Variable class

The variable class for a value and related metadata.

A variable is a result value taken by a sensor or calculated from the results of one or more sensors. It is characterized by a name (what it is a measurement of), a unit of measurement, and a resolution. The names and units of measurements for all variables come from the controlled vocabularies developed for the ODM2 data system. (http://vocabulary.odm2.org/) The resolution is determined by the method used to take the measurement by the sensor. A variable may also be assigned a universally unique identifier (UUID) and a unique variable code. Many sensors are capable of measuring multiple variables at a single time. For example, a Decagon CTD-10 is a sensor. It is able to measure 3 variables: specific conductance, temperature, and water depth. The variable named "specificConductance" has units of microsiemens per centimeter (µS/cm) and a resolution of 1 µS/cm. Each measured variable is explicitly tied to the "parent" sensor that "notifies" the variable when a new value has been measured. Each calculated variable has a parent function returning a float which is the value for that variable.

Variables are expected to be grouped together into VariableArrays.

Derived classes

class AOSongAM2315_Humidity: The Variable sub-class used for the relative humidity output from an AOSong AM2315.
class AOSongAM2315_Temp: The Variable sub-class used for the temperature output from an AOSong AM2315.
class AOSongDHT_HI: The Variable sub-class used for the heat index output calculated from measurements made by an AOSong DHT.
class AOSongDHT_Humidity: The Variable sub-class used for the humidity output from an AOSong DHT.
class AOSongDHT_Temp: The Variable sub-class used for the temperature output from an AOSong DHT.
class AlphasenseCO2_CO2: The Variable sub-class used for the carbon dioxide (CO2) output from an Alphasense IRC-A1 CO2.
class AlphasenseCO2_Voltage: The Variable sub-class used for the raw voltage output from an Alphasense IRC-A1 CO2.
class AnalogElecConductivity_EC: The Variable sub-class used for electrical conductivity measured using an analog pin connected to electrodes submerged in the medium.
class ApogeeSQ212_PAR: The Variable sub-class used for the photosynthetically active radiation (PAR) output from an Apogee SQ-212.
class ApogeeSQ212_Voltage: The Variable sub-class used for the raw voltage output from an Apogee SQ-212.
class AtlasScientificCO2_CO2: The Variable sub-class used for the CO2 concentration output from an Atlas Scientific CO2 circuit.
class AtlasScientificCO2_Temp: The Variable sub-class used for the temperature output from an Atlas Scientific CO2 circuit.
class AtlasScientificDO_DOmgL: The Variable sub-class used for the dissolved oxygen concentration output from an Atlas Scientific EZO dissolved oxygen circuit.
class AtlasScientificDO_DOpct: The Variable sub-class used for the dissolved oxygen percent of saturation output from an Atlas Scientific EZO dissolved oxygen circuit.
class AtlasScientificEC_Cond: The Variable sub-class used for the conductivity output from an Atlas Scientific EC EZO circuit.
class AtlasScientificEC_Salinity: The Variable sub-class used for the salinity output from an Atlas Scientific EC EZO circuit.
class AtlasScientificEC_SpecificGravity: The Variable sub-class used for the specific gravity output from an Atlas Scientific EC EZO circuit.
class AtlasScientificEC_TDS: The Variable sub-class used for the total dissolved solids output from an Atlas Scientific EC EZO circuit.
class AtlasScientificORP_Potential: The Variable sub-class used for the oxidation/reduction potential output from an Atlas Scientific EZO-ORP circuit.
class AtlasScientificRTD_Temp: The Variable sub-class used for the temperature output from an Atlas Scientific RTD temperature sensor.
class AtlasScientificpH_pH: The Variable sub-class used for the pH output from an Atlas Scientific EZO pH circuit.
class BoschBME280_Altitude: The Variable sub-class used for the altitude calculated from the measurements made by a Bosch BME280.
class BoschBME280_Humidity: The Variable sub-class used for the relative humidity output from a Bosch BME280.
