working principle
TEROS 21 Soil Water Potential SensorComposed of a humidity sensor and a porous material with a known moisture release curve, when the porous material reaches moisture equilibrium with the surrounding soil, the humidity sensor measures the moisture content of the porous material and converts it into water potential based on the moisture release curve.

Main Features

• Greatly improved accuracy:Using 6-point calibration, the sensors were calibrated one by one using an automatic calibration device. guaranteeTEROS 21The results of sensors and other water potential measurement methods are comparable.

• Durable and sturdy:The overlapping injection molding process of epoxy resin ensures its suitability for long-term field monitoring and research.

• No need for further calibration:There is no drift caused by degradation in ceramic materials with silica matrix.

• Salt insensitivity:Even in high salt environments with variable salt content, soil sensors remain accurate.

• Attached temperature measurement:At the same time, it can obtain another important indicator of plant growth.
  

• Plug and play:As long as the sensors are buried, the data collection is connected, the clock and measurement interval are set, and data collection can begin. No programming required.

• Remote data acquisition:useTEROS 21When connecting to ZL6 data acquisition, you can obtain data through the Internet.

• Compatible with SDI-12:TEROS 21Almost compatible with all mainstream data acquisition systems that support SDI-12, using a universal communication protocol.

Technical Specifications

Measurement frequency:70 MHz

output:RS232 (TTL) with 3.6 V or SDI-12 communication protocol

Support data collection (purchased separately):METER ZL6, EM50/60 series data acquisition, or 3.6-15VDC power supply, supports serial port or SDI-12 communication data acquisition

Size:9.6 cm (L) × 3.5 cm (W) × 1.5 cm (D), detection head diameter: 3.2cm

Work environment:-40~60 ℃ * (Water potential measurement may not be accurate below 0 ℃)

Cable length:5m， Other lengths can be customized, up to a maximum of 75m

Interface type:3.5mm headphone jack or tin plated bare wire jack (3-wire head)

Supply voltage (VCC to GND):最小3.6 VDC， 最大15.0VDC

Digital input voltage (logic high):Minimum 2.8V, typical 3.6V, maximum 3.9V

Digital input voltage (logic low):Minimum -0.3V, typical 0.0V, maximum 0.8V
Power line conversion rate:Minimum 1.0V/ms
Current: During measurement:Minimum 3.0mA; Typical 3.6mA; Maximum 10.0mA; Static waiting period: Typical 0.03mA
Start time: DDI serial port:Maximum 100ms; SDI-12: Minimum 100ms; Typical 150ms; Maximum 200ms
Measurement time:Typical 150ms; Maximum: 200ms
Following standards:Production under ISO 9001:2015 standard; EM ISO/IEC 17050:2010 (CE marking)

noteSensors can also be used in higher temperature environments in certain situations. If needed, please contact METER company for more information.

The measurement range of sensors with serial numbers before T21 is -9 kPa to -100000 kPa

Origin and Manufacturer:METER from the United StatesCompany_{(Former Decagon)}

Installation of TEROS 21 Soil Water Potential Sensor