ConvertPressure

Short summary

This function can be used to convert pressures from one physical pressure unit into another. The value will change corresponding to the conversion. Example:
1 Pa = 0.00001 Bar = 0.000145038 Psi

Return: CNM_RecipeHandling.Pressure: a copy of the given pressure converted into the desired unit

• Return type: Pressure

Parameters

Name	Type	Comment	Kind
pressureToConvert	Pressure	the pressure that should be converted	inout
convertTo	PressureUnit	the physical pressure unit it should be converted to	input
resultPrefix	MetricPrefixes	the metrical prefix (for SI units)	input

Code

Declaration

FUNCTION ConvertPressure : Pressure
VAR_IN_OUT CONSTANT
	(* the pressure that should be converted *)
	pressureToConvert :Pressure;
END_VAR
VAR_INPUT
	(* the physical pressure unit it should be converted to *)
	convertTo :PressureUnit := PressureUnit.PASCAL;
	(* the metrical prefix (for SI units) *)
	resultPrefix :MetricPrefixes := MetricPrefixes.NONE;
END_VAR
VAR
	factor :LREAL;
	exponent :INT := 1;
END_VAR
VAR CONSTANT
	(* length convertions related to pascal *)
	PRESSURES : ARRAY[PressureUnit.PASCAL..PressureUnit.PSI] OF LREAL := [1.0, 100000.0, 6894.76];
END_VAR

Implementation

factor := PRESSURES[pressureToConvert.unit] / PRESSURES[convertTo];
exponent := pressureToConvert.prefix - resultPrefix;
ConvertPressure.prefix := resultPrefix;
ConvertPressure.unit := convertTo;
IF CheckValueIsANumber(pressureToConvert.value) THEN
	ConvertPressure.value := pressureToConvert.value * factor * FastPow10(exponent);	
ELSE
	ConvertPressure.value := pressureToConvert.value;
END_IF