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Room air quality sensor · BACnet points list
Honeywell TR50 indoor air quality sensor (BACnet MS/TP) BACnet points list
Updated 12 November 2026Unofficial source
The TR50 is a wall-mount indoor air quality sensor that reports temperature, humidity, CO2, particulates, TVOC and an air quality score on BACnet MS/TP (it also speaks Modbus and Sylk). Readings are Analog Inputs; alarm limits, deadbands, delays, offsets and display settings are writable Analog, Multistate and Binary Values, and each measurement has an out-of-range multistate. Which objects appear depends on the SKU (3-sensor models lack PM and TVOC).
This page lists 69 BACnet objects for the Honeywell TR50 indoor air quality sensor (BACnet MS/TP) — 58 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from a copy of Honeywell’s documentation hosted by Stromquist & Company, not by Honeywell itself, so treat it as unofficial.
- Manufacturer
- Honeywell
- Model
- TR50 indoor air quality sensor (BACnet MS/TP)
- Equipment
- Room air quality sensor
- Equipment type
- Thermostats, sensors & meters
- BACnet objects
- 69 (58 writable)
- Transport
- BACnet MS/TP
- Firmware
- Not stated
- Default device instance
- Same as the MS/TP MAC address
- Also known as
- TR50, TR50-5D, TR50-5N, TR50-3D, TR50-3N, TR50-5D-U, TR50-3D-U, Honeywell TR50 IAQ sensor
- Source document
- TR50 User Guide, section 4.4.5 BACnet Points (unofficial copy, hosted by Stromquist & Company)
Reference only, provided as-is: verify against Honeywell’s current documentation and the live device before use. Not official Honeywell information. Terms of use.
BMS integration notes: Honeywell TR50 indoor air quality sensor (BACnet MS/TP)
Set the MS/TP MAC on the DIP switches, let the sensor auto-detect the baud rate, discover it and give it a unique device instance. Then read the sensor AIs and the out-of-range multistates; adjust alarm limits only if the sensor's own alarms are used.
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.
| Object | Name | Why | Access |
|---|---|---|---|
| AI 1 | SS_AI_SensorReading_Temp | Space temperature | Read |
| AI 2 | SS_AI_SensorReading_Humi | Space relative humidity, % | Read |
| AI 3 | SS_AI_SensorReading_CO2 | CO2, ppm | Read |
| AI 4 | SS_AI_SensorReading_PM2.5 | PM2.5, ug/m3 | Read |
| AI 5 | SS_AI_SensorReading_TVOC | TVOC, ppb or ug/m3 | Read |
| AI 6 | SS_AI_AIR_QUALITY_SCORE | Air quality score, 0-100 | Read |
| MV 3 | SS_MV_OutOfRange_CO2 | CO2 state: normal, over high, over high-high | Write |
Network setup
- MS/TP MAC by DIP switch; default MAC range 1-30, Max Master 35.
- Device instance defaults to the MAC address; set a unique instance after discovery.
- Auto baud for the first 4 minutes after power-up (9600-115200); falls back to the last found rate, else 38400.
Watch out for
- Allow at least 3 minutes between two CO2 offset writes (cfgCO2SensorOffset).
- The out-of-range multistates (MV 1-5) are listed as R/W but report the alarm state; treat them as status.
Honeywell TR50 indoor air quality sensor (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.
