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Air-cooled screw chiller · BACnet points list

York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) BACnet points list

Updated 4 November 2026

Short answer

YORK by Johnson Controls YSAA chillers have BACnet MS/TP, Modbus RTU and N2 built into the 031-02550 board, so no gateway is needed. The BAS writes the remote setpoint and start/stop (AV 1, BV 1). Everything else is read-only analog and binary inputs: chilled liquid and ambient temperatures, per-system suction and discharge pressures and temperatures, EEV output, slide valve status, timers, cutouts, operational and fault codes, and system alarms.

This page lists 57 BACnet objects for the York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) — 2 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from York’s own free documentation, linked below.

Manufacturer
York
Model
YSAA Air-Cooled Screw Chiller (native BACnet MS/TP)
Equipment
Air-cooled screw chiller
Equipment type
Chillers
BACnet objects
57 (2 writable)
Transport
BACnet MS/TP
Firmware
Y.ACS.50.01 (031-03635-001)
Also known as
YORK YSAA, YSAA chiller, 031-02550, YSAA Native
Source document
YSAA Modbus, BACnet MS/TP, N2 Data Map (YSAA Native) · rev. 2017-02-17
Download CSV 57 rows Download EDE B.I.G.-EU JSON Manufacturer PDF ↗ Compare with your scan Download Easy BACnet Mobile App Google Play

Reference only, provided as-is: verify against York’s current documentation and the live device before use. Not official York information. Terms of use.

BMS integration notes: York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP)

Integration in brief

Put the chiller in automatic/remote control (BI 16 reads Auto), then start/stop it with BV 1 and write the remote setpoint (AV 1). Read the leaving chilled liquid temperature, compressor run status, each system's operational code and the two system alarms.

Minimum points to map

The short list most integrators start with — enough to run the unit from a BMS. Map more as the job needs.

ObjectNameWhyAccess
BV 1START_STOPRemote start/stop (1 = run)Write
AV 1REM_SETPRemote leaving chilled liquid setpointWrite
AI 21S1_OP_CODESys 1 operational codeRead
BI 6S1_C_RUNSys 1 compressor runningRead
BI 10S2_C_RUNSys 2 compressor runningRead
BI 16CNTL_MODELocal/remote control mode (1 = Auto)Read
AI 1LCHLTLeaving chilled liquid temperatureRead
BI 1S1_ALARMSystem 1 alarmRead
BI 2S2_ALARMSystem 2 alarmRead

Enable & remote start

BI 16 shows the local/remote control mode (0 = Manual, 1 = Auto). The sheet gives no point to change it and no write-enable point.

Network setup

Watch out for

York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) BACnet objects

Type: AI, AO, AV, BI, BO, BV, MI/MO/MV (multi-state) · Access: Read read-only, Write writable, Command writable with a priority array.

