Air Quality Profile (24000-24999)

Carbon dioxide (CO2) and volatile organic compound (TVOC) measurement.

Sensor Data Messages

Carbon Dioxide Level (24100)

Reports the latest CO2 measurement.

{
    "carbonDioxide": Number,
    "status": Number
}

Field	Description
`carbonDioxide`	CO2 level in parts per million (ppm)
`status`	Measurement status

Status values:

Value	Meaning
`-1`	Measurement failed
`0`	OK
`1`	Auto-calibrated during this measurement
`2`	Auto-calibration failed

Example:

{
    "carbonDioxide": 538,
    "status": 1
}

Total Volatile Organic Compounds (24101)

Reports the latest TVOC measurement.

{
    "tvoc": Number
}

Field	Description
`tvoc`	TVOC level in parts per billion (ppb)

Example:

{
    "tvoc": 72
}

Configuration Messages

Carbon Dioxide Configuration (24200)

Configure CO2 sensor behavior and reporting. Sent with tsmEv: 30.

{
    "transactionId": Number,
    "averaging": Number,
    "rounding": Number,
    "samples": Number,
    "staticFilter": Number,
    "dynamicFilter": Number,
    "autoCalibration": Number,
    "calibrationValue": Number,
    "pressureCompensate": Number,
    "carbonDioxideHysteresis": Number
}

Measurement Settings

Field	Range	Default	Description
`averaging`	1–10	1	Number of measurements to average
`rounding`	1–1000	1	Round values down to nearest N ppm
`samples`	1–32	8	Samples per measurement (higher = more accurate, more power)

Filter Settings

Field	Range	Default	Description
`staticFilter`	0–10	2	`0`: Disabled, `2–10`: IIR filter strength (reduces noise, adds lag)
`dynamicFilter`	0+	1	`0`: Disabled, `1+`: Reduces static filter lag
`pressureCompensate`	0+	1	`0`: Disabled, `1+`: Compensate for air pressure

Auto-Calibration

Field	Range	Default	Description
`autoCalibration`	0–65535	192	Hours between auto-calibration (uses lowest detected value)
`calibrationValue`	0–65535	400	Target ppm for auto-calibration

Important

Set autoCalibration interval so the sensor is exposed to fresh air (≈400 ppm) at least once during the period. Incorrect settings will cause calibration drift.

Reporting

Field	Default	Description
`carbonDioxideHysteresis`	10	Change threshold (ppm) for immediate reporting

Example - Change hysteresis:

[{
    "tsmId": 24200,
    "tsmEv": 30,
    "tsmDstTuid": "TSARXXSERIAL1",
    "transactionId": 2147,
    "carbonDioxideHysteresis": 5
}]

Carbon Dioxide Manual Calibration (24201)

Manually calibrate the sensor to a known CO2 concentration. This is an instantaneous calibration that resets the auto-calibration counter.

{
    "transactionId": Number,
    "calibrationValue": Number
}

Field	Description
`calibrationValue`	Current actual CO2 concentration (ppm)

Tip

For manual calibration, expose the sensor to fresh outdoor air and set calibrationValue to 400 ppm, or use a calibrated reference gas.