microtech water-cooled screw chiller controller · ethernet® network and mcquay memory locations...

BACnet Data Information Packet BD 02-8

Group: Controls

Date: January 2003

© 2003 McQuay International

MicroTech®

Water-Cooled Screw Chiller Controller

Point mapping data for the MicroTech BACdrop™ Gateway with PMF version 1.10 softwareand the following MicroTech water-cooled screw chiller applications:

• B vintage (models PFS-B)• C vintage (models WHS and PFS-C)

ContentsRevision History................................................................................................................................... 2

Overview ............................................................................................................................................ 3

Introduction.......................................................................................................................................... 3

Network Configuration ........................................................................................................................ 3

Software Identification and Compatibility ........................................................................................... 3BACdrop Software: The PMF File.................................................................................................. 3MicroTech Controller Software: IDENTs ....................................................................................... 3Compatibility................................................................................................................................... 4

Supplemental Literature ....................................................................................................................... 5

Conversions and Conventions.............................................................................................................. 5

B-Vintage Water-Cooled Screw Chiller ...................................................................................... 6

Analog Value Objects........................................................................................................................... 6

Analog Input Objects ......................................................................................................................... 14

Analog Output Objects....................................................................................................................... 16

Binary Input Objects .......................................................................................................................... 18

Binary Output Objects........................................................................................................................ 19

C-Vintage Water-Cooled Screw Chiller .................................................................................... 20

Analog Value Objects......................................................................................................................... 20

Analog Input Objects ......................................................................................................................... 29

Analog Output Objects....................................................................................................................... 31

Binary Input Objects .......................................................................................................................... 36

Binary Output Objects........................................................................................................................ 36

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Revision HistoryVersion 1 1999-05-24 Initial release. For PMF version 1.01.

Version 2 1999-07-14 No changes to point mapping data. For PMF versions 1.01through 1.03.



Version 5 1999-08-27 For PMF version 1.06.

PFS-B: Changed the OAT AI object from low resolution to highresolution and changed its name. Added alarm data objects forcurrent alarm. Added a previous alarm object. Changed the orderof all AV objects. Changed the units and object name for therefrigerant leak detection AI. Changed the names of several AVand AI objects for consistency and clarity. Changed the name ofthe chilled water setpoint object (AO3) and the BAS OAT object(AO5) for consistency with keypad and IM documentation.Deleted the OutdoorAirTempMethod object (old AO6). Deletedthe CondEvapRatio object (old AV40). Changed the name of theclear alarm BO object.

PFS-C/WHS: Added alarm data objects for current circuit alarms.Added previous circuit alarm objects. Added saturated condenserand evaporator temp AV objects. Deleted the condenser pump andevaporator pump hours AV objects since the controller does nottrack them. Added compressor start totalization AV objects.Deleted the last compressor start and stop time-stamp AV objectsbecause the data is updated whenever either compressor starts orstops—confusing and of little value. Changed the order of all AVobjects. Changed the units and object name for the refrigerant leakdetection AI. Changed the names of several AV and AI objects forconsistency and clarity. Fixed a mapping error for the liquid linepressure AI. Changed the name of the chilled water setpoint object(AO1) and the BAS OAT object (AO9) for consistency withkeypad and IM documentation. Deleted the OutdoorAirTemp-Method object (old AO6). Changed the names of the clear alarmBO objects.

Version 6 1999-11-19 No changes to point mapping data. For PMF versions 1.06 and1.07.

Version 7 2000-02-25 No changes to point mapping data. For PMF versions 1.06through 1.08. See updated software compatibility table on page 4.

Version 8 2003-01-06 No changes to point mapping data. For PMF versions 1.09 and1.10. Minor editorial changes.

NoticeCopyright © 2003 McQuay International, Minneapolis, MN.

All rights reserved throughout the world.

McQuay International reserves the right to change any information contained herein without priornotice. No guarantees are given as to the accuracy of the information provided.McQuay and MicroTech are registered trademarks of McQuay International.BACdrop and Monitor are trademarks of McQuay International.All other trademarks are the property of their respective owners.

BD 02-8 3

Overview

IntroductionThe MicroTech® BACdrop™ Gateway integrates a MicroTech network into a BACnet™ buildingautomation system (BAS) network so that you can monitor and control McQuay Internationalequipment from the BAS network. The gateway translates between BACnet variables on anEthernet® network and McQuay memory locations on the proprietary McQuay network.

This document provides point mapping information for the MicroTech water-cooled screw chillerapplications used in models PFS-B, PFS-C, and WHS. For other MicroTech applications, refer to theappropriate BACnet Data Information Packet documentation.

Network ConfigurationThe BACnet network interface to the BACdrop gateway must be Ethernet, 10BaseT.

Once the MicroTech network has been commissioned (typically by a McQuay representative), theBAS vendor can connect the Ethernet network to the BACdrop gateway. The network must be intactfor the BAS to control the chillers; however, the chillers are capable of operating even ifcommunications with the BAS are lost.

For more information, refer to IM 689, MicroTech BACdrop Gateway.

It is worth noting here that the B-vintage chiller has two MicroTech controllers (one for eachcompressor) and the C vintage chiller has one MicroTech controller. Refer to the chillerdocumentation for more information (see “Supplemental Literature” below).

Software Identification and CompatibilityIt is extremely important that compatibility be maintained between the software in the BACdropgateway and its associated MicroTech controllers. This section provides information about softwarecompatibility for both current and old releases of BACdrop and MicroTech software. New releases ofBACdrop software and the BACnet Data Information Packets will be made available on the McQuayInternational bulletin board system called McQuay OnLine. For access to McQuay OnLine, contactthe McQuay Controls group in Minneapolis.

BACdrop Software: The PMF FileThe BACdrop gateway contains a single point mapping file (PMF) that contains specific pointmapping information for MicroTech control applications. The standard PMF file contains allcurrently supported standard MicroTech control applications. This BACnet Data Information Packet(BDIP) describes only the portion of the standard PMF that pertains to standard MicroTech water-cooled screw chiller applications. Other BDIPs describe other portions of the PMF file and otherMicroTech applications.

Custom PMF files can be written for custom MicroTech control applications, but in such instancesthe information in this document may not apply. Custom PMF files will have an “x” in their names;e.g., “PMFx122.”

MicroTech Controller Software: IDENTsAll MicroTech application software is labeled with an “IDENT.” In most cases, the IDENT has anomenclature scheme, which is described in the installation and operation manuals for the controller.The last two or three characters of the IDENT are always used to denote the version and revision ofthe software. For example, the characters “03G” would mean revision G of the third version. Ingeneral, the revision level is incremented for very minor changes and the version level is incrementedfor major changes.

4 BD 02-8

The IDENT can be read from a MicroTech controller in one of four ways:

1. Using the keypad/display

If a MicroTech controller is equipped with a keypad/display, you can use it to find the IDENT(except on series-100 centrifugal chillers).

2. Using the BACdrop commissioning software

A network diagnostic can be used to show the IDENTs.

3. Using MicroTech Monitor™ software

If Monitor software is available, it will typically show the IDENT on an application screen. Or anetwork diagnostic can be used to show the IDENTs. The read/write memory function can alsobe used to read IDENTs directly from memory.

4. Using the BACnet BAS

From the BACnet side of the gateway, an IDENT can be read in the propertyApplication_Software_Version, which is part of the DEVICE object for the MicroTechcontroller.

CompatibilityThe PMF file contains a detailed map that associates BACnet objects with the memory locations andfunctions within the MicroTech controllers. These memory locations are defined by the MicroTechapplication software within the controllers, and thus compatibility between the PMF file and theMicroTech application software (IDENTs) must be maintained.

Note that the BACdrop gateway is not able to check for software compatibility. It is the responsibilityof the installer (typically a representative of McQuay International) to assure software compatibilityusing the information presented here.

This edition of this BDIP documents the versions of BACdrop and MicroTech controller software asshown in the table below. If you encounter a later version of software, please refer to McQuayOnLine for an update to this document.

Software CompatibilityBACnet DataInformation Packet

DescribesPMF versions

CompatibleIDENTs Application description

BD 02-7 - 8- 1.06 – 1.10 PES2E03H Models PFS-B, water-cooled screw chillerPES2S03HPES3E03HPES3S03HPES4E03HPES4S03H

FLU2E02D Models WHS and PFS-C, water-cooled screw chillerFLU2S02DFLU3E02DFLU3S02DFLU4E02DFLU4S02D

BD 02-8 5

Supplemental LiteratureFor more information on the BACdrop gateway and the MicroTech control applications, see thefollowing documents:

IM 689 MicroTech BACdrop Gateway, Installation and Maintenance Data

OM 135 MicroTech Water-Cooled Screw Compressor Chiller Controller,Operation Manual (WHS/PFS-C only)

Conversions and ConventionsTemperaturesAll temperatures are stated in degrees Fahrenheit (°F). To get degrees Celsius (°C), use thefollowing:

C F=

− 3218.

PressuresAll pressures are stated in pounds per square inch (psi). To get kilo-Pascals (kPa), use the following:

kPa psi= ×6 89.

Flow RatesAll flow rates are stated in gallons per minute (gpm). To get liters per second (L/s), use thefollowing:

L/s = 0.0631 × gpm

AbbreviationsBAS building automation system

kPa kilo-Pascals

OAT outdoor air temperature

psi pounds per square inch

gpm gallons per minute

RLA rated load amps

6 BD 02-8

B-Vintage Water-Cooled Screw Chiller

Analog Value ObjectsInstance Object_Name Property

UnitsProp.

