctionalityofanelectricalinstallation.
Aconsequenceofthisconceptisthateventhenumberofwirespercontrolpointneedstobeplanned,i.
e.
toggleswitchesrequirethreewiresandcrossswitchesrequirefourwires.
Theaboveisaboutthedirectconclusions,butespeciallyforlargerbuildingstheindirectconclusionsareactuallyevenmoreimportant,theirconventionalelectricalsystems:··Haveacomplex,cumbersome,timeconsumingandthusexpensivecabling.
··Haveanunfavorablefunctionality/cableratio,i.
e.
theyrelativelyrequirelargecablequantitiesforlittlefunctionality(lighting).
··Arenotflexible,addinge.
g.
oneextraoperatingpoint(switch)isverycumbersome.
··Havenoseparationbetweenpowerandoperation,i.
e.
conventionalswitchescontrolelectricalconsumersdirectly.
8|KNXSystemPrinciplesWhatisthealternativeThebestalternativeisabussystemThebestalternativeiscalledICT,whichistheabbreviationforInformationandCommunicationTechnology.
OrbettersaidthealternativetobemorepreciseisaconceptbasedonICT.
Thethreekeyaspectsofthisconceptare:··ToreplaceALLconventionalswitches(regardlessofthetype)bypushbuttonsbeingabletocommunicateortoconnectconventionalpushbuttons/switchestointerfacesbeingabletocommunicate.
··ToaddtoALLelectricalconsumers(regardlessofthetype)aninterfacebeingabletocommunicateortocontrolelectri-calconsumersindirectlybyswitchingdevicesbeingabletocommunicate.
··Tolinkalldevicesbeingabletocommunicateviaadedicatedextralowvoltagecable.
··Thisconceptiscalleda'BusSystem'andthecablelinkingthemicrocontrollersiscalledthe'BusCable'orshortthe'Bus'.
Bussystem=collectionofbusdevicesTheelectronicsforthecommunicationisequippedwithamicrocontrollerwhichhasononehandaninterfacetotheappli-ance,e.
g.
operatingelements,andontheotherhandtothebus,seeFigure1:··Thecomposedelectronicsimplementingtheinterfacetobuscalled'bustransceiver'.
··Thecomposedelectronicsimplementingtheappliancecalled'applicationmodule'.
··Adevicebeingconnectedtothebusandabletocommunicatewithotherdevicesiscalledabusdevice.
Conclusion–A(bus)deviceconsistsoutof:··Amicrocontroller(C)··Abustransceiver··AnapplicationmoduleThecombinationofmicrocontrollerandbustransceiveriscalledbusaccessunit(BAU).
Figure1.
busdeviceApplicationModuleBAUBusTransceiverKNXThisclauseexplainstheworkingofabussystemstepbystep.
EachsuchstepexplainsoneaspectofabussystemingeneralandatthesametimeaKNXsystemprinciplespecifically,whereapplicableatleast.
ComponentsDevicesAbussystemistobeseenasacollectionofbusdevices.
Asjustexplainedabove,aKNX(bus)deviceconsistsoutofamicro-controller,abustransceiverandanapplicationmodule.
KNXdevicescanbedividedintotwogroups:activedevicesandpassivedevices.
PassivedevicesdonothaveICTonboard,they'only'haveasupportingorindirectrole;i.
e.
theydonotcom-municatewithotherdevicesbutareabsolutelyrequiredinordertosetupbussystemsproperly.
Examplesofpassivedevicesarepowersupplies.
Pleasenote,thate.
g.
alsopowersuppliescouldbeextendedwithICT,butthisisnotverycommon.
Theothergroup,i.
e.
theactivedevicescanbedividedintothefollowingdevicecategories:InterfacestheirroleistoconnectaPCwithabussystemCouplerstheirroleistooptimizethecommunicationefficiencyofbussystemsSensorstheycontributeinformationtobussystems,e.
g.
'requestedlivingroomtemperature=22.
