TEROS 12
The TEROS 11/12 sensors are designed to be installed in mineral soils, many types of growing media, and other porous materials. This manual guides the customer through the sensor features and describes how to use the sensor successfully. TEROS 11/12 sensors are accurate tools for monitoring volumetric water content (VWC), temperature in soil and soilless substrates, and EC (TEROS 12 only). The TEROS 11/12 determines VWC using capacitance/frequency-domain technology. The sensor uses a 70-MHz frequency, which minimizes textural and salinity effects, making the TEROS 11/12 accurate in most mineral soils. The TEROS 11/12 uses a thermistor to measure temperature and EC (TEROS 12 only) using a stainless-steel electrode array. Prior to use, verify the TEROS 11/12 sensors arrived in good condition. METER recommends testing the sensors with the data logging device and software before going to the field.
Specification
Measurement Specification
Volumetric Water Content (VWC)
Range
| Mineral Soil Calibration | 0.00–0.70 m³/m³ |
| Soilless Media Calibration | 0.0–1 m³/m³ |
| Apparent dielectric permittivity (εa) | 1 (air) to 80 (water) |
| NOTE: The VWC range is dependent on the media the sensor is calibrated to. A custom calibration will accommodate the necessary ranges for most substrates. | |
| Resolution | 0.001 m³/m³ |
Accuracy
| Mineral Soil Calibration | ±0.03 m³/m³ typical in mineral soils that have solution EC <8 dS/m |
| Medium Specific Calibration | ±0.01–0.02 m³/m³ in any porous medium |
| Apparent dielectric permittivity (εa) | 1–40 (soil range) , ±1 εa (unitless) 40–80, 15% of measurement |
Dielectric Measurement Frequency
70MHz
Temperature
TERROS 12
| Range | −40 to +60 °C |
| Resolution | 0.1 °C |
| Accuracy | ±0.5 °C from −40 to 0 °C ±0.3 °C from 0 to +60 °C |
NOTE: Temperature measurement for applicable sensors may not be accurate if sensor is not fully immersed in the medium of interest due to longer equilibration time
Communication Specifications
Output
DDI serial or SDI-12 communications protocol
Data Logger Compatibility
Data acquisition systems capabl
METER ZL6, EM60, and Em50 data loggers or any data acquisition system capable of 4.0- to 15-VDC power and serial or SDI-12 communication
Physical Specifications
Dimensions
| Length | 9.4 cm (3.70 in) |
| Width | 2.4 cm (0.95 in) |
| Height | 7.5 cm (2.95 in) |
Needle Length
5.5 cm (2.17 in)
Operating Temperature Range
| Minimum | –40 °C |
| Typical | NA |
| Maximum | +60 °C |
NOTE: Sensors may be used at higher temperatures under certain conditions; contact Customer Support for assistance.
Cable Length
5 m (standard)
75 m (maximum custom cable length)
NOTE: Contact Customer Support if a nonstandard cable length is needed.
Cable Diameter
0.165 ± 0.004 (4.20 ± 0.10 mm) with minimum jacket of 0.030 (0.76 mm)
Connector Types
Stereo plug connector or stripped and tinned wires
Stereo Plug Connector Diameter
3.50 mm
Conductor Gauge
22 AWG/24 AWG drain wire
Electrical and Timing Characteristics
Supply Voltage (VIN to GND)
| Minimum | 4.0 VDC |
| Typical | NA |
| 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 |
Digital Output Voltage (logic high)
| Minimum | NA |
| Typical | 3.6 V |
| Maximum | NA |
Power Line Slew Rate
| Minimum | 1.0 V/ms |
| Typical | NA |
| Maximum | NA |
Current Drain (during 25-ms measurement)
| Minimum | 3.0 mA |
| Typical | 3.6 mA |
| Maximum | 16.0 mA |
Current Drain (while asleep)
| Minimum | NA |
| Typical | 0.03 mA |
| Maximum | NA |
Power-Up Time (DDI serial)
| Minimum | 80 ms |
| Typical | NA |
| Maximum | 100 ms |
Power Up Time (SDI-12, DDI disabled)
| Minimum | 145 ms |
| Typical | 155 ms |
| Maximum | 165 ms |
Measurement Duration
| Minimum | 25 ms |
| Typical | NA |
| Maximum | 150 ms |
Power-Up Time (SDI-12)
| Minimum | NA |
| Typical | 245 ms |
| Maximum | NA |
COMPLIANCE
Manufactured under ISO 9001:2015
EM ISO/IEC 17050:2010 (CE Mark)
2014/30/EU and 2011/65/EU
EN61326-1:2013 and EN55022/CISPR 22
For inquiries contact us
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