Measuring stations, SDI12 sensors in the Mezőfalva pilot network

Measuring stations, SDI12 sensors in the Mezőfalva pilot network

 

In the area of Mezőfalvai ZRT, 77 measuring stations were installed to monitor meteorological, environmental and soil data in support of the pilot data collection within the framework of the GINOP PLUSZ-2.1.1-21-2022-00229 project.

 

A detailed description of the pilot monitoring can be found in the publication “A unique solution for crop production with IoT systems for a secure harvest”.

The measuring stations were deployed in several sensor configurations in the production plots of wheat, sunflower, maize, sugar beet, at the GNSS points precisely defined by the experiment’s technical management.

 

The 1. Figure 3 shows the configuration of a measuring station installed in a wheat plot.

 

The visible subunits above the surface are 1. as indicated in Figure 5:

❶ TBS-12S data logger with solar panel and built-in battery

❷ Leaf moisture meter

❸ Meter ATMOS14 air temperature and humidity sensor (TRH)

❹ Cable junction box

❺ Polycarbonate bird repellent spikes

 

From Figure 1 does not show soil sensors installed in the soil at 5 different depths. Figure 2 shows a demonstration photograph of the monitoring station, including the soil sensors used.

The 5 types of soil moisture sensors installed in the soil are shown in Figure 2. as indicated in the figure:

❶ 2 pcs Meter Teros21v2 soil tensiometer

❷ 2 Acclima TDR315 volumetric soil moisture sensors

❸ 1 Acclima TDR310 volumetric soil moisture sensor

Measuring station configurations

In total, there are nearly 400 SDI12 sensors in 77 measuring stations, in six different sensor configurations, as shown below:

 

MST1: Meteorological Station located in the centre of the site, with sensors installed (Figure 3):

Meter ATMOS41 integrated sensor with bird spike,

Apogee SQ521 PAR sensor,

Truebner SMT100 soil sensor

MST2: Meteorological station located on the corner of the site, with integrated sensor:

Meter ATMOS41 integrated sensor with bird spike,

MST3: Soil moisture monitoring station:

5 soil moisture sensors of the types described above

MST4: Indoor temperature and humidity station:

Meter ATMOS14 TRH

MST5: Combined canopy and soil moisture monitor station 1:

5 soil moisture sensors,

1 meter ATMOS14 TRH sensor

MST6: Combined canopy and soil moisture monitoring station 2:

5 soil moisture sensors,

1db Meter ATMOS14 TRH,

1 Tekbox LWS01 leaf moisture sensor

Description of components, sensors

TBS-12S data logger

The Tekbox data logger can handle sensors with SDI12 protocol and can configure up to 40 SDI12 commands. The data logger can be registered to a LoRaWAN network, has a configurable sampling time of 1min – 24 hours and can be used for sampling during the whole growing season with solar power.

 

Meter ATMOS14 Air temperature and humidity sensor

Device available on SDI12 communication bus

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 bus

Two parameters are transmitted to the data collector:

Relative leaf humidity (0-100%)

Sensor internal temperature (°C)

Acclima TDR 310, 315 soil moisture sensors

Device available on SDI12 communication bus

Five parameters are transmitted to the data collector:

Volumetric soil moisture (%),

Soil temperature (°C),

Permittivity

Bulk EC (µS/cm)

Pore EC (µS/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 sensor

Device available on SDI12 communication bus

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

Distance to lightning strikes (km)

Apogee SQ521 PAR (photosynthetic radiation) sensor

Device available on SDI12 communication line

Two parameters are transmitted to the data collector:

Photosynthetic radiation intensity (^µmol/m2/sec)

Sensor tilt (degrees)

Truebner TDR100 soil moisture sensor

Device available on SDI12 communication line

Three parameters are transmitted to the data logger:

Soil moisture (%)

Soil temperature (°C)

Pole voltage (V)

The meteorological measuring station will remain in the field all year round, while the attached SMT-100 soil moisture meter will measure the soil temperature throughout the entire period. In the spring sowing period, when the measuring stations are not yet installed in the plots, knowledge of soil temperature is important.

The other measuring stations with the configured set of sensors will be placed in the pilot plots after sowing.

 

 

Using SDI12 sensors

The SDI12 bus is a 3-wire 1200 baud sensor specific bus system with a rather slow data rate but high noise immunity. 62 sensors can be connected to the bus, with a nominal cable distance of 60m, but if only a few sensors are used on the bus, it will remain operational over hundreds of meters of cable. The communication on the bus is visualised in a way that is visually understandable and easy to decode. ASCII encoding is used.

Advantages: the bus consists of 3 wires, easier wiring and troubleshooting in case of multiple sensors.

Each sensor is equipped with a microcomputer that sends the measured values to the data logger, calibrated if necessary or, in some cases, converted according to an externally specified function.

Digital data transmission ensures lossless signal transmission.

Disadvantage: special knowledge and tools are needed to program and service the system.

 

Example

Let’s see how data transmission is done in practice with an Acclima TDR315 sensor programmed to address “1”.

The measurement cycle of a package:

• The data logger sends the code “1M!” to the sensor, which means “measure”.
• When the sensor recognises the command, it signals back to the data collector that it has accepted it and starts sampling. When you have finished measuring, you send the measurement result to the data logger.
• Sensor response ASCII data packet: 1+24.4+19.5+12.6+534+2345

Meaning:

address of the sensor:1;

soil moisture value:24.4%;

soil temperature value: 19.5°C;

permittivity: 12.6;

Bulk EC, conductivity: 534 µS/cm;

Pore water EC, conductivity: 2354 µS/cm.

 

The measurement cycle is approx. it happens in 1 second.

 

Author:

Dr. Csaba Tóth

Tóth Tóth, electrical engineer, precision farming engineer

T-Markt Kereskedőház Kft.

2013 Pomáz Határ u 5/A
0626-525-500
www.agrismartgreen.com