5°C'Actuatorstheylink(conventional)electricalconsumerswithbussystems,e.
g.
lampconnectedtoalightingactuatoroutputAboutsensorsandactuatorsApplicationmodulesofsensorstypicallyconvertanaloguesignalsoruseractions,like:··temperature··pushbuttonrockeroperations··raindetection··windspeed··touchscreenmanipulations··etc.
Applicationmodulesofactuatorsaretypicallyconnectedwith:··anelectricalconsumer(e.
g.
alightballastviarelays)··HVACsystemsviavalves··etc.
Applicationmodulesareelectronicallyconnectedtomicrocontrollers.
BUSSYSTEMKNXSystemPrinciples|9HowtoconvertaconventionalsystemintoabussystemInthisexample,seeFigure2:aconventionaltripleswitchfunctionisreplacedbythreesensorsandoneactuator:··Eachswitchisreplacedbyapushbutton+busaccessunit.
Allbyallthesearethreeindividualdevicesthatbelongtothesamenetwork.
··Theelectricalconsumerisreplacedbyarelay+busaccessunit(+theactuallampofcourse).
Thisisagainanextraindi-vidualdevicethatalsobelongstothesamenetwork.
Figure2.
ConvertingaconventionalsystemintoabussystemBusCableNE1LS1LS3E1NS2BAU'E1'BAU'E1'BAU'E1'BAUFigure3.
DividedfunctionalityofabussystemBusCableNE1LBAU'E1'BAU'E1'BAU'E1'BAUSensorsActuatorWorkingDividedfunctionalityFigure3illustratesthedividedfunctionalityaspectofbussystems:Thethreesensorsarelocatedonthelefthandside.
Eachofthesesensorsconvertsrockermanipulationsintoelectronicpulses.
EachsuchelectronicpulserepresentsanE1useropera-tion.
TheactuatorislocatedontherighthandsideandcontrolstherelayconnectedtoE1.
ExchangingmessagesinordertolinkdevicesThewaysensorsandactuatorscommunicateinbussystemsisbyexchangingmessages.
Example,seetheaboveFigure3:dividedfunctionalityofabussystem,supposethattheusermanipulatesoneofthesensorrockers,thiswillinduceanelectronicpulsewhichwillbepro-cessedbythemicrocontroller.
Theresultisthatthesensorwillbroadcastamessageonthebus,hereinthiscasethemessageis:'someonewantstooperateE1'.
InKNXsuchmessageiscalledatelegram.
AKNXsensorwillintheabovecasesendoutatelegramwithamongstothersthefollowingdata:··The'FunctionID':heretheFunctionID=E1··The'FunctionValue':hereFunctionValue=0(switchoff)orFunctionValue=1(switchon)Allothersensorsandactuatorsofthebuswillreceivethistel-egramandprocessit:··Sensorswillsimplyignorethistelegram··ONLYtheactuatorswiththeSAMEFunctionID=E1willreactaccordingly:i.
e.
switchon/offE1Conclusion:inKNX,sensorsandactuatorsareconnectedtogetherbyexchangingtelegrams,orinotherwords:··Inconventionalsystemsoperatingelementsandelectricalconsumersaredirectlyandphysicallylinkedviawires··Inbussystemsoperatingelementsandelectricalconsumersareindirectlyandvirtuallylinkedviamessagesexchangedbetweenmicrocontrollers10|KNXSystemPrinciplesToolBussystems=easymodificationsMakingmodificationstoabussystemgenerallycanbesplitintotwoseparatetasks:··Physicallyaddingand/orremovingand/orreplacingdevices··ModifyingdevicefunctionalityThefirstparthasalreadybeenaddressedbefore,i.
e.
makingmodificationstotheelectricalpartofabussystemiseasyandmoreoversafebecauseoftheextralowvoltagewires.
Alsoforactuatorsthisisthecase;theyaretypicallyinstalledinacabi-net,i.
e.
safeandwellhiddenfromanyuseroftheinstallation.
