Sensors at the Mezőfalva measuring stations
Author: dr. Csaba Tóth electrical engineer, precision agriculture engineer
A measuring station with sensors above ground, installed in the wheat.
Its components:
- The data collector with bird control
- Leaf moisture meter
- Meter ATMOS14 air temperature and humidity sensor


5 soil moisture sensors were installed in the soil:
- 1 Acclima TDR310
- 2 pcs Acclima TDR315
- 2 pcs Meter Teros21v2
The measuring stations are available in four different sensor configurations.
MST3: 5 soil moisture sensors
MST4: 1 meter ATMOS14
MST5: 5 soil moisture sensors, 1 ATMOS14
MST6: 5 soil moisture sensors, 1 ATMOS14, 1 Tekbox LWS01 leaf moisture meter
Description of components, sensors
TBS12S data logger
The data logger, manufactured by the Vietnamese company Tekbox, can handle SDI12 sensors, max. Capable of recording 40 SDI12 commands. The adjustable sampling time is 1min – 24 hours. With solar power, it can be used for sampling throughout the growing season.
ATMOS14 Air sensor
- Device available on SDI12 communication line
- Four parameters are transmitted to the data collector:
- Air temperature (C)
- Air relative humidity (%)
- Air pressure (kPa)
- Vapour pressure from which the dew point can be calculated (kPa)

LWS01 leaf moisture sensor
- Device available on SDI12 communication line
- Two parameters are transmitted to the data collector:
- Relative leaf humidity (0-100%)
- Sensor internal temperature (C)

ATMOS14 Air sensor
- Device available on SDI12 communication line
- Four parameters are transmitted to the data collector:
- Air temperature (C)
- Air relative humidity (%)
- Air pressure (kPa)
- Vapour pressure from which the dew point can be calculated (kPa)

Acclima TDR 310, 315 soil moisture sensors
- Device available on SDI12 communication line
- Four parameters are transmitted to the data collector:
- Volumetric soil moisture (%),
- Soil temperature (C),
- Bulk EC (us/cm)
- Pore EC (us/cm)

Meter Teros21v2 tensiometer
- Device available on SDI12 communication line
- Two parameters are transmitted to the data collector:
- Matrix tensiometry value (0…..-10.000 kPa)
- Soil temperature (C)

Weather station sensor inventory
Meter ATMOS41 integrated meteorological station
- Device available on SDI12 communication line
- 18 parameters are transmitted to the data logger:
- Air temperature (C)
- Vapour pressure (kPa)
- Air pressure (kPa)
- Relative humidity (%)
- Precipitation (mm)
- Wind speed (m/s)
- Wind gust (m/s)
- Wind direction (degrees)
- Humidity sensor temperature (C)
- Sunshine Intensity (W/m2)
- Number of lightning strikes
- Lightning distance (km)
Apogee SQ521 PAR (photosynthetic radiation) sensor
- Device available on SDI12 communication line
- Two parameters are transmitted to the data collector:
- Photosynthetic radiation intensity (umol/m2/sec)
- Sensor tilt (degrees)

Truebner TDR100 soil moisture sensor
- Device available on SDI12 communication line
- Two parameters are transmitted to the data collector:
- Soil moisture (%)
- Soil temperature (C)
The meteorological measuring station will remain on site throughout the year, while the soil moisture meter will measure the temperature of the topsoil throughout the entire period. The data is relevant for the spring sowing season. The measuring stations are placed in the designated plots after sowing.
Using SDI12 sensors
The SDI12 bus is a 3-wire 1200 baud sensor specific bus system. 62 sensors can be connected to the bus within a distance of 60m, but 1 sensor remains operational over hundreds of metres of cable. Communication on the bus is visually understandable for humans, known as. It is ASCII encoded, easy to decode.
Example: TDR315 measurement sequence with sensor programmed to address “1”.
Data acquisition measurement start: sends the 1M! code to the sensor. When the sensor recognises the command, it gives feedback to the data logger and starts sampling. When you have finished measuring, you send the measurement result to the data logger.
Sensor response: 1+24.4+19.5+12.6+534+2345
Mean: 1:title; soil moisture:24.4%; soil temperature: 19.5C; permittivity: 12.6;
Bulk EC: 534 uS/cm; Pore water EC: 2354uS/cm.