UnitsDescription

ValidRange

1 UnitStatus0 = All Systems Off1 = Off: Alarm2 = Off: Ambient Lockout3 = Off: Panel Switch4 = Off: Manual5 = Off: Remote Switch6 = Off: Remote Communications7 = Off: Time Schedule8 = Start Requested9 = Evaporator Pump Off10 = Evaporator Pump On: Recirculate11 = Evaporator Pump On: Cycle Timers12 = Evaporator Pump On: Waiting For Load13 = Evaporator Pump On: Waiting For Flood14 = Condenser Pump Off15 = Condenser Pump On: Waiting For Flow16 = Start-Up Unloading17 = MCR Started18 = MCR On: Prepurge19 = MCR On: Open Solenoid20 = Running OK21 = MCR Off: Rapid Shutdown22 = Shutdown Unloading—Pumpdown23 = MCR Off: Routine Shutdown24 = Condenser Pump Off: Shutdown25 = Evaporator Pump Off: Shutdown

95 no units 0 – 25

2 ChilledWaterTempActiveSpt 64 °F 0 – 80

3 CompressorMotorCurrent 3 Amps 0 – 65,535

4 CompressorSuperheatSuction 64 °F 0 – 999*

5 CompressorSuperheatDischarge 64 °F 0 – 999*

6 CompressorLiftPressure 56 psi 0 – 999*

7 CondPumpStatus0 = Condenser Pumps Off1 = Starting Condenser Pump #12 = Starting Condenser Pump #23 = Condenser Pump #1 On4 = Condenser Pump #2 On5 = Condenser Pump #1 Fail; Starting #26 = Condenser Pump #2 Fail; Starting #17 = Condenser Pumps #1 & #2 Failed

95 no units 0 – 7

8 CondSatRefrigerantTemp 64 °F -40 – 999;5786.5 = N/A

9 CondApproachTemp 64 °F 0 – 999*

10 CondSubcoolingTemp 64 °F 0 – 999*

11 CondWaterTempDelta 64 °F 0 – 999*

12 CoolingTowerStage 95 no units 0 – 6

13 CoolingTowerValvePosition 98 percent 0 – 100

BD 02-8 7

Instance Object_Name PropertyUnitsProp.

UnitsDescription

ValidRange

14 EvapPumpStatus0 = Evaporator Pumps Off1 = Starting Evaporator Pump #12 = Starting Evaporator Pump #23 = Evaporator Pump #1 On4 = Evaporator Pump #2 On5 = Evaporator Pump #1 Fail; Starting #26 = Evaporator Pump #2 Fail; Starting #17 = Evaporator Pumps #1 & #2 Failed

95 no units 0 – 7

15 EvapSatRefrigerantTemp 64 °F -40 – 999;5786.5 = N/A

16 EvapApproachTemp 64 °F 0 – 999*

17 EvapWaterTempDelta 64 °F 0 – 999*

18 FilterPressureDrop 56 psi 0 – 999*

19 CompressorNumberOfStarts 95 no units 0 – 49,999

20 CompressorOperatingHours 71 hours 0 – 49,999

21 LastStartHour 95 no units 0 – 23

22 LastStartMinute 95 no units 0 – 59

23 LastStartMonth 95 no units 1 – 12

24 LastStartDate 95 no units 1 – 31

25 LastStartYear 95 no units 0 – 99

26 LastStopHour 95 no units 0 – 23

27 LastStopMinute 95 no units 0 – 59

28 LastStopMonth 95 no units 1 – 12

29 LastStopDate 95 no units 1 – 31

30 LastStopYear 95 no units 0 – 99

31 CondPump1OperHours 71 hours 0 – 49,999

32 CondPump2OperHours 71 hours 0 – 49,999

33 EvapPump1OperHours 71 hours 0 – 49,999

34 EvapPump2OperHours 71 hours 0 – 49,999

35 CommunicationStatus0 = No Comm1 = Comm. OK

95 no units 0, 1

36 ChillerUnitTempTypeConfig0 = Standard1 = Low Temp

95 no units 0, 1

37 CondWaterFlowRateSensorConfig0 = Not Present1 = Present

95 no units 0, 1

38 EvapWaterFlowRateSensorConfig0 = Not Present1 = Present

95 no units 0, 1

39 CoolingTowerControlConfig0 = External1 = Chiller

95 no units 0, 1

40 RefrigLeakDetectSensorConfig0 = Not Present1 = Present

95 no units 0, 1

41 MasterSlaveSetpointConfig0 = Master1 = Slave

95 no units 0, 1

8 BD 02-8


UnitsDescription

ValidRange

42 LeadLagStatus0 = Lead and lag are off1 = Lead is on2 = Lag is on3 = Lead and lag are on

95 no units 0 – 3

43 LeadUnit0 = Master1 = Slave

95 no units 0, 1

44 LeadUnitStatusSame as UnitStatus (1)

95 no units 0 – 25

45 LagUnitStatusSame as UnitStatus (1)

95 no units 0 – 25

46 LeadMotorCurrentPct 98 percent 0 – 125

47 LagMotorCurrentPct 98 percent 0 – 125

48 LeadStatus0 = Disabled1 = Enabled

95 no units 0, 1

49 LagStatus0 = Disabled1 = Enabled

95 no units 0, 1

50 CurrentAlarm0 = None1 = Liquid Line Temp Sensor Warning2 = Entering Evaporator Temp Sensor Warning3 = Leaving Condenser Temp Sensor Warning4 = Low Discharge Superheat5 = High Discharge Superheat6 = Entering Evaporator Temp Sensor Problem7 = Outside Air Temp Sensor Problem8 = High Condenser Pressure: No Load9 = High Condenser Pressure: Unload10 = Low Evaporator Pressure: Unload11 = Condenser Pressure Low—Freeze Protect12 = Evaporator Pressure Low—Freeze Protect13 = Evaporator Pump 1 Fail14 = Evaporator Pump 2 Fail15 = Condenser Pump 1 Fail16 = Condenser Pump 2 Fail17 = Failed Pump Down18 = Low Evaporator Pressure: Shutdown19 = Low Evaporator Pressure: No Start20 = Pre Purge Fail21 = Open Solenoid Fail22 = Low Motor Current23 = High Discharge Temperature24 = High Condenser Pressure25 = Mechanical High Cond Pressure Switch26 = High Motor Temperature27 = Starter Fault28 = No Starter Transition29 = No Evaporator Water Flow30 = No Condenser Water Flow31 = Failed Stop—High Motor Current32 = No Liquid Run33 = No Superheat Drop At Start34 = High Discharge Superheat35 = Evaporator Pressure Sensor Failure36 = Entering Condenser Temp Sensor Failure37 = Suction Temp Sensor Failure38 = Discharge Temp Sensor Failure39 = Condenser Pressure Sensor Failure40 = Leaving Evap Temp Sensor Failure41 = not used

95 no units 0 – 44

BD 02-8 9


UnitsDescription

ValidRange

42 = not used43 = not used44 = Voltage Ratio Sensor Failure

51 AtCurrAlarm_UnitStatusSame as UnitStatus (1)

95 no units 0 – 25

52 AtCurrAlarm_MotorCurrentPct 98 percent 0 – 125

53 AtCurrAlarm_EntEvapWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

54 AtCurrAlarm_LvgEvapWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

55 AtCurrAlarm_EntCondWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

56 AtCurrAlarm_LvgCondWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

57 AtCurrAlarm_EvapPressure 56 psi 0 – 200;5886.5 = N/A;6142.5 = open;6398.5 = short

58 AtCurrAlarm_CondPressure 56 psi 0 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

59 AtCurrAlarm_EvapApproachTemp 64 °F 0 – 999*

60 AtCurrAlarm_CondApproachTemp 64 °F 0 – 999*

61 AtCurrAlarm_DischargeTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

62 AtCurrAlarm_DischargeSuperheat 64 °F 0 – 999*

63 AtCurrAlarm_SuctionSuperheat 64 °F 0 – 999*

64 AtCurrAlarm_Subcooling 64 °F 0 – 999*

65 AtCurrAlarm_EXVPosition 95 no units 0 – 760;0 = fully closed760 = fully open

66 AtCurrAlarm_EXVControl0 = None1 = Water Pressure2 = Fuzzy Logic

95 no units 0 – 2

67 AtCurrAlarm_EvapFlow 89 gpm 0 – 65,535

68 AtCurrAlarm_CondFlow 89 gpm 0 – 65,535

69 PreviousAlarmSame as CurrentAlarm (50)

95 no units 0 – 44

* Under normal conditions, the upper end of this object’s range will be 999.0 or less. If one of the sensors used to calculate theobject’s value is bad or disconnected, this object’s value may go out of range to some arbitrary 4-digit value.

ANALOG_VALUE 1: UnitStatusThe overall state of the compressor controller. See IM manual for more information.

10 BD 02-8

ANALOG_VALUE 2: ChilledWaterTempActiveSptThe chilled water temperature setpoint the chiller uses for temperature control. It is set by one ofseveral control scenarios that depend on upon chiller configuration parameters. The BAS can set thissetpoint by writing to the NetworkChilledWaterTempSetpoint object (ANALOG_OUTPUT 3). Theresolution is 0.5°F.

ANALOG_VALUE 3: CompressorMotorCurrentThe compressor motor current. The actual range depends on the size of the motor. The resolution is1 A.

ANALOG_VALUE 4: CompressorSuperheatSuctionThe difference between the actual refrigerant temperature entering the compressor and the saturatedsuction temperature. The resolution is 0.1°F.

ANALOG_VALUE 5: CompressorSuperheatDischargeThe difference between the actual refrigerant temperature leaving the compressor and the saturatedcondensing temperature. The resolution is 0.1°F.

ANALOG_VALUE 6: CompressorLiftPressureThe pressure rise of the refrigerant as it passes through the compressor. It is calculated by subtractingthe evaporator pressure from the condenser pressure. The resolution is 0.1 psi.

ANALOG_VALUE 7: CondPumpStatusThe operating status of the condenser water pumps.

ANALOG_VALUE 8: CondSatRefrigerantTempThe saturated temperature of the refrigerant in the condenser shell. It is calculated from the measuredcondenser pressure. The resolution is 0.1°F.

ANALOG_VALUE 9: CondApproachTempThe difference between the condenser refrigerant temperature and the condenser leaving watertemperature. The resolution is 0.1°F.

ANALOG_VALUE 10: CondSubcoolingTempThe subcooling temperature. It is calculated by subtracting the actual refrigerant temperature in theliquid line from the saturated condensing temperature. The resolution is 0.1°F.

ANALOG_VALUE 11: CondWaterTempDeltaThe difference between the entering and leaving condenser water temperatures. The resolution is0.1°F.