Pleasealsonotethatpossiblemodificationstothebuildingstructure(i.
e.
demolitionwork)areinmostcasesonlyrequiredforsensorsandthusforextralowvoltagecabling,becauseactuatorsusuallyareinstalledincabinets.
EquipmentrequiredinordertomodifybussystemsSeeFigure4,theequipmentrequiredinordertomodifybussystemsis:··APCwithasoftwaretoolonboard··AninterfaceconnectingthebustoaPCThesoftwaretoolforKNXiscalledETS,whichistheabbrevia-tionforEngineeringToolSoftware.
Devicefunctionalityisstoredintothememoryofeachdeviceindividually.
Inordertochangethefunctionalityofadevice,itsmemoryimageneedstobemodified,andexactlythisistheroleofETS:changingdevicememory.
Conclusion:modifyingaKNXinstallationmeansreprogrammingwithETS.
Modifyingaconventionalsystemmeansrewiring,whichagainisaverycumbersometask.
Figure4.
Required=Interface+Computer+SoftwaretoolBusCableBAUBAUBAUBAUBAUFigure5.
WorkingwithETSisconvenientBusCableBAU'E1'BAU'E2'BAUBAUE1BAUE2WorkingwithETSisconvenientSeeFigure5,typicalETStasksare:Finetuningfunctionality:e.
g.
setupastairwayfunctionfortheE2actuator.
Suchstair-wayfunctionwillswithE2automaticallyoffafterawhile,thisisconvenientforresidentsofthebuildinganditsavesenergyatthesametime.
Modifyingfunctionality:e.
g.
makesurethataspecificsensor(operatingpoint)nolongerservesE1butE2instead.
Addingfunctionality:e.
g.
anactuatoralreadyservingE1shallalsoserveE2(giventhereisatleaststilloneoutputchannelavailable).
Extendingexistingfunctionality:e.
g.
addanextrasensor(operatingpoint)forE2.
AvirtuallinkinKNX=GroupAddressThefollowingscreenshotsillustratethetrueconvenienceofworkingwithETS.
Butfirstthis:··Remember:inbussystemssensorsandactuatorsarevirtuallylinkedbyexchangingmessages.
··InKNXsuchmessageiscalledaTelegram.
··Eachvirtuallinkcanbedefinedasafunctionidentifierrepresentingoneelectricalconsumeroftheinstallation,likee.
g.
'E1'.
··InKNXsuchvirtuallinkiscalledaGroupAddress.
KNXSystemPrinciples|11AddmoresensorsforE1Thesensorsaddedarethedevices'1.
1.
11'till'1.
1.
19'.
AddmoreactuatorsforE1Thesensorsaddedarethedevices'1.
1.
101'till'1.
1.
103'.
Andagain:imaginedoingthesamewithaconventionalsystem,thisreflectionmakesitreallyeasytounderstandtheenormouspotentialofKNXinstallations.
Initialsituation,onesensorandoneactuatorinE1'E1'isthenameoftheGroupAddress=0/0/1,thisGroupAddressrepresentsalldevicesthatareinvolvedinthisfunction.
IntheinitialsituationonlytwodevicesarepresentinthebuildingfunctionE1:··Onesensor,beingdevice'1.
1.
10'··Oneactuator,beingdevice'1.
1.
100'12|KNXSystemPrinciplesFlexibilityTheflexibilityaspectisindeedthemostimportantadvantageofthebusconcept.
Acomparisonwithaconventionalmultipleswitchfunctionhelpsunderstandingthis.
SeeFigure6–e.
g.
n=2.
SupposethatoneextraoperatingpointforE1needstobeadded,i.
e.
oneextracrossedswitch(C3).
Assuchthismightlooklikeasimpletaskbutinpracticeitreallyisnot:rememberthatconventionalsystemshavehard-wiredfunctionality:itisabsolutelynecessarytofindoutwhichwiregoeswhereexactly,i.
e.
fourlowvoltagewiresintotalneedtobeconnected.
