DFRobot - RS485 MODBUS-RTU IP68 Soil Temperature & Moisture Sensor for Automatic Irrigation (Arduino Compatible)

This RS485 soil temperature and moisture sensor brings two key soil measurements into one buried probe for irrigation and growing-environment projects. MODBUS-RTU communication and a DC 5-30V supply range support integration with compatible controllers, while an Arduino UNO and a separate TTL-to-RS485 interface provide a practical route for prototyping. An IP68 enclosure, epoxy sealing and 316 stainless steel probe support long-term placement in soil. From greenhouse beds to orchard monitoring, this sensor supplies temperature and moisture readings that a controller can use for logging, display or application-specific irrigation decisions.

Temperature and Moisture Readings from One Probe

This soil sensor measures temperature and moisture together, simplifying the sensing hardware needed to observe conditions around plant roots. Moisture is reported across a 0-100% range with 0.1% resolution, while temperature resolution is 0.1°C. These readings support tracking changes in soil conditions over time rather than relying only on watering schedules. Irrigation thresholds should be chosen for the crop and actual soil conditions, since soil salt content can influence the sensor's readings.

RS485 MODBUS-RTU Integration with 5-30V Power

This soil sensor uses RS485 communication with the MODBUS-RTU protocol, providing a digital interface for compatible monitoring and control systems. The wide DC 5-30V supply range accommodates different project power arrangements. For an Arduino UNO test setup, use a TTL-to-RS485 expansion board to connect the controller to the sensor's bus interface. The product wiki provides a reading example and protocol reference, helping bring up temperature and moisture data before adding application-specific logging or irrigation logic.

Wiring Diagram of soil sensor and Arduino Uno

IP68 Sealing for Long-Term Soil Placement

This soil probe combines IP68 protection with vacuum filling and black flame-retardant epoxy sealing for long-term burial applications. The 316 stainless steel probe provides corrosion-resistant construction for use across different soil environments. A compact 123*45*15mm body and 2m cable help position the sensor at the monitoring point while routing the connection to a controller. The stated working-temperature range is -40°C~+60°C; installation and operation should remain within that environmental limit.

How to install and use the soil sensor

For more detailed insights on selecting the most suitable sensor, refer to the guide on [How to Select the Best Soil Moisture Sensors for Agriculture and Research Lab].

• Combined soil temperature and moisture measurement
• DC 5-30V wide-range power supply
• RS485 output using MODBUS-RTU communication
• Arduino integration through a separate TTL-to-RS485 interface
• Fast data acquisition for monitoring projects
• 316 stainless steel probe designed for long-term soil burial
• IP68 protection with vacuum-filled flame-retardant epoxy sealing

• Agricultural irrigation monitoring
• Greenhouse soil monitoring
• Orchard irrigation projects
• Flower and vegetable cultivation
• Plant-cultivation and soil research experiments

• Power supply voltage: DC 5-30V
• Power consumption: 0.5W@24V
• Output mode: RS485
• Detection parameters: Temperature, Humidity
• Humidity parameters
           Measuring range: 0-100%
           Resolution: 0.1%
           Accuracy: 0-50%@±2%, 50-100%@±3%
• Temperature parameters
           Measuring range: -40°C~+80°C
           Resolution: 0.1°C
           Accuracy: ±0.5°C
• Protection level: IP68
• Probe material: anti-corrosion special electrode
• Sealing material: black flame retardant epoxy resin
• Working temperature: -40°C~+60°C
• Cable length: 2m
• Size: 123*45*15mm

• RS485 Soil Sensor (Temperature & Humidity) x1