ANALOG_VALUE 12: CoolingTowerStageThe number of energized cooling tower stages. The data is valid only if tower control is provided bythe chiller.

ANALOG_VALUE 13: CoolingTowerValvePositionThe position of the cooling tower valve. It is given as a percent of full open to the tower and has a1% resolution. It is valid only if tower control is provided by the chiller.

ANALOG_VALUE 14: EvapPumpStatusThe operating status of the evaporator water pumps.

ANALOG_VALUE 15: EvapSatRefrigerantTempThe temperature of the refrigerant in the evaporator shell. The resolution is 0.1°F.

BD 02-8 11

ANALOG_VALUE 16: EvapApproachTempThe difference between the evaporator refrigerant temperature and the leaving evaporator watertemperature. The resolution is 0.1°F.

ANALOG_VALUE 17: EvapWaterTempDeltaThe difference between the entering and leaving evaporator water temperatures. The resolution is0.1°F.

ANALOG_VALUE 18: FilterPressureDropThe pressure difference between the condenser and the liquid line. It is measured across therefrigerant filter-drier.

ANALOG_VALUE 19: CompressorNumberOfStartsThe total number of compressor motor starts that have occurred. The value rolls over to 0 after49,999 starts.

ANALOG_VALUE 20: CompressorOperatingHoursThe total number of hours the compressor has run. The value rolls over to 0 after 49,999 hours.

ANALOG_VALUE 21: LastStartHourThe hour the compressor last started.

ANALOG_VALUE 22: LastStartMinuteThe minute the compressor last started.

ANALOG_VALUE 23: LastStartMonthThe month the compressor last started.

ANALOG_VALUE 24: LastStartDateThe date the compressor last started.

ANALOG_VALUE 25: LastStartYearThe year the compressor last started.

ANALOG_VALUE 26: LastStopHourThe hour the compressor last stopped.

ANALOG_VALUE 27: LastStopMinuteThe minute the compressor last stopped.

ANALOG_VALUE 28: LastStopMonthThe month the compressor last stopped.

ANALOG_VALUE 29: LastStopDateThe date the compressor last stopped.

ANALOG_VALUE 30: LastStopYearThe year the compressor last stopped.

ANALOG_VALUE 31: CondPump1OperHoursThe number of hours condenser pump #1 has run. The value rolls over to 0 after 49,999 hours.

ANALOG_VALUE 32: CondPump2OperHoursThe number of hours condenser pump #2 has run. The value rolls over to 0 after 49,999 hours.

ANALOG_VALUE 33: EvapPump1OperHoursThe number of hours evaporator pump #1 has run. The value rolls over to 0 after 49,999 hours.

12 BD 02-8

ANALOG_VALUE 34: EvapPump2OperHoursThe number of hours evaporator pump #2 has run. The value rolls over to 0 after 49,999 hours.

ANALOG_VALUE 35: CommunicationStatusThe status of network communications with the BAS. Communications with the BAS must exist orelse the chiller controller will revert to internal control setpoints. This analog value object indicateswhether communications with the BAS are active. Communications are considered active when anon-zero value is periodically written to the CommunicationsSignal object (ANALOG_OUTPUT 4).See the “Analog Output Objects” section for more information.

ANALOG_VALUE 36: ChillerUnitTempTypeConfigA configuration parameter that indicates whether the chiller is set up for standard or low dischargetemperatures.

ANALOG_VALUE 37: CondWaterFlowRateSensorConfigA configuration variable that indicates whether a condenser water flow rate sensor is connected tothe chiller. Condenser water flow rate data (ANALOG_INPUT 4) is valid only when this sensor ispresent.

ANALOG_VALUE 38: EvapWaterFlowRateSensorConfigA configuration variable that indicates whether an evaporator water flow rate sensor is connected tothe chiller. Evaporator water flow rate data (ANALOG_INPUT 9) is valid only when this sensor ispresent.

ANALOG_VALUE 39: CoolingTowerControlConfigA configuration variable that indicates whether cooling tower functions are being controlled by thechiller or an external control system. Cooling tower data points are valid only when the chiller is incontrol.

ANALOG_VALUE 40: RefrigLeakDetectSensorConfigA configuration variable that indicates whether a refrigerant leak detection sensor is connected to thechiller. Refrigerant sensor data (ANALOG_INPUT 15) is valid only when this sensor is present.

ANALOG_VALUE 41: MasterSlaveSetpointConfigA configuration variable that indicates whether the compressor is lead-lag Master or Slave. TheMaster controls lead-lag processing for the entire chiller (i.e., for both compressors), and thus certainanalog output objects that control the lead-lag function should be written to only in the lead-lagMaster. The MasterSlaveSetpointConfig object can be written to locally with the controller’skeypad/display. A McQuay International representative should do this during the commissioningprocess.

Note that the terms lead-lag “Master” and “Slave” refer only to the chiller’s lead-lag function, not theMicroTech network architecture or communication port configurations.

ANALOG_VALUE 42: LeadLagStatusThis object indicates which compressors are running, in terms of their lead-lag status.

ANALOG_VALUE 43: LeadUnitThis object indicates which compressor is currently lead, the Master or Slave. See IM manual formore information.

ANALOG_VALUE 44: LeadUnitStatusThe unit status of the lead compressor.

ANALOG_VALUE 45: LagUnitStatusThe unit status of the lag compressor.

BD 02-8 13

ANALOG_VALUE 46: LeadMotorCurrentPctThe current draw of the lead compressor motor as a percentage of its RLA.

ANALOG_VALUE 47: LagMotorCurrentPctThe current draw of the lag compressor motor as a percentage of its RLA.

ANALOG_VALUE 48: LeadStatusThe enabled/disabled status of the lead compressor.

ANALOG_VALUE 49: LagStatusThe enabled/disabled status of the lag compressor.

ANALOG_VALUE 50: CurrentAlarmThe current unit alarm. If multiple alarms exist at the same time, the most serious alarm (i.e., the onewith the highest code number) is given.

ANALOG_VALUE 51: AtCurrAlarm_UnitStatusThe unit status of the chiller at the time the current alarm occurred.

ANALOG_VALUE 52: AtCurrAlarm_MotorCurrentPctThe motor current at which the compressor was running at the time the current alarm occurred. Theresolution is 1%.

ANALOG_VALUE 53: AtCurrAlarm_EntEvapWaterTempThe evaporator entering water temperature at the time the current alarm occurred. The resolution is0.1°F.

ANALOG_VALUE 54: AtCurrAlarm_LvgEvapWaterTempThe evaporator leaving water temperature at the time the current alarm occurred. The resolution is0.1°F.

ANALOG_VALUE 55: AtCurrAlarm_EntCondWaterTempThe condenser entering water temperature at the time the current alarm occurred. The resolution is0.1°F.

ANALOG_VALUE 56: AtCurrAlarm_LvgCondWaterTempThe condenser leaving water temperature at the time the current alarm occurred. The resolution is0.1°F.

ANALOG_VALUE 57: AtCurrAlarm_EvapPressureThe evaporator pressure at the time the current alarm occurred. The resolution is 0.1 psi.

ANALOG_VALUE 58: AtCurrAlarm_CondPressureThe condenser pressure at the time the current alarm occurred. The resolution is 0.1 psi.

ANALOG_VALUE 59: AtCurrAlarm_EvapApproachTempThe evaporator approach temperature at the time the current alarm occurred. The resolution is 0.1°F.

ANALOG_VALUE 60: AtCurrAlarm_CondApproachTempThe condenser approach temperature at the time the current alarm occurred. The resolution is 0.1°F.

ANALOG_VALUE 61: AtCurrAlarm_DischargeTempThe compressor discharge temperature at the time the current alarm occurred. The resolution is 0.1°F.

ANALOG_VALUE 62: AtCurrAlarm_DischargeSuperheatThe discharge superheat temperature at the time the current alarm occurred. The resolution is 0.1°F.

14 BD 02-8

ANALOG_VALUE 63: AtCurrAlarm_SuctionSuperheatThe suction line superheat temperature at the time the current alarm occurred. The resolution is0.1°F.

ANALOG_VALUE 64: AtCurrAlarm_SubcoolingThe liquid line subcooling temperature at the time the current alarm occurred. The resolution is0.1°F.

ANALOG_VALUE 65: AtCurrAlarm_EXVPositionThe position of the electronic expansion valve (EXV) at the time the current alarm occurred. Thevalue is expressed in “steps.”

ANALOG_VALUE 66: AtCurrAlarm_EXVControlThe control state of the electronic expansion valve (EXV) at the time the current alarm occurred.

ANALOG_VALUE 67: AtCurrAlarm_EvapFlowThe evaporator water flow rate at the time the current alarm occurred. The resolution is 1 gpm. Notethat the evaporator flow rate sensor is optional.

ANALOG_VALUE 68: AtCurrAlarm_CondFlowThe condenser water flow rate at the time the current alarm occurred. The resolution is 1 gpm. Notethat the condenser flow rate sensor is optional.

ANALOG_VALUE 69: PreviousAlarmThe previous alarm. In most cases, a previous alarm is a cleared alarm. An exception will occur whenan active higher priority alarm replaces an active lower priority alarm. In this instance, the lowerpriority alarm will be pushed into the previous alarm spot even though it is still active.

Analog Input ObjectsInstance Object_Name Property

UnitsProp.

UnitsDescription

ValidRange

1 CompressorMotorCurrentPct 98 percent 0 – 125

2 CompSuctionTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

3 CondRefrigerantPressure 56 psi 0 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

4 CondWaterFlowRate 89 gpm 0 – 65,535

5 CondWaterTempEnt 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

6 CondWaterTempLvg 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

7 DischargeRefrigerantTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

8 EvapRefrigerantPressure 56 psi 0 – 200;5886.5 = N/A;6142.5 = open;6398.5 = short

9 EvapWaterFlowRate 89 gpm 0 – 65,535

BD 02-8 15


UnitsDescription

ValidRange

10 EvapWaterTempEnt 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

11 EvapWaterTempLvg 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

12 LiquidLineRefrigerantTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

13 LiquidLinePressure 56 psi 0 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

14 OutdoorAirTemp 64 °F -50 – 280 (local),-99 – 155 (network);5786.5 = N/A;6042.5 = open;6298.5 = short

15 RefrigerantLeakConcentration 98 percent 0 – 100;0 = 4 mA input;100 = 20 mA input;253 = N/A

ANALOG_INPUT 1: CompressorMotorCurrentPctThe compressor motor current as a percentage of its RLA. The resolution is 1%.