| Description | States | |||||
|---|---|---|---|---|---|---|
| AImin | 1 | SS_AI_SensorReading_Temp | Temperature reading | °F or °C | Read | |
| AImin | 2 | SS_AI_SensorReading_Humi | Relative humidity | % | Read | |
| AImin | 3 | SS_AI_SensorReading_CO2 | CO2 | ppm | Read | |
| AImin | 4 | SS_AI_SensorReading_PM2.5 | PM2.5 | ug/m3 | Read | |
| AImin | 5 | SS_AI_SensorReading_TVOC | TVOC | ppb or ug/m3 | Read | |
| AImin | 6 | SS_AI_AIR_QUALITY_SCORE | Air quality score 0-100 | Read | ||
| AI | 7 | SS_AI_SensorReading_PM1.0 | PM1.0 | ug/m3 | Read | |
| AI | 8 | SS_AI_SensorReading_PM10 | PM10 | ug/m3 | Read | |
| AV | 1 | CfgAlarmTempLowLimit | Alarm temperature low limit (default 65(°F) 18(°C)) | °F or °C | Write | |
| AV | 2 | CfgAlarmTempHighLimit | Alarm temperature high limit (default 86(°F) 30(°C)) | °F or °C | Write | |
| AV | 3 | CfgAlarmTempDeadband | Alarm temperature deadband (default 1(°F) 1(°C)) | °F or °C | Write | |
| AV | 4 | CfgAlarmTempTimeDelay | Alarm temperature time delay (default 60(s)) | s | Write | |
| MV | 1 | SS_MV_OutofRange_Temp | Out-of-range state, temperature (default 1) | Write | 1=Normal, 2=Off normal | |
| AV | 281 | CfgTempSensorOffset | Temperature sensor offset (default 0) | °F or °C | Write | |
| MV | 21 | CfgAlarmTempLimitEnable | Alarm temperature limit enable (default 4) | Write | 1=Temp Low Limit And High Limit Disable, 2=Temp Low Limit Enable, 3=Temp High Limit Enable, 4=Temp Low Limit And High Limit Enable | |
| MV | 101 | cfgDisplayUnitTemp | Display unit temperature (default 1) | Write | 1=Degrees Fahrenheit (°F), 2=Degrees Celsius (°C) | |
| AV | 51 | CfgAlarmHumiLowLimit | Alarm humidity low limit (default 10(%)) | % | Write | |
| AV | 52 | CfgAlarmHumiHighLimit | Alarm humidity high limit (default 80(%)) | % | Write | |
| AV | 53 | CfgAlarmHumiDeadband | Alarm humidity deadband (default 2) | Write | ||
| AV | 54 | CfgAlarmHumiTimeDelay | Alarm humidity time delay (default 60(s)) | s | Write | |
| MV | 2 | SS_MV_OutofRange_Humi | Out-of-range state, humidity (default 1) | Write | 1=Normal, 2=Off normal | |
| MV | 22 | cfgAlarmHumiLimitEnable | Alarm humidity limit enable (default 4) | Write | 1=Humidity Low Limit And High Limit Disable, 2=Humidity Low Limit Enable, 3=Humidity High Limit Enable, 4=Humidity Low Limit And High Limit Enable | |
| AV | 282 | cfgHumiSensorOffset | Humidity sensor offset (default 0) | Write | ||
| AV | 101 | CfgAlarmCO2HighLimit | Alarm CO2 high limit (default 1000(ppm)) | ppm | Write | |
| AV | 102 | CfgAlarmCO2HighHighLimit | Alarm CO2 high-high limit (default 1400(ppm)) | ppm | Write | |
| AV | 103 | CfgAlarmCO2Deadband | Alarm CO2 deadband (default 100) | Write | ||
| AV | 104 | CfgAlarmCO2TimeDelay | Alarm CO2 time delay (default 60(s)) | s | Write | |
| AV | 283 | cfgCO2SensorOffset | CO2 sensor offset (default 0) | Write | ||
| MVmin | 3 | SS_MV_OutOfRange_CO2 | Out-of-range state, CO2 (default 1) | Write | 1=Normal, 2=Over high limit, 3=Over highhigh limit | |
| MV | 23 | CfgAlarmCO2LimitEnable | Alarm CO2 limit enable (default 4) | Write | 1=CO2 High Limit And High High Limit Disable, 2=CO2 High Limit Enable, 3=CO2 High High Limit Enable, 4=CO2 High Limit And High High Limit Enable | |
| AV | 151 | CfgAlarmPM2.5HighLimit | Alarm PM2.5 high limit (default 35(ug/m3)) | ug/m3 | Write | |
