sht3x

Overview

The sht3x node reads temperature and humidity from the Sensirion SHT30, SHT31, or SHT35 sensor via I2C. Known for exceptional accuracy and long-term stability, this sensor family is the gold standard for precision climate monitoring in greenhouses, cleanrooms, and HVAC systems.

Wiring (I2C)

Properties

Output

{
  "payload": {
    "temperature": 23.45,
    "humidity": 52.8
  },
  "temperature": 23.45,
  "humidity": 52.8,
  "dewPoint": 13.2,
  "timestamp": 1640000000000
}

Example: Greenhouse Climate Monitoring

Monitor temperature and humidity with alerts when conditions drift outside optimal ranges for plant growth.

// Function node: Greenhouse climate controller
var temp = msg.temperature;
var humidity = msg.humidity;

// Optimal ranges for tomatoes
var tempMin = 18, tempMax = 27;
var humMin = 60, humMax = 80;

var alerts = [];
var actions = [];

if (temp < tempMin) {
    alerts.push("Temperature too low: " + temp + "°C");
    actions.push("heater_on");
} else if (temp > tempMax) {
    alerts.push("Temperature too high: " + temp + "°C");
    actions.push("fan_on");
}

if (humidity < humMin) {
    alerts.push("Humidity too low: " + humidity + "%");
    actions.push("mister_on");
} else if (humidity > humMax) {
    alerts.push("Humidity too high: " + humidity + "%");
    actions.push("vent_open");
}

msg.payload = {
    temperature: temp,
    humidity: humidity,
    status: alerts.length === 0 ? "optimal" : "alert",
    alerts: alerts,
    actions: actions
};

return msg;

Use Cases