ANALOG_INPUT 2: CompSuctionTempThe measured temperature of the refrigerant entering the compressor. The resolution is 0.1°F.

ANALOG_INPUT 3: CondRefrigerantPressureThe pressure of the refrigerant in the condenser. The resolution is 0.1 psi.

ANALOG_INPUT 4: CondWaterFlowRateThe rate of water flow through the condenser. The resolution is 1 gpm, and the actual range dependson the condenser flow sensor. If a sensor is present the data is always valid.

ANALOG_INPUT 5: CondWaterTempEntThe temperature of the water entering the condenser. The resolution is 0.1°F.

ANALOG_INPUT 6: CondWaterTempLvgThe temperature of the water leaving the condenser. The resolution is 0.1°F.

ANALOG_INPUT 7: DischargeRefrigerantTempThe temperature of the refrigerant as it leaves the compressor. The resolution is 0.1°F.

ANALOG_INPUT 8: EvapRefrigerantPressureThe pressure of the refrigerant in the evaporator. The resolution is 0.1 psi.

ANALOG_INPUT 9: EvapWaterFlowRateThe rate of water flow through the evaporator. The resolution is 1 gpm, and the range depends on theevaporator flow sensor. If a sensor is present the data is always valid.

ANALOG_INPUT 10: EvapWaterTempEntThe temperature of the water entering the evaporator. The resolution is 0.1°F.

16 BD 02-8

ANALOG_INPUT 11: EvapWaterTempLvgThe temperature of the water leaving the evaporator. The resolution is 0.1°F.

ANALOG_INPUT 12: LiquidLineRefrigerantTempThe measured temperature of the liquid refrigerant leaving the condenser. The resolution is 0.1°F.

ANALOG_INPUT 13: LiquidLinePressureThe pressure of the liquid refrigerant leaving the condenser. The resolution is 0.1 psi.

ANALOG_INPUT 14: OutdoorAirTempThe outdoor air temperature. If a temperature sensor is present at the chiller and the Outdoor AirSensor configuration parameter (available at keypad/display) is set to “Local,” this object will givethe local value. If the Outdoor Air Sensor configuration parameter is set to “Remote,” this object willgive the value written by the BAS. The resolution is 0.1°F.

ANALOG_INPUT 15: RefrigerantLeakConcentrationThe concentration of refrigerant in the ambient air as measured by an optional refrigerant leakdetection sensor. The value is expressed as a percentage of the sensor’s full output range. Forexample, if a 4–20 mA sensor is calibrated to provide a 20 mA signal at an R-134a concentration of250 ppm, a value of 50% would indicate the presence of a 125 ppm concentration of R-134a. Theresolution is 1%.

Analog Output ObjectsInstance Object_Name Property

UnitsProp.

UnitsDescription

ValidRange

1 CapacityLimitPct 98 percent 0 – 100

2 ChillerOperationMode0 = Stop1 = Stop (initial default)2 = Recirculate3 = Run

95 no units 0 – 3

3 NetworkChilledWaterTempSetpoint 64 °F 0 – 80

4 CommunicationsSignal0 = No Comm.1 – 255 = Comm.

95 no units 0 – 255

5 NetworkOutdoorAirTemp 64 °F -40 – 152

6 LeadLagModeSetpoint0 = Master Always Lead1 = Slave Always Lead2 = Auto Select

95 no units 0 – 2

7 EnableLagSetpoint 98 percent 0 – 100

8 DisableLagSetpoint 98 percent 0 – 100

9 LagStandbySetpoint0 = No1 = Yes

95 no units 0, 1

10 LeadLagSwitchSetpointDay0 = N/A1 = Sun2 = Mon3 = Tue4 = Wed5 = Thu6 = Fri7 = Sat

95 no units 0 – 7

11 LeadLagSwitchSetpointHour 95 no units 0 – 23

BD 02-8 17

ANALOG_OUTPUT 1: CapacityLimitPctThe upper limit for cooling capacity. The normal value is 100%, which enables maximum cooling.The unit’s ability to cool will be reduced by setting the limit to less than 100%. The value is apercentage of full capacity.

Note: This object’s value is stored in volatile memory, so after a power reset the desired value mustbe rewritten to the MicroTech controller.

ANALOG_OUTPUT 2: ChillerOperationModeThe chiller operating mode. This object is effective only when the chiller’s Control Mode parameteras set at the keypad/display is “Auto:Network” and the CommunicationStatus object(ANALOG_VALUE 35) holds a value of “1.” In the Stop mode (0), the compressor and water pumpsare disabled and all valves are closed. In the Recirculate mode (2), the pumps operate and the valvesopen to allow water to circulate through the system, but the compressor does not start. In the Runmode (3), the pumps operate, the compressor is enabled, and the valves modulate as required.

If communications with the chiller are lost (i.e., the CommunicationStatus object holds a value of“0”), the chiller will revert to an enabled mode that acts just like the Run mode (3), regardless of thelast write to the ChillerOperationMode object.

The ChillerOperationMode object initializes to a default value of “1,” which acts just like the Stopmode (0) when communications exist. If communications are lost, the “1” value will enable thechiller. For the purposes of a BACnet interface, it is best not to write the “1” value.

When in the lead-lag configuration, the chiller operation mode must be written to both the Masterand Slave units.


ANALOG_OUTPUT 3: NetworkChilledWaterTempSetpointThe leaving evaporator water temperature setpoint as written by the BAS. The chiller also maintainsa local setpoint in non-volatile memory. This object’s value will be used for chilled water temperaturecontrol (i.e., the Active Setpoint is set equal to it) when the following two conditions are true: (1) thechiller’s chilled water setpoint source parameter (available at the keypad/display) is set to “Network”and (2) the CommunicationStatus object (ANALOG_VALUE 35) holds a value of “1.” Otherwise,the chiller will use the local leaving evaporator water temperature setpoint, plus any local chilledwater reset bias, for control. This setpoint should not be set below 40.0°F for standard temperaturechillers, but it may be set in the 0 to 39.5°F range for low temperature units. The resolution is 0.5°F.

Unlike some other MicroTech chiller controllers (e.g., reciprocating), the B-vintage water-cooledscrew chiller controller will not allow the local chilled water reset methods to be used in conjunctionwith a base setpoint written by the BAS. If a reset scheme for the chilled water setpoint is desired, theBAS must coordinate it and write the resultant setpoint to this object.


ANALOG_OUTPUT 4: CommunicationsSignalA BAS-to-chiller network communications “watchdog.” A non-zero value should be written to thisobject once every 60 seconds. If the CommunicationsSignal object is not updated for five minutes,the MicroTech controller will assume there has been a loss of network communications and revert tolocal setpoints for unit control.

18 BD 02-8

ANALOG_OUTPUT 5: NetworkOutdoorAirTempThe outdoor air temperature as written by the BAS. The resolution is 1°F. To use this object, theOutdoor Air Sensor configuration parameter (available on the keypad/display) must be set to“Remote.”

ANALOG_OUTPUT 6: LeadLagModeSetpointControls the selection of the lead compressor. If “Auto Select” (2) is chosen, the compressor with theleast run hours will become lead the next time both compressors are off.

This object is effective only in the lead-lag Master. The MasterSlaveSetpointConfig object(ANALOG_VALUE 41) tells you whether the controller is Master or Slave.

ANALOG_OUTPUT 7: EnableLagSetpointIf the lead compressor is running alone and its motor current (in % RLA) exceeds this value, theinterstage timer begins to run. When it expires, the lag compressor turns on (unless the lagcompressor has been designated as standby). The default value is 95%.


ANALOG_OUTPUT 8: DisableLagSetpointIf both the lead and lag compressors are running and the motor current (in % RLA) of either dropsbelow this value, the interstage timer begins to run. When it expires, the lag compressor shuts down.The default value is 40%.


ANALOG_OUTPUT 9: LagStandbySetpointA configuration variable that designates whether the lag compressor is to be used for standbyoperation only.


ANALOG_OUTPUT 10: LeadLagSwitchSetpointDayThe day on which the lead-lag Master should auto-select the lead compressor. TheLeadLagModeSetpoint object (ANALOG_OUTPUT 6) must be set to “Auto Select” (2) to use thisfeature. This feature can be useful for applications in which the chiller runs continuously.


ANALOG_OUTPUT 11: LeadLagSwitchSetpointHourThe hour at which the lead-lag Master should auto-select the lead compressor. SeeANALOG_OUTPUT 10 above.


Binary Input ObjectsInstance Object_Name Property

Active_TextProperty

Inactive_TextProperty

1 CondWaterFlowStatus1 = Flow0 = No Flow

Flow No Flow

2 EvapWaterFlowStatus1 = Flow0 = No Flow

Flow No Flow

BD 02-8 19

BINARY_INPUT 1: CondWaterFlowStatusThe state of the condenser water flow switch.

BINARY_INPUT 2: EvapWaterFlowStatusThe state of the evaporator water flow switch.

Binary Output ObjectsInstance Object_Name Property

Active_TextProperty


1 ClearCurrentAlarm1 = Clear Alarm0 = No Action

Clear Alarm No Action

BINARY_OUTPUT 1: ClearCurrentAlarmClears the current active alarm. The object’s value automatically changes to zero when the alarm iscleared. Note that some alarms are self-clearing. This object would need to be used only for manual-clear alarms. (If a self-clearing alarm is cleared with this object, it will recur immediately since thealarm condition is still present. No harm will occur.)

Note: Never command this object without investigating and correcting the cause of the alarm.

20 BD 02-8

C-Vintage Water-Cooled Screw Chiller

Analog Value ObjectsInstance Object_Name Property

UnitsProp.