Withabussystem,thesametaskismucheasier:justconnectanothersensorandmakesureitislinkedtothesameFunctionID,seeFigure3:dividedfunctionalityofabussystem.
Theonlyrequirementinordertoaddasensor(oranybusdeviceforthatmatter)istomakesurethatitisproperlycon-nectedtothebus,incaseofKNXTP:justtwoextralowvoltagewiresneedtobeconnected.
Nowimaginethatthesametaskneedstobedoneforfive,tenorevenmoreoperatingpointsforE1.
Withaconventionalsystemthiswilltakehoursormaybeevendays,thetimespentonthesametaskforabussystemissimplynotcomparableanymore,nottosayneglectable.
Pleasenotethatsuchactionwithaconventionalsystemisnotaverycom-monpractise,itisonlytoexplainaprinciple.
Bottomline:withbussystemsitisfarmoreeasierto:··firstofallcreatecomplexfunctions··tomodifyand/ortoextendthem.
PowerseparatedfromoperationThisisadirectconsequenceofthedividedfunctionalityaspect:··Sensorsareconnectedtothebusviaextralowvoltage(i.
e.
KNXTP=~29V)wires,theapplicationmodules(e.
g.
rocker)areconnectedtosensorsviaevenlowervoltages(3.
3Vor5V).
··Actuatorsarealsoconnectedtothebusviaextralowvoltagewires,theapplicationmodules(e.
g.
relay)operateinmostcaseslowvoltageconsumers.
Butactuatorsaretypicallyin-stalledinseparatecabinets,i.
e.
safeandwellhiddenfromanyuseroftheinstallation.
Assuchthismightnotlooklikearealadvantagebecauseitdoesnotreallychangethefunctionality,therealadvantageisthesafetyaspect:ifanythingwouldgowrongtheninworstcasetheuserisonlyexposedtoextralowvoltages,whichinnowaycancauseanyharmtohumanbeings.
BUSSYSTEMADVANTAGESOptimizedcablingCheapercablingThisisadirectconsequenceoftheflexibilityaspect.
Comparedwithconventionalsystem,thefollowingtaskscanbedoneinnotime:··Addingdevices··Removingdevices··ReplacingdevicesConclusion:easycabling=fastercabling.
Moreover:extralowvoltagewiresarethinnerandarethereforeeasiertohandleandinstall.
Higherfunctionality/cableratioThequestionhereis:howmuchcableandhencecopperisrequiredtosetupthecomposedfunctionalityofanentireelectricalinstallationSettingupe.
g.
aswitchfunctionwith20controllingpointsinaconventionalsystemtakestremendouslymorecableandhencemorecopperthanforthesamefunc-tionrealizedwithabussystem.
Thiscomparisonbecomesevenmoreimpressivewhenlookingattheentireinstallation,andcertainlyforbiggerinstallations,likee.
g.
anofficebuildingwithxfloors.
Moreover,untilnowonlyoneapplicationtype,namelylighting,hasbeenaddressed:whenalsootherapplica-tiontypes,likeblinds,HVAC,security,whitegoods,etc.
needtobeconsideredthenacomparisonbetweenbussystemsandconventionalsystemssimplyisnolongerapplicable:settingadditionalapplicationtypes(likeblinds)basedonconventionalsystemmakesthejobonlymorecomplicated,alsoitwillagainonlytakemorecable.
Assuchthismightactuallyevenbethemostimportantargumentforbussystems:inordertoaddotherbuildingfunctionsand/orbuildingfunctiontypesnoparallelcablingisrequired,simpleuseand/orextendthebuscablethatisalreadyinuse.
LT1C1.
.
.
CnT2NE1C1.
.
.
CncadbcadbFigure6.
