Tensiometer Soil Moisture Sensor, 4-20mA/RS485

The tensiometer soil moisture sensor features a transparent PVC plastic tube design, suitable for soil depth measurements ranging from 15cm to 120cm. It has a measurement range of -100 kPa to 0, with an accuracy of ±0.5 kPa (at 25°C), and a fast response time of just 200 ms. The high-quality soil tensiometer sensor supports optional 4-20mA and RS485 (Modbus protocol) signal output, operates at a voltage of 10-24V DC, and consumes only 0.8W (when powered by 24V). It features an IP67 protection rating, enabling stable operation in environments ranging from 0°C~80°C, making it suitable for harsh field conditions.

Feature

• Mobile APP to view the history curve, real-time monitoring of soil moisture and temperature data.
• Powered by three No. 5 batteries, low power consumption and high endurance.
• Highly sensitive 304 stainless steel probe, fast response speed, accurate measurement.
• Plug and play, convenient and fast measurement.

Dimension (Unit:mm)

Details

1. High-quality Terracotta Head: The terracotta head is the sensing component of the instrument and has many tiny pores. The sensitivity of the soil moisture sensor depends on the permeability (water permeability) of the terracotta head.
2. Transparent PVC Plastic Tube: The shell is made of transparent PVC plastic tube, which allows for direct observation of the water level response speed and effectively senses the soil environment.
3. The tensiometer soil moisture sensor uses a stainless steel mechanical vacuum gauge, which can be used outdoors for a long time.

Tensiometer Soil Moisture Sensor Usage Steps

1. Use a soil drill to drill holes in the appropriate locations.
2. Prepare mud: mix water and soil together.
3. Slowly pour in about half of the mud and install the grout.
4. Tensiometer soil moisture sensor installation complete.

Instructions for Use

• Prepare cool boiled water (water without air). Boil tap water for 20 minutes, then let it cool and set aside.
• Vent the clay head by unscrewing the top cap, removing the silicone plug, and filling it with cool boiled water. Fill it to the top, then stand the tensiometer soil moisture sensor upright for 10~40 minutes (do not cover it), and observe water dripping from the surface of the clay head. Then reinsert the silicone plug, wrap the clay head with paper towels to absorb water, and adjust the soil tension to approximately -40 kPa. If bubbles rise, shake the device to expel air. Repeat this process 2~3 times.
• Submerge the clay head in water, wait until the soil tension returns to within -10 kPa, refill with water, reattach the silicone plug, secure the top cover, and set aside for use.

Wiring Diagram

Category	Line Color	Description
Power Supply	Brown	Power supply positive (10~30V DC)
	Black	Power supply negative
Communication	Green	485-A
	Blue	485-B

Power Supply and RS485 Signal Wiring Precautions: The power supply can accept a wide voltage range of 10 to 24 V. When connecting the 485 signal lines, make sure that the A and B lines are not reversed, and that the addresses of multiple devices on the bus do not conflict.