UnitsDescription

ValidRange

1 UnitStatus0 = Off: Alarm, Both Circ Fault1 = Off: System Switch2 = Off: Manual3 = Off: Pumpdown Switches4 = Off: Ambient Lockout5 = Off: Remote Communications6 = Off: Remote Switch7 = Off: Time Schedule8 = Off: Waiting for Flood9 = Start Requested10 = Evaporator Pump Off11 = Evaporator Pump On: Waiting For Flow12 = Evaporator Pump On: Recirculate13 = Evaporator Pump On: Cycle Timers14 = Evaporator Pump On: Waiting For Load15 = Condenser Pump Off16 = Condenser Pump On: Waiting For Flow17 = Cool Staging18 = Manual Cool Staging19 = Cool Stage Up20 = Cool Stage Down21 = Shutdown/Pumpdown22 = Condenser Pump Off: Shutdown23 = Evaporator Pump Off: Shutdown

95 no units 0 – 23

2 StageOfCapacity 95 no units 0 – 8

3 CapacityLimitingInEffect0 = No Capacity Override1 = High Amps2 = Demand Limiting3 = Max Pulldown4 = Soft Loading5 = High Cond Pressure: Unload6 = Low Evap Pressure: Unload7 = High Cond Pressure: No Load8 = High Discharge Superheat: No Load9 = High Discharge Superheat: Unload

95 no units 0 – 9

4 Circuit1Status0 = Off: Alarm1 = Off: System Switch2 = Off: Manual3 = Off: Pumpdown Switch4 = Off: Ambient Lockout5 = Off: Remote Communications6 = Off: Remote Switch7 = Off: Time Schedule8 = Off: Wait For Cycle9 = Off: Wait For Flood10 = Off: Ready To Start11 = Start Requested12 = Start-up Unloading13 = MCR Started14 = MCR On, Open Solenoid15 = Running16 = Shutdown/Pumpdown17 = MCR Off: Rapid Shutdown18 = MCR Off: Routine Shutdown

95 no units 0 – 18

5 Circuit2StatusSame as Circuit1Status (4)

95 no units 0 – 18

BD 02-8 21


UnitsDescription

ValidRange

6 ChilledWaterTempActiveSpt 64 °F 0 – 127

7 CompSuperheatSuction_Cir1 64 °F 0 – 999*

8 CompSuperheatSuction_Cir2 64 °F 0 – 999*

9 CompSuperheatDischarge_Cir1 64 °F 0 – 999*

10 CompSuperheatDischarge_Cir2 64 °F 0 – 999*

11 CompressorLiftPressure 56 psi 0 – 999*

12 CondPumpStatus0 = Condenser Pump Off1 = Starting Condenser Pump2 = Condenser Pump On3 = Condenser Pump Fail

95 no units 0 – 3

13 CondSatRefrigerantTemp 64 °F 0 – 999;5786.5 = N/A

14 CondApproachTemp 64 °F 0 – 999*

15 CondSubcoolingTemp 64 °F 0 – 999*

16 CondWaterTempDelta 64 °F 0 – 999*

17 CoolingTowerStage 95 no units 0 – 4

18 CoolingTowerValvePosition 98 percent 0 – 100

19 EvapPumpStatus0 = Evaporator Pump Off1 = Starting Evaporator Pump2 = Evaporator Pump On3 = Evaporator Pump Fail

95 no units 0 – 3

20 EvapSatRefrigerantTemp 64 °F 0 – 999;5786.5 = N/A

21 EvapApproachTemp 64 °F 0 – 999*

22 EvapWaterTempDelta 64 °F 0 – 999*

23 FilterPressureDrop 56 psi 0 – 999*

24 Comp1NumberOfStarts 95 no units 0 – 65,535

25 Comp2NumberOfStarts 95 no units 0 – 65,535

26 Comp1OperatingHours 71 hours 0 – 65,279

27 Comp2OperatingHours 71 hours 0 – 65,279

28 ChillerUnitTempTypeConfig0 = Standard1 = Low Temp

95 no units 0, 1

29 CondWaterFlowRateSensorConfig0 = Not Present1 = Present

95 no units 0, 1

30 EvapWaterFlowRateSensorConfig0 = Not Present1 = Present

95 no units 0, 1

31 CoolingTowerControlConfig0 = External1 = Chiller

95 no units 0, 1

32 RefrigLeakDetectSensorConfig0 = Not Present1 = Present

95 no units 0, 1

22 BD 02-8


UnitsDescription

ValidRange

33 Circuit1CurrentAlarm0 = None1 = Liquid Line Temp Sensor Warning2 = Entering Evap Temp Sensor Warning3 = Leaving Cond Temp Sensor Warning4 = Entering Evap Temp Sensor Problem5 = Outside Air Temp Sensor Problem6 = High Condenser Pressure: No Load7 = High Condenser Pressure: Unload8 = Low Evaporator Pressure: Unload9 = Condenser Freeze Protect10 = Evaporator Freeze Protect11 = Low Evaporator Pressure: Shutdown12 = Low Evaporator Pressure: No Start13 = Low Motor Current14 = High Discharge Line Temp15 = High Condenser Pressure16 = Mechanical High Cond Pressure Switch17 = High Motor Temperature18 = Starter Fault19 = No Starter Transition20 = No Evaporator Water Flow21 = No Condenser Water Flow22 = High Motor Current23 = No Liquid Run24 = No Superheat Drop At Start25 = High Discharge Superheat26 = Evaporator Pressure Sensor Failure27 = Entering Cond Temp Sensor Failure28 = Suction Temperature Sensor Failure29 = Discharge Temperature Sensor Failure30 = Condenser Pressure Sensor Failure31 = Leaving Evap Temp Sensor Failure32 = Voltage Ratio Sensor Failure

95 no units 0 – 32

34 Circuit2CurrentAlarmSame as Circuit1CurrentAlarm (33)

95 no units 0 – 32

35 Cir1AtAlarm_EntEvapWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

36 Cir1AtAlarm_LvgEvapWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

37 Cir1AtAlarm_EntCondWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

38 Cir1AtAlarm_LvgCondWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

39 Cir1AtAlarm_EvapPressure 56 psi 0 – 200;5886.5 = N/A;6142.5 = open;6398.5 = short

40 Cir1AtAlarm_CondPressure 56 psi 0 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

41 Cir1AtAlarm_EvapApproachTemp 64 °F 0 – 999*

42 Cir1AtAlarm_CondApproachTemp 64 °F 0 – 999*

BD 02-8 23


UnitsDescription

ValidRange

43 Cir1AtAlarm_DischargeTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

44 Cir1AtAlarm_DischargeSuperheat 64 °F 0 – 999*

45 Cir1AtAlarm_SuctionSuperheat 64 °F 0 – 999*

46 Cir1AtAlarm_Subcooling 64 °F 0 – 999*

47 Cir1AtAlarm_EXVPosition 95 no units 0 – 760;0 = fully closed760 = fully open

48 Cir1AtAlarm_EvapFlow 89 gpm 0 – 65,535

49 Cir1AtAlarm_CondFlow 89 gpm 0 – 65,535

50 Cir1AtAlarm_StageCapacityPct 98 percent 0 – 100

51 Cir2AtAlarm_EntEvapWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

52 Cir2AtAlarm_LvgEvapWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

53 Cir2AtAlarm_EntCondWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

54 Cir2AtAlarm_LvgCondWaterTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

55 Cir2AtAlarm_EvapPressure 56 psi 10 – 155 (for R22 orR134a),

10 – 500 (for R410a);5886.5 = N/A;6142.5 = open;6398.5 = short

56 Cir2AtAlarm_CondPressure 56 psi 0 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

57 Cir2AtAlarm_EvapApproachTemp 64 °F 0 – 999*

58 Cir2AtAlarm_CondApproachTemp 64 °F 0 – 999*

59 Cir2AtAlarm_DischargeTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

60 Cir2AtAlarm_DischargeSuperheat 64 °F 0 – 999*

61 Cir2AtAlarm_SuctionSuperheat 64 °F 0 – 999*

62 Cir2AtAlarm_Subcooling 64 °F 0 – 999*

63 Cir2AtAlarm_EXVPosition 95 no units 0 – 760;0 = fully closed760 = fully open

64 Cir2AtAlarm_EvapFlow 89 gpm 0 – 65,535

65 Cir2AtAlarm_CondFlow 89 gpm 0 – 65,535

66 Cir2AtAlarm_StageCapacityPct 98 percent 0 – 100

67 Circuit1PreviousAlarmSame as Circuit1CurrentAlarm (33)

95 no units 0 – 32

68 Circuit2PreviousAlarmSame as Circuit1CurrentAlarm (33)

95 no units 0 – 32

24 BD 02-8

ANALOG_VALUE 1: UnitStatusThe overall state of the chiller. See OM manual for more information.

ANALOG_VALUE 2: StageOfCapacityThe stage of compressor capacity at which the unit is currently operating.

ANALOG_VALUE 3: CapacityLimitingInEffectThe type capacity limiting that is currently preventing the chiller from staging up further or causing itto stage down—at a time when the chiller would otherwise be holding steady or adding capacity inorder to maintain control of the leaving evaporator water temperature.

ANALOG_VALUE 4: Circuit1StatusThe overall state of refrigerant circuit #1. See OM manual for more information.

ANALOG_VALUE 5: Circuit2StatusThe overall state of refrigerant circuit #2. See OM manual for more information.

ANALOG_VALUE 6: ChilledWaterTempActiveSptThe Active Setpoint, which is used to control the leaving evaporator water temperature. It includesany chilled water reset that may be in effect. The resolution is 0.5°F.

ANALOG_VALUE 7: CompSuperheatSuction_Cir1The difference between the actual temperature of the refrigerant entering compressor #1 and thesaturated evaporator temperature. The resolution is 0.1°F.

ANALOG_VALUE 8: CompSuperheatSuction_Cir2The difference between the actual temperature of the refrigerant entering compressor #2 and thesaturated evaporator temperature. The resolution is 0.1°F.

ANALOG_VALUE 9: CompSuperheatDischarge_Cir1The difference between the actual temperature of the refrigerant leaving compressor #1 and thesaturated condensing temperature. The resolution is 0.1°F.

ANALOG_VALUE 10: CompSuperheatDischarge_Cir2The difference between the actual temperature of the refrigerant leaving compressor #2 and thesaturated condensing temperature. The resolution is 0.1°F.