class BoschBME280_Pressure: The Variable sub-class used for the atmospheric pressure output from a Bosch BME280.
class BoschBME280_Temp: The Variable sub-class used for the temperature output from a Bosch BME280.
class BoschBMP3xx_Altitude: The Variable sub-class used for the altitude calculated from the measurements made by a Bosch BMP3xx.
class BoschBMP3xx_Pressure: The Variable sub-class used for the atmospheric pressure output from a Bosch BMP3xx.
class BoschBMP3xx_Temp: The Variable sub-class used for the temperature output from a Bosch BMP3xx.
class CampbellClariVUE10_ErrorCode: The Variable sub-class used for the error code output from a Campbell ClariVUE10 turbidity sensor.
class CampbellClariVUE10_Temp: The Variable sub-class used for the temperature output from a Campbell ClariVUE10 turbidity sensor.
class CampbellClariVUE10_Turbidity: The Variable sub-class used for the turbidity output from a Campbell ClariVUE10 turbidity sensor.
class CampbellOBS3_Turbidity: The Variable sub-class used for the turbidity output from a Campbell OBS3+.
class CampbellOBS3_Voltage: The Variable sub-class used for the raw voltage output from a Campbell OBS3+.
class CampbellRainVUE10_Precipitation: The Variable sub-class used for the precipitation output from a Campbell RainVUE10 precipitation sensor.
class CampbellRainVUE10_RainRateAve: The Variable sub-class used for the average rainfall rate output from a Campbell RainVUE10 precipitation sensor.
class CampbellRainVUE10_RainRateMax: The Variable sub-class used for the maximum rainfall rate output from a Campbell RainVUE10 precipitation sensor.
class CampbellRainVUE10_Tips: The Variable sub-class used for the tip count output from a Campbell RainVUE10 precipitation sensor.
class Decagon5TM_Ea: The Variable sub-class used for the apparent dielectric permittivity (εa, matric potential) output from a Meter ECH20 or Decagon 5TM soil moisture probe.
class Decagon5TM_Temp: The Variable sub-class used for the temperature output output from a Meter ECH20 or Decagon 5TM soil moisture probe.
class Decagon5TM_VWC: The Variable sub-class used for the volumetric water content output from a Meter ECH20 or Decagon 5TM soil moisture probe.
class DecagonCTD_Cond: The Variable sub-class used for the conductivity output from a Decagon CTD-10 3-in-1 water level sensor..
class DecagonCTD_Depth: The Variable sub-class used for the depth output from a Decagon CTD-10 3-in-1 water level sensor..
class DecagonCTD_Temp: The Variable sub-class used for the temperature output from a Decagon CTD-10 3-in-1 water level sensor..
class DecagonES2_Cond: The Variable sub-class used for the conductivity output from a Decagon ES-2 electrical conductivity sensor.
class DecagonES2_Temp: The Variable sub-class used for the temperature output from a Decagon ES-2 electrical conductivity sensor.
class EverlightALSPT19_Current: The Variable sub-class used for the relative current output from an Everlight ALS-PT19.
class EverlightALSPT19_Illuminance: The Variable sub-class used for the calculated illuminance output from an Everlight ALS-PT19.
class EverlightALSPT19_Voltage: The Variable sub-class used for the relative current output from an Everlight ALS-PT19.
class FreescaleMPL115A2_Pressure: The Variable sub-class used for the pressure output from a Freescale Semiconductor MPL115A2.
class FreescaleMPL115A2_Temp: The Variable sub-class used for the temperature output from a Freescale Semiconductor MPL115A2.
class GroPointGPLP8_Moist: The Variable sub-class used for the soil moisture output from a GroPoint Profile GPLP8 probe.
class GroPointGPLP8_Temp: The Variable sub-class used for the temperature output from a GroPoint Profile GPLP8 probe.
class InSituRDO_DOmgL: The Variable sub-class used for the dissolved oxygen concentration output from a In-Situ RDO PRO-X dissolved oxygen sensor.
class InSituRDO_DOpct: The Variable sub-class used for the dissolved oxygen percent saturation output from a In-Situ RDO PRO-X dissolved oxygen sensor.
class InSituRDO_Pressure: The Variable sub-class used for the oxygen partial pressure output from a In-Situ RDO PRO-X dissolved oxygen sensor.
