Calculated Sensors

Virtual sensors can be created that calculate their values from other sensors.

In this example (with hourly readings), daily maximum, minimum and average values are being calculated from 06:00 to 06:00 - the period could have been weekly or monthly.

In addition to separate calculated sensors, each sensor can 'internally' calculate and graph varying upper, varying lower, smooth, rate, and integration using GraphMenu/PlotExtras.

The advantage of using the extra, internal, sensors is that they are easy to use; but they cannot be individually customised. Colours and lines styles can be set on LoggerMenu/Options.

If you need to customise a calculated sensor you will need to create a separate sensor with LoggerMenu/Calculated. Calculated sensors are customised in the same way as a normal sensor (GraphMenu/Options and LoggerMenu/Details)

The following functions are available...

ID Formula Notes Inputs required
3 Smooth Smooths the values Sensor,Factor
3.1  Method1 Moving average over the previous number of day(s) Sensor,day(s)
3.2  Method2 Digital filter, with factor and Jump Sensor,Factor,Jump
3.3  Method3 Polynomial (not implemented) Sensor
3.4  Method4 FFT (not implemented) Sensor
Rate Rate of change (per day) Sensor
1.  Method1 Difference between 2 consecutive readings Sensor
1.21  Method2* Difference between reading a numbers of days)(s) apart (with Jump from Smooth) Sensor, Days(s), Jump
1.3  Method3* Difffrence between readings at 6:00 a.m. on consecutive days Time (hh:mm)
2 Integrate Accumulates total of value Sensor
15 RTOTAL * Total of values in period Sensor,Period**
14 RAVERAGE * Average value in period Sensor, Period**
16 RCOUNT * Count of values in period Sensor, Period**
10 RMAXIMUM * Maximum value in period Sensor, Period**
12 RMINIMUM * Minimum value in period Sensor, Period**
8 GDD Growing degree days MaxTemp, MinTemp, base temperature
9 PENMAN ET0 FAO12345 - replaced by below MaxTep, MinTemp, RH, WR
23 AVERAGE Average of 2 other sensors at same date Sensor1, Sensor2
24 Difference Difference between 2 other sensors Sensor1, Sensor2
25 Sum Total of 2 other sensors Sensor1, Sensor2
26 Max Maximum of 2 other sensors Sensor1, Sensor2
27 Min Minimum of 2 other sensors Sensor1, Sensor2
4 LOOKUP Looks up a value in another file Sensor
File name (comma or tab delimited)
Column in file of known values
Column in file with result
Style - interpolated
5 DWULOOKUP Calculated value from DWU file on DayOfYear()
file needs to be in DWU format
DWU file name
Column in file with dwu value (default = Col2)
Style = interpolate | use previous | use next value in file
6 LOOKUPOTHER Interpolates value of sensor in another logger (with different dates)
Note: v2.1.036 all functions allow the target sensor to be in any logger.
7 ROOTZONE Total amount of water in root zone All sensors in same logger with a 'depth' >0
20 DELTAT Calculates DeltaT from air temperature and RH - see Bureau of Meteorology Air temperature (degC)
22 RDI Calculate value of varying upper or lower limit from file.
Limit can be either...
  • = Sensor.Lower + Factor * (Sensor.Upper - Sensor.Lower)
  • = Sensor.Upper + Factor
  • = Sensor.Lower + Factor
And Factor is calculated from a file - see example
File must be in DWU format
RDI file name
Column in file with RDI value (default = Col2)
30 CWSI(Zen) Calculation of Zen Crop Water Stress Index
Value = (AirTemperature - CanopyTemperature) * RH
Geoffrey Phelps
Sensor1: Air Temperature
Sensor2: Canopy Temperature
Sensor3: RH
31 CWSI Calculation of Crop Water Stress Index
Value = f(AirTemperature, CanopyTemperature, VPD, RH ??)
Sensor1: Air Temperature
Sensor2: Canopy Temperature
Sensor3: VPD
Factor1: Upper Limit
Factor2: Lower Slope
Factor3: Lower(Offset)
32 ET0 Hourly (FAO 56) ET0 from Temperature, RH, SR, Wind Speed Sensor1: Air Temperature
Sensor2: Solar Radiation
Sensor3: RH
Sensor4: Wind Speed
Factor1: Station (e.g. Goanna)
Factor2: Crop Factor (e.g. 0.9)
33 ET0 Daily (FAO 56) ET0 from daily Temperature, RH, Wind
using FAO 56 (CSIRO, Griffith)

Sensor1: Temperature Max
Sensor2: Temperature Min
Sensor3: RH Max
Sensor4: RH Min
Sensor5: Solar Rad
Sensor6: Wind speed
Factor1: StationName (e.g. Goanna)
Factor2: Crop Factor
Factor3: Adjust
34 SoilMoisture from ET0 Calculate the soil water balance using ET
Sensor2 is measured soil moisture
Starting value from Sensor2
Increase if gain detected in Sensor2
Sensor1: ET
Sensor2: Measured
Sensor3: Rain
Sensor4: Irrigations

* Needs continuous logged data at equal time intervals.

** Period can be in days (e.g. '1d'), weeks (e.g. '1w') or months (e.g. '1m')

After v 2.1.036, the sensors can be in any logger. This would allow, for example, a sensor to calculate the difference between temperature recorded on two separate loggers.