DFRobot RS485 4-in-1 Soil Moisture Temperature pH EC Sensor (IP68, 5-30V, 2m Cable)

The sensor uses the RS485 physical layer with the MODBUS-RTU protocol. To connect to an Arduino, you will need a TTL-to-RS485 converter module (such as a MAX485 board). Connect the sensor's RS485 lines (A/B) to the converter, and the converter's TTL lines (RO, DI) to the Arduino's serial pins. Then, use a MODBUS library to communicate with the sensor via its device address.

While the RS485 standard supports distances up to 1200 meters, practical limits depend on cable quality, baud rate, and electrical noise. With the included 2-meter cable and standard 9600 baud rate, you can reliably extend the connection several hundred meters using shielded twisted-pair cable. For very long runs, consider using repeaters and proper termination resistors.

The sensor has built-in memory temperature compensation for EC measurements within the 0-50°C range. It uses the internally measured soil temperature to automatically correct the raw EC reading to a standardized value (typically referenced to 25°C). This process is handled internally by the sensor's firmware and is not user-configurable, ensuring accurate salinity readings despite soil temperature fluctuations.

Yes, the probe is designed for permanent burial. The IP68 rating signifies complete protection against dust ingress and continuous submersion in water under specified conditions. This is achieved through vacuum-filling the probe body with black flame-retardant epoxy resin, creating a hermetic seal around the 316 stainless steel shell and internal electronics, preventing moisture and corrosive salts from causing damage.

Soil moisture measures the volumetric water content in the soil. Electrical Conductivity (EC) measures the concentration of soluble salts (ions) in the soil solution, which is an indicator of soil salinity and nutrient levels. They are distinct parameters: high moisture doesn't imply high EC, and vice versa. This sensor provides both measurements independently, which is crucial for managing irrigation in saline soils to prevent plant stress.