OBJECTIVES
o Understand what a DDC system is and its application
o Identify control points and recognize differences between them
o Explain how closed loop control works and why it’s effective
o Discuss various protocols and BACnet basics
o Introduce 3rd-party integration
WHAT IS DDC?
o Direct Digital Control of an HVAC system
o A method of monitoring and controllingHVAC system performance by collecting,processing, and sending information usingsensors, actuators, and microprocessors
WHAT IS A POINT?
o A point is ANY input or outputdevice used to monitor andcontrol the overall or specificperformance of equipment
FOUR KINDS OF POINTS
Binary output - changes or maintains device status; ON/OFF
AI
BI
AO
BO
Analog input - a sensor that monitors physical variable data
Binary input - a sensor that monitors status; ON/OFF
Analog output - a physical action of a proportional device in thecontrolled equipment
POINT IDENTIFICATION EXERCISE
Think of a sensor, status oraction device used as the
control point.
Is it analog (A) or(B) Binary?
Is it an input (I)or an output
(O)?Supply air temperature (SAT)Supply fan start/stop (SF)Return air relative humidityHot water pump status (PMPS)Cooling coil valve (CCV)Variable frequency drive (VFD)Filter Status (FLTS)Boiler able/disable (BLR)
IOI
OOIO
ABABAABB
I
CLOSED LOOP CONTROL
Controller DeviceMicroprocessor
that digitallyprocesses inputs
and sendscommands tocreate outputs
The HVAC system
(Controlled device)
Inputs
REACTIONS
AIBIOutputs
ACTIONS
AO BO
…is accomplished by the control signalbeing sent to the controlled device with
constant feedback from the sensor/statusdevice providing input to the controller.
EXERCISE – AHU W/ECONOMIZER
A N A LOGIN PU T
B IN A R YIN PU T
A N A LOGOU T PU T
B IN A R YOU TPU T
POINTS LIST
ALGORITHMS:
SPT SFS MAD SFSAT
OAT
FTLRENTH
DX1DX2HS1HS2
BO-TIMECLKAO-ECONO
BO-COOLINGBO-HEATING
ALM-FILTERDCV
FILTER
RETURN AIR
SUPPLY AIR
EXAUST AIR
OUTSIDE AIR
SPACE SENSOR
T E T
ACTUATOR
SPACE CO2SENSOR
COOL
(2)
HEAT
(2)
CO2
#1 #5
#3#7 #6
#9
#4#8
#10 #11
#2
Reset Questions
A Programmable Thermostat is aDirect Digital Controller
True
Incorrect
False
Correct
Reset Questions
TrueIncorrect
FalseCorrect
Closed Loop Control is accomplishedwithout constant feedback from the
device being controlled
PAGE
WorkbookEXERCISE
1
A N A LOGIN PU T
B IN A R YIN PU T
A N A LOGOU T PU T
B IN A R YOU TPU T
CWS CTFS P1VFD P1CWR
DP
B1ALMP1STAT
P2B1
CTSPCTF
HWS
WSHP CENTRAL PLANTFill in the Points List
P2VFDCTVFD
P2STAT
STANDARD PROTOCOL BENEFITS
Why a standard protocol?
Single-seat workstationOwners not “locked in”
Many building systemsMultiple manufacturers
Protocol is a set of rules governing the exchange of data over a network
MODBUS
o Developed by Modicon, todaySchneider Electric, in 1979
o From the Process Control Industry
o Openly published and royalty-free
LON (Local Operating Network)
o Developed by Echelon Corp in 1988
o LonTalk - Open Protocol Standard
o LonWorks (Platform)
o Manufactures must purchaseNeuron Chip from Echelon
BACNET
o Developed by ASHRAE in 1995
o ASHRAE Standard 135o Building Automation & Control Networks
o Designed for HVAC Control Systems
o No Associated Cost
BACNET
o Why Carrier picked BACneto Biggest piece of the pie and growing
BACnet37%
LonWorks14%
Modbus7%
Johnson N213%
Standaloneor
Hardwired23%
Other 6%(proprietary)
BACNET
BACnet Standard Development• Clarifications• Corrections• Extensions
BACnet Community Development• Education• Interoperability Testing• Promotional Activities
BIGsMarketing, Training, and Certification
BACNET
Source: http://www.bacnet.org
Vendor Growth since 1995
As of Nov 2017, 1025 Vendor IDs have been issued & distributed
BACNET BASICS
Device Modeling ConceptPhysical BACnet Device Appears as:
Collection of ObjectsDifferent Properties of Data & FunctionalityInputs, Outputs, Values
Device
BinaryOutput
BinaryInput
AnalogInput
AnalogOutput
Values
BACNET BASICS
ObjectsBelong to different Object Types
Number and Type of Properties vary
If temp > 78 THEN
Sensor Valve Calculation
Examples:Analog Input Analog Output Analog Value
BACNET BASICS
Sensor Object PropertiesObject_Name = SPACE TEMPObject_Type = ANALOGINPUTPresent_Value = 78.0High_Limit = 79.0Low_Limit = 68.0
ObjectsHave properties, which tell what informationmay be read or written
BACNET BASICS
Object PropertiesObject_Name = SPACE TEMPObject_Type = ANALOG INPUTPresent_Value = 78.0High_Limit = 79.0Low_Limit = 68.0
Object ServicesWho-Is and I-AmWho-Has and I-HaveRead PropertyWrite PropertyEtc… (37 Total)
ServicesObject information can be read or writtenusing Standard Services
BACNET BASICS
-BACnet IP-BACnet MS/TP-ARCnet-Ethernet-PTP (Point-to-Point)
Transport SystemsData can be transferred using standardtransport systems
Reset Questions
Protocol is a set of rules governing theexchange of data over a network
True
Incorrect
False
Correct
Reset Questions
TrueIncorrect
FalseCorrect
Objects are a group of graphics used torepresent the controlled device
Reset Questions
are the developers of BACnetIncorrect
is not open to manufacturesIncorrect
performs independent testing of products forconformanceCorrect
BACnet Testing Laboratories…
PAGE
WorkbookEXERCISE
2Draw a line from each item listed on the left tothe item on the right that describes its function
RepresentsInformation
MakingRequest
TransportSystem
Objects
Services
LANsNetworks
THIRD PARTY INTEGRATION
3rd party BAS(Building Automation System)
CarrierEquipment
System Integrator = Third Party
Sharing Carrier equipment data with others!
Honeywell, Siemens, Alerton, etc.
BACNET MS/TP & BACNET IP
BACnetMS/TP
Open PIC(Product Integrated Controller)Carrier
Equipment
i-Vu Open Router(CIV-OR)
CCN PIC(Product Integrated Controller)
CCN
BACnetMS/TP
BACnetIP
UPC Open Factory Installed
UPC Open Field Installed (OPN-UPC)
THIRD PARY INTEGRATION
Third PartyRouter
Third PartyWEB Server
IP Network
Device Network
CCN Network
Carrier Gateway
Carrier Factory Installed ComfortLink Controls
Reset Questions
TrueIncorrect
FalseCorrect
All HVAC equipment with factory installedcontrols are Native BACnet
Reset Questions
The Mechanical EngineerIncorrect
The Controls ContractorIncorrect
The manufacture of the equipment being integratedCorrect
Who must supply the third partyPoints List to the integrator
Reset Questions
Who is going to win the 2017 World Series?
LA Dodgers
Incorrect
Houston Astros
Correct
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