ANALOG_VALUE 11: CompressorLiftPressureThe pressure rise of the refrigerant as it passes through the compressor. It is calculated by subtractingthe evaporator pressure from the condenser pressure. The resolution is 0.1 psi.

ANALOG_VALUE 12: CondPumpStatusThe operating status of the condenser water pump.

ANALOG_VALUE 13: CondSatRefrigerantTempThe saturated temperature of the refrigerant in the condenser shell. It is calculated from the measuredcondenser pressure. The resolution is 0.1°F.

ANALOG_VALUE 14: CondApproachTempThe difference between the condenser refrigerant temperature and the condenser leaving watertemperature. The resolution is 0.1°F.

ANALOG_VALUE 15: CondSubcoolingTempThe subcooling temperature. It is calculated by subtracting the actual refrigerant temperature in theliquid line from the saturated condensing temperature. The resolution is 0.1°F.

BD 02-8 25

ANALOG_VALUE 16: CondWaterTempDeltaThe difference between the entering and leaving condenser water temperatures. The resolution is0.1°F.

ANALOG_VALUE 17: CoolingTowerStageThe number of energized cooling tower stages. The data is valid only if tower control is provided bythe chiller.

ANALOG_VALUE 18: CoolingTowerValvePositionThe position of the cooling tower valve. It is given as a percent of full open to the tower and has a1% resolution. It is valid only if tower control is provided by the chiller.

ANALOG_VALUE 19: EvapPumpStatusThe operating status of the evaporator water pump.

ANALOG_VALUE 20: EvapSatRefrigerantTempThe saturated temperature of the refrigerant in the evaporator shell. It is calculated from themeasured evaporator pressure. The resolution is 0.1°F.

ANALOG_VALUE 21: EvapApproachTempThe difference between the evaporator refrigerant temperature and the leaving evaporator watertemperature. The resolution is 0.1°F.

ANALOG_VALUE 22: EvapWaterTempDeltaThe difference between the entering and leaving evaporator water temperatures. The resolution is0.1°F.

ANALOG_VALUE 23: FilterPressureDropThe pressure difference between the condenser and the liquid line. It is measured across therefrigerant filter-drier.

ANALOG_VALUE 24: Comp1NumberOfStartsThe total number of compressor #1 motor starts that have occurred.

ANALOG_VALUE 25: Comp2NumberOfStartsThe total number of compressor #2 motor starts that have occurred.

ANALOG_VALUE 26: Comp1OperatingHoursThe number of hours compressor #1 has run. The value rolls over to 0 after 65,279 hours.

ANALOG_VALUE 27: Comp2OperatingHoursThe number of hours compressor #2 has run. The value rolls over to 0 after 65,279 hours.

ANALOG_VALUE 28: ChillerUnitTempTypeConfigA configuration parameter that indicates whether the chiller is set up for standard or low dischargetemperatures.

ANALOG_VALUE 29: CondWaterFlowRateSensorConfigA configuration variable that indicates whether a condenser water flow rate sensor is connected tothe chiller. Condenser water flow rate data (ANALOG_INPUT 6) is valid only when this sensor ispresent.

ANALOG_VALUE 30: EvapWaterFlowRateSensorConfigA configuration variable that indicates whether an evaporator water flow rate sensor is connected tothe chiller. Evaporator water flow rate data (ANALOG_INPUT 12) is valid only when this sensor ispresent.

26 BD 02-8

ANALOG_VALUE 31: CoolingTowerControlConfigA configuration variable that indicates whether cooling tower functions are being controlled by thechiller or an external control system. Cooling tower data points are valid only when the chiller is incontrol.

ANALOG_VALUE 32: RefrigLeakDetectSensorConfigA configuration variable that indicates whether a refrigerant leak detection sensor is connected to thechiller. Refrigerant sensor data (ANALOG_INPUT 18) is valid only when this sensor is present.

ANALOG_VALUE 33: Circuit1CurrentAlarmThe current alarm in refrigerant circuit #1. If multiple alarms exist at the same time, the most seriousalarm (i.e., the one with the highest code number) is given. Some alarms affect the entire chiller (e.g.,High Condenser Pressure) and are thus reported at the same time for both circuits.

ANALOG_VALUE 34: Circuit2CurrentAlarmThe current alarm in refrigerant circuit #2. If multiple alarms exist at the same time, the most seriousalarm (i.e., the one with the highest code number) is given. Some alarms affect the entire chiller (e.g.,High Condenser Pressure) and are thus reported at the same time for both circuits.

ANALOG_VALUE 35: Cir1AtAlarm_EntEvapWaterTempThe evaporator entering water temperature at the time the current circuit #1 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 36: Cir1AtAlarm_LvgEvapWaterTempThe evaporator leaving water temperature at the time the current circuit #1 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 37: Cir1AtAlarm_EntCondWaterTempThe condenser entering water temperature at the time the current circuit #1 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 38: Cir1AtAlarm_LvgCondWaterTempThe condenser leaving water temperature at the time the current circuit #1 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 39: Cir1AtAlarm_EvapPressureThe evaporator pressure at the time the current circuit #1 alarm occurred. The resolution is 0.1 psi.

ANALOG_VALUE 40: Cir1AtAlarm_CondPressureThe condenser pressure at the time the current circuit #1 alarm occurred. The resolution is 0.1 psi.

ANALOG_VALUE 41: Cir1AtAlarm_EvapApproachTempThe evaporator approach temperature at the time the current circuit #1 alarm occurred. The resolutionis 0.1°F.

ANALOG_VALUE 42: Cir1AtAlarm_CondApproachTempThe condenser approach temperature at the time the current circuit #1 alarm occurred. The resolutionis 0.1°F.

ANALOG_VALUE 43: Cir1AtAlarm_DischargeTempThe compressor #1 discharge temperature at the time the current circuit #1 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 44: Cir1AtAlarm_DischargeSuperheatThe compressor #1 discharge superheat temperature at the time the current circuit #1 alarm occurred.The resolution is 0.1°F.

BD 02-8 27

ANALOG_VALUE 45: Cir1AtAlarm_SuctionSuperheatThe compressor #1 suction superheat temperature at the time the current circuit #1 alarm occurred.The resolution is 0.1°F.

ANALOG_VALUE 46: Cir1AtAlarm_SubcoolingThe liquid line subcooling temperature at the time the current circuit #1 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 47: Cir1AtAlarm_EXVPositionThe position of electronic expansion valve #1 (EXV) at the time the current circuit #1 alarmoccurred. The value is expressed in “steps.”

ANALOG_VALUE 48: Cir1AtAlarm_EvapFlowThe evaporator water flow rate at the time the current circuit #1 alarm occurred. The resolution is1 gpm. Note that the evaporator flow rate sensor is optional.

ANALOG_VALUE 49: Cir1AtAlarm_CondFlowThe condenser water flow rate at the time the current circuit #1 alarm occurred. The resolution is1 gpm. Note that the condenser flow rate sensor is optional.

ANALOG_VALUE 50: Cir1AtAlarm_StageCapacityPctThe compressor #1 stage of capacity at the time the current circuit #1 alarm occurred. The value isexpressed as a percentage of total compressor capacity in 25% increments. (This is not percent ofRLA.)

ANALOG_VALUE 51: Cir2AtAlarm_EntEvapWaterTempThe evaporator entering water temperature at the time the current circuit #2 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 52: Cir2AtAlarm_LvgEvapWaterTempThe evaporator leaving water temperature at the time the current circuit #2 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 53: Cir2AtAlarm_EntCondWaterTempThe condenser entering water temperature at the time the current circuit #2 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 54: Cir2AtAlarm_LvgCondWaterTempThe condenser leaving water temperature at the time the current circuit #2 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 55: Cir2AtAlarm_EvapPressureThe evaporator pressure at the time the current circuit #2 alarm occurred. The resolution is 0.1 psi.

ANALOG_VALUE 56: Cir2AtAlarm_CondPressureThe condenser pressure at the time the current circuit #2 alarm occurred. The resolution is 0.1 psi.

ANALOG_VALUE 57: Cir2AtAlarm_EvapApproachTempThe evaporator approach temperature at the time the current circuit #2 alarm occurred. The resolutionis 0.1°F.

ANALOG_VALUE 58: Cir2AtAlarm_CondApproachTempThe condenser approach temperature at the time the current circuit #2 alarm occurred. The resolutionis 0.1°F.

28 BD 02-8

ANALOG_VALUE 59: Cir2AtAlarm_DischargeTempThe compressor #2 discharge temperature at the time the current circuit #2 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 60: Cir2AtAlarm_DischargeSuperheatThe compressor #2 discharge superheat temperature at the time the current circuit #2 alarm occurred.The resolution is 0.1°F.

ANALOG_VALUE 61: Cir2AtAlarm_SuctionSuperheatThe compressor #2 suction superheat temperature at the time the current circuit #2 alarm occurred.The resolution is 0.1°F.

ANALOG_VALUE 62: Cir2AtAlarm_SubcoolingThe liquid line subcooling temperature at the time the current circuit #2 alarm occurred. Theresolution is 0.1°F.

ANALOG_VALUE 63: Cir2AtAlarm_EXVPositionThe position of electronic expansion valve #2 (EXV) at the time the current circuit #2 alarmoccurred. The value is expressed in “steps.”

ANALOG_VALUE 64: Cir2AtAlarm_EvapFlowThe evaporator water flow rate at the time the current circuit #2 alarm occurred. The resolution is1 gpm. Note that the evaporator flow rate sensor is optional.

ANALOG_VALUE 65: Cir2AtAlarm_CondFlowThe condenser water flow rate at the time the current circuit #2 alarm occurred. The resolution is1 gpm. Note that the condenser flow rate sensor is optional.

ANALOG_VALUE 66: Cir2AtAlarm_StageCapacityPctThe compressor #2 stage of capacity at the time the current circuit #2 alarm occurred. The value isexpressed as a percentage of total compressor capacity in 25% increments. (This is not percent ofRLA.)

ANALOG_VALUE 67: Circuit1PreviousAlarmThe previous alarm for refrigerant circuit #1. For this C-vintage water cooled screw chillerapplication, a previous alarm will not be registered unless it has first been cleared. (This is not true ofmost other MicroTech applications.)