MultipleswitchKNXSystemPrinciples|13IndividualdevicescanhavemultiplefunctionsTwoseparateactuatorsforE1andE2Actuators:servemorethanoneelectricalconsumer··OnesensorsendstelegramsforE1onthebus··AnothersensordoesthesameforE2··OneactuatorservesE1··AnotheractuatorservesE2BusCableBAU'E1'BAU'E2'BAUBAUE1BAUE2BusCableBAU'E2''E4'BAUBAUE1E2BAUE3ME4MSensorservingbothE1andE4Sensors:combinefunctionsandfunctiontypes··E1andE2representtwolightpoints··E3andE4representtwoelectricalmotors(e.
g.
E3=blinds,E4=garagegate)··ThesensoronthelefthandsidecansendtelegramsbothforE1andE4··OneactuatorservesbothE1andE2··AnotheractuatorservesbothE3andE4Notonlydoesthisexampleillustratethatsensorscancombinefunctions,italsopointsoutthatsensorscancombinefunctiontypes,hereinthiscase:··Onerockerservingalamp··Anotherrockerservinge.
g.
blinds(electricalmotor)Moreover,alsoactuatorscancombinefunctiontypes.
BusCableBAU'E1'BAU'E2'BAUBAUE1E2OneactuatorservingbothE1andE2InthisFigurethesituationisabitdifferent:nowthereisonlyoneactuatorservingbothE1andE2.
Theadvantagesare:··lessbuscable(certainlyforinstallationwiththousandsofbuildingfunctions/busdevices)··reducednumberofdevices14|KNXSystemPrinciplesKNXSPECIFICADVANTAGESProductcertificationKNXmemberscanonlybringKNXproductsonthemarketviatheKNXproductcertificationprocedure,whichmeansthattheuseoftheKNXlogoforadeviceisonlygrantedafterasucces-fulcertificationprocedure.
TheKNXlogoprintedoneachKNXdeviceassuresusofatleastfouraspects:QualityOneoftheprerequisitesinordertoapplyforproductcertifica-tion;isfortheKNXmembertobeISO9001compliant.
ThismeansthattheKNXmemberneedstohaveaqualitycontrolsysteminstalledwhitinitsorganisation.
SuchqualitycontrolsystemwillobviouslyhaveapositiveinfluenceonthequalityandreliabilityoftheKNXproductsmanufacturedbythatKNXmember.
RuntimecompatibilityOnepartofthecertifictiontestsistoassurethecompatibilityoftheproductundertest.
Theresultismanufacturerindepend-ency:devicesandapplicationsofdifferentmanufacturerscanbecombinedinaninstallationinanywayandwillwherevermeaningfulbeabletocommunicateandunderstandeachother.
ConfigurationcompatibilityAnotherpartofthecertificationtestsistoassuretheconfigura-tioncompatibilityoftheproduct.
Theresultisthatonlytoolisrequired:i.
e.
anyKNXdevicefromanymanufacturercanbeconfiguredwiththeKNXEngineeringToolSoftware,alsoknownas'ETS'.
BackwardscompatibilityKNXisandalwayswillbebackwardscompatible:thismeansthate.
g.
20yearoldinstallationscanstillbeextended/equippedwithKNXdevicesbroughttothemarkettoday.
Italsomeansthattoday'sinstallationscanbeextendedwithanyKNXdevicebroughtonthemarketinthefuture.
SavingenergyBuildingeventsSincetheverybeginningofKNXitispossibletoadaptbuildingloadsautomaticallybasedoneventsoccuringinsidethebuild-ingitself.
Example1–windowcontacts:i.
e.
thebussystemofabuildingcan'know'whetherawindowisopenorclosed.
Nowimagineanofficebuildingwheretheheatingissettocomfortmode,ifatthesametimesomeoneopensawindowinoneoftheroomsofthatbuilding,thenitsinstallationcandetectthisconflictandsettheheatingtoe.
g.
economymodeintheroomorinthezonewheretheopenwindowwasdetected.
Example2–presencedetection:thebussystemofabuildingcan'know'whethersomeoneispresentinaroom,thiswillmakeitpossibletoonlyilluminatethoseroomswherealsosomeoneisreallypresent.