class InSituRDO_Temp: The Variable sub-class used for the temperature output from a In-Situ RDO PRO-X dissolved oxygen sensor.
class InSituTrollSdi12a_Depth: The Variable sub-class used for the depth output from a Insitu TROLL 3-in-1 water level sensor..
class InSituTrollSdi12a_Pressure: The Variable sub-class used for the pressure output from a Insitu TROLL 3-in-1 water level sensor..
class InSituTrollSdi12a_Temp: The Variable sub-class used for the temperature Output from a Insitu TROLL 3-in-1 water level sensor..
class KellerAcculevel_Height: The Variable sub-class used for the gauge height (water level with regard to an arbitrary gage datum) output from a Keller Acculevel.
class KellerAcculevel_Pressure: The Variable sub-class used for the gauge pressure (vented and barometric pressure corrected) output from a Keller Acculevel.
class KellerAcculevel_Temp: The Variable sub-class used for the temperature output from a Keller Acculevel.
class KellerNanolevel_Height: The Variable sub-class used for the gauge height (water level with regard to an arbitrary gage datum) output from a Keller Nanolevel ceramic capacitive level transmitter.
class KellerNanolevel_Pressure: The Variable sub-class used for the gauge pressure (vented and barometric pressure corrected) output from a Keller Nanolevel ceramic capacitive level transmitter.
class KellerNanolevel_Temp: The Variable sub-class used for the temperature output from a Keller Nanolevel ceramic capacitive level transmitter.
class MaxBotixSonar_Range: The Variable sub-class used for the range output from a MaxBotix HRXL-MaxSonar ultrasonic range finder.
class MaximDS18_Temp: The Variable sub-class used for the temperature output from a Maxim one-wire temperature sensor.
class MaximDS3231_Temp: The Variable sub-class used for the temperature output from a DS3231.
class MeaSpecMS5803_Pressure: The Variable sub-class used for the pressure output from a Measurement Specialties MS5803 digital pressure sensor.
class MeaSpecMS5803_Temp: The Variable sub-class used for the temperature output from a Measurement Specialties MS5803 digital pressure sensor.
class MeterHydros21_Cond: The Variable sub-class used for the conductivity output from a Meter Hydros 21 3-in-1 water level sensor..
class MeterHydros21_Depth: The Variable sub-class used for the depth output from a Meter Hydros 21 3-in-1 water level sensor..
class MeterHydros21_Temp: The Variable sub-class used for the temperature output from a Meter Hydros 21 3-in-1 water level sensor..
class MeterTeros11_Count: The Variable sub-class used for the raw calibrated VWC counts from a Meter Teros soil moisture/water content sensor.
class MeterTeros11_Ea: The Variable sub-class used for the apparent dielectric permittivity (εa, matric potential) from a Meter Teros soil moisture/water content sensor.
class MeterTeros11_Temp: The Variable sub-class used for the temperature output output from a Teros soil moisture/water content sensor.
class MeterTeros11_VWC: The Variable sub-class used for the volumetric water content output from a Teros soil moisture/water content sensor.
class Modem_BatteryPercent: The Variable sub-class used for the battery charge percent measured by a modem.
class Modem_BatteryState: The Variable sub-class used for the battery charge state measured by a modem.
class Modem_BatteryVoltage: The Variable sub-class used for the battery voltage measured by a modem.
class Modem_RSSI: The Variable sub-class used for the RSSI measured by a modem.
class Modem_SignalPercent: The Variable sub-class used for the percent of maximum signal measured by a modem.
class Modem_Temp: The Variable sub-class used for the chip temperature as measured by the modem.
class PaleoTerraRedox_Voltage: The Variable sub-class used for the voltage output from a PaleoTerra redox sensor.
class ProcessorStats_Battery: The Variable sub-class used for the battery voltage output measured by the processor's on-board ADC.
class ProcessorStats_FreeRam: The Variable sub-class used for the free RAM measured by the MCU.
class ProcessorStats_SampleNumber: The Variable sub-class used for the sample number output from the main processor.