| AV | 152 | cfgAlarmPM2.5HighHighLimit | Alarm PM2.5 high-high limit (default 55(ug/m3)) | ug/m3 | Write | |
| AV | 153 | CfgAlarmPM2.5Deadband | Alarm PM2.5 deadband (default 5) | Write | ||
| AV | 154 | CfgAlarmPM2.5TimeDelay | Alarm PM2.5 time delay (default 60(s)) | s | Write | |
| AV | 284 | CfgPM2.5SensorOffset | PM2.5 sensor offset (default 0) | Write | ||
| MV | 4 | SS_MV_OutOfRange_PM2.5 | Out-of-range state, PM2.5 (default 1) | Write | 1=Normal, 2=Over high limit, 3=Over highhigh limit | |
| MV | 24 | CfgAlarmPM2.5LimitEnable | Alarm PM2.5 limit enable (default 4) | Write | 1=PM2.5 High Limit And High High Limit Disable, 2=PM2.5 High Limit Enable, 3=PM2.5 High High Limit Enable, 4=PM2.5 High Limit And High High Limit Enable | |
| AV | 287 | CfgPM1.0SensorOffset | PM1.0 sensor offset (default 0) | Write | ||
| AV | 288 | CfgPM10SensorOffset | PM10 sensor offset (default 0) | Write | ||
| AV | 201 | CfgAlarmTVOCHighLimit | Alarm TVOC high limit (default 250(ppb) 500(ug/m3)) | ppb or ug/m3 | Write | |
| AV | 202 | CfgAlarmTVOCHighHighLimit | Alarm TVOC high-high limit (default 350(ppb) 700(ug/m3)) | ppb or ug/m3 | Write | |
| AV | 203 | CfgAlarmTVOCDeadband | Alarm TVOC deadband (default 20(ppb) 40(ug/m3)) | ppb or ug/m3 | Write | |
| AV | 204 | CfgAlarmTVOCTimeDelay | Alarm TVOC time delay (default 60(s)) | s | Write | |
| AV | 285 | CfgTVOCSensorOffset | TVOC sensor offset (default 0) | Write | ||
| MV | 5 | SS_MV_OutOfRange_TVOC | Out-of-range state, TVOC (default 1) | Write | 1=Normal, 2=Over high limit, 3=Over highhigh limit | |
| MV | 25 | CfgAlarmTVOCLimitEnable | Alarm TVOC limit enable (default 4) | Write | 1=TVOC High Limit And High High Limit Disable, 2=TVOC High Limit Enable, 3=TVOC High High Limit Enable, 4=TVOC High Limit And High High Limit Enable | |
| MV | 102 | cfgDisplayUnitTVOC | Display unit TVOC (default 1) | Write | 1=Parts Per Billion, 2=Micrograms Per Cubic Meter | |
| MV | 6 | SS_MV_AQI_level | Air quality level (default 1) | Read | 1=Good, 2=Moderate, 3=Unhealthy | |
| AV | 251 | cfgAQIUnhealthyScore | AQI Unhealthy Score (default 40) | Write | ||
| AV | 252 | cfgAQIModerateScore | AQI Moderate Score (default 80) | Write | ||
| AV | 253 | CfgAlarmAQIDeadband | Alarm AQI deadband (default 2) | Write | ||
| AV | 254 | CfgAlarmAQITimeDelay | Alarm AQI time delay (default 60(s)) | s | Write | |
| MV | 26 | CfgAlarmAQILimitEnable | Alarm AQI limit enable (default 4) | Write | 1=AQI Moderate Limit And Unhealthy Limit Disable, 2=AQI Moderate Limit Enable, 3=AQI Unhealthy Limit Enable, 4=AQI Moderate And Unhealthy Limit Enable | |
| AV | 301 | cfgLedRingBrightness | Led Ring Brightness (default 50) | Write | ||
| AV | 302 | CfgLedRingDimBrightness | Led Ring Dim Brightness (default 10) | Write | ||
| AV | 321 | CfgLcdBrightness | Lcd Brightness (default 80) | Write | ||
| AV | 322 | CfgLcdDimBrightness | Lcd Dim Brightness (default 40) | Write | ||
| AV | 341 | CfgLcdAutoCycleTime | Lcd Auto Cycle Time (default 5(s)) | s | Write | |
| AV | 361 | cfgLedRingLcdTimeoutTime | Led Ring Lcd Timeout Time (default 0(s)) | s | Write | |
| AV | 362 | cfgLedRingLcdDimTime | Led Ring Lcd Dim Time (default 10(s)) | s | Write | |
| AV | 381 | CfgIsParaDisplayed | Bit mask of values shown on the LCD (default TR50-5D: 63 TR50-3D: 15) | Write | ||
| BV | 21 | cfgLedRingLcdEnable | Led Ring Lcd Enable (default 1) | Write | 0=Off, 1=On | |
