Introduction to Sensor
The TEROS 21 is an accurate and affordable soil matric potential sensor designed to measure soil water potential across a wide range, from 0 kPa to air-dry conditions. Its six-point factory calibration ensures improved accuracy without the need for recalibration, while onboard temperature measurement provides additional soil condition data. With plug-and-play operation, low salt sensitivity, and a durable design, it offers reliable long-term soil monitoring with minimal maintenance.
Specifications
Specifications
Measurement Specifications
| Parameter | Specification |
|---|---|
| Water Potential | Range: –8 to –100,000 kPa (1.90 to 6.00 pF) Resolution: 0.1 kPa Accuracy: ±(10% of reading + 2 kPa) from –100 to –5 kPa |
| Water Potential Notes | TEROS 21 Gen 2 can read up to 0 kPa on a wetting path. Soil air entry limits sensor performance to 0 kPa on the drying curve. TEROS 21 is not well calibrated beyond –100 kPa. |
| Temperature | Range: –40.00 to 60.00 °C Resolution: 0.10 °C Accuracy: ±1.00 °C |
| Dielectric Measurement Frequency | 70 MHz |
Communication Specifications
| Parameter | Specification |
|---|---|
| Output | DDI serial or SDI-12 communication protocol |
| Data Logger Compatibility | METER ZL6, EM60, and Em50 data loggers, or any data acquisition system capable of 3.6–15 VDC power and serial or SDI-12 communication |
Physical Specifications
| Parameter | Specification |
|---|---|
| Dimensions | Length: 9.6 cm (3.8 in)Width: 3.5 cm (1.4 in)Height: 1.5 cm (0.6 in) |
| Sensor Diameter | 3.2 cm (1.3 in) |
| Operating Temperature Range | –40.00 to 60.00 °C |
| Operating Temperature Note | Sensors may be used at higher temperatures under certain conditions; contact Customer Support for assistance. |
| Cable Length | Standard: 5 mMaximum Custom: 75 m |
| Cable Length Note | Contact Customer Support if a nonstandard cable length is needed. |
| Connector Types | 3.5-mm stereo plug connector or stripped and tinned wires |
Electrical & Timing Characteristics
| Parameter | Specification |
|---|---|
| Supply Voltage (VCC to GND) | Minimum: 3.9 VDC Maximum: 15.0 VDC |
| Digital Input Voltage – Logic High | Minimum: 2.8 V Typical: 3.6 V Maximum: 5.0 V |
| Digital Input Voltage – Logic Low | Minimum: –0.3 V Typical: 0.0 V Maximum: 0.8 V |
| Power Line Slew Rate | Minimum: 1.0 V/ms |
| Current Drain During Measurement | Minimum: 3.0 mA Typical: 5.0 mA Maximum: 16.0 mA |
| Current Drain While Asleep | Minimum: 0.0 mA |
| Power Up Time | DDI Serial: Maximum 50 msSDI-12: Typical: 175 ms |
| Measurement Duration | Typical: 175 ms |
Other Specifications
| Parameter | Specification |
|---|---|
| Product Award | Winner of the 2022 AE50 Innovation Award |
| Compliance | EM ISO/IEC 17050:2010 (CE Mark); EN 55011:2016 / A1:2017 (RCM Mark) |
| Prop 65 Warning | Applicable |
| EU Declaration of Conformity | Available for TEROS 21 Gen 2 |
| GSA | GSA purchasing details available |
Features
Applications