Managing Your Sensor

Once your sensor is deployed, you can manage it remotely via MQTT commands — calibrate sensors, check status, update location, and restart the device without physical access.

Command Topic Structure

Commands are sent to your device's MQTT topic:

{deviceTopicPrefix}/command/{category}/{target}/{action}

For example:

wesense/v2/wifi/nz/wko/device123/command/sensor/scd4x/calibrate

All command responses are published to:

{deviceTopicPrefix}/status/command

Responses include a status (SUCCESS, ERROR, or INFO), a message, and a timestamp.

Sensor Commands

CO2 Sensors

SCD30 / SCD4x (Sensirion)

Command	Action	Payload
sensor/scd4x/calibrate	Calibrate to known CO2 level	PPM value (e.g. 400 for outdoor air)
sensor/scd4x/asc_enable	Enable Automatic Self-Calibration	—
sensor/scd4x/asc_disable	Disable ASC	—
sensor/scd4x/asc_status	Check ASC status	—
sensor/scd4x/reset	Reset sensor	—
sensor/scd4x/selftest	Run self-test	—
sensor/scd4x/factory_reset	Factory reset (wipes all calibration)	—
sensor/scd4x/pressure_compensation_status	Check pressure compensation	—
sensor/scd4x/pressure_compensation_apply	Apply pressure compensation	—

The same commands are available for scd30 (replace scd4x with scd30 in the topic). The SCD30 also supports:

Command	Action	Payload
sensor/scd30/set_interval	Set measurement interval	Seconds (2-1800)
sensor/scd30/set_altitude	Set altitude compensation	Metres
sensor/scd30/status	Get sensor status	—

CM1106-C

Command	Action	Payload
sensor/cm1106c/calibrate	Calibrate to known CO2 level	PPM value (400-1500)
sensor/cm1106c/abc_enable	Enable Automatic Baseline Correction	—
sensor/cm1106c/abc_disable	Disable ABC	—
sensor/cm1106c/status	Check sensor status	—
sensor/cm1106c/serial_number	Read serial number	—
sensor/cm1106c/version	Read firmware version	—

Air Quality

Command	Action	Payload
sensor/sgp41/baseline_status	Check VOC/NOx baseline learning status	—
sensor/bme680/gas_heater	Enable/disable gas heater	ON or OFF

Pressure

Command	Action	Payload
sensor/bmp280/diagnostic	Run diagnostic test	—

Device Commands

LED Control

Command	Action	Payload
device/led/set	Control status LED	ON, OFF, BLINK_FAST, BLINK_SLOW

Location

Command	Action	Payload
device/config/location	Update sensor location	JSON: {"latitude": -36.8, "longitude": 174.7, "name": "Auckland", "enable": true}
device/config/location_status	Check current location	—
device/config/location_reset	Reset to firmware defaults	—

This lets you move a sensor to a new location without reflashing the firmware.

System Commands

Command	Action	Payload
system/restart	Restart the device	— (3-second delay for safety)
system/status	Get uptime, memory, connectivity	—
system/syslog_enable	Enable remote syslog	—
system/syslog_disable	Disable remote syslog	—
system/syslog_status	Check syslog status	—

Calibration Management

Command	Action	Payload
system/calibration_status	Status of all sensors' calibration	—
system/calibration_reset	Reset calibration state	all or sensor name (e.g. scd4x)
system/calibration_restart	Reset and restart calibration	all or sensor name
system/calibration_backup	Backup calibration data to MQTT	—
system/calibration_restore	Restore from backup	JSON calibration payload
system/testing_enable	Suppress ALL data (testing mode)	—
system/testing_disable	Resume normal publishing	—

Sending Commands

You can send commands using any MQTT client. Here's an example using mosquitto_pub:

# Calibrate SCD4x to outdoor air (400 ppm)
mosquitto_pub -h mqtt.wesense.earth -p 8883 \
  --capath /etc/ssl/certs \
  -u "your_user" -P "your_password" \
  -t "wesense/v2/wifi/nz/wko/device123/command/sensor/scd4x/calibrate" \
  -m "400"

# Check system status
mosquitto_pub -h mqtt.wesense.earth -p 8883 \
  --capath /etc/ssl/certs \
  -u "your_user" -P "your_password" \
  -t "wesense/v2/wifi/nz/wko/device123/command/system/status" \
  -m ""

You can also use a GUI like MQTT Explorer, Home Assistant's MQTT integration, or any MQTT dashboard to send commands and view responses.

CO2 Calibration Tips

SCD30 / SCD4x — When to Calibrate

• Recommended approach: Enable ASC and place the sensor where it gets at least 1 hour of fresh air (~400ppm) daily. ASC takes 7 days to find its initial baseline.
• Manual calibration: Place the sensor outdoors in fresh air for 2+ minutes, then send the calibrate command with 400 as the payload.
• Never calibrate indoors — indoor CO2 varies too much for a reliable reference point.

CM1106-C — ABC Considerations

• ABC is disabled by default — the sensor uses factory calibration on startup.
• Only enable ABC if the sensor regularly sees outdoor air (~400ppm).
• ABC uses a 15-day cycle (vs 7 days for SCD4x).
• Incorrect ABC setup can cause a persistent 50-100ppm offset.

Remote Debug via Telnet

If you enabled Secure Telnet in the firmware configuration, you can connect to your sensor's serial output remotely:

telnet <sensor-ip-address> 23

This shows the same output as the Arduino IDE Serial Monitor — sensor readings, connection status, errors, and calibration state. Useful for diagnosing issues without physical access.