| MV | 61 | CfgLedRingColorOption | Led Ring Color Option (default 1) | Write | 1=Color mode, 2=Neutral mode | |
| MV | 81 | CfgLcdParameterSwitch | Lcd Parameter Switch (default 1) | Write | TR50-5D: 1=Auto cycling (default), 2=Manual + AQI (as the static page), 3=Manual + Temperature (as the static page), 4=Manual + Humidity (as the static page), 5=Manual + CO2 (as the static page), 6=Manual + PM2.5 (as the static page), 7=Manual + TVOC (as the static page), 8=Manual + no static page; TR50-3D: 1=Auto cycling (default), 2=Manual + AQI (as the static page), 3=Manual + Temperature (as the static page), 4=Manual + Humidity (as the static page), 5=Manual + CO2 (as the static page), 6=Manual + no static page | |
| MV | 41 | CfgAlarmIndicatorEnable | Alarm Indicator Enable (default 4) | Write | 1=Disable, 2=cfgOutOfRangeAlarm IndicatorEnable, 3=cfgSensorFailureAlarm IndicatorEnable, 4=cfgOutOfRangeAlarm IndicatorEnable && cfgSensorFailureAlarm IndicatorEnable | |
| AV | 500 | MstpHeaderCrcErrCount | MS/TP header CRC error count | Read | ||
| AV | 501 | MstpDataCrcErrCount | MS/TP data CRC error count | Read | ||
| BV | 41 | CfgIsMstpBadCrcClear | Clear the CRC error counters (default 1) | Write | 0=Uncleared, 1=Cleared | |
| BV | 1 | cfgIsAlarmLocalDetectionEnable | Local alarm detection on/off (default 1) | Write | 0=Disable, 1=Enable |
No points match these filters.
Object ID lookup: Honeywell TR50 indoor air quality sensor point IDs by name
AI1SS_AI_SensorReading_TempAI2SS_AI_SensorReading_HumiAI3SS_AI_SensorReading_CO2AI4SS_AI_SensorReading_PM2.5AI5SS_AI_SensorReading_TVOCAI6SS_AI_AIR_QUALITY_SCOREAI7SS_AI_SensorReading_PM1.0AI8SS_AI_SensorReading_PM10AV1CfgAlarmTempLowLimitAV2CfgAlarmTempHighLimitAV3CfgAlarmTempDeadbandAV4CfgAlarmTempTimeDelayMV1SS_MV_OutofRange_TempAV281CfgTempSensorOffsetMV21CfgAlarmTempLimitEnableMV101cfgDisplayUnitTempAV51CfgAlarmHumiLowLimitAV52CfgAlarmHumiHighLimitAV53CfgAlarmHumiDeadbandAV54CfgAlarmHumiTimeDelayMV2SS_MV_OutofRange_HumiMV22cfgAlarmHumiLimitEnableAV282cfgHumiSensorOffsetAV101CfgAlarmCO2HighLimitAV102CfgAlarmCO2HighHighLimitAV103CfgAlarmCO2DeadbandAV104CfgAlarmCO2TimeDelayAV283cfgCO2SensorOffsetMV3SS_MV_OutOfRange_CO2MV23CfgAlarmCO2LimitEnableAV151CfgAlarmPM2.5HighLimitAV152cfgAlarmPM2.5HighHighLimitAV153CfgAlarmPM2.5DeadbandAV154CfgAlarmPM2.5TimeDelayAV284CfgPM2.5SensorOffsetMV4SS_MV_OutOfRange_PM2.5MV24CfgAlarmPM2.5LimitEnableAV287CfgPM1.0SensorOffsetAV288CfgPM10SensorOffsetAV201CfgAlarmTVOCHighLimitAV202CfgAlarmTVOCHighHighLimitAV203CfgAlarmTVOCDeadbandAV204CfgAlarmTVOCTimeDelayAV285CfgTVOCSensorOffsetMV5SS_MV_OutOfRange_TVOCMV25CfgAlarmTVOCLimitEnableMV102cfgDisplayUnitTVOCMV6SS_MV_AQI_levelAV251cfgAQIUnhealthyScoreAV252cfgAQIModerateScoreAV253CfgAlarmAQIDeadbandAV254CfgAlarmAQITimeDelayMV26CfgAlarmAQILimitEnableAV301cfgLedRingBrightnessAV302CfgLedRingDimBrightnessAV321CfgLcdBrightnessAV322CfgLcdDimBrightnessAV341CfgLcdAutoCycleTimeAV361cfgLedRingLcdTimeoutTimeAV362cfgLedRingLcdDimTimeAV381CfgIsParaDisplayedBV21cfgLedRingLcdEnableMV61CfgLedRingColorOptionMV81CfgLcdParameterSwitchMV41CfgAlarmIndicatorEnableAV500MstpHeaderCrcErrCountAV501MstpDataCrcErrCountBV41CfgIsMstpBadCrcClearBV1cfgIsAlarmLocalDetectionEnable
Integration notes
- Objects created depend on the SKU: the 5-parameter models (TR50-5x) have PM2.5 and TVOC; the 3-parameter models do not.
