Wittelb WIN-SN-TNH-AHT20-M Digital Temperature & Humidity Sensor with RS485 Modbus & Display

The module uses the Modbus RTU protocol over an RS485 interface. Key parameters like slave ID (1-247), baud rate (9600, 19200, etc.), data bits, stop bits, and parity are configurable via Modbus write commands to the internal holding registers, allowing seamless integration into existing industrial networks.

The sensor requires a 12-24V DC power supply, typically drawing up to 1A. Connect the positive and negative power wires to the designated terminals. The RS485 communication lines (A/B or D+/D-) must be connected with correct polarity and typically require a termination resistor at the end of the bus line for reliable data transmission.

While the sensor's AHT20 core and electronics operate from -40°C to +85°C, the module as provided may not have a specific IP rating for waterproofing. For outdoor use, it must be installed within a protective enclosure (e.g., a weatherproof junction box) to shield it from direct rain, condensation, and UV exposure to ensure long-term reliability.

Values are accessed by reading specific holding registers via Modbus function code 0x03. The temperature (in °C) and humidity (in %RH) are typically stored as integer values in consecutive registers. You will need to consult the product's Modbus register map to apply any necessary scaling factors to convert the raw register data into engineering units.