57 of 57 shown
Type
Access
Show
York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) BACnet Points List
DescriptionStates
AVmin1REM_SETPRemote setpoint (99 = auto)°FWrite
BVmin1START_STOPRemote Start/Stop CommandWrite0=Stop, 1=Run
AImin1LCHLTLeaving Chilled Liquid Temp°FRead
AI2ECHLTEntering Chilled Liquid Temp°FRead
AI3ELTEvaporator Liquid Temp°FRead
AI5S1_SUCT_TEMPSys 1 Suction Temp°FRead
AI6OATAmbient Air Temp°FRead
AI7S1_SUCT_SHSys 1 Suction Superheat°F (diff)Read
AI8S1_RUN_TIMESys 1 run time, secondsRead
AI9S1_SUCT_PRSys 1 Suction PressurePSIRead
AI10S1_DSCH_PRSys 1 Discharge PressurePSIRead
AI11S1_EEV_OUTSys 1 EEV Output %%Read
AI12S1_AR_TIMERSys 1 anti-recycle timer, secondsRead
AI13AC_TIMERAnti-coincident timer, secondsRead
AI14S2_SUCT_TEMPSys 2 Suction Temperature°FRead
AI15S2_RUN_TIMESys 2 run time, secondsRead
AI16S2_SUCT_PRSys 2 Suction PressurePSIRead
AI17S2_DSCH_PRSys 2 Discharge PressurePSIRead
AI18S2_SUCT_SHSys 2 Suction Superheat°F (diff)Read
AI19S2_AR_TIMERSys 2 Anti-Recycle TimerRead
AI20S2_EEV_OUTSys 2 EEV Output %%Read
AImin21S1_OP_CODESys 1 Operational CodeRead0=No Abnormal Condition, 1=Unit Switch OFF, 2=System Switch OFF, 3=Lockout, 4=Unit Fault, 5=System Fault, 6=Remote Shutdown, 7=Daily Schedule Shutdown, 8=No Run Permissive, 9=No Cool Load, 10=Anti-Coincidence Timer Active, 11=Anti-Recycle Timer Active, 12=Manual Override, 13=Suction Limiting, 14=Discharge Limiting, 17=Compressor Running, 19=Flow Switch Shutdown
AI22S1_FLT_CODESys 1 Fault CodeRead0=No Fault Code, 2=Low Ambient Temperature, 4=Low Leaving Chilled Liquid Temperature, 5=High Discharge Pressure, 7=Low Suction Pressure, 12=High Discharge Temperature, 18=MP/HPCO Fault, 19=Low Evaporator Temperature, 23=Low Suction Superheat, 24=Pressure Sensor Fault, 26=MP/HPCO Inhibit, 27=Pump Trip, 28=Pump Fail Make Flow, 29=High Ambient Temperature, 30=Anti-Vacuum Low Pressure, 31=Low Discharge Superheat, 32=Low Discharge Pressure, 33=Leaving Chilled Liquid Temperature Sensor Fault, 34=Evaporator Temperature Sensor Fault, 35=Suction Temperature Sensor Fault
AI23S2_OP_CODESys 2 Operational CodeRead0=No Abnormal Condition, 1=Unit Switch OFF, 2=System Switch OFF, 3=Lockout, 4=Unit Fault, 5=System Fault, 6=Remote Shutdown, 7=Daily Schedule Shutdown, 8=No Run Permissive, 9=No Cool Load, 10=Anti-Coincidence Timer Active, 11=Anti-Recycle Timer Active, 12=Manual Override, 13=Suction Limiting, 14=Discharge Limiting, 17=Compressor Running, 19=Flow Switch Shutdown
AI24S2_FLT_CODESys 2 Fault CodeRead0=No Fault Code, 2=Low Ambient Temperature, 4=Low Leaving Chilled Liquid Temperature, 5=High Discharge Pressure, 7=Low Suction Pressure, 12=High Discharge Temperature, 18=MP/HPCO Fault, 19=Low Evaporator Temperature, 23=Low Suction Superheat, 24=Pressure Sensor Fault, 26=MP/HPCO Inhibit, 27=Pump Trip, 28=Pump Fail Make Flow, 29=High Ambient Temperature, 30=Anti-Vacuum Low Pressure, 31=Low Discharge Superheat, 32=Low Discharge Pressure, 33=Leaving Chilled Liquid Temperature Sensor Fault, 34=Evaporator Temperature Sensor Fault, 35=Suction Temperature Sensor Fault
AI25S1_FAN_STAGESys 1 Condenser Fan StageRead
AI26S2_FAN_STAGESys 2 Condenser Fan StageRead
AI28AR_TIMEAnti-Recycle Time ProgrammedRead
AI29LCHLT_CUTLeaving Chilled Liquid Temp Cutout°FRead
AI30LOW_AMB_CUTLow Ambient Temperature Cutout°FRead
AI31L_SUCT_P_COLow Suction Pressure CutoutPSIRead
AI32H_DSCH_P_COHigh Discharge Pressure CutoutPSIRead
AI34SP_SETP_S1Sys 1 Cooling Setpoint (SP Unit)PSIRead
AI38SP_CTL_RG_S2Sys 2 Cooling Range (SP Unit)PSIRead
AI39S1_DSCH_TEMPSys 1 Discharge Temperature°FRead
AI40S1_DSCH_SHSys 1 Discharge Superheat°F (diff)Read
AI41S2_DSCH_TEMPSys 2 Discharge Temperature°FRead
AI42S2_DSCH_SHSys 2 Discharge Superheat°F (diff)Read
AI43R_COOL_SETPRemote Setpoint°FRead
BImin1S1_ALARMSys 1 AlarmRead0=No Alarm, 1=Alarm
BImin2S2_ALARMSys 2 AlarmRead0=No Alarm, 1=Alarm
BI3EVAP_HTREvaporator Heater StatusRead
BI4EVAP_PUMP1Evaporator Pump 1Read
BI5EVAP_PUMP2Evaporator Pump 2Read
BImin6S1_C_RUNSys 1 Comp RunRead
BI7S1_SV_MIN_LOADSys 1 Slide Valve Min LoadRead
BI8S1_SV_UNLSys 1 Slide Valve UnloadRead
BI9S1_SV_LDSys 1 Slide Valve LoadRead
BImin10S2_C_RUNSys 2 Comp RunRead
BI11S2_SV_MIN_LOADSys 2 Slide Valve Min LoadRead
BI12S2_SV_UNLSys 2 Slide Valve UnloadRead
BI13S2_SV_LDSys 2 Slide Valve LoadRead
BI14LEAD_SYSLead SystemRead0=Sys 1, 1=Sys 2
BI15CH_LIQ_TYPEChilled Liquid TypeRead0=Water, 1=Glycol
BImin16CNTL_MODELocal Remote Control ModeRead0=Manual, 1=Auto
BI17DATA_UNITDisplay UnitsRead0=Imperial, 1=SI
BI18AUTO_LLLead Lag Control ModeRead0=Manual, 1=Auto
Object ID lookup: York YSAA point IDs by name

