ConvertTemperature

Short summary

This function can be used to convert temperatures from one temperature scale into another. The value will change corresponding to the conversion. Example:
300 K = 26.85°C = 80.33 °F

Return: CNM_RecipeHandling.Temprature: a copy of the given temperature converted into the desired scale

• Return type: Temperature

Parameters

Name	Type	Comment	Kind
temperatureToConvert	Temperature	the temperature that should be converted	inout
convertTo	TemperatureUnit	the temperature scale unit it should be converted to	input

Code

Declaration

FUNCTION ConvertTemperature : Temperature
VAR_IN_OUT CONSTANT
	(* the temperature that should be converted *)
	temperatureToConvert :Temperature;
END_VAR
VAR_INPUT
	(* the temperature scale unit it should be converted to *)
	convertTo :TemperatureUnit := TemperatureUnit.KELVIN;
END_VAR
VAR CONSTANT
	CELSIUS_OFFSET :LREAL := 273.15;
	FAHRENHEIT_OFFSET :LREAL := 32.0;
	FAHRENHEIT_FACTOR :LREAL := 1.8;
END_VAR

Implementation

ConvertTemperature.unit := convertTo;
IF (NOT CheckValueIsANumber(temperatureToConvert.value)) THEN
	ConvertTemperature.value := temperatureToConvert.value;
	RETURN;
END_IF

CASE temperatureToConvert.unit OF
TemperatureUnit.KELVIN:
	CASE convertTo OF
	TemperatureUnit.DEGREE_CELSIUS:
		ConvertTemperature.value := temperatureToConvert.value - CELSIUS_OFFSET;
	TemperatureUnit.DEGREE_FAHRENHEIT:
		ConvertTemperature.value := ((temperatureToConvert.value - CELSIUS_OFFSET) * FAHRENHEIT_FACTOR) + FAHRENHEIT_OFFSET;
	ELSE
		ConvertTemperature.value := temperatureToConvert.value;
	END_CASE
TemperatureUnit.DEGREE_CELSIUS:
	CASE convertTo OF
	TemperatureUnit.KELVIN:
		ConvertTemperature.value := temperatureToConvert.value + CELSIUS_OFFSET;
	TemperatureUnit.DEGREE_FAHRENHEIT:
		ConvertTemperature.value := (temperatureToConvert.value * FAHRENHEIT_FACTOR) + FAHRENHEIT_OFFSET;
	ELSE
		ConvertTemperature.value := temperatureToConvert.value;
	END_CASE
TemperatureUnit.DEGREE_FAHRENHEIT:
	CASE convertTo OF
	TemperatureUnit.KELVIN:
		ConvertTemperature.value := (temperatureToConvert.value - FAHRENHEIT_OFFSET)/FAHRENHEIT_FACTOR + CELSIUS_OFFSET;
	TemperatureUnit.DEGREE_CELSIUS:
		ConvertTemperature.value := (temperatureToConvert.value - FAHRENHEIT_OFFSET)/FAHRENHEIT_FACTOR;
	ELSE
		ConvertTemperature.value := temperatureToConvert.value;
	END_CASE
ELSE
	ConvertTemperature.value := temperatureToConvert.value;
END_CASE