- The guide prints CO2 names with the 2 as a subscript (e.g. 'CO 2'); names here join them (SS_AI_SensorReading_CO2). Name capitalisation (cfg / Cfg) is as printed.
- Defaults are given in the descriptions. Temperature-type settings follow the display unit (MV 101).
- CfgIsParaDisplayed (AV 381) is a bit mask of what the LCD shows; the bit meanings differ between TR50-5D and TR50-3D.
- The BTL PICS (Dec 2022) lists the same instances with ranges but no names.
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 TR50 indoor air quality sensor (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 Honeywell TR50 indoor air quality sensor (BACnet MS/TP)
How many BACnet points does the Honeywell TR50 indoor air quality sensor (BACnet MS/TP) have?
This list has 69 BACnet objects: 8 analog inputs, 41 analog values, 3 binary values, 17 multi-state values. The exact set on a given unit depends on its firmware, installed options and configuration.
Which Honeywell TR50 indoor air quality sensor (BACnet MS/TP) BACnet points are writable?
58 of the 69 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 Honeywell TR50 indoor air quality sensor (BACnet MS/TP) BACnet documentation?
Honeywell does not publish it on its own website. This list comes from TR50 User Guide, section 4.4.5 BACnet Points, a copy hosted by Stromquist & Company at https://lit.stromquist.com/docs/honeywell/tr50user.pdf. Ask Honeywell or its representative for the current revision.
What are the minimum BACnet points to integrate the Honeywell TR50 indoor air quality sensor (BACnet MS/TP)?
Start with AI 1 SS_AI_SensorReading_Temp (Space temperature); AI 2 SS_AI_SensorReading_Humi (Space relative humidity, %); AI 3 SS_AI_SensorReading_CO2 (CO2, ppm); AI 4 SS_AI_SensorReading_PM2.5 (PM2.5, ug/m3); AI 5 SS_AI_SensorReading_TVOC (TVOC, ppb or ug/m3); AI 6 SS_AI_AIR_QUALITY_SCORE (Air quality score, 0-100); MV 3 SS_MV_OutOfRange_CO2 (CO2 state: normal, over high, over high-high).
How do I check these points on the real TR50 indoor air quality sensor (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 Honeywell BACnet points lists
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Honeywell TB3026B and TB3026B-W BACnet FF wall-mount fixed-function thermostats, all 19 built-in applications (platform objects).
Also known as: TB3026B, TB3026B-W, BACnet FF, Honeywell BACnet Fixed Function thermostat, 31-00098 - Thermostat (fan coil, conventional and heat pump)
Honeywell TC300 Commercial Thermostats (TC300B-G / TC300C-G / TC320B-G / TC320C-G)
Honeywell TC300 and Wi-Fi TC320 commercial touchscreen thermostats for fan coils, conventional units and heat pumps.
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Honeywell TC500A Commercial Thermostat
Honeywell TC500A commercial touchscreen thermostat for conventional rooftop units, heat pumps and fan coils, with economizer, DCV and Sylk bus sensors.
Also known as: TC500A, TC500A-N, TC500
Source: TR50 User Guide, section 4.4.5 BACnet Points. Object names, instances and units are reproduced as published; descriptions are our own.