class RainCounterI2C_Depth: The Variable sub-class used for the depth of rain output from an Adafruit Trinket based I2C tipping bucket counter.
class RainCounterI2C_Tips: The Variable sub-class used for the total tip count output from an Adafruit Trinket based I2C tipping bucket counter.
class SensirionSHT4x_Humidity: The Variable sub-class used for the relative humidity output from an Sensirion SHT4x.
class SensirionSHT4x_Temp: The Variable sub-class used for the temperature output from an Sensirion SHTx0.
class TIADS1x15_Voltage: The Variable sub-class used for the voltage output from a TI ADS1115 or ADS1015.
class TIINA219_Current: The Variable sub-class used for the current output from a TI INA219 power and current monitor.
class TIINA219_Power: The Variable sub-class used for the power use output calculated from the voltage and current measured by a TI INA219 power and current monitor.
class TIINA219_Voltage: The Variable sub-class used for the bus voltage output from a TI INA219 power and current monitor.
class TallyCounterI2C_Events: The Variable sub-class used for the events output from a Tally Counter I2C - shows the number of events since last read.
class TurnerCyclops_BTEX: The Variable sub-class used for the refined fuels (BTEX) output from a Turner Cyclops-7F.
class TurnerCyclops_Brighteners: The Variable sub-class used for the opticalBrighteners output from a Turner Cyclops-7F.
class TurnerCyclops_CDOM: The Variable sub-class used for the CDOM output from a Turner Cyclops-7F.
class TurnerCyclops_Chlorophyll: The Variable sub-class used for the chlorophyll output from a Turner Cyclops-7F.
class TurnerCyclops_CrudeOil: The Variable sub-class used for the crude oil output from a Turner Cyclops-7F.
class TurnerCyclops_Fluorescein: The Variable sub-class used for the fluorescein output from a Turner Cyclops-7F.
class TurnerCyclops_PTSA: The Variable sub-class used for the PTSA output from a Turner Cyclops-7F.
class TurnerCyclops_Phycocyanin: The Variable sub-class used for the phycocyanin output from a Turner Cyclops-7F.
class TurnerCyclops_Phycoerythrin: The Variable sub-class used for the phycoerythrin output from a Turner Cyclops-7F.
class TurnerCyclops_RedChlorophyll: The Variable sub-class used for the chlorophyll output from a Turner Cyclops-7F.
class TurnerCyclops_Rhodamine: The Variable sub-class used for the Rhodamine output from a Turner Cyclops-7F.
class TurnerCyclops_Tryptophan: The Variable sub-class used for the tryptophan output from a Turner Cyclops-7F.
class TurnerCyclops_Turbidity: The Variable sub-class used for the turbidity output from a Turner Cyclops-7F.
class TurnerCyclops_Voltage: The Variable sub-class used for the raw voltage output from a Turner Cyclops-7F.
class TurnerTurbidityPlus_Turbidity: The Variable sub-class used for the turbidity output from a Turner Turbidity Plus.
class TurnerTurbidityPlus_Voltage: The Variable sub-class used for the [raw voltage output](sensor_turbidity_plus_voltage) from a [Turner Turbidity Plus](Turner Turbidity Plus).
class VegaPuls21_Distance: The Variable sub-class used for the temperature output from a VEGAPULS C 21 radar level sensor.
class VegaPuls21_ErrorCode: The Variable sub-class used for the error code output from a VEGAPULS C 21 radar level sensor.
class VegaPuls21_Reliability: The Variable sub-class used for the reliability output from a VEGAPULS C 21 radar level sensor.
class VegaPuls21_Stage: The Variable sub-class used for the temperature output from a VEGAPULS C 21 radar level sensor.
class VegaPuls21_Temp: The Variable sub-class used for the temperature output from a VEGAPULS C 21 radar level sensor.
class YosemitechY4000_BGA: The Variable sub-class used for the blue green algae (BGA) concentration output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_Chlorophyll: The Variable sub-class used for the chlorophyll concentration output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_Cond: The Variable sub-class used for the conductivity output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_DOmgL: The Variable sub-class used for the dissolved oxygen concentration output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_ORP: The Variable sub-class used for the electrode electrical potential output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_Turbidity: The Variable sub-class used for the turbidity output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY4000_pH: The Variable sub-class used for the pH output from a Yosemitech Y4000 multiparameter sonde.