ANALOG_VALUE 68: Circuit2PreviousAlarmThe previous alarm for refrigerant circuit #2. For this C-vintage water cooled screw chillerapplication, a previous alarm will not be registered unless it has first been cleared. (This is not true ofmost other MicroTech applications.)

Analog Input ObjectsInstance Object_Name Property

UnitsProp.

UnitsDescription

ValidRange

1 Comp1MotorCurrentPct 98 percent 0 – 125

2 Comp2MotorCurrentPct 98 percent 0 – 125

3 Comp1SuctionTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

4 Comp2SuctionTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

BD 02-8 29


UnitsDescription

ValidRange

5 CondRefrigerantPressure 56 psi 10 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

6 CondWaterFlowRate 89 gpm 0 – 65,535

7 CondWaterTempEnt 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

8 CondWaterTempLvg 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

9 DischargeRefrigTemp_Cir1 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

10 DischargeRefrigTemp_Cir2 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

11 EvapRefrigerantPressure 56 psi 10 – 155 (for R22 orR134a),

10 – 500 (for R410a);5886.5 = N/A;6142.5 = open;6398.5 = short

12 EvapWaterFlowRate 89 gpm 0 – 65,535

13 EvapWaterTempEnt 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

14 EvapWaterTempLvg 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

15 LiquidLineRefrigerantTemp 64 °F -50 – 280;5786.5 = N/A;6042.5 = open;6298.5 = short

16 LiquidLinePressure 56 psi 10 – 500;5886.5 = N/A;6142.5 = open;6398.5 = short

17 OutdoorAirTemp 64 °F -50 – 280 (local),-99 – 155 (network);5786.5 = N/A;6042.5 = open;6298.5 = short

18 RefrigerantLeakConcentration 98 percent 0 – 100;0 = 4 mA input;100 = 20 mA input;253 = N/A

ANALOG_INPUT 1: Comp1MotorCurrentPctThe compressor #1 motor current as a percentage of its RLA. The resolution is 1%.

ANALOG_INPUT 2: Comp2MotorCurrentPctThe compressor #2 motor current as a percentage of its RLA. The resolution is 1%.

30 BD 02-8

ANALOG_INPUT 3: Comp1SuctionTempThe measured temperature of the refrigerant entering compressor #1. The resolution is 0.1°F.

ANALOG_INPUT 4: Comp2SuctionTempThe measured temperature of the refrigerant entering compressor #2. The resolution is 0.1°F.

ANALOG_INPUT 5: CondRefrigerantPressureThe pressure of the refrigerant in the condenser. The resolution is 0.1 psi.

ANALOG_INPUT 6: CondWaterFlowRateThe rate of water flow through the condenser. The resolution is 1 gpm, and the actual range dependson the condenser flow sensor. If a sensor is present the data is always valid.

ANALOG_INPUT 7: CondWaterTempEntThe temperature of the water entering the condenser. The resolution is 0.1°F.

ANALOG_INPUT 8: CondWaterTempLvgThe temperature of the water leaving the condenser. The resolution is 0.1°F.

ANALOG_INPUT 9: DischargeRefrigTemp_Cir1The temperature of the refrigerant as it leaves compressor #1. The resolution is 0.1°F.

ANALOG_INPUT 10: DischargeRefrigTemp_Cir2The temperature of the refrigerant as it leaves compressor #2. The resolution is 0.1°F.

ANALOG_INPUT 11: EvapRefrigerantPressureThe pressure of the refrigerant in the evaporator. The resolution is 0.1 psi.

ANALOG_INPUT 12: EvapWaterFlowRateThe rate of water flow through the evaporator. The resolution is 1 gpm, and the range depends on theevaporator flow sensor. If a sensor is present the data is always valid.

ANALOG_INPUT 13: EvapWaterTempEntThe temperature of the water entering the evaporator. The resolution is 0.1°F.

ANALOG_INPUT 14: EvapWaterTempLvgThe temperature of the water leaving the evaporator. The resolution is 0.1°F.

ANALOG_INPUT 15: LiquidLineRefrigerantTempThe measured temperature of the liquid refrigerant leaving the condenser. The resolution is 0.1°F.

ANALOG_INPUT 16: LiquidLinePressureThe pressure of the liquid refrigerant leaving the condenser. The resolution is 0.1 psi.

ANALOG_INPUT 17: OutdoorAirTempThe outdoor air temperature. If a temperature sensor is present at the chiller and the Outdoor AirSensor configuration parameter (available at keypad/display) is set to “Local,” this object will givethe local value. If the Outdoor Air Sensor configuration parameter is set to “Remote,” this object willgive the value written by the BAS. The resolution is 0.1°F.

ANALOG_INPUT 18: RefrigerantLeakConcentrationThe concentration of refrigerant in the ambient air as measured by an optional refrigerant leakdetection sensor. The value is expressed as a percentage of the sensor’s full output range. Forexample, if a 4–20 mA sensor is calibrated to provide a 20 mA signal at an R-134a concentration of250 ppm, a value of 50% would indicate the presence of a 125 ppm concentration of R-134a. Theresolution is 1%.

BD 02-8 31

Analog Output ObjectsInstance Object_Name Property

UnitsProp.

UnitsDescription

ValidRange

1 LeavingEvapWaterTempSpt 64 °F 10 – 80

2 EnteringEvapWaterTempSpt 64 °F 20 – 80

3 MaxChilledWaterResetSpt 64 °F 10 – 80

4 NetworkDemandLimit 98 percent 0 – 100

5 NetworkLvgEvapWaterTempReset 98 percent 0 – 100

6 ResetOptionSetpoint0 = No Reset1 = Return2 = 4–20 mA3 = Network4 = Ice5 = Outdoor Air Temperature

95 no units 0 – 5

7 MaxReset@OAT 64 °F 50 – 65

8 NoReset@OAT 64 °F 70 – 85

9 NetworkOutdoorAirTemp 64 °F -99 – 155

10 LeadCircuitSetpoint0 = Auto Lead-Lag1 = Circuit #1 Lead2 = Circuit #2 Lead

95 no units 0 – 2

11 TowerStage1OnSpt 64 °F 40 – 120




15 TowerStageDifferential 64 °F 1 – 10

16 TowerValveSetpoint_TempCtrl 64 °F 40 – 99

17 TowerValveDeadband_TempCtrl 64 °F 1 – 10

18 TowerValveSetpoint_PressureCtrl 56 psi 20 – 200

19 TowerValveDeadband_PressureCtrl 56 psi 1 – 9

ANALOG_OUTPUT 1: LeavingEvapWaterTempSptThe leaving evaporator water temperature setpoint. This object can be used to set the base coolingsetpoint before any chilled water reset is added to produce the Active Setpoint (i.e., theChilledWaterTempActiveSpt object, ANALOG_VALUE 6). If no reset is being used, the ActiveSetpoint will always be set equal to this object’s value. The default value is 44°F and the resolution is0.5°F.

When a MicroTech chiller controller is not configured for low temperature operation, it willautomatically limit the low end of the valid range to 40°F.

Caution: If the chiller application calls for chilled water reset, the BAS should use the Networkchilled water reset strategy, which involves writing a reset value to theNetworkLvgEvapWaterTempReset object (ANALOG_OUTPUT 5). The BAS should not continuallychange the LeavingEvapWaterTempSpt object’s value because it is stored in non-volatile EEPROMmemory which has a write limitation. If this write limitation is exceeded, the MicroTech controllerwill eventually fail.

ANALOG_OUTPUT 2: EnteringEvapWaterTempSptThe entering evaporator water temperature (i.e., “return”) setpoint. This setpoint is used only with theReturn chilled water reset option. The default value is 54°F and the resolution is 0.5°F.

32 BD 02-8

With Return reset, the controller automatically modulates the Active Setpoint (i.e., the actual leavingevaporator water temperature setpoint) as required to maintain the entering evaporator watertemperature at this setpoint.

ANALOG_OUTPUT 3: MaxChilledWaterResetSptThe maximum amount of reset that can be used to modify the Active Setpoint. See“ANALOG_OUTPUT 6: ResetOptionSetpoint” below for more information on how this object isused. The default value is 10°F and the resolution is 0.5°F.

ANALOG_OUTPUT 4: NetworkDemandLimitThe demand limiting signal from the BAS.

The chiller can be demand limited in two ways: (1) a hardwired 4–20 mA signal or (2) a BAS vianetwork communications. Either or both ways can be used. Here is the formula:

( ) ( )[ ]D C

C S N= −

− × + +1 50

100

where: D = Demand limit on available cooling stagesC = Number of cooling stages equipment hasS = 4–20 mA demand limit signal in percent of 4–20 rangeN = Network demand limit signal in percent

Example 1:Assume that a chiller has eight cooling stages and “50” has been written to the Network DemandLimit object. No external 4–20 mA signal is present.

( ) ( )[ ]D = −

− × + +8

8 1 0 50 50

100

[ ]D = −

× +8

7 50 50100

D = 4 stages, maximum limit

Example 2:Assume that a chiller has eight cooling stages, the input from the 4–20 mA signal is 8 mA, and thevalue of the Network Demand Limit object is “0.”

( ) ( )[ ]D = −

− × + +8

8 1 25 0 50

100

[ ]D = −

× +8

7 25 50100

D = 5.75, which when rounded equals 6 stages, maximum limit


ANALOG_OUTPUT 5: NetworkLvgEvapWaterTempResetThe percentage of chilled water temperature reset to be used when “Network” (3) is selected as theReset Option Setpoint. See “ANALOG_OUTPUT 6: ResetOptionSetpoint” below for moreinformation.


BD 02-8 33

ANALOG_OUTPUT 6: ResetOptionSetpointSets the chilled water reset method.

No Reset (0)When No Reset is selected, the Active Setpoint simply assumes the value of the leaving evaporatorwater temperature setpoint (ANALOG_OUTPUT 1).

