AF SDK Reference

UOMGroup.Convert Method

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UOMGroup.Convert Method

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Last UpdatedNov 18, 2025
5 minute read

This method converts the specified value from the specified unit of measure (UOM) to the mapped UOM represented by this UOMGroup.

Namespace: OSIsoft.AF.UnitsOfMeasure
Assembly: OSIsoft.AFSDK (in OSIsoft.AFSDK.dll) Version: 3.1.1.1182

Syntax

public double Convert(
	Object fromValue,
	UOM fromUOM
)

Public Function Convert ( 
	fromValue As Object,
	fromUOM As UOM
) As Double

Dim instance As UOMGroup
Dim fromValue As Object
Dim fromUOM As UOM
Dim returnValue As Double

returnValue = instance.Convert(fromValue, 
	fromUOM)

public:
double Convert(
	Object^ fromValue, 
	UOM^ fromUOM
)

member Convert : 
        fromValue : Object * 
        fromUOM : UOM -> float

Parameters

fromValue: Type: SystemObject
The value to be converted. Normally, this is sent as a double.
fromUOM: Type: OSIsoft.AF.UnitsOfMeasureUOM
The unit of measure of the specified value. If this is not specified, or is specified, then the unit of measure should be specified in the fromValue by passing it as a string.

Return Value

Type: Double
Returns the value converted to the mapped unit of measure as defined by this UOMGroup.

Exceptions

Exception	Condition
InvalidCastException	Thrown when the conversion cannot be performed.

Remarks

The mappings defined for this UOMGroup are used to determine resulting UOM for the fromValue based upon the specified fromUOM. If the two UOMs share the same reference object, or are a direct reference to each other, then the conversion is done directly using these reference units. This allows fewer mathematical operations and reduces the loss of precision during conversion. Otherwise, the canonical unit-of-measure factors are used to convert.

Optionally, you can specify for the fromUOM parameter and specify the units in the input parameter if it is represented in string notation. For example, "100.0 ft". In this case, the Convert function looks up the UOM from the text name or abbreviation that follows the floating point number.

Examples

// This example will create a UOM Group with mappings, display its information,
//  and then perform some conversions.

// Get the Database
PISystems myPISystems = new PISystems();
UOMDatabase myDB = myPISystems.DefaultPISystem.UOMDatabase;

// Create a UOM Group
UOMGroup MyCustomGroup = myDB.UOMGroups.Add("MyCustomUOMGroup*");
MyCustomGroup.Description = "Custom UOM Group for Length";

// Add mappings to group
MyCustomGroup.Mappings[myDB.UOMs["ft"]] = myDB.UOMs["m"];
MyCustomGroup.Mappings[myDB.UOMs["in"]] = myDB.UOMs["cm"];
MyCustomGroup.Mappings[myDB.UOMs["nmi"]] = myDB.UOMs["km"];
MyCustomGroup.Mappings[myDB.UOMs["mi"]] = myDB.UOMs["km"];
MyCustomGroup.Mappings[myDB.UOMs["mm"]] = myDB.UOMs["cm"];
MyCustomGroup.Mappings[myDB.UOMs["sxi"]] = myDB.UOMs["cm"];
MyCustomGroup.Mappings[myDB.UOMs["yd"]] = myDB.UOMs["m"];
myDB.CheckIn();

// Display the UOM Groups
foreach (UOMGroup group in myDB.UOMGroups)
{
    Console.WriteLine("Name of UOM Group = {0}", group.Name);
    Console.WriteLine("Description = {0}", group.Description);
    Console.WriteLine("Mappings:");
    foreach (KeyValuePair<UOM, UOM> item in group.Mappings)
    {
        Console.WriteLine("    {0} ==> {1}", item.Key, item.Value);
    }
}

// Perform some conversions
AFValue origAFValue = new AFValue(55.3, AFTime.Now, myDB.UOMs["mi"]);
double mappedValue = MyCustomGroup.Convert(100.0, myDB.UOMs["yd"]);
Console.WriteLine("Convert 100.0 ft ==> {0}", mappedValue);
AFValue mappedAFValue = origAFValue.Convert(MyCustomGroup);
Console.WriteLine("Convert {0} {1} ==> {2} {3}",
    origAFValue.Value, origAFValue.UOM, mappedAFValue.Value, mappedAFValue.UOM);

// Display attribute value using Display UOM
myDB.DisplayUOMGroup = MyCustomGroup;
origAFValue = MyAttr.GetValue();
mappedAFValue = MyAttr.GetValue(MyAttr.DisplayUOM);
Console.WriteLine("GetValue {0} {1} ==> {2} {3}",
    origAFValue.Value, origAFValue.UOM, mappedAFValue.Value, mappedAFValue.UOM);

' This example will create a UOM Group with mappings, display its information,
'  and then perform some conversions.

' Get the Database
Dim myPISystems As New PISystems()
Dim myDB As UOMDatabase = myPISystems.DefaultPISystem.UOMDatabase

' Create a UOM Group
Dim MyCustomGroup As UOMGroup = myDB.UOMGroups.Add("MyCustomUOMGroup*")
MyCustomGroup.Description = "Custom UOM Group for Length"

' Add mappings to group
MyCustomGroup.Mappings(myDB.UOMs("ft")) = myDB.UOMs("m")
MyCustomGroup.Mappings(myDB.UOMs("in")) = myDB.UOMs("cm")
MyCustomGroup.Mappings(myDB.UOMs("nmi")) = myDB.UOMs("km")
MyCustomGroup.Mappings(myDB.UOMs("mi")) = myDB.UOMs("km")
MyCustomGroup.Mappings(myDB.UOMs("mm")) = myDB.UOMs("cm")
MyCustomGroup.Mappings(myDB.UOMs("sxi")) = myDB.UOMs("cm")
MyCustomGroup.Mappings(myDB.UOMs("yd")) = myDB.UOMs("m")
myDB.CheckIn()

' Display the UOM Groups
For Each group As UOMGroup In myDB.UOMGroups
    Console.WriteLine("Name of UOM Group = {0}", group.Name)
    Console.WriteLine("Description = {0}", group.Description)
    Console