class YosemitechY504_DOmgL: The Variable sub-class used for the dissolved oxygen concentration output from a Yosemitech Y502-A or Y504-A optical dissolved oxygen sensor.
class YosemitechY504_DOpct: The Variable sub-class used for the dissolved oxygen percent saturation output from a Yosemitech Y502-A or Y504-A optical dissolved oxygen sensor.
class YosemitechY504_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y504 optical dissolved oxygen sensor.
class YosemitechY510_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y510-B optical turbidity sensor.
class YosemitechY510_Turbidity: The Variable sub-class used for the turbidity output from a Yosemitech Y510-B optical turbidity sensor.
class YosemitechY511_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y511-A optical turbidity sensor with wiper.
class YosemitechY511_Turbidity: The Variable sub-class used for the turbidity output from a Yosemitech Y511-A optical turbidity sensor with wiper.
class YosemitechY513_BGA: The Variable sub-class used for the blue green algae concentration output from a Yosemitech Y513 Blue Green Algae (BGA) sensor with wiper.
class YosemitechY513_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y513-A blue green algae sensor with wiper.
class YosemitechY514_Chlorophyll: The Variable sub-class used for the chlorophyll concentration output from a Yosemitech Y514-A chlorophyll sensor with wiper.
class YosemitechY514_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y514-A chlorophyll sensor with wiper.
class YosemitechY520_Cond: The Variable sub-class used for the conductivity output from a Yosemitech Y520-A 4-electrode conductivity sensor.
class YosemitechY520_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y520-A 4-electrode conductivity sensor.
class YosemitechY532_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y532-A digital pH sensor.
class YosemitechY532_Voltage: The Variable sub-class used for the electrode electrical potential output from a Yosemitech Y532-A digital pH sensor.
class YosemitechY532_pH: The Variable sub-class used for the pH output from a Yosemitech Y532-A digital pH sensor.
class YosemitechY533_ORP: The Variable sub-class used for the pH output from a Yosemitech Y533 ORP sensor.
class YosemitechY533_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y533 ORP sensor.
class YosemitechY551_COD: The Variable sub-class used for the carbon oxygen demand (COD) output from a Yosemitech Y551-B UV254/COD sensor with wiper.
class YosemitechY551_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y551-B UV254/COD sensor with wiper.
class YosemitechY551_Turbidity: The Variable sub-class used for the turbidity output from a Yosemitech Y551-B UV254/COD sensor with wiper.
class YosemitechY560_NH4_N: The Variable sub-class used for the NH4_N output from a Yosemitech Y560-Ammonium sensor.
class YosemitechY560_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y560-Ammonium sensor.
class YosemitechY560_pH: The Variable sub-class used for the pH output from a Yosemitech Y560-Ammonium sensor.
class YosemitechY700_Pressure: The Variable sub-class used for the pressure output from a Yosemitech Y700 pressure sensor.
class YosemitechY700_Temp: The Variable sub-class used for the temperature output from a Yosemitech Y700 pressure sensor.
class ZebraTechDOpto_DOmgL: The Variable sub-class used for the dissolved oxygen concentration output from a Zebra-Tech D-Opto dissolved oxygen sensor.
class ZebraTechDOpto_DOpct: The Variable sub-class used for the dissolved oxygen percent saturation output from a Zebra-Tech D-Opto dissolved oxygen sensor.
class ZebraTechDOpto_Temp: The Variable sub-class used for the temperature output from a Zebra-Tech D-Opto dissolved oxygen sensor.

