# Air Quality Sensor

{% hint style="info" %}
This document is currently in the preliminary stage, and therefore, device specifications are subject to change without notice.
{% endhint %}

This device measures VOC, NOx, CO2, PM (Particulate Matter), relative humidity, and temperature. It transmits data using Modbus RTU communication protocol over the RS-485 standard.

<div><figure><img src="/files/70NCEdZeKNQNHpLmnDxk" alt=""><figcaption><p>Front View</p></figcaption></figure> <figure><img src="/files/7fYDt6RghqeCXpnmDT7l" alt=""><figcaption><p>Bottom View</p></figcaption></figure></div>

## Technical Specifications

The following table outlines the capabilities of the device.

<table><thead><tr><th width="222">Property</th><th>Value</th></tr></thead><tbody><tr><td>Onboard sensors</td><td>Sensirion SEN55 Environmental Sensor<br>Sensirion SCD41 CO2 Sensor<br>Optional accelerometer for 2-axis angle detection</td></tr><tr><td>Memory</td><td>Historical data for internal statistics<br>Configuration and calibration storage</td></tr><tr><td>Microcontroller</td><td>STM32 C0 Series MCU, 32-bit ARM Cortex-M0+</td></tr></tbody></table>

## Sensing Specifications

The following table shows sensor characteristics.

<table><thead><tr><th width="167">Measurement</th><th width="355">Accuracy</th><th width="113">Min</th><th>Max</th></tr></thead><tbody><tr><td>VOC Index</td><td>&#x3C;±15 VOC Index points or % VOC Index m.v. (the larger)</td><td>1</td><td>500</td></tr><tr><td>NOx Index</td><td>&#x3C;±15 NOx Index points or % NOx Index m.v. (the larger)</td><td>1</td><td>500</td></tr><tr><td>Relative Humidity</td><td>@ 25 °C, 30-70 %RH: ±4.5% rH (typical), ±6% rH (maximum)</td><td></td><td></td></tr><tr><td>Temperature</td><td>@ 15-30 °C, 50 %RH: ±0.45°C (typical), ±0.7°C (maximum)</td><td></td><td></td></tr><tr><td>PM 1.0</td><td>0 to 100 μg/m3: ±[5 μg/m3 + 5 % m.v.]<br>100 to 1000 μg/m3: ±10 % m.v.</td><td>N/A</td><td>N/A</td></tr><tr><td>PM 2.5</td><td>0 to 100 μg/m3: ±[5 μg/m3 + 5 % m.v.]<br>100 to 1000 μg/m3: ±10 % m.v.</td><td>N/A</td><td>N/A</td></tr><tr><td>PM 4.0</td><td>0 to 100 μg/m3: ±25 μg/m3<br>100 to 1000 μg/m3: ±25 % m.v.</td><td>N/A</td><td>N/A</td></tr><tr><td>PM 10</td><td>0 to 100 μg/m3: ±25 μg/m3<br>100 to 1000 μg/m3: ±25 % m.v.</td><td>N/A</td><td>N/A</td></tr><tr><td>CO2</td><td>400 ppm ... 1000 ppm ±(50 ppm + 2.5% of reading)<br>1001 ppm ... 2000 ppm ±(50 ppm + 3% of reading)<br>2001 ppm ... 5000 ppm ±(40 ppm + 5% of reading)</td><td>400 ppm</td><td>5000 ppm</td></tr></tbody></table>

## Physical Properties

This table shows the mechanical properties of the device.

<table><thead><tr><th width="206">Property</th><th>Value</th></tr></thead><tbody><tr><td>Mounting Style</td><td>Screw Mount</td></tr><tr><td>Dimensions</td><td>80w x 60h x 35d mm</td></tr><tr><td>Base Material</td><td>ASA (Acrylonitrile Styrene Acrylate)<br>Impact, wear, and UV resistant</td></tr><tr><td>Weight</td><td>&#x3C; 200g</td></tr></tbody></table>

## Environmental Conditions

Environmental Conditions refer to the physical and atmospheric conditions surrounding the device.

<table><thead><tr><th width="312">Property</th><th>Value</th></tr></thead><tbody><tr><td>Operating Ambient Temperature</td><td>10°C…+40°C</td></tr><tr><td>Relative Humidity</td><td>20%...80% RH</td></tr><tr><td>Storage</td><td><p>-20°C…+60°C</p><p>10%…90% RH (non-condensing)</p></td></tr></tbody></table>

## Electrical Characteristics

This table indicates the electrical specifications of the device.

<table><thead><tr><th width="280">Property</th><th>Value</th></tr></thead><tbody><tr><td>Main Supply</td><td>DC 5…24V</td></tr><tr><td>RS-485</td><td>-7…+12V (No internal termination)</td></tr><tr><td>Internal Fuse</td><td>DC 60V 6A 1206 Case Slow-burning</td></tr></tbody></table>

## Absolute Maximum Ratings

Absolute maximum ratings indicate the maximum electrical or environmental parameters this device can withstand without damage.

{% hint style="warning" %}
Stresses above the absolute maximum ratings listed in the table may cause permanent damage to the device. These are stress ratings only, and the functional operation of the device under these conditions is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
{% endhint %}

<table><thead><tr><th width="209">Property</th><th>Value</th></tr></thead><tbody><tr><td>Operating Ambient Temperature</td><td>-10°C…+50°C</td></tr><tr><td>Relative Humidity</td><td>0%...90% RH (non-condensing)</td></tr><tr><td>Main Supply</td><td>DC 30V</td></tr><tr><td>RS-485</td><td>-7…+12V</td></tr></tbody></table>

## Connectivity Options

This table lists the communication options of the device.

<table><thead><tr><th width="209">Property</th><th>Value</th></tr></thead><tbody><tr><td>RS-485</td><td>4-Pin connectivity (Power, GND, RS-485 A, RS-485 B)</td></tr></tbody></table>

## Communication Protocols

This device supports the following communication protocols.

{% content-ref url="/pages/mMKJuwpcjDC79s9yoFm3" %}
[Modbus Protocol](/hw/environmental-monitoring/air-quality-sensor/modbus-protocol.md)
{% endcontent-ref %}


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