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PLC Building Automation and Control Systems

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Chad Weiss

The document describes a PLC program for controlling various subsystems in a building, including lighting, HVAC, access/security, communications, and fire safety/water/plumbing. It provides details on how a PLC could be programmed using ladder logic to control a lighting subsystem with 16 lights over 4 rooms. The PLC program includes a master switch input to enable or disable control of the lighting subsystem. It also allows individual manual control of each light and monitoring of their power status. Tables and figures illustrate the PLC I/O mapping and interface. Similar PLC programs are described for other subsystems.

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PLC Building Automation and Control Systems SSET 295 Internship Project Tags: Automation,BAS, BuildingAutomationSystems,Control, Control Panels,Critical Infrastructure,EnergyEfficiency,Fire Safety,LadderLogic,LightingSystems,PLCs,PLCLogix,Power Management,Programmable LogicControllers,SecuritySystems, Smart Buildings,Sustainability. Chad Ryan Weiss 6/17/2016
1 Abstract: Imagine abuildingthatcan respondto emergency situations. Eventslike Chernobyl,Fukushimaand Three-Mile Islandmaynothave beensocostlyif automatedprocessesandcontrol systemshadbeen properlyimplemented. Furthermore,imagine abuildingthatcanincrease itsoverall energyefficiency usingpredictive analyticswithautomation andcontrol systems;humancivilizationwouldbe takingone stepcloserto achievingsustainability thuspromotinglongevityforourplanetandall of itsinhabitants. Thisdocumentprovidesaside-by-sidecomparison of critical infrastructure bothlackingandcontaining automationandcontrol systems. Finally,thisreportconcludes byprovidingan implementation example of a PLC (programmable logiccontroller) forvarioussubsystems. Usingladderlogicwiththe PLCLogix software, the case studyseeks toaddressthe sustainability andemergencyresponseissues plaguing critical infrastructure whichlacks bothbuildingautomation andPLCcontrol systems.
2 Table of Contents I. Introduction 4 A. Smart Buildings 4 B. Critical Infrastructure 4 C. SubsystemOverview 4 1. Accessand Security 5 2. CommunicationSystems 5 3. ElevatorsandEscalators 5 4. Fire Safety 5 5. HVAC 6 6. Lighting 6 7. PowerandEnergy 6 8. ManufacturingEquipment 6 9. Water andPlumbing 6 II.Programmable LogicControllers 7 A. LightingSubsystem 7 B. HVACSubsystem 11 C. Accessand SecuritySubsystems 17 D. CommunicationsSubsystem 19 E. Water,PlumbingandFire SafetySubsystems 20 III.Conclusion 23 IV.References 25
3 List of Tables and Figures Table 1: LightingSubsystemI/OMapping Table 2: HVACSubsystemI/OMapping Table 3: AccessControl SubsystemI/OMapping Table 4: CommunicationSubsystemI/OMapping Table 5: Fire Safety,WaterandPlumbingI/OMapping Figure 1: PLCLogix I/Orack Figure 2: Initial Conditions –Master SwitchON Figure 3: Manual Override Illustration Figure 4: Fault DetectionIllustration Figure 5: Gas PoweredHeatingUnit Figure 6: CondensingCoolingUnit Figure 7: HVAC PLCI/O Interface - Initial Conditions Figure 8: HVAC PLCI/O Interface – Furnace ON Figure 9: HVAC PLCI/O Interface – CondensingUnitON Figure 10: Heaterand CoolerON Figure 11: HeatingInspection Figure 12: CoolingInspection Figure 13: HeatingandCoolingInspection Figure 14: ElectronicKeypadLock Figure 15: AccessControl Subsystem- Initial Conditions Figure 16: AccessControl Subsystem - Unlocked Figure 17: CommunicationSubsystemI/ORack - FSO Figure 18: CommunicationSubsystemI/ORack - RF Figure 19: Water DispensingNozzle Figure 20: IonizingFire Detector Figure 21: Fire SafetySubsystemI/Orack Figure 22: Fire SafetySimulation - Fire Detected
4 I. Introduction A. Smart Buildings Everysmart buildinghasacontrol room, especiallybuildingslike airports,hospitals,prisonsandpower plants. These control roomsallowoperatorstomonitorandmanage subsystems remotelyand sometimesautomatically. Subsystemslike energy,water, plumbing,HVAC,lighting,fire safety,access and security,elevators,communication,robotsandpower equipmentall requirespecialattention, because failure in anyone of these subsystemscouldspell disasterunderthe wrongsetof circumstances. Althougheachsubsystemhasvariable importance,failureisintolerable because somethingassimple as waterunexpectedly shuttingoff inabuildingcanhave consequencesranging fromminordiscomforttonuclearmeltdown. The importance of eachsubsystemisentirelydependent on the type of critical infrastructure that isbeingsupporting. B. Critical Infrastructure Critical infrastructurereferstothe infrastructure whoseassets,systemsandnetworks are consideredso importantto the UnitedStates thattheirdysfunction would bringforthdire consequences fornational economicsecurity aswell as national publicsafetyorhealth concerns[1]. Accordingtothe United StatesDepartmentof HomelandSecurity,there are 16 differentcritical infrastructuresincludingthe following: Nearlyall of the sectorslistedhere,aside fromtransportationsystems,relymostlyonbuildingsor superstructuresforshelter. Hence,the subsystems comprisingnearly100% of all critical infrastructures inthe UnitedStatesare subsystemsrelatedtocommercial andindustrial buildings. Formore oncritical infrastructures,referto[1]. C. SubsystemOverview Withoutthe implementationof automationandcontrol systemssome of the subsystemstalkedabout previously are prone tocatastrophicfailure. The followingsection providesinsighttohow each subsystemcanbe improvedbyimplementingautomationandcontrols. Furthermore,some sections provide acomparisonbetweensystemshavingautomationandcontrols tosystemslackingautomation and controls. Here isa listof the subsystems previousmentioned:  Dams  Defense industrial bases  Emergencyservicessector  Energysector  Informationtechnologysectors  Nuclearreactors,materialsandwaste  Transportationsystems sectors  Water andwastewatersystems  Financial servicessector  Foodand agriculture  Governmentfacilities sector  Healthcare andpublichealthsectors  Chemical sector  Commercial facilitiessector  Communicationssector  Critical manufacturingsector
5 1. Access and Security Since the year2013, there have beenover180 school shootings inthe UnitedStates;hence,accessand securityisa top concernwhenitcomesto establishingsubsystemswithincritical infrastructure. A good securitysystemhasbothactive andpassive sensorsusedforremote sensing. Furthermore,automated alarmingsystems aswell asphysical barriershelpcontribute tothe overall effectivenessof the security systeminplay. Whenhumansencounterdanger,ourfirstresponse isautomatic,i.e.eitherfightor flight. Witha properautomationandcontrol system, accessand securitysubsystemsinbuildings may be able to assistindeterringfuture school shootings,bankrobberies, terroristattacks orsimilaractsof crime and terror. 2. CommunicationSystems Aside fromaccessand security,abuilding’scommunication systemisatop subsystemconsideration because communicationishalf of whatmakes abuildingsmart,the otherhalf beingautomationand control. Integratingautomationandcontrol techniquesin communicationsystemswithinbuildings may allowformore robustinternal andexternal formsof communication. Forexample,manual orautomatic control of the methodsof communicationusedcouldincrease buildingenergyefficiencywhileenabling a widerrange of possibilitieswhenitcomestointernal orexternal buildingcommunications. Furthermore,implementingautomationandcontrolsin communicationsystems couldhelp technicians or buildingoccupantstroubleshootthe systemsduringtimesof unexpectedfailure. Thistopicis discussedinfurtherdetail inthe PLCsolutioncase study. See Ref [2] or the ZigBee Alliance/BACnet. 3. Elevators and Escalators Althoughthissubsystemhasnorelevance in singlestorybuildings,itisalmostalwaysreasonforconcern inbuildingsof twoormore stories. Hospitals,schools,banks,mallsandlibrariesall have elevators or escalators toaccommodate those who are handicappedorthose whohave beendisabledinsome way shape or form. Elevatorsor escalatorswithoutautomationorcontrol systemsare notonlydangerous but alsowasteful inregardstopower andenergy consumption. Inthe case that one or more floors withinabuildingare onfire,allowingthese systemstoremainoperational isnotonlystupidbutit could leadto unnecessary lossof life. Furthermore, leavingescalatorsoncontinuously isaproblemdue tothe fact that cost will goup, energyefficiency will godownand emergency responseorroutine maintenance will become negligible. 4. Fire Safety Anotherimportantsubsystem,thatwhichprotectsthe building’sinhabitants,isthe fire safetysystem. Withoutautomationandcontrol,response toanemergencysituationsuchasa fire wouldbe much slowerthanif there were sensorsandautomaticproceduresinvolved. Peoplewouldhave torunaround tryingto findthe fire extinguisherthenrunall the wayback to the fire,whichhasspreaduncontrollably by that point. Implementingautomationandcontrol featurestoalreadyexistingfire safetysystems couldnot onlyreactinstantlytofire;moreover,manual operationsof the fire safetysystemcomponents like the waterlinescouldpreventwastedwaterincasesof false alarm.