Constructors, destructors, conversion operators

Variable(Sensor* parentSense, const uint8_t sensorVarNum, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode, const char* uuid): Construct a new Variable objectfor a measured variable - that is, one whose values are updated by a sensor.
Variable(const uint8_t sensorVarNum, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode): Construct a new Variable objectfor a measured variable - that is, one whose values are updated by a sensor - but do not tie it to a specific sensor.
Variable(float(*)() calcFxn, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode, const char* uuid): Construct a new Variable object for a calculated variable - that is, one whose value is calculated by the calcFxn which returns a float.
Variable(float(*)() calcFxn, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode): Construct a new Variable object for a calculated variable - that is, one whose value is calculated by the calcFxn which returns a float.
Variable(): Construct a new Variable object.
~Variable(): Destroy the Variable object - no action taken.

Public functions

Variable* begin(Sensor* parentSense, const char* uuid, const char* customVarCode) -> Variable*: Begin for the Variable object.
Variable* begin(Sensor* parentSense, const char* uuid) -> Variable*: Begin for the Variable object.
Variable* begin(Sensor* parentSense) -> Variable*: Begin for the Variable object.
Variable* begin(float(*)() calcFxn, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode, const char* uuid) -> Variable*: Begin for the Variable object.
Variable* begin(float(*)() calcFxn, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode) -> Variable*: Begin for the Variable object.
void attachSensor(Sensor* parentSense): Notify the parent sensor that it has an observing variable.
void onSensorUpdate(Sensor* parentSense): Updates the interally stored data value.
String getParentSensorName(void) -> String: Get the parent sensor name, if applicable.
String getParentSensorNameAndLocation(void) -> String: Get the parent sensor name and location, if applicable.
void setCalculation(float(*)() calcFxn): Set the calculation function for a calculted variable.
uint8_t getResolution(void) -> uint8_t: Get the variable's resolution - in decimal places.
void setResolution(uint8_t decimalResolution): Set the variable's resolution.
String getVarName(void) -> String: Get the variable name.
void setVarName(const char* varName): Set the variable name.
String getVarUnit(void) -> String: Get the variable unit.
void setVarUnit(const char* varUnit): Set the variable unit.
String getVarCode(void) -> String: Get the customized code for the variable.
void setVarCode(const char* varCode): Set a customized code for the variable.
String getVarUUID(void) -> String: Get the customized code for the variable.
void setVarUUID(const char* uuid): Set a customized code for the variable.
bool checkUUIDFormat(void) -> bool: Verify the the UUID is correctly formatted.
float getValue(bool updateValue = false) -> float: Get current value of the variable as a float.
String getValueString(bool updateValue = false) -> String: Get current value of the variable as a string with the correct decimal resolution.
String formatValueString(float value) -> String: Get a particular value of the variable as a string with the correct decimal resolution.

Public variables

Sensor* parentSensor: Pointer to the parent sensor.
bool isCalculated: Internal note as to whether the value is calculated.

Protected variables

float _currentValue: The current data value.

Function documentation

Variable::Variable(Sensor* parentSense, const uint8_t sensorVarNum, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode, const char* uuid)

Construct a new Variable objectfor a measured variable - that is, one whose values are updated by a sensor.

Parameters
parentSense	The Sensor object supplying values.
sensorVarNum	The position in the sensor's value array of this variable's value.
decimalResolution	The resolution (in decimal places) of the value.
varName	The name of the variable per the ODM2 variable name controlled vocabulary
varUnit	The unit of the variable per the ODM2 unit controlled vocabulary
varCode	A custom code for the variable. This can be any short text helping to identify the variable in files.
uuid	A universally unique identifier for the variable.

Variable::Variable(const uint8_t sensorVarNum, uint8_t decimalResolution, const char* varName, const char* varUnit, const char* varCode)

Construct a new Variable objectfor a measured variable - that is, one whose values are updated by a sensor - but do not tie it to a specific sensor.

Parameters
sensorVarNum	The position in the sensor's value array of this variable's value.
decimalResolution	The resolution (in decimal places) of the value.
varName	The name of the variable per the ODM2 variable name controlled vocabulary
varUnit	The unit of the variable per the ODM2 unit controlled vocabulary
varCode	A custom code for the variable. This can be any short text helping to identify the variable in files.

Variable::Variable(float()() calcFxn, uint8_t decimalResolution, const char varName, const char* varUnit, const char* varCode, const char* uuid)

Construct a new Variable object for a calculated variable - that is, one whose value is calculated by the calcFxn which returns a float.

Parameters
calcFxn	Any function returning a float value
decimalResolution	The resolution (in decimal places) of the value.
varName	The name of the variable per the ODM2 variable name controlled vocabulary
varUnit	The unit of the variable per the ODM2 unit controlled vocabulary
varCode	A custom code for the variable. This can be any short text helping to identify the variable in files.
uuid	A universally unique identifier for the variable.

Variable::Variable(float()() calcFxn, uint8_t decimalResolution, const char varName, const char* varUnit, const char* varCode)

Construct a new Variable object for a calculated variable - that is, one whose value is calculated by the calcFxn which returns a float.

Parameters
calcFxn	Any function returning a float value
decimalResolution	The resolution (in decimal places) of the value.
varName	The name of the variable per the ODM2 variable name controlled vocabulary
varUnit	The unit of the variable per the ODM2 unit controlled vocabulary
varCode	A custom code for the variable. This can be any short text helping to identify the variable in files.