SmartgridsKNXcontributestotheSmartGridconcept:inthenearfuturetheconnectionbetweentheelectricalinstallationofabuildingandtheenergyproviderwillbeextendedwithICT,i.
e.
therewillbeaninformationflowintwodirections:theinformationexchangefromtheprovidertothebuilding,isaboutthetariffoftheenergysuppliedvalidforthatverytimeinterval.
Theexchangedinformationintheotherdirection,isabouttheac-tualenergyconsumptionofthebuildingduringthatverytimeinterval.
Thisconceptwillmakeitpossibletoadaptbuildingloadsauto-maticallybasedontariff.
E.
g.
switchoffloadswithlowerprioritywhentheenergy,tariffreachesaparticularpricelevel.
Thisdoesassuchnotnecessiralydirectlyreduceourconsumptionofenergy,butitwillatleaststimulateuse.
g.
topostponethecon-sumptionofenergyforlowerpriorityloadstill(more)renewalenergyisavailable.
Result:reducedenergycosts.
KNXSystemPrinciples|15MakingcombinationsBuildingapplicationtypesWithKNXitispossibletocombinewithinoneinstallationalltypesofbuildingfunctions,like:lighting,shutters/blinds,HVAC,metering,energymanagement,audio/video,whitegoods,ac-cesscontrol,fire/smokedetection,physicalsensors(e.
g.
water)etc.
CommunicationmediaFirstofall,KNXsupportsfourdifferentcommunicationmedia,theyallserveaspecificpurposeorusecase:TP|TwistedPairIsthemostcommonusedsolution,becauseofitssimplicityinordertosetitup(freetopology,nonetworkterminatorsrequired,…).
PL|PowerlineWhichallowsKNXdevicestocommunicateover230Vmainswires.
Thisisoftenthepreferredsolutionforrenovations.
IPTypicallyusedasafastandreliablebackbonebetweenseveralTPbasedsegmentsofaKNXinstallation,thiscertainlycanbeveryimportantforbiggerinstallations.
RF|RadioFrequencyAllowsKNXdevicestocommunicateoverradiosignals,wherenocable(TP,IPorPL)isavailableorcannotbeinstalled.
Second:allfourcommunicationmediacanbecombinedwithinoneandthesameKNXinstallation.
Inordertolinktwodiffer-entcommunicationmedia,asocalled'KNXMediaCoupler'isrequired:afewexamplesofpossiblecombinationsare(primarymedium/secondarymedium):TP/RF,TP/PL,IP/TP.
DecentralisedbussystemThismeansthattheentirefunctionalityoftheinstallationisdividedovertheindividualbusdevicesthatformtogethertheinstallation,orinotherwords:eachindividualbusdeviceis'only'informedaboutitsownspecificrolewithintheinstallation.
ThisconceptmakestheflexibilityaspectofKNXinstallationscomplete:changing,addingorremovingdeviceshasonlyaminorinfluenceonthecompositeinstallationfunctionality.
Centralisedbussystemshaveacentralunitthatcontrolstheentireinstallation.
Thedisadvantageisthecompletelackofflexiblity:aproblemwiththecentralunitwilleffecttheentireinstallation,inworstcasetheentireinstallationsimplystopsworking.
Orevenjustupdatingthecentralunitcouldinworstcasecompromisetheentireinstallation.
Yet,thoughKNXdoesnotrequireanycentralcomponent,centralfunctionsarepossible,likeoneormorecentralvisualisa-tions,schedulers,acentralclock,managementstationsetc.
AppendixThispublication'only'explainedtheKNXsystemprinciples.
Werecommendtoreadthe'KNXBasics'flyer,the'KNXHandbook'andtousetheKNXeCampusplatform,whichisaccessibleviayour'MyKNX'account,inordertounderstandwhathappensliveinaKNXinstallation,orinotherwordsincaseyouareinterestedinthebitsandthebytes.
Joinuswww.
knx.
orgSmarthomeandbuildingsolutions.
Global.
Secure.
Connected.
V10–19