Integration notes

Check it against the live device. A points list tells you what the controller can expose; the unit in front of you may differ by firmware or installed options. This list is provided as-is for reference only and may contain mistakes — confirming it before you write, map or commission anything is up to you (terms). Easy BACnet scans a network for BACnet IP devices from an Android phone, reads every object on the YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) and exports what it actually has to Excel — free. New to BACnet? Start with what a BACnet points list is and what the object types mean.

Questions about the York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP)

How many BACnet points does the York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) have?

This list has 57 BACnet objects: 37 analog inputs, 1 analog value, 18 binary inputs, 1 binary value. The exact set on a given unit depends on its firmware, installed options and configuration.

Which York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) BACnet points are writable?

2 of the 57 objects accept a write. Points marked Command have a priority array: a write holds until it is released, so release it back to automatic when you are done.

Where is the official York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP) BACnet documentation?

The source is YSAA Modbus, BACnet MS/TP, N2 Data Map (YSAA Native), revision 2017-02-17, published free by York at https://docs.johnsoncontrols.com/chillers/api/khub/documents/p4EqvB3xJO6bhqQzS114Tw/content.

What are the minimum BACnet points to integrate the York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP)?

Start with BV 1 START_STOP (Remote start/stop (1 = run)); AV 1 REM_SETP (Remote leaving chilled liquid setpoint); AI 21 S1_OP_CODE (Sys 1 operational code); BI 6 S1_C_RUN (Sys 1 compressor running); BI 10 S2_C_RUN (Sys 2 compressor running); BI 16 CNTL_MODE (Local/remote control mode (1 = Auto)); AI 1 LCHLT (Leaving chilled liquid temperature); BI 1 S1_ALARM (System 1 alarm); BI 2 S2_ALARM (System 2 alarm).

How do I enable BMS control of the York YSAA Air-Cooled Screw Chiller (native BACnet MS/TP)?

BI 16 shows the local/remote control mode (0 = Manual, 1 = Auto). The sheet gives no point to change it and no write-enable point.

How do I check these points on the real YSAA Air-Cooled Screw Chiller (native BACnet MS/TP)?

Scan the network with a BACnet IP browser such as Easy BACnet, open the device and compare its object list with this table. Anything missing is usually an option that isn't installed or a point that is disabled in the controller's configuration.

More York BACnet points lists

Source: YSAA Modbus, BACnet MS/TP, N2 Data Map (YSAA Native) · rev. 2017-02-17. Object names, instances and units are reproduced as published; descriptions are our own.