RS485 Temperature & Humidity Sensor (IP34)

The RS485 Temperature & Humidity Sensor (IP34) is an industrial-grade environmental monitoring probe enclosed in a durable aluminium alloy casing. Designed for long-distance data transmission using the Modbus RTU protocol, it is ideal for makers, engineers, and educators managing greenhouse monitoring, warehouse automation, and HVAC projects.

Long-distance industrial monitoring

Unlike standard I2C or UART sensors limited to short wiring runs, this unit uses RS485 communication to reliably transmit data across distances of up to 1200 metres. Its rugged aluminium alloy shell protects the digital processing circuitry in demanding industrial environments.

Interface and power requirements

Because this probe outputs raw RS485 signals, it cannot connect directly to GPIO pins or USB ports. It requires an RS485 shield when used with microcontrollers like Arduino or ESP32, a USB-to-RS485 adapter for PC debugging, and an external 12V to 36V DC power supply.

Pinout and Modbus wiring

The sensor communicates over standard Modbus RTU at a default baud rate of 9600. Wiring is broken out into four leads: red for 12V to 36V DC power, black for GND, yellow for RS485 A, and white for RS485 B.

Measurement range and accuracy

The probe covers a temperature range of -40°C to 120°C with an accuracy of ±0.3°C at 25°C, and a humidity range of 0 to 99.9% RH with ±2% RH accuracy. It operates on a 3-second sampling cycle with current consumption remaining within 20mA.

Installation and environmental protection

With an IP34 rating, the sensor is protected against splashing water but must never be submerged or washed. When installing outdoors or in greenhouses, mount the probe pointing vertically downwards beneath a protective weather shield to prevent moisture accumulation and dust from blocking the breathable membrane.