6 5. HVAC HVACor heating,ventilationandairconditioning systems constitute one of the mostimportant subsystemsabuildingcould have formanydifferenttypesof critical infrastructure. Chemical and nuclearfacilitiesuse themtoexhauststeamandtoxicchemicals; furthermore, heating, ventilation and coolingextendsnotonlytobuildingsbutalsotothe humanbodyand motorizedvehicles. The human bodyneedstoventall of the carbon dioxide thatbuildsupovertime otherwise hypercapnia,a.k.a.CO2 poisoningcouldhappen. Mostcritical infrastructure HVACsystemsplayahuge role inmaintaining essential processes. Forexample,HVACsystems keepdatawarehouseequipment cool enough to ensure thatprocessorsdon’toverheatwhichwouldcompromisefunctionality. Heating,ventilationand air conditioningwithoutautomation orcontrol wouldmake itimpossibletoholdcertaininternal buildingconditionssuchastemperature,pressure orhumidity. 6. Lighting Lightingwithoutautomationorcontrol systemsmake foraveryinefficientsystem. Implementingan automationsettingcouldreduce the amountof energyusedwhennoone isina roomthus reducing wastedenergy. Also,addingacontrol systemtolightingandloadsmayenable buildingoperatorsto detectunexpected burn-outs,shorts,open-circuitsorfaults. 7. Power and Energy Thissubsystemreferstothe powergenerationandpowerdistributionsubsystems. Powerandenergy, beingthe backbone of the entire superstructure,requiresimmense automationandcontrol techniques to ensure nothingcanthwarttheirabilitytoproduce andsupplypowertothe buildingandall of its critical features. Inthe case of a lightningstrike,hurricaneorsome othernatural disaster,power systemscouldbecome compromisedthuscompromisinganentire buildingorso. Eventslike the New York Blackouta couple of yearsago leftthousandsof people freezinginthe wintercoldweatherfor days. With properimplementationof automationandcontrol systems,troubleshootingmaynothave takenso longto fix thussavingmanyfromneedlesssuffering. 8. Manufacturing Equipment For industrial plantsormanufacturingfacilities,industrial powerequipmentcanbe verydemandingon energyandalsohazardousto the inhabitantsof thatbuilding. If automationandcontrol systemsare obsolete withinthesesystemsrobotscouldspinout of control or breakdown. Not toolongago, a robot tooka man’slife ata VolkswagenfacilityinGermany forunexplainedreasons. These typesof incidents can be reducedtoa minimumwithoutcompromisingproductivitybyaddingsimple automationand control featurestothe alreadyexistingsystems. Furthermore,one mightevenbe able tosave money by implementingautomationandcontrol techniques. 9. Water and Plumbing Water andplumbingmightseemtrivialbutthere are manythingsrelyingonthese subsystems. Hydraulics,HVACsystemsandhumansare some of the few persons,placesorthingsthatrelyon this
7 absolutelycritical subsystem,whichiswhyitisimportantto know all the detailsasto how flow is currentlybeingcontrolled. Furthermore,itisnecessarytoenactprecisionprocedural protocol executioninresponse toemergencysituations. Eventslike TMI,FukushimaandChernobyl couldhave possibly been avoidedif everysubsystem, includingwaterandplumbing,hadbeenworkingproperly. II. PLC Programs A. Lighting Subsystem A buildinghasfourroomswithfourlightsperroom. Table 1: Lighting Subsystem I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Master Switch R1L1_POWER MO_R1L1 R1L1_FAULT R1L2_POWER MO_R1L2 R1L2_FAULT R1L3_POWER MO_R1L3 R1L3_FAULT R1L4_POWER MO_R1L4 R1L4_FAULT R2L1_POWER MO_R2L1 R2L1_FAULT R2L2_POWER MO_R2L2 R2L2_FAULT R2L3_POWER MO_R2L3 R2L3_FAULT R2L4_POWER MO_R2L4 R2L4_FAULT R3L1_POWER MO_R3L1 R3L1_FAULT R3L2_POWER MO_R3L2 R3L2_FAULT R3L3_POWER MO_R3L3 R3L3_FAULT R3L4_POWER MO_R3L4 R3L4_FAULT R4L1_POWER MO_R4L1 R4L1_FAULT R4L2_POWER MO_R4L2 R4L2_FAULT R4L3_POWER MO_R4L3 R4L3_FAULT R4L4_POWER MO_R4L4 R4L4_FAULT Input Output Input Output Input1 isthe Master Switch;it has twoconditions: 𝑀𝑎𝑠𝑡𝑒𝑟 𝑆𝑤𝑖𝑡𝑐ℎ = { 1 𝐸𝑛𝑎𝑏𝑙𝑒 𝐶𝑜𝑛𝑡𝑟𝑜𝑙 𝑃𝑎𝑛𝑒𝑙 0 𝐾𝑖𝑙𝑙 𝑆𝑤𝑖𝑡𝑐ℎ The 1 signifiesthatthe Master Switchhasbeenturned“ON”whereasthe 0 representsthe Master Switchwhenitisturned“OFF”. Whenthe Master Switch has a bitvalue of 1, the program will execute rung zeroof the mainroutine thusjumpingtothe lightingsubroutine. Onthe contrary, whenthe Master Switchhas a bitvalue of 0, the programwill execute rungone;hence,disablingall system input/outputfunctionality. Furthermore,the systemcan be resetuponexecutionof the Kill-Switch operation. Thisisto make troubleshootingeasierandresponse toemergencysituationsfaster. UtilizingPLCLogix andthe I/Ointerface,the PLCcontrol panel supportsupto16 lights. Inthisscenario, a buildinghasfourroomsor floorswithfourlightsperfloor/room. The lightingsubsystemMaster
8 Switchhas the abilitytocut all powertothe building’slightingsubsystems. Furthermore,the PLC control panel wasdesignedtoallowuserstomanuallycontrol eachlightspecificallyaccordingtothe I/O mappingof the PLC program and control panel. See Table 1above. The I/O mappingseeninTable 1 correspondsto the PLCLogix I/Orack or interface. Fig.1 shownbelow presentsthe layoutof PLCLogix I/Orack. Figure 1: PLCLogix I/O Rack ReferringtoFig.1, the discrete I/Ointerface allows forsupervisedandunsupervisedcontrol of the building’slightingsubsystem. Slot1,input00 is reservedforthe MasterSwitch. The usercan enable or disable the control panel/buildinglightingsubsystembyopeningorclosingthe MasterSwitchcircuit. Initially,whenthe MasterSwitchisturnedON,the building’slightsall turnoninthe orderspecifiedby the PLC ladderlogic. Whenthe Master SwitchisOFF andhence,the control panel andbuildinglighting subsystemsare deactivated,users nolongerhave anycontrol overanypart of this particularsubsystem and control panel. Table 1 slot2, correspondingtoslot2 data entries fromthe discrete I/Ointerface showninFig.1 reads, R1L1_POWER. This standsfor roomone (R1) lightone (L1) powerindicator. The nextentryreads R1L2_POWER whichstandsfor room one (R1) lighttwo(L2) powerindicator,etc... Forthisscenario,the buildinghasfourroomswithfourlightsperroom. In otherscenarios,abuildingmayhave fourfloors withfouroverheadlightsperfloor. All canbe changedaccordingly,dependingonthe situation, from
9 withinthe PLCprogram. Fromthe PLCLogix discrete I/Ointerface,all of the dataentrieslocatedinslot2 are reserved forthe statusof each individual lightingfixture regardingpower. Inotherwords, this columnindicateswhetherthe lightisON orOFF. Thisisshownrather clearlyfromthe I/Orack. When an entrylightsup,thismeansthe lightisON,whenthe entryisnot litup,thismeansthe lightisOFF. Fig.2 showsthe I/Orack whenall lightsinthe buildingare turnedonrightafteractivatingthe Master Switch. See Fig.2 below. The Master Switchoccupyingslot1 data entry00 has the powertoenable ordisable the entire building’slightingsubsystemandcontrol panel. Sometimes however, itisnecessarytokeepall other lightsonwhile troubleshootingorrewiringanotherlight. Hence,slot3entries00 through15 are dedicated tomanual override switchesfor eachlightrespectively. Togglingtheseswitchesturnsthe lightsOFFand ON. See Fig.3 belowfor anillustration. Figure 3: Manual Override IllustrationFigure 2: Initial Conditions - Master Switch ON
10 The fourthand final columnof the I/Orack isusedas a faultdetectionindicator. These outputswillonly activate if the system,foranyreason,shouldfail undernormal operatingcircumstances. Inreal world situations,PLCcontrollerscontainI/Omodulesthatcansupportcountless variationsof digital and analogsensingequipmentthusallowingforsophisticatedfaultdetectiontechniques. However,forthe purposesof thisproject,asimulationwasmade toillustrate how the PLCprogramrespondsto detected faults. For the lightingsubsystem,thissimulationusesaseriesof timersandcountersandmultipliersto effectivelycreate afaultinthe system. Everyso often,the lightoccupyingdataentries 03,goesinto arrest andunexpectedlyshutsoff. Althoughthe source of errorisunknown,operatorsare able to detectthat thislighthas “effectivelyfailed”due tothe faultindicatoroutput statusinslot4 on the discrete I/Ointerface (i.e.slot4). See Fig.4 below foranillustrationof faultdetection. Figure 4: Fault Detection Illustration If undernormal operatingcircumstancesa lightshouldfail,the faultdetection indicatorwill appearinslot4. Then,if the lightwasnormallyON before the fault,operatorscan manuallyoverride the systembyactivatingthe corresponding ‘flipswitch’locatedinslot3thus cutting powerto the lighttobe examined. (All flipswitcheshave beenplacedinseries withtheircorrespondinglightingfixturesas to create a convenientergonomicdesign for simplicity’ssake). Note: ReferringtoTable 1, Slot3 hasdata entries entitled‘MO_R1L1,MO_R1L2…’. MO simplystandsfor“manual override”and the meaningof R1L1, R1L2, etc… have alreadybeendiscussed. Furthermore,Slot 4 has data entriesentitled‘R1L1_FAULT and R1L2_FAULT’, etc… Thiswasmeantto be self-explanatoryyetmerelyresembles the indicationstatusof whetherafaulthas or has not beendetectedforagiven lightingfixture withinthe building.
11 The PLC program is ladderlogicbasedandconsistsof two routines,i.e.the mainroutine(whichcontrols the control panel) andthe building’slightingsubroutine. Originally,the building’slightingsubsystem was remotelyuncontrollableandabsolutelyunsupervised. This PLCprogram fixesbothof those problems. Itisdone by providingremote control capabilities tothe building’ssubsystem aswell asfault detection techniquesincase of an unexpectedlightingfailure. See AppendixA forthe PLC Program. B. HVAC Subsystem A typical HVACsystemconsistsof afurnace,heatexchanger,evaporatorcoil,condensingunit, refrigerantlines, thermostat,ductsandvents. Fromthese 8 basiccomponents,the furnace,heat exchanger,evaporatorcoil,condensingunitandrefrigerantlinesare able tobe automatedorremotely controlledfromthe PLCcontrol panel. StudiesshowthatimplementingPLCdevicesinbuildingHVACsystemscanleaddirectlytomore stable environmentsaswell ashigherenergy-efficientprocesses. Thisisusuallyaccomplishedwiththe use of PID controllerswhichcanbe implementedwithinPLCprograms. Standingforproportional integral derivative the PIDcontrollercanhelp withthe overall rise times,settling times,andpercentovershoot withinasystem. For HVAC,thiswouldcorrespondtothe temperature of aroom. Less energycanbe usedif the heatingandcoolingsystemswere able tohitthe markwithoutmuch oscillationaboutthe desiredsteadystate value. Inotherwords,the fastera systemisable toconverge uponthe final steady state value,the more efficientitwill become. The PLC solutionforthissubsystemwill include processcontrol switchesthatcontrol the temperature of a room. Furthermore,the PLCprogramwill utilizeadigital heaterwhichcaneitherbe ON orOFF. This heaterwill nothave anyanalogsignal drivingthe controlstherefore itissubjectonlytomanual operationaswell ascertainconditionsthatenable automaticresponses. Table 2: HVAC Subsystem I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Furnace Motor_1 Switch_1 Temp_Stable Condensing_Unit Motor_2 Switch_2 Temp_Increasing Valve_1 Switch_3 Temp_Decreasing Motor_3 Switch_4 Motor_4 Switch_5 Heating_Inspection Valve_2 Switch_6 Cooling_Inspection Valve_3 Switch_7 Input Output Input Output Table 2 above showsthe I/Omappingof the HVACsubsystem. There are twoinitial inputs,i.e.the Furnace and the Condensing_Unitswitcheslocatedinslot1. These twoinputsare responsible forthe heatingandcoolingof the building. WhenFurnace is closed,the heatingcomponentsof the HVAC systemare enabled,i.e.Motor_1,Motor_2 andValve_1. Motor_1 is responsible fordrawingairfrom the returnair duct and blowingitthroughthe furnace combustionchamberandintothe airducts.
12 Motor_2 is the exhaustfanmotor,solelyresponsibleforventingthe fumesaccumulatedinthe combustionchamber. Valve_1isthe gasvalve andis responsible forsupplyingthe furnace burnerswith fuel forcombustion. See Fig.5belowfora visual representationof a typical heatingunit. Figure 5: Gas Powered Heating Unit Ref. [2]
13 The secondinitial input,i.e.the condensingunit,isresponsibleforcoolingthe building. When Condensing_Unitisclosed,the coolingcomponentsactivate,i.e.Motor_3,Motor_4, Valve_2and Valve_3. Motor_3 isresponsibleforthe condensingunitfanmotor,Motor_4 isthe compressorpump motor,Valve_3and Valve_4are the suctionline andliquidline valves. Valves3and 4 are essentiallythe twovalvesassociatedwiththe coolantlines. See Fig.6below forthe anatomyof a condensingunit. Slots1 and2 correspondtothe heatingandcoolingunitsandtheirconstituentcomponents respectively. Slot3 isusedfor controllingeachof the individual componentswithinthe heatingor coolingunits. Switches1through7 can be manuallytriggeredtocutoff orrestore powertoone of the componentsinsuch casesas the motor. For valves,these switcheswill eitheropenorclose a valve with directinstruction. Slot4 isdedicatedtothe systemstatusindicators,i.e.the temperature rising,temperaturefallingand temperature stable statuses. Eachstatus isdiscernedbya lightturningon. Furthermore,there isthe heatinginspectionstatuswhichmeansone of the heatingunitswitcheshave beenflippedandthere is the coolinginspectionstatuswhichindicatesthata coolingunitswitchhasbeenflipped, mostlikelyfor inspectionpurposes. See Table 2above forthe complete I/Omap. Figure 6: Condensing Cooling Unit Ref. [3]
14 The simulationusedforthissubsystemincludesatemperature readingof aroom. Data fromthe simulationisstoredinthe analogtemperatureinputorslot7 data entry03 withinPLCLogix;the output isdisplayedinslot8 data entry03 onthe I/Ointerface. Under initial conditions,the temperature of aroomis setto 70 degreesFahrenheit. Whenthe heating unit(i.e.the furnace) isturnedon,the temperature will begintorise andthe temperature increasing indicatorlightwill turnon. Onthe otherhand,whenthe coolingunit,orthe condensingunit,isturned on the temperature of the roomwill begintofall andthe temperature decreasingstatuslightwill turn on. It can reach temperaturesof upto120 degreesFahrenheit. Figure 7: HVAC PLC I/O Interface - Initial Conditions Figure 8: HVAC PLC I/O Interface - Furnace ON Fig.7 showsthe initial conditionsof the program. Both the furnace and condenserare off,the temperature stable lightisonand the temperature readout is displaying70 degrees Fahrenheit. Fig.8 showsthe I/Ointerface when the heatingunitisactivated. Immediatelyafteractivatingthe furnace switch,the heating componentslightupandthe temperature increasing statuslight activates. Afterone secondof activationthe temperature will start to rise as seeninslot8 data entry03.
15 It can reach temperaturesaslowas20 degreesFahrenheit. Figure 9: HVAC PLC I/O Interface - Condensing Unit ON Fig.9 showsthe I/Ointerface when the coolingunitis ON. Whenthe condensingunitisturnedon,the coolingunitcomponentsactivated immediatelyalongwiththe temperature decreasingstatus indicatorlight. Furthermore,the temperature canbe seentobe droppinginslot8 data entry03. Figure 10: Heater and Cooler ON In thisPLC program, whenboththe condensingunit and furnace are turnedon, the temperature will stabilize around70degrees,inactualityitfluctuates between69and 71 degreesFahrenheit. Hence,all three statusindicatorlights,i.e.temp_stable, temp_increasingandtemp_decreasingare all onat thispoint. If for some reasonan operatordecidestoshutoff one of the heatingunitcomponentssuchasthe gas valve orvalve_1,the systemwill registerthe furnace as beingshutoff and the temp_increasingstatus lightwill turnoff automatically. Furthermore,the heating_inspectionlightwill turnonalso. See Fig. 11 below foran illustrationof this. Temp_Decreasing Heating_Inspection Figure 11: Heating Inspection
16 On the contrary,if an operatordecidestoshutoff one of the coolingunitcomponents,thenthe system will registerthe condensing_unittobe effectivelyshutoff andthe temp_decreasing statusindicatorwill turn off and the cooling_inspectionstatusindicatorwill turnon. See Fig.12 for an illustrationof this. If componentsfromboththe heatingandcoolingunitsare turnedoff,thenthe systemwill registerthat bothunitsare turnedoff;therefore,the temp_stablestatusindicatorlightwillappearaswell asthe heatingandcoolinginspectionlights. See Fig.13 foran illustrationof this. In conclusion,the HVACPLCprogramis a digital heatingandcoolingsystem. Itisladderlogicbasedwith onlyone mainroutine forsimplicity. All inputsandoutputsare digital. The simulationproducesone analogoutput,i.e. the effective roomtemperature. Producedsolelybysimulation,the effective room temperature isaportrayal of the possibilitiesof thisprogram. Inactuality,thisPLCprogramwould utilize I/Omodulesandsensorstogive actual data. See AppendixBforthe PLCladderlogicprogram. Figure 12: Cooling Inspection Temp_Increasing Cooling_Inspection Figure 13: Heating and Cooling Inspection Temp_Stable Heating_Inspection Cooling_Inspection Here,the furnace and condensingunitare onbut the compressorpumpmotor has beenshutoff for inspection. Hence,the coolingunitiseffectivelyshut off and the furnace heating unitwill dominate. The temp increasinglightandcooling inspectionlightappearas showninFig.12. Here,the furnace and condensingunitare onbut the compressorpumpmotor and the exhaustfanmotor has beenshutoff for inspection. Hence,boththe heatingandcoolingunitsare effectivelyshutoff. Therefore,the temperature stable statusindicatoraswell as the cooling/heating inspectionstatuslight indicatorshappenstobe on as showninFig.13.
17 C. Access and SecuritySubsystems There are twodifferenttypesof securitytechniques,i.e.perimetercontrol andinternal breach. Perimetercontrol isamethodusedtokeepintruders/perpetratorsoutof the safetyarea,whereas internal breachsecurityisusedwhenthe intruder/perpetratorhasbreachedthe premises. Differenttypesof critical infrastructure require differentlevelsof security. Forexample,anairport requiresmore securitythaneducationalfacilitiesbecause theyare subjecttomore damagesif perpetrated. Eventhoughitisdifficulttoharborthe truth that casinoshave greatersecuritycounter measuresthanlocal highschoolsorelementary schools;realityis,statisticssaythatpremiseslike banks, casinos,airports,prisons,powerplants,etcetera;all require higherstandards andoftentimes harbor incrediblyexpensive securitysystems toprotecttheirassets;soexpensive that mosteducational facilitiesare unable toaffordsuchcountermeasures. Althoughschoolsare unlikelytoaffordgreatbigsecuritysystems,theycanaffordsome of the basicsas to preventperimeterbreachesduringafterhours. All securitysystemsbigorsmall runonsome type of PLC or microcontrolleralongwith24hour supervision. Thissystemwill preventperpetratorsfrom obtainingaccesstothe safetyareathrougha PLC access control programusingPLCLogix. The simulationcreatedusingthe PLCLogix software emulatesanelectronickeypaddoorlock. This device isusedtokeepunwantedsuspectslackingauthorityornecessarycredentialsoutof a designated area. For example,agunmantryingto gainaccess to a school wouldbe deniedthe opportunity to wreakhavoc due to the perimeter“accesscontrol”systeminplace. Thatiswhat thisprogramseeksto do. Figure 14: Electronic Keypad Lock Ref. [4]
18 Table 3: Access Control Subsystem I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Lock_1 Locked One Lock_2 Unlocked Two Lock_3 Three Lock_4 Four Lock_5 Five Input Output Input Output Table 3 showsthe I/Omap of the AccessControl PLCprogram. The inputsinslot1, i.e.One,Two,Three, Four and Five representthe keypadnumbersusedtounlockthe device. Outputslocatedinslot2shows whethereachstage hasbeenbypassed. Forthisparticularsystem, five unlockingstagesmustbe activatedinorderto unlockthe systementirely. There are no inputsassociatedwiththisprogram regardingslot3 and slot4 isusedto indicate whetherthe systemislockedorunlocked. Figure 15: Access Control Subsystem - Initial Conditions Upon initial startupthe systemislockedas indicatedbydataentry00, slot4 seeninFig. 14. In orderto unlockthe system, the right combinationorsequence of numbersmustbe pressedusingthe inputsinslot1. Once the right combinationhasbeenpressed withinthe giventime frames,the unlockedstatus indicatorlightwill appearondataentry01 in slot 4. See Fig. 15 foran illustration. Afterthe systemisunlockeditwill remain unlockedforfive secondsbefore returntoa lockedstate whichgivesthe userenoughtime to turn the door handle before havingtore-enter the necessarycredentials. If the wrongcredentialsare entered,the system will enteralockdownsituationforfiveseconds before resettingthe systemautomatically. RefertoAppendix Ctosee the PLC program ladderlogicandto discernthe rightcombination neededtounlockthe system. Figure 16: Access Control Subsystem - unlocked
19 Accesscontrol is a huge part of infrastructure securityandPLCsallow for promisingsecuritysystems. One couldutilize the inputsinslot3to manuallycontrol the perimeteraccesscontrol device andwith furtherequipment,suchasremote sensors,one couldbuildaprettysophisticatedaccesscontrol and internal breach securitysystembyutilizingPLCs. D. CommunicationsSubsystem A buildinghastwomethodsof communication,i.e.byfree space optical (FSO) orradiofrequency(RF). Table 4: Communication Subsystem I/O Mapping Slot1 Slot2 Slot3 Slot4 Master Switch N/A FSO_Switch FSO_Communication N/A RF_Switch RF_Communication INPUT OUTPUT INPUT OUTPUT Free space optical communicationismore efficient andsecure thanotherformsof communication,such as radiofrequency andthe Internet. Hence,more buildingsare turningtoFSOtechnologiesasaprimary methodforcommunicatingbetween one pointandanother. The onlyproblemfacingthistype of communicationisthe atmosphericchannel throughwhichitpropagates. Intimesof heavyfog,rainor snow,the optical source isattenuatedinthe atmosphere byatmosphericturbulence,scatteringand absorption. For thisreason,it isnecessarytohave backupin the formof RF communicationduring timesof inclementweather. ThisPLCprogram seekstoaddressthatissue bycreatinga hybridRF/FSO communicationsystem. ReferringtoTable 2, Slot1 data entry00 isreservedforthe Master Switch,whichcontrolsthe platform. The data entrieslocatedinslot3 are reservedforthe manual override switches,thustheyare consideredinputs. Finally,the outputstatusof the overall systemisstoredinthe dataentrieslocatedin slot4. Furthermore,the programsimulatesbadweatherasa resultof temperaturesdropping. When the temperature reachesacertainthresholdaround30 degrees,the systemwill automaticallyswitch fromone form of communicationtoanother,i.e.FSOtoRF. Figure 17: Communication Subsystem I/O Rack - FSO
20 Whenthe simulatedtemperature isabove 30degreesFahrenheit,the FSOcommunicationlightswitch will be turnedon. On the otherhand,whenthe temperature is30 degreesFahrenheitorless,the RF lightswitchwill be on. RefertoFig.17 below foran illustrationof this. As showninFig.16 and 17, automaticprocessescan be usedto switchmethodsof communicationto ensure continuity.Furthermore,withmanual overrideswitchesone couldcontrol the methodof communicationdirectly. Thismaybe useful underaspecificsetof circumstances. E. Water,Plumbingand Fire Safety Subsystems Everysmart buildinghasafire safetysysteminstalled. The bestwaytodetectfireswithoutdirect supervisionisbyusingsmoke detectors. Ionizationsmoke detectorsare apopularchoice fordetecting smoke because of theirsensitivitytoit. Theyuse a radioactive substance thatgeneratescurrentinside the detector. If there issmoke presentinthe detector,the currentwill cease toflow andthe alarmwill be triggered. Underthiscondition,alongwithseveral others,fire mitigationdevicessuchaswater dispersionsystemstendtoturnonautomatically. For thisreason,itis incrediblyimportanttohave functionalwaterandplumbingsystemsincase of fire or otherrelatedcatastrophes. Thismayinclude core meltdownsinnuclearpowerplants. Automation and control systemsforwater,plumbingandfire safetysubsystemscansave livesandprevent emergenciesfromescalating. ThisPLCprogramwill create a watermanagementsystemaswell asafire safetysystemthatutilizesautomationandcontrol practicestoensure sustainabilityandsafety. Figure 18: Communication Subsystem I/O rack - RF
21 Table 5: Fire Safety, Water and Plumbing I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Simulator F1R1V1 MO_SWITCH_1 F1R1V2 FLOOR_1_SWITCH F1R2V1 MO_SWITCH_2 F1R2V2 FLOOR_2_SWITCH F1R3V1 MO_SWITCH_3 F1R3V2 FLOOR_3_SWITCH F1R4V1 MO_SWITCH_4 F1R4V2 FLOOR_4_SWITCH F2R1V1 MO_SWITCH_5 F2R1V2 ALL_ON F2R2V1 MO_SWITCH_6 F2R2V2 ALL_OFF F2R3V1 MO_SWITCH_7 F2R3V2 F2R4V1 MO_SWITCH_8 F2R4V2 F3R1V1 MO_SWITCH_9 F3R1V2 F3R2V1 MO_SWITCH_10 F3R2V2 F3R3V1 MO_SWITCH_11 F3R3V2 F3R4V1 MO_SWITCH_12 F3R4V2 F4R1V1 MO_SWITCH_13 F4R1V2 F4R2V1 MO_SWITCH_14 F4R2V2 F4R3V1 MO_SWITCH_15 F4R3V2 F4R4V1 MO_SWITCH_16 F4R4V2 Input Output Input Output Table 5 isan input/outputmapof the fire safety,waterandplumbingsubsystems. Slot1controlsthe built-insimulationaswell asthe variouswaterdistributionsystemsforeachfloor. The outputsare locatedinslots2 and4. Theyare simplystatus indicatorlightsthatshow whetheradevice hasbeen turnedon;in thiscase,the devicesbeingturnedoff andonare water line valvescomingbefore and afterthe sprinklernozzle(s). Legend:  F – Floor  R – Room  V – Valve  MO – Manual Override Thisbuilding,the programwasbuiltfor,consistsof fourfloorswithfourroomsperfloor. Slot3 isa control panel usedtocontrol the waterdispersingsystems. Forexample,MO_SWITCH_1controlsthe valveslocatedoverroomone floorone (F1R1V1and F1R1V2). The inputslocatedinslot1 are furthercontrols. Floorcontrolsactivate anddisable the valveslocated on floorone,two,three andfourrespectively. Slot1 alsocontainsan ‘all on’and ‘all off’switch. Lastly, there isthe simulatorswitchwhichcontrolsthe built-insimulation,i.e.anionizingfire detector detectingsmoke bynoticingasignificantdropof electrical currentinthe device.
22 Figures19 and 20 showthe twomaindevicesusedinfire safetysystemswithinbuildings. Fig.19 shows the waterdispensingnozzle whichisresponsibleforthwartingactive firesandFig.20 showsan ionizing fire detectorwhichisusedindetectingthe signsof anactive fire. These twodevicesworkinharmonyto ensure buildingsafetyagainstthreatregardingfire safety. The PLCprogram forthisbuildingsubsystem shouldallowfora more efficient approachtohandlingbuildingfires. Byallowingformore precise control of the water,plumbingandfire safetysystem, the situationislesslikelytoresultinloss,i.e.loss of water,resourcesandlife. The simulationbuiltintothisprogramruns ona 60 secondtimerthat alternatesbetweentwoscenarios, 1) an ionizingfire detectordetectssmoke and2) an ionizingfiredetectordoesnotdetectsmoke. When no smoke isdetected,the I/OmaplooksasshowninFig.21 below. Figure 19: Water Dispersing Nozzle Ref. [5] Figure 10: Ionizing Fire Detector Ref. [6] Figure 11: Fire Safety Subsystem I/O Rack
23 In Fig.21 slot8 data entry01, 5.0 mA of currentindicatesthatnosmoke isdisruptingthe alphaparticle emission –stimulatedcurrentof the ionizingsmoke detector. Conversely,whenthe display reads1.0 mA whichmeansthe ionizingbeamof alphaparticleshasbeendisruptedbysmoke,thusreducingthe currentwithinthe device. See Fig.22. The 1.0 mA of current showninFig.22 slot8 data entry01 indicatesthatthe fire detectorhasdetected smoke. Asshowninslots2 and4, all lightshave beenlituptoindicate the valvesleadingtothe water distributionnozzles have beenopened. Hence waterisflowingandextinguishingthe fire inthe building. On topof thisautomaticprocess,the PLC programutilizesdigital switchestoissue variouscontrol responses. Suchresponsesinclude:activating/deactivatingnozzlesindividually,byfloororaltogether. Thisis to ensure thatwaterisnot wastedinan eventsuchas a false alarmbut alsoto ensure that actionscan be takenintothe handsof a humanintervenerwhenthe time isright. Combiningboth automaticprocesseswithcontrol methodsissuedbydirectsupervisionwill allow forasmarterand safer environment. See Appendix Eforthe PLC program. Conclusion Everysmart buildinghasautomatedprocessesinadditiontovariouscontrol systems. Inthisreportwe introducedthe conceptof a smart buildingandhow itmightextendtovarioustypesof critical infrastructure acrossthe UnitedStates. Upondoingso, we identifiednine majorsubsystemswithin Figure 12: Fire Safety Simulation - Fire Detected
24 smart buildings. Outof these nine,we addressedfivebycreatingPLCprogramsto enhance subsystems lackingautomationandcontrol processes,i.e.Lighting,HVAC,AccessandSecurity,Communicationsand Fire Safety. While introducingthe lightingsubsystem, we were abletodistinguishwhatcontrolsmayhelpincrease sustainabilityandemergencyresponse times. Thiswasachievedbycreatingacontrol panel thatwould allowforfaultdetectionandmanual overridecapabilities. Bybeingable tocontrol the lightingsystem withinabuildingremotelycreates notonly aconvenience topeoplebuta practical applicationaswell. For the HVACsubsystem,we analyzedHVACsystemcomponentsinordertofindareasthatmay allow for controlsimplementation. Upondoingsowe discoveredthatthe heatingandcondensing(cooling) unitseachhave fans (motors) andvalvesthatare critical to the functionalityof the units. Therefore, controlswere implementedtoeachof these components. Furthermore,the PLCprogramthat was built simulatesadigital heater/coolerwitharange from20 degreesFahrenheitto 120 degreesFahrenheit. It alsohas a temperature stabilizationsettingwhichhoversaround70 degreesFahrenheit. The third smartbuildingsubsystemwasthe accessandsecuritysubsystem. Forthissubsystemwe built an electronicperimeteraccesscontrol securitylock. Usingonlytimersand conditions,the lockonly openstothose whoknowthe correct sequence andforthose whocanexecute thissequence withina giventimeframe. Followingthe accessandsecuritysubsystemwasthe communicationssubsystem. The PLCprogram constructedforthissubsystemwasnotfor internal buildingcommunicationbutforexternal building communication. Essentially,the PLCprogramsimulatesanautomaticswitchinghybridRF/FSO communicationsystemgiventhe atmosphericconditionsasaninput. Lastlywas the fire safetywaterandplumbingsubsystems;here we constructedasimulationthatranon a 60 secondtimeralternatingbetweentimesof fire andtimeswithout. The PLCprogram wasbuiltto respondtothe built-insimulationbyissuingcommandsautomatically. Furthermore,the systemwas builttoresponddirectlytouserinputmeaningthat,underdirectsupervision,the systemcouldbe controlledatwill. By creatingPLC programsfor eachindividual buildingsubsystem,we create smarterbuildings. The conceptof a safer,smarterbuildingwasthe drivingforce behindtheseprojects. Furthermore, utilizing PLCs wasa greatway to gaininsightintothe worldof programmable logiccontrollersandhow effective they can be in makingourworlda saferandsmarter place tolive in.
25 References [1] Critical Infrastructure Sectors https://www.dhs.gov/critical-infrastructure-sectors [2] Coolingunit https://www.google.com/search?q=condenser+unit+anatomy&biw=1366&bih=705&source=lnms&tbm =isch&sa=X&ved=0ahUKEwj-kd65j_vMAhWly4MKHW_fD4UQ_AUIBygB#imgrc=pl-hCZdwfG7tSM%3A [3] Heatingunit https://www.google.com/search?biw=1366&bih=705&tbm=isch&sa=1&q=furnace+anatomy&oq=furnac e+ana&gs_l=img.3.0.0.188580.201657.0.203118.37.16.20.1.3.0.166.1904.1j15.16.0....0...1c.1.64.img..0. 37.2109...0i10j0i10i24.izOMcytuEiQ#imgrc=qZUHA4RAqXuCrM%3A [4] AccessControl Keypad https://www.google.com/search?q=keypad+door+lock&espv=2&source=lnms&tbm=isch&sa=X&ved=0a hUKEwjfsdmEoJbNAhUEbD4KHQiFDM4Q_AUICSgC#imgrc=x_dz4OeLzSGfvM%3A [5] Water DispersingNozzle https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahU KEwjvxJv9maDNAhVS72MKHa_kD8gQjRwIBw&url=http%3A%2F%2Findore.all.biz%2Fwater-sprinkler- system-g110729&psig=AFQjCNFLaQqW5ZLlNZLuhahhiDBRV7gKFg&ust=1465742318225508 [6] IonizingFire Detector https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahU KEwjNke7Dm6DNAhVT1GMKHcDOCtsQjRwIBw&url=http%3A%2F%2Fwww.cableorganizer.com%2Fsmo ke-detectors%2F&psig=AFQjCNFxjfliyPZSHFSaVHlxI1gWNKWavQ&ust=1465742780592482

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PLC Building Automation and Control Systems

  • 1. PLC Building Automation and Control Systems SSET 295 Internship Project Tags: Automation,BAS, BuildingAutomationSystems,Control, Control Panels,Critical Infrastructure,EnergyEfficiency,Fire Safety,LadderLogic,LightingSystems,PLCs,PLCLogix,Power Management,Programmable LogicControllers,SecuritySystems, Smart Buildings,Sustainability. Chad Ryan Weiss 6/17/2016
  • 2. 1 Abstract: Imagine abuildingthatcan respondto emergency situations. Eventslike Chernobyl,Fukushimaand Three-Mile Islandmaynothave beensocostlyif automatedprocessesandcontrol systemshadbeen properlyimplemented. Furthermore,imagine abuildingthatcanincrease itsoverall energyefficiency usingpredictive analyticswithautomation andcontrol systems;humancivilizationwouldbe takingone stepcloserto achievingsustainability thuspromotinglongevityforourplanetandall of itsinhabitants. Thisdocumentprovidesaside-by-sidecomparison of critical infrastructure bothlackingandcontaining automationandcontrol systems. Finally,thisreportconcludes byprovidingan implementation example of a PLC (programmable logiccontroller) forvarioussubsystems. Usingladderlogicwiththe PLCLogix software, the case studyseeks toaddressthe sustainability andemergencyresponseissues plaguing critical infrastructure whichlacks bothbuildingautomation andPLCcontrol systems.
  • 3. 2 Table of Contents I. Introduction 4 A. Smart Buildings 4 B. Critical Infrastructure 4 C. SubsystemOverview 4 1. Accessand Security 5 2. CommunicationSystems 5 3. ElevatorsandEscalators 5 4. Fire Safety 5 5. HVAC 6 6. Lighting 6 7. PowerandEnergy 6 8. ManufacturingEquipment 6 9. Water andPlumbing 6 II.Programmable LogicControllers 7 A. LightingSubsystem 7 B. HVACSubsystem 11 C. Accessand SecuritySubsystems 17 D. CommunicationsSubsystem 19 E. Water,PlumbingandFire SafetySubsystems 20 III.Conclusion 23 IV.References 25
  • 4. 3 List of Tables and Figures Table 1: LightingSubsystemI/OMapping Table 2: HVACSubsystemI/OMapping Table 3: AccessControl SubsystemI/OMapping Table 4: CommunicationSubsystemI/OMapping Table 5: Fire Safety,WaterandPlumbingI/OMapping Figure 1: PLCLogix I/Orack Figure 2: Initial Conditions –Master SwitchON Figure 3: Manual Override Illustration Figure 4: Fault DetectionIllustration Figure 5: Gas PoweredHeatingUnit Figure 6: CondensingCoolingUnit Figure 7: HVAC PLCI/O Interface - Initial Conditions Figure 8: HVAC PLCI/O Interface – Furnace ON Figure 9: HVAC PLCI/O Interface – CondensingUnitON Figure 10: Heaterand CoolerON Figure 11: HeatingInspection Figure 12: CoolingInspection Figure 13: HeatingandCoolingInspection Figure 14: ElectronicKeypadLock Figure 15: AccessControl Subsystem- Initial Conditions Figure 16: AccessControl Subsystem - Unlocked Figure 17: CommunicationSubsystemI/ORack - FSO Figure 18: CommunicationSubsystemI/ORack - RF Figure 19: Water DispensingNozzle Figure 20: IonizingFire Detector Figure 21: Fire SafetySubsystemI/Orack Figure 22: Fire SafetySimulation - Fire Detected
  • 5. 4 I. Introduction A. Smart Buildings Everysmart buildinghasacontrol room, especiallybuildingslike airports,hospitals,prisonsandpower plants. These control roomsallowoperatorstomonitorandmanage subsystems remotelyand sometimesautomatically. Subsystemslike energy,water, plumbing,HVAC,lighting,fire safety,access and security,elevators,communication,robotsandpower equipmentall requirespecialattention, because failure in anyone of these subsystemscouldspell disasterunderthe wrongsetof circumstances. Althougheachsubsystemhasvariable importance,failureisintolerable because somethingassimple as waterunexpectedly shuttingoff inabuildingcanhave consequencesranging fromminordiscomforttonuclearmeltdown. The importance of eachsubsystemisentirelydependent on the type of critical infrastructure that isbeingsupporting. B. Critical Infrastructure Critical infrastructurereferstothe infrastructure whoseassets,systemsandnetworks are consideredso importantto the UnitedStates thattheirdysfunction would bringforthdire consequences fornational economicsecurity aswell as national publicsafetyorhealth concerns[1]. Accordingtothe United StatesDepartmentof HomelandSecurity,there are 16 differentcritical infrastructuresincludingthe following: Nearlyall of the sectorslistedhere,aside fromtransportationsystems,relymostlyonbuildingsor superstructuresforshelter. Hence,the subsystems comprisingnearly100% of all critical infrastructures inthe UnitedStatesare subsystemsrelatedtocommercial andindustrial buildings. Formore oncritical infrastructures,referto[1]. C. SubsystemOverview Withoutthe implementationof automationandcontrol systemssome of the subsystemstalkedabout previously are prone tocatastrophicfailure. The followingsection providesinsighttohow each subsystemcanbe improvedbyimplementingautomationandcontrols. Furthermore,some sections provide acomparisonbetweensystemshavingautomationandcontrols tosystemslackingautomation and controls. Here isa listof the subsystems previousmentioned:  Dams  Defense industrial bases  Emergencyservicessector  Energysector  Informationtechnologysectors  Nuclearreactors,materialsandwaste  Transportationsystems sectors  Water andwastewatersystems  Financial servicessector  Foodand agriculture  Governmentfacilities sector  Healthcare andpublichealthsectors  Chemical sector  Commercial facilitiessector  Communicationssector  Critical manufacturingsector
  • 6. 5 1. Access and Security Since the year2013, there have beenover180 school shootings inthe UnitedStates;hence,accessand securityisa top concernwhenitcomesto establishingsubsystemswithincritical infrastructure. A good securitysystemhasbothactive andpassive sensorsusedforremote sensing. Furthermore,automated alarmingsystems aswell asphysical barriershelpcontribute tothe overall effectivenessof the security systeminplay. Whenhumansencounterdanger,ourfirstresponse isautomatic,i.e.eitherfightor flight. Witha properautomationandcontrol system, accessand securitysubsystemsinbuildings may be able to assistindeterringfuture school shootings,bankrobberies, terroristattacks orsimilaractsof crime and terror. 2. CommunicationSystems Aside fromaccessand security,abuilding’scommunication systemisatop subsystemconsideration because communicationishalf of whatmakes abuildingsmart,the otherhalf beingautomationand control. Integratingautomationandcontrol techniquesin communicationsystemswithinbuildings may allowformore robustinternal andexternal formsof communication. Forexample,manual orautomatic control of the methodsof communicationusedcouldincrease buildingenergyefficiencywhileenabling a widerrange of possibilitieswhenitcomestointernal orexternal buildingcommunications. Furthermore,implementingautomationandcontrolsin communicationsystems couldhelp technicians or buildingoccupantstroubleshootthe systemsduringtimesof unexpectedfailure. Thistopicis discussedinfurtherdetail inthe PLCsolutioncase study. See Ref [2] or the ZigBee Alliance/BACnet. 3. Elevators and Escalators Althoughthissubsystemhasnorelevance in singlestorybuildings,itisalmostalwaysreasonforconcern inbuildingsof twoormore stories. Hospitals,schools,banks,mallsandlibrariesall have elevators or escalators toaccommodate those who are handicappedorthose whohave beendisabledinsome way shape or form. Elevatorsor escalatorswithoutautomationorcontrol systemsare notonlydangerous but alsowasteful inregardstopower andenergy consumption. Inthe case that one or more floors withinabuildingare onfire,allowingthese systemstoremainoperational isnotonlystupidbutit could leadto unnecessary lossof life. Furthermore, leavingescalatorsoncontinuously isaproblemdue tothe fact that cost will goup, energyefficiency will godownand emergency responseorroutine maintenance will become negligible. 4. Fire Safety Anotherimportantsubsystem,thatwhichprotectsthe building’sinhabitants,isthe fire safetysystem. Withoutautomationandcontrol,response toanemergencysituationsuchasa fire wouldbe much slowerthanif there were sensorsandautomaticproceduresinvolved. Peoplewouldhave torunaround tryingto findthe fire extinguisherthenrunall the wayback to the fire,whichhasspreaduncontrollably by that point. Implementingautomationandcontrol featurestoalreadyexistingfire safetysystems couldnot onlyreactinstantlytofire;moreover,manual operationsof the fire safetysystemcomponents like the waterlinescouldpreventwastedwaterincasesof false alarm.
  • 7. 6 5. HVAC HVACor heating,ventilationandairconditioning systems constitute one of the mostimportant subsystemsabuildingcould have formanydifferenttypesof critical infrastructure. Chemical and nuclearfacilitiesuse themtoexhauststeamandtoxicchemicals; furthermore, heating, ventilation and coolingextendsnotonlytobuildingsbutalsotothe humanbodyand motorizedvehicles. The human bodyneedstoventall of the carbon dioxide thatbuildsupovertime otherwise hypercapnia,a.k.a.CO2 poisoningcouldhappen. Mostcritical infrastructure HVACsystemsplayahuge role inmaintaining essential processes. Forexample,HVACsystems keepdatawarehouseequipment cool enough to ensure thatprocessorsdon’toverheatwhichwouldcompromisefunctionality. Heating,ventilationand air conditioningwithoutautomation orcontrol wouldmake itimpossibletoholdcertaininternal buildingconditionssuchastemperature,pressure orhumidity. 6. Lighting Lightingwithoutautomationorcontrol systemsmake foraveryinefficientsystem. Implementingan automationsettingcouldreduce the amountof energyusedwhennoone isina roomthus reducing wastedenergy. Also,addingacontrol systemtolightingandloadsmayenable buildingoperatorsto detectunexpected burn-outs,shorts,open-circuitsorfaults. 7. Power and Energy Thissubsystemreferstothe powergenerationandpowerdistributionsubsystems. Powerandenergy, beingthe backbone of the entire superstructure,requiresimmense automationandcontrol techniques to ensure nothingcanthwarttheirabilitytoproduce andsupplypowertothe buildingandall of its critical features. Inthe case of a lightningstrike,hurricaneorsome othernatural disaster,power systemscouldbecome compromisedthuscompromisinganentire buildingorso. Eventslike the New York Blackouta couple of yearsago leftthousandsof people freezinginthe wintercoldweatherfor days. With properimplementationof automationandcontrol systems,troubleshootingmaynothave takenso longto fix thussavingmanyfromneedlesssuffering. 8. Manufacturing Equipment For industrial plantsormanufacturingfacilities,industrial powerequipmentcanbe verydemandingon energyandalsohazardousto the inhabitantsof thatbuilding. If automationandcontrol systemsare obsolete withinthesesystemsrobotscouldspinout of control or breakdown. Not toolongago, a robot tooka man’slife ata VolkswagenfacilityinGermany forunexplainedreasons. These typesof incidents can be reducedtoa minimumwithoutcompromisingproductivitybyaddingsimple automationand control featurestothe alreadyexistingsystems. Furthermore,one mightevenbe able tosave money by implementingautomationandcontrol techniques. 9. Water and Plumbing Water andplumbingmightseemtrivialbutthere are manythingsrelyingonthese subsystems. Hydraulics,HVACsystemsandhumansare some of the few persons,placesorthingsthatrelyon this
  • 8. 7 absolutelycritical subsystem,whichiswhyitisimportantto know all the detailsasto how flow is currentlybeingcontrolled. Furthermore,itisnecessarytoenactprecisionprocedural protocol executioninresponse toemergencysituations. Eventslike TMI,FukushimaandChernobyl couldhave possibly been avoidedif everysubsystem, includingwaterandplumbing,hadbeenworkingproperly. II. PLC Programs A. Lighting Subsystem A buildinghasfourroomswithfourlightsperroom. Table 1: Lighting Subsystem I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Master Switch R1L1_POWER MO_R1L1 R1L1_FAULT R1L2_POWER MO_R1L2 R1L2_FAULT R1L3_POWER MO_R1L3 R1L3_FAULT R1L4_POWER MO_R1L4 R1L4_FAULT R2L1_POWER MO_R2L1 R2L1_FAULT R2L2_POWER MO_R2L2 R2L2_FAULT R2L3_POWER MO_R2L3 R2L3_FAULT R2L4_POWER MO_R2L4 R2L4_FAULT R3L1_POWER MO_R3L1 R3L1_FAULT R3L2_POWER MO_R3L2 R3L2_FAULT R3L3_POWER MO_R3L3 R3L3_FAULT R3L4_POWER MO_R3L4 R3L4_FAULT R4L1_POWER MO_R4L1 R4L1_FAULT R4L2_POWER MO_R4L2 R4L2_FAULT R4L3_POWER MO_R4L3 R4L3_FAULT R4L4_POWER MO_R4L4 R4L4_FAULT Input Output Input Output Input1 isthe Master Switch;it has twoconditions: 𝑀𝑎𝑠𝑡𝑒𝑟 𝑆𝑤𝑖𝑡𝑐ℎ = { 1 𝐸𝑛𝑎𝑏𝑙𝑒 𝐶𝑜𝑛𝑡𝑟𝑜𝑙 𝑃𝑎𝑛𝑒𝑙 0 𝐾𝑖𝑙𝑙 𝑆𝑤𝑖𝑡𝑐ℎ The 1 signifiesthatthe Master Switchhasbeenturned“ON”whereasthe 0 representsthe Master Switchwhenitisturned“OFF”. Whenthe Master Switch has a bitvalue of 1, the program will execute rung zeroof the mainroutine thusjumpingtothe lightingsubroutine. Onthe contrary, whenthe Master Switchhas a bitvalue of 0, the programwill execute rungone;hence,disablingall system input/outputfunctionality. Furthermore,the systemcan be resetuponexecutionof the Kill-Switch operation. Thisisto make troubleshootingeasierandresponse toemergencysituationsfaster. UtilizingPLCLogix andthe I/Ointerface,the PLCcontrol panel supportsupto16 lights. Inthisscenario, a buildinghasfourroomsor floorswithfourlightsperfloor/room. The lightingsubsystemMaster
  • 9. 8 Switchhas the abilitytocut all powertothe building’slightingsubsystems. Furthermore,the PLC control panel wasdesignedtoallowuserstomanuallycontrol eachlightspecificallyaccordingtothe I/O mappingof the PLC program and control panel. See Table 1above. The I/O mappingseeninTable 1 correspondsto the PLCLogix I/Orack or interface. Fig.1 shownbelow presentsthe layoutof PLCLogix I/Orack. Figure 1: PLCLogix I/O Rack ReferringtoFig.1, the discrete I/Ointerface allows forsupervisedandunsupervisedcontrol of the building’slightingsubsystem. Slot1,input00 is reservedforthe MasterSwitch. The usercan enable or disable the control panel/buildinglightingsubsystembyopeningorclosingthe MasterSwitchcircuit. Initially,whenthe MasterSwitchisturnedON,the building’slightsall turnoninthe orderspecifiedby the PLC ladderlogic. Whenthe Master SwitchisOFF andhence,the control panel andbuildinglighting subsystemsare deactivated,users nolongerhave anycontrol overanypart of this particularsubsystem and control panel. Table 1 slot2, correspondingtoslot2 data entries fromthe discrete I/Ointerface showninFig.1 reads, R1L1_POWER. This standsfor roomone (R1) lightone (L1) powerindicator. The nextentryreads R1L2_POWER whichstandsfor room one (R1) lighttwo(L2) powerindicator,etc... Forthisscenario,the buildinghasfourroomswithfourlightsperroom. In otherscenarios,abuildingmayhave fourfloors withfouroverheadlightsperfloor. All canbe changedaccordingly,dependingonthe situation, from
  • 10. 9 withinthe PLCprogram. Fromthe PLCLogix discrete I/Ointerface,all of the dataentrieslocatedinslot2 are reserved forthe statusof each individual lightingfixture regardingpower. Inotherwords, this columnindicateswhetherthe lightisON orOFF. Thisisshownrather clearlyfromthe I/Orack. When an entrylightsup,thismeansthe lightisON,whenthe entryisnot litup,thismeansthe lightisOFF. Fig.2 showsthe I/Orack whenall lightsinthe buildingare turnedonrightafteractivatingthe Master Switch. See Fig.2 below. The Master Switchoccupyingslot1 data entry00 has the powertoenable ordisable the entire building’slightingsubsystemandcontrol panel. Sometimes however, itisnecessarytokeepall other lightsonwhile troubleshootingorrewiringanotherlight. Hence,slot3entries00 through15 are dedicated tomanual override switchesfor eachlightrespectively. Togglingtheseswitchesturnsthe lightsOFFand ON. See Fig.3 belowfor anillustration. Figure 3: Manual Override IllustrationFigure 2: Initial Conditions - Master Switch ON
  • 11. 10 The fourthand final columnof the I/Orack isusedas a faultdetectionindicator. These outputswillonly activate if the system,foranyreason,shouldfail undernormal operatingcircumstances. Inreal world situations,PLCcontrollerscontainI/Omodulesthatcansupportcountless variationsof digital and analogsensingequipmentthusallowingforsophisticatedfaultdetectiontechniques. However,forthe purposesof thisproject,asimulationwasmade toillustrate how the PLCprogramrespondsto detected faults. For the lightingsubsystem,thissimulationusesaseriesof timersandcountersandmultipliersto effectivelycreate afaultinthe system. Everyso often,the lightoccupyingdataentries 03,goesinto arrest andunexpectedlyshutsoff. Althoughthe source of errorisunknown,operatorsare able to detectthat thislighthas “effectivelyfailed”due tothe faultindicatoroutput statusinslot4 on the discrete I/Ointerface (i.e.slot4). See Fig.4 below foranillustrationof faultdetection. Figure 4: Fault Detection Illustration If undernormal operatingcircumstancesa lightshouldfail,the faultdetection indicatorwill appearinslot4. Then,if the lightwasnormallyON before the fault,operatorscan manuallyoverride the systembyactivatingthe corresponding ‘flipswitch’locatedinslot3thus cutting powerto the lighttobe examined. (All flipswitcheshave beenplacedinseries withtheircorrespondinglightingfixturesas to create a convenientergonomicdesign for simplicity’ssake). Note: ReferringtoTable 1, Slot3 hasdata entries entitled‘MO_R1L1,MO_R1L2…’. MO simplystandsfor“manual override”and the meaningof R1L1, R1L2, etc… have alreadybeendiscussed. Furthermore,Slot 4 has data entriesentitled‘R1L1_FAULT and R1L2_FAULT’, etc… Thiswasmeantto be self-explanatoryyetmerelyresembles the indicationstatusof whetherafaulthas or has not beendetectedforagiven lightingfixture withinthe building.
  • 12. 11 The PLC program is ladderlogicbasedandconsistsof two routines,i.e.the mainroutine(whichcontrols the control panel) andthe building’slightingsubroutine. Originally,the building’slightingsubsystem was remotelyuncontrollableandabsolutelyunsupervised. This PLCprogram fixesbothof those problems. Itisdone by providingremote control capabilities tothe building’ssubsystem aswell asfault detection techniquesincase of an unexpectedlightingfailure. See AppendixA forthe PLC Program. B. HVAC Subsystem A typical HVACsystemconsistsof afurnace,heatexchanger,evaporatorcoil,condensingunit, refrigerantlines, thermostat,ductsandvents. Fromthese 8 basiccomponents,the furnace,heat exchanger,evaporatorcoil,condensingunitandrefrigerantlinesare able tobe automatedorremotely controlledfromthe PLCcontrol panel. StudiesshowthatimplementingPLCdevicesinbuildingHVACsystemscanleaddirectlytomore stable environmentsaswell ashigherenergy-efficientprocesses. Thisisusuallyaccomplishedwiththe use of PID controllerswhichcanbe implementedwithinPLCprograms. Standingforproportional integral derivative the PIDcontrollercanhelp withthe overall rise times,settling times,andpercentovershoot withinasystem. For HVAC,thiswouldcorrespondtothe temperature of aroom. Less energycanbe usedif the heatingandcoolingsystemswere able tohitthe markwithoutmuch oscillationaboutthe desiredsteadystate value. Inotherwords,the fastera systemisable toconverge uponthe final steady state value,the more efficientitwill become. The PLC solutionforthissubsystemwill include processcontrol switchesthatcontrol the temperature of a room. Furthermore,the PLCprogramwill utilizeadigital heaterwhichcaneitherbe ON orOFF. This heaterwill nothave anyanalogsignal drivingthe controlstherefore itissubjectonlytomanual operationaswell ascertainconditionsthatenable automaticresponses. Table 2: HVAC Subsystem I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Furnace Motor_1 Switch_1 Temp_Stable Condensing_Unit Motor_2 Switch_2 Temp_Increasing Valve_1 Switch_3 Temp_Decreasing Motor_3 Switch_4 Motor_4 Switch_5 Heating_Inspection Valve_2 Switch_6 Cooling_Inspection Valve_3 Switch_7 Input Output Input Output Table 2 above showsthe I/Omappingof the HVACsubsystem. There are twoinitial inputs,i.e.the Furnace and the Condensing_Unitswitcheslocatedinslot1. These twoinputsare responsible forthe heatingandcoolingof the building. WhenFurnace is closed,the heatingcomponentsof the HVAC systemare enabled,i.e.Motor_1,Motor_2 andValve_1. Motor_1 is responsible fordrawingairfrom the returnair duct and blowingitthroughthe furnace combustionchamberandintothe airducts.
  • 13. 12 Motor_2 is the exhaustfanmotor,solelyresponsibleforventingthe fumesaccumulatedinthe combustionchamber. Valve_1isthe gasvalve andis responsible forsupplyingthe furnace burnerswith fuel forcombustion. See Fig.5belowfora visual representationof a typical heatingunit. Figure 5: Gas Powered Heating Unit Ref. [2]
  • 14. 13 The secondinitial input,i.e.the condensingunit,isresponsibleforcoolingthe building. When Condensing_Unitisclosed,the coolingcomponentsactivate,i.e.Motor_3,Motor_4, Valve_2and Valve_3. Motor_3 isresponsibleforthe condensingunitfanmotor,Motor_4 isthe compressorpump motor,Valve_3and Valve_4are the suctionline andliquidline valves. Valves3and 4 are essentiallythe twovalvesassociatedwiththe coolantlines. See Fig.6below forthe anatomyof a condensingunit. Slots1 and2 correspondtothe heatingandcoolingunitsandtheirconstituentcomponents respectively. Slot3 isusedfor controllingeachof the individual componentswithinthe heatingor coolingunits. Switches1through7 can be manuallytriggeredtocutoff orrestore powertoone of the componentsinsuch casesas the motor. For valves,these switcheswill eitheropenorclose a valve with directinstruction. Slot4 isdedicatedtothe systemstatusindicators,i.e.the temperature rising,temperaturefallingand temperature stable statuses. Eachstatus isdiscernedbya lightturningon. Furthermore,there isthe heatinginspectionstatuswhichmeansone of the heatingunitswitcheshave beenflippedandthere is the coolinginspectionstatuswhichindicatesthata coolingunitswitchhasbeenflipped, mostlikelyfor inspectionpurposes. See Table 2above forthe complete I/Omap. Figure 6: Condensing Cooling Unit Ref. [3]
  • 15. 14 The simulationusedforthissubsystemincludesatemperature readingof aroom. Data fromthe simulationisstoredinthe analogtemperatureinputorslot7 data entry03 withinPLCLogix;the output isdisplayedinslot8 data entry03 onthe I/Ointerface. Under initial conditions,the temperature of aroomis setto 70 degreesFahrenheit. Whenthe heating unit(i.e.the furnace) isturnedon,the temperature will begintorise andthe temperature increasing indicatorlightwill turnon. Onthe otherhand,whenthe coolingunit,orthe condensingunit,isturned on the temperature of the roomwill begintofall andthe temperature decreasingstatuslightwill turn on. It can reach temperaturesof upto120 degreesFahrenheit. Figure 7: HVAC PLC I/O Interface - Initial Conditions Figure 8: HVAC PLC I/O Interface - Furnace ON Fig.7 showsthe initial conditionsof the program. Both the furnace and condenserare off,the temperature stable lightisonand the temperature readout is displaying70 degrees Fahrenheit. Fig.8 showsthe I/Ointerface when the heatingunitisactivated. Immediatelyafteractivatingthe furnace switch,the heating componentslightupandthe temperature increasing statuslight activates. Afterone secondof activationthe temperature will start to rise as seeninslot8 data entry03.
  • 16. 15 It can reach temperaturesaslowas20 degreesFahrenheit. Figure 9: HVAC PLC I/O Interface - Condensing Unit ON Fig.9 showsthe I/Ointerface when the coolingunitis ON. Whenthe condensingunitisturnedon,the coolingunitcomponentsactivated immediatelyalongwiththe temperature decreasingstatus indicatorlight. Furthermore,the temperature canbe seentobe droppinginslot8 data entry03. Figure 10: Heater and Cooler ON In thisPLC program, whenboththe condensingunit and furnace are turnedon, the temperature will stabilize around70degrees,inactualityitfluctuates between69and 71 degreesFahrenheit. Hence,all three statusindicatorlights,i.e.temp_stable, temp_increasingandtemp_decreasingare all onat thispoint. If for some reasonan operatordecidestoshutoff one of the heatingunitcomponentssuchasthe gas valve orvalve_1,the systemwill registerthe furnace as beingshutoff and the temp_increasingstatus lightwill turnoff automatically. Furthermore,the heating_inspectionlightwill turnonalso. See Fig. 11 below foran illustrationof this. Temp_Decreasing Heating_Inspection Figure 11: Heating Inspection
  • 17. 16 On the contrary,if an operatordecidestoshutoff one of the coolingunitcomponents,thenthe system will registerthe condensing_unittobe effectivelyshutoff andthe temp_decreasing statusindicatorwill turn off and the cooling_inspectionstatusindicatorwill turnon. See Fig.12 for an illustrationof this. If componentsfromboththe heatingandcoolingunitsare turnedoff,thenthe systemwill registerthat bothunitsare turnedoff;therefore,the temp_stablestatusindicatorlightwillappearaswell asthe heatingandcoolinginspectionlights. See Fig.13 foran illustrationof this. In conclusion,the HVACPLCprogramis a digital heatingandcoolingsystem. Itisladderlogicbasedwith onlyone mainroutine forsimplicity. All inputsandoutputsare digital. The simulationproducesone analogoutput,i.e. the effective roomtemperature. Producedsolelybysimulation,the effective room temperature isaportrayal of the possibilitiesof thisprogram. Inactuality,thisPLCprogramwould utilize I/Omodulesandsensorstogive actual data. See AppendixBforthe PLCladderlogicprogram. Figure 12: Cooling Inspection Temp_Increasing Cooling_Inspection Figure 13: Heating and Cooling Inspection Temp_Stable Heating_Inspection Cooling_Inspection Here,the furnace and condensingunitare onbut the compressorpumpmotor has beenshutoff for inspection. Hence,the coolingunitiseffectivelyshut off and the furnace heating unitwill dominate. The temp increasinglightandcooling inspectionlightappearas showninFig.12. Here,the furnace and condensingunitare onbut the compressorpumpmotor and the exhaustfanmotor has beenshutoff for inspection. Hence,boththe heatingandcoolingunitsare effectivelyshutoff. Therefore,the temperature stable statusindicatoraswell as the cooling/heating inspectionstatuslight indicatorshappenstobe on as showninFig.13.
  • 18. 17 C. Access and SecuritySubsystems There are twodifferenttypesof securitytechniques,i.e.perimetercontrol andinternal breach. Perimetercontrol isamethodusedtokeepintruders/perpetratorsoutof the safetyarea,whereas internal breachsecurityisusedwhenthe intruder/perpetratorhasbreachedthe premises. Differenttypesof critical infrastructure require differentlevelsof security. Forexample,anairport requiresmore securitythaneducationalfacilitiesbecause theyare subjecttomore damagesif perpetrated. Eventhoughitisdifficulttoharborthe truth that casinoshave greatersecuritycounter measuresthanlocal highschoolsorelementary schools;realityis,statisticssaythatpremiseslike banks, casinos,airports,prisons,powerplants,etcetera;all require higherstandards andoftentimes harbor incrediblyexpensive securitysystems toprotecttheirassets;soexpensive that mosteducational facilitiesare unable toaffordsuchcountermeasures. Althoughschoolsare unlikelytoaffordgreatbigsecuritysystems,theycanaffordsome of the basicsas to preventperimeterbreachesduringafterhours. All securitysystemsbigorsmall runonsome type of PLC or microcontrolleralongwith24hour supervision. Thissystemwill preventperpetratorsfrom obtainingaccesstothe safetyareathrougha PLC access control programusingPLCLogix. The simulationcreatedusingthe PLCLogix software emulatesanelectronickeypaddoorlock. This device isusedtokeepunwantedsuspectslackingauthorityornecessarycredentialsoutof a designated area. For example,agunmantryingto gainaccess to a school wouldbe deniedthe opportunity to wreakhavoc due to the perimeter“accesscontrol”systeminplace. Thatiswhat thisprogramseeksto do. Figure 14: Electronic Keypad Lock Ref. [4]
  • 19. 18 Table 3: Access Control Subsystem I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Lock_1 Locked One Lock_2 Unlocked Two Lock_3 Three Lock_4 Four Lock_5 Five Input Output Input Output Table 3 showsthe I/Omap of the AccessControl PLCprogram. The inputsinslot1, i.e.One,Two,Three, Four and Five representthe keypadnumbersusedtounlockthe device. Outputslocatedinslot2shows whethereachstage hasbeenbypassed. Forthisparticularsystem, five unlockingstagesmustbe activatedinorderto unlockthe systementirely. There are no inputsassociatedwiththisprogram regardingslot3 and slot4 isusedto indicate whetherthe systemislockedorunlocked. Figure 15: Access Control Subsystem - Initial Conditions Upon initial startupthe systemislockedas indicatedbydataentry00, slot4 seeninFig. 14. In orderto unlockthe system, the right combinationorsequence of numbersmustbe pressedusingthe inputsinslot1. Once the right combinationhasbeenpressed withinthe giventime frames,the unlockedstatus indicatorlightwill appearondataentry01 in slot 4. See Fig. 15 foran illustration. Afterthe systemisunlockeditwill remain unlockedforfive secondsbefore returntoa lockedstate whichgivesthe userenoughtime to turn the door handle before havingtore-enter the necessarycredentials. If the wrongcredentialsare entered,the system will enteralockdownsituationforfiveseconds before resettingthe systemautomatically. RefertoAppendix Ctosee the PLC program ladderlogicandto discernthe rightcombination neededtounlockthe system. Figure 16: Access Control Subsystem - unlocked
  • 20. 19 Accesscontrol is a huge part of infrastructure securityandPLCsallow for promisingsecuritysystems. One couldutilize the inputsinslot3to manuallycontrol the perimeteraccesscontrol device andwith furtherequipment,suchasremote sensors,one couldbuildaprettysophisticatedaccesscontrol and internal breach securitysystembyutilizingPLCs. D. CommunicationsSubsystem A buildinghastwomethodsof communication,i.e.byfree space optical (FSO) orradiofrequency(RF). Table 4: Communication Subsystem I/O Mapping Slot1 Slot2 Slot3 Slot4 Master Switch N/A FSO_Switch FSO_Communication N/A RF_Switch RF_Communication INPUT OUTPUT INPUT OUTPUT Free space optical communicationismore efficient andsecure thanotherformsof communication,such as radiofrequency andthe Internet. Hence,more buildingsare turningtoFSOtechnologiesasaprimary methodforcommunicatingbetween one pointandanother. The onlyproblemfacingthistype of communicationisthe atmosphericchannel throughwhichitpropagates. Intimesof heavyfog,rainor snow,the optical source isattenuatedinthe atmosphere byatmosphericturbulence,scatteringand absorption. For thisreason,it isnecessarytohave backupin the formof RF communicationduring timesof inclementweather. ThisPLCprogram seekstoaddressthatissue bycreatinga hybridRF/FSO communicationsystem. ReferringtoTable 2, Slot1 data entry00 isreservedforthe Master Switch,whichcontrolsthe platform. The data entrieslocatedinslot3 are reservedforthe manual override switches,thustheyare consideredinputs. Finally,the outputstatusof the overall systemisstoredinthe dataentrieslocatedin slot4. Furthermore,the programsimulatesbadweatherasa resultof temperaturesdropping. When the temperature reachesacertainthresholdaround30 degrees,the systemwill automaticallyswitch fromone form of communicationtoanother,i.e.FSOtoRF. Figure 17: Communication Subsystem I/O Rack - FSO
  • 21. 20 Whenthe simulatedtemperature isabove 30degreesFahrenheit,the FSOcommunicationlightswitch will be turnedon. On the otherhand,whenthe temperature is30 degreesFahrenheitorless,the RF lightswitchwill be on. RefertoFig.17 below foran illustrationof this. As showninFig.16 and 17, automaticprocessescan be usedto switchmethodsof communicationto ensure continuity.Furthermore,withmanual overrideswitchesone couldcontrol the methodof communicationdirectly. Thismaybe useful underaspecificsetof circumstances. E. Water,Plumbingand Fire Safety Subsystems Everysmart buildinghasafire safetysysteminstalled. The bestwaytodetectfireswithoutdirect supervisionisbyusingsmoke detectors. Ionizationsmoke detectorsare apopularchoice fordetecting smoke because of theirsensitivitytoit. Theyuse a radioactive substance thatgeneratescurrentinside the detector. If there issmoke presentinthe detector,the currentwill cease toflow andthe alarmwill be triggered. Underthiscondition,alongwithseveral others,fire mitigationdevicessuchaswater dispersionsystemstendtoturnonautomatically. For thisreason,itis incrediblyimportanttohave functionalwaterandplumbingsystemsincase of fire or otherrelatedcatastrophes. Thismayinclude core meltdownsinnuclearpowerplants. Automation and control systemsforwater,plumbingandfire safetysubsystemscansave livesandprevent emergenciesfromescalating. ThisPLCprogramwill create a watermanagementsystemaswell asafire safetysystemthatutilizesautomationandcontrol practicestoensure sustainabilityandsafety. Figure 18: Communication Subsystem I/O rack - RF
  • 22. 21 Table 5: Fire Safety, Water and Plumbing I/O Mapping Slot 1 Slot 2 Slot 3 Slot 4 Simulator F1R1V1 MO_SWITCH_1 F1R1V2 FLOOR_1_SWITCH F1R2V1 MO_SWITCH_2 F1R2V2 FLOOR_2_SWITCH F1R3V1 MO_SWITCH_3 F1R3V2 FLOOR_3_SWITCH F1R4V1 MO_SWITCH_4 F1R4V2 FLOOR_4_SWITCH F2R1V1 MO_SWITCH_5 F2R1V2 ALL_ON F2R2V1 MO_SWITCH_6 F2R2V2 ALL_OFF F2R3V1 MO_SWITCH_7 F2R3V2 F2R4V1 MO_SWITCH_8 F2R4V2 F3R1V1 MO_SWITCH_9 F3R1V2 F3R2V1 MO_SWITCH_10 F3R2V2 F3R3V1 MO_SWITCH_11 F3R3V2 F3R4V1 MO_SWITCH_12 F3R4V2 F4R1V1 MO_SWITCH_13 F4R1V2 F4R2V1 MO_SWITCH_14 F4R2V2 F4R3V1 MO_SWITCH_15 F4R3V2 F4R4V1 MO_SWITCH_16 F4R4V2 Input Output Input Output Table 5 isan input/outputmapof the fire safety,waterandplumbingsubsystems. Slot1controlsthe built-insimulationaswell asthe variouswaterdistributionsystemsforeachfloor. The outputsare locatedinslots2 and4. Theyare simplystatus indicatorlightsthatshow whetheradevice hasbeen turnedon;in thiscase,the devicesbeingturnedoff andonare water line valvescomingbefore and afterthe sprinklernozzle(s). Legend:  F – Floor  R – Room  V – Valve  MO – Manual Override Thisbuilding,the programwasbuiltfor,consistsof fourfloorswithfourroomsperfloor. Slot3 isa control panel usedtocontrol the waterdispersingsystems. Forexample,MO_SWITCH_1controlsthe valveslocatedoverroomone floorone (F1R1V1and F1R1V2). The inputslocatedinslot1 are furthercontrols. Floorcontrolsactivate anddisable the valveslocated on floorone,two,three andfourrespectively. Slot1 alsocontainsan ‘all on’and ‘all off’switch. Lastly, there isthe simulatorswitchwhichcontrolsthe built-insimulation,i.e.anionizingfire detector detectingsmoke bynoticingasignificantdropof electrical currentinthe device.
  • 23. 22 Figures19 and 20 showthe twomaindevicesusedinfire safetysystemswithinbuildings. Fig.19 shows the waterdispensingnozzle whichisresponsibleforthwartingactive firesandFig.20 showsan ionizing fire detectorwhichisusedindetectingthe signsof anactive fire. These twodevicesworkinharmonyto ensure buildingsafetyagainstthreatregardingfire safety. The PLCprogram forthisbuildingsubsystem shouldallowfora more efficient approachtohandlingbuildingfires. Byallowingformore precise control of the water,plumbingandfire safetysystem, the situationislesslikelytoresultinloss,i.e.loss of water,resourcesandlife. The simulationbuiltintothisprogramruns ona 60 secondtimerthat alternatesbetweentwoscenarios, 1) an ionizingfire detectordetectssmoke and2) an ionizingfiredetectordoesnotdetectsmoke. When no smoke isdetected,the I/OmaplooksasshowninFig.21 below. Figure 19: Water Dispersing Nozzle Ref. [5] Figure 10: Ionizing Fire Detector Ref. [6] Figure 11: Fire Safety Subsystem I/O Rack
  • 24. 23 In Fig.21 slot8 data entry01, 5.0 mA of currentindicatesthatnosmoke isdisruptingthe alphaparticle emission –stimulatedcurrentof the ionizingsmoke detector. Conversely,whenthe display reads1.0 mA whichmeansthe ionizingbeamof alphaparticleshasbeendisruptedbysmoke,thusreducingthe currentwithinthe device. See Fig.22. The 1.0 mA of current showninFig.22 slot8 data entry01 indicatesthatthe fire detectorhasdetected smoke. Asshowninslots2 and4, all lightshave beenlituptoindicate the valvesleadingtothe water distributionnozzles have beenopened. Hence waterisflowingandextinguishingthe fire inthe building. On topof thisautomaticprocess,the PLC programutilizesdigital switchestoissue variouscontrol responses. Suchresponsesinclude:activating/deactivatingnozzlesindividually,byfloororaltogether. Thisis to ensure thatwaterisnot wastedinan eventsuchas a false alarmbut alsoto ensure that actionscan be takenintothe handsof a humanintervenerwhenthe time isright. Combiningboth automaticprocesseswithcontrol methodsissuedbydirectsupervisionwill allow forasmarterand safer environment. See Appendix Eforthe PLC program. Conclusion Everysmart buildinghasautomatedprocessesinadditiontovariouscontrol systems. Inthisreportwe introducedthe conceptof a smart buildingandhow itmightextendtovarioustypesof critical infrastructure acrossthe UnitedStates. Upondoingso, we identifiednine majorsubsystemswithin Figure 12: Fire Safety Simulation - Fire Detected
  • 25. 24 smart buildings. Outof these nine,we addressedfivebycreatingPLCprogramsto enhance subsystems lackingautomationandcontrol processes,i.e.Lighting,HVAC,AccessandSecurity,Communicationsand Fire Safety. While introducingthe lightingsubsystem, we were abletodistinguishwhatcontrolsmayhelpincrease sustainabilityandemergencyresponse times. Thiswasachievedbycreatingacontrol panel thatwould allowforfaultdetectionandmanual overridecapabilities. Bybeingable tocontrol the lightingsystem withinabuildingremotelycreates notonly aconvenience topeoplebuta practical applicationaswell. For the HVACsubsystem,we analyzedHVACsystemcomponentsinordertofindareasthatmay allow for controlsimplementation. Upondoingsowe discoveredthatthe heatingandcondensing(cooling) unitseachhave fans (motors) andvalvesthatare critical to the functionalityof the units. Therefore, controlswere implementedtoeachof these components. Furthermore,the PLCprogramthat was built simulatesadigital heater/coolerwitharange from20 degreesFahrenheitto 120 degreesFahrenheit. It alsohas a temperature stabilizationsettingwhichhoversaround70 degreesFahrenheit. The third smartbuildingsubsystemwasthe accessandsecuritysubsystem. Forthissubsystemwe built an electronicperimeteraccesscontrol securitylock. Usingonlytimersand conditions,the lockonly openstothose whoknowthe correct sequence andforthose whocanexecute thissequence withina giventimeframe. Followingthe accessandsecuritysubsystemwasthe communicationssubsystem. The PLCprogram constructedforthissubsystemwasnotfor internal buildingcommunicationbutforexternal building communication. Essentially,the PLCprogramsimulatesanautomaticswitchinghybridRF/FSO communicationsystemgiventhe atmosphericconditionsasaninput. Lastlywas the fire safetywaterandplumbingsubsystems;here we constructedasimulationthatranon a 60 secondtimeralternatingbetweentimesof fire andtimeswithout. The PLCprogram wasbuiltto respondtothe built-insimulationbyissuingcommandsautomatically. Furthermore,the systemwas builttoresponddirectlytouserinputmeaningthat,underdirectsupervision,the systemcouldbe controlledatwill. By creatingPLC programsfor eachindividual buildingsubsystem,we create smarterbuildings. The conceptof a safer,smarterbuildingwasthe drivingforce behindtheseprojects. Furthermore, utilizing PLCs wasa greatway to gaininsightintothe worldof programmable logiccontrollersandhow effective they can be in makingourworlda saferandsmarter place tolive in.
  • 26. 25 References [1] Critical Infrastructure Sectors https://www.dhs.gov/critical-infrastructure-sectors [2] Coolingunit https://www.google.com/search?q=condenser+unit+anatomy&biw=1366&bih=705&source=lnms&tbm =isch&sa=X&ved=0ahUKEwj-kd65j_vMAhWly4MKHW_fD4UQ_AUIBygB#imgrc=pl-hCZdwfG7tSM%3A [3] Heatingunit https://www.google.com/search?biw=1366&bih=705&tbm=isch&sa=1&q=furnace+anatomy&oq=furnac e+ana&gs_l=img.3.0.0.188580.201657.0.203118.37.16.20.1.3.0.166.1904.1j15.16.0....0...1c.1.64.img..0. 37.2109...0i10j0i10i24.izOMcytuEiQ#imgrc=qZUHA4RAqXuCrM%3A [4] AccessControl Keypad https://www.google.com/search?q=keypad+door+lock&espv=2&source=lnms&tbm=isch&sa=X&ved=0a hUKEwjfsdmEoJbNAhUEbD4KHQiFDM4Q_AUICSgC#imgrc=x_dz4OeLzSGfvM%3A [5] Water DispersingNozzle https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahU KEwjvxJv9maDNAhVS72MKHa_kD8gQjRwIBw&url=http%3A%2F%2Findore.all.biz%2Fwater-sprinkler- system-g110729&psig=AFQjCNFLaQqW5ZLlNZLuhahhiDBRV7gKFg&ust=1465742318225508 [6] IonizingFire Detector https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahU KEwjNke7Dm6DNAhVT1GMKHcDOCtsQjRwIBw&url=http%3A%2F%2Fwww.cableorganizer.com%2Fsmo ke-detectors%2F&psig=AFQjCNFxjfliyPZSHFSaVHlxI1gWNKWavQ&ust=1465742780592482