A LvgEvap=

where: A = the Active Setpoint (ANALOG_VALUE 6)LvgEvap = the leaving evaporator water temperature setpoint (ANALOG_OUTPUT 1)

Return Water (1)If the entering evaporator water temperature falls below the return setpoint (ANALOG_OUTPUT 2),the Active Setpoint object (ANALOG_VALUE 6) is slowly modulated upward. If the enteringevaporator water temperature goes above this return setpoint, the Active Setpoint is slowlymodulated downward. The Active Setpoint’s modulation range is limited by the leaving evaporatorwater temperature setpoint (ANALOG_OUTPUT 1) on the low side and the return setpoint(ANALOG_OUTPUT 2) on the high side.

The Return reset method is really a cascade control loop, not a reset function per se. The return wateris maintained at its setpoint by incrementally varying the leaving evaporator water setpoint over time.For more information, see the chiller controller OM manual.

External 4–20 mA Signal (2)A 4–20 mA signal is used to vary the Active Setpoint according to the following formula:

A LvgEvap mA MaxR= +−

×4

16

where: A = the Active Setpoint (ANALOG_VALUE 6)LvgEvap = the leaving evaporator water temperature setpoint (ANALOG_OUTPUT 1)MaxR = the max reset setpoint (ANALOG_OUTPUT 3)mA = the value of the external 4–20 mA reset signal (assume values less than 4 mA areequal to 4 mA)

Network Signal (3)A written network value is used to vary the Active Setpoint according to the following formula:

A LvgEvap Net MaxR= + ×100

where: A = the Active Setpoint (ANALOG_VALUE 6)LvgEvap = the leaving evaporator water temperature setpoint (ANALOG_OUTPUT 1)MaxR = the max reset setpoint (ANALOG_OUTPUT 3)Net = the value of the network reset signal (ANALOG_OUTPUT 5) in percent

34 BD 02-8

Ice (4)The Active Setpoint is set according to a hardwired digital input (DI-14) as follows:

A LvgEvap MaxR= + Normal mode, input DI-14 open

A LvgEvap= Ice mode, input DI-14 closed

where: A = the Active Setpoint (ANALOG_VALUE 6)LvgEvap = the leaving evaporator water temperature setpoint (ANALOG_OUTPUT 1)MaxR = the max reset setpoint (ANALOG_OUTPUT 3)

Outdoor Air Temperature (5)The outdoor air temperature is used to vary the active setpoint according to the following formulawhen the outdoor air temperature is within the range defined by the MaxReset@OAT andNoReset@OAT values:

A LvgEvap NoOaT TNoOaT MaxOaT

MaxRo= +

−−

×

where: A = the Active Setpoint (ANALOG_VALUE 6)LvgEvap = the leaving evaporator water temperature setpoint (ANALOG_OUTPUT 1)MaxR = the max reset setpoint (ANALOG_OUTPUT 3)NoOaT = the NoReset@OAT value (ANALOG_OUTPUT 8)MaxOaT = the MaxReset@OAT value (ANALOG_OUTPUT 7)To = the outdoor air temperature

When the outdoor air temperature is less than the MaxReset@OAT value, the Active Setpoint is setequal to the sum of the leaving evaporator water temperature setpoint and the max reset setpoint.

When the outdoor air temperature is greater than the NoReset@OAT value, the Active Setpoint is setequal to the leaving evaporator water temperature setpoint.

ANALOG_OUTPUT 7: MaxReset@OATThe outdoor air temperature at or below which the maximum amount of reset will be used. Thisobject is used only with the Outdoor Air Temperature reset method. The resolution is 1°F.

See “ANALOG_OUTPUT 6: ResetOptionSetpoint” above for more information.

ANALOG_OUTPUT 8: NoReset@OATThe outdoor air temperature at or above which no reset will be used. This object is used only with theOutdoor Air Temperature reset method. The resolution is 1°F.

See “ANALOG_OUTPUT 6: ResetOptionSetpoint” above for more information.

ANALOG_OUTPUT 9: NetworkOutdoorAirTempThe outdoor air temperature as written by the BAS. The resolution is 1°F. To use this object, theOutdoor Air Sensor configuration parameter (available on the keypad/display) must be set to“Remote.” This object’s value is stored in volatile memory, so it may be written to often with nodanger of exceeding a EEPROM write limit.

ANALOG_OUTPUT 10: LeadCircuitSetpointThe lead-lag configuration setpoint for the refrigeration circuits. The “Auto Lead-Lag” setting willallow the MicroTech controller to change the designated lead circuit according to compressor runtime. The other settings allow the user to designate which circuit will be lead.

ANALOG_OUTPUT 11: TowerStage1OnSptThe entering condenser water temperature at or above which the cooling tower stage 1 output willturn on. The stage-up timer must be satisfied before this action will occur, and the tower bypass valve(if any) must be open. The MicroTech controller will also use this setpoint to control the towerbypass valve during stage-1 operation when the tower valve control configuration parameter

BD 02-8 35

(available at the keypad/display) is set to “Stage Setpoint.” See the OM manual for more information.The resolution is 0.5°F.

ANALOG_OUTPUT 12: TowerStage2OnSptThe entering condenser water temperature at or above which the cooling tower stage 2 output willturn on. The stage-up timer must be satisfied before this action will occur, and the tower bypass valve(if any) must be open. The MicroTech controller will also use this setpoint to control the towerbypass valve during stage-2 operation when the tower valve control configuration parameter(available at the keypad/display) is set to “Stage Setpoint.” See the OM manual for more information.The resolution is 0.5°F.



ANALOG_OUTPUT 15: TowerStageDifferentialThe differential for all cooling tower stages. When the entering condenser water temperature fallsbelow a cooling tower stage setpoint by more than this differential, that stage output will turn off.The stage-down timer must be satisfied before this action will occur. If the tower valve controlconfiguration parameter (available at the keypad/display) is set to “Stage Setpoint” or “Pressure,” thebypass valve position must also be less than the minimum valve position setpoint (available at thekeypad/display) before a stage-down will occur. See the OM manual for more information. Theresolution is 0.5°F.

ANALOG_OUTPUT 16: TowerValveSetpoint_TempCtrlThe entering condenser water temperature setpoint for cooling tower bypass valve control, usedwhen the tower valve control configuration parameter (available at the keypad/display) is set to“Valve Setpoint.” In this control strategy, the cooling tower bypass valve is used as a first stage ofcooling and also acts as a low-limit control on the entering condenser water temperature. See the OMmanual for more information. The resolution is 0.5°F.

ANALOG_OUTPUT 17: TowerValveDeadband_TempCtrlThe temperature deadband for the cooling tower valve control loop. This deadband is used when thetower valve control configuration parameter (available at the keypad/display) is set to “ValveSetpoint” or “Stage Setpoint.” See the OM manual for more information. The resolution is 0.5°F.

ANALOG_OUTPUT 18: TowerValveSetpoint_PressureCtrlThe lift pressure setpoint for cooling tower bypass valve control, used when the tower valve controlconfiguration parameter (available at the keypad/display) is set to “Pressure.” In this control strategy,the cooling tower bypass valve is modulated to maintain a fairly constant lift pressure regardless ofthe current cooling tower stage. The resolution is 2 psi (use even integers).

36 BD 02-8

ANALOG_OUTPUT 19: TowerValveDeadband_PressureCtrlThe pressure deadband for the cooling tower valve control loop. This deadband is used only whenthe tower valve control configuration parameter (available at the keypad/display) is set to “Pressure.”See the OM manual for more information. The resolution is 1 psi.

Binary Input ObjectsInstance Object_Name Property

Active_TextProperty


1 CondWaterFlowStatus1 = Flow0 = No Flow

Flow No Flow

2 EvapWaterFlowStatus1 = Flow0 = No Flow

Flow No Flow

BINARY_INPUT 1: CondWaterFlowStatusThe state of the condenser water flow switch.

BINARY_INPUT 2: EvapWaterFlowStatusThe state of the evaporator water flow switch.

Binary Output ObjectsInstance Object_Name Property

Active_TextProperty


1 ClearCircuit1Alarm1 = Clear Alarm0 = No Action


2 ClearCircuit2Alarm1 = Clear Alarm0 = No Action


3 ChillerOperationMode1 = Disable0 = Enable

Disable Enable

4 Circuit1OverrideMode1 = Off0 = Auto

Off Auto

5 Circuit2OverrideMode1 = Off0 = Auto

Off Auto

BINARY_OUTPUT 1: ClearCircuit1AlarmClears the current active alarm in circuit #1. The object’s value automatically changes to zero whenthe alarm is cleared. Note that some alarms are self-clearing. This object would need to be used onlyfor manual-clear alarms. (If a self-clearing alarm is cleared with this object, it will recur immediatelysince the alarm condition is still present. No harm will occur.)

Note: Never command this object without investigating and correcting the cause of the alarm.

BINARY_OUTPUT 2: ClearCircuit2AlarmClears the current active alarm in circuit #2. See “BINARY_OUTPUT 1: ClearCircuit1Alarm” abovefor more information.

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BINARY_OUTPUT 3: ChillerOperationModeThe ChillerOperationMode object can be used to disable the chiller through the network interface. Ifall other chiller enable/disable features are enabled (e.g., remote start/stop switch closed and localschedule in the “occupied” state), commanding the object to “Enable”(0) enables the chiller andcommanding the object to “Disable” (1) disables the chiller, causing it to shut down in a routine,orderly manner. If any of the other chiller enable/disable features are disabled (e.g., remote start/stopswitch open or local schedule in the “unoccupied” state), the chiller is disabled and theChillerOperationMode object’s value has no effect. The object is initialized to “Enable” (0).

Note: This object’s value is stored in volatile memory. After a power reset, it will initialize to“Enable” (0). If the desired value is “Disable,” a 1 must be rewritten to the MicroTech controller afterthe reset.

BINARY_OUTPUT 4: Circuit1OverrideModeThe Circuit1OverrideMode object can be used to disable refrigeration circuit #1 through the networkinterface. In this instance, the circuit #1 status would be Off: Manual. The object is initialized to“Auto” (0).

BINARY_OUTPUT 5: Circuit2OverrideModeThe Circuit2OverrideMode object can be used to disable refrigeration circuit #2 through the networkinterface. In this instance, the circuit #2 status would be Off: Manual. The object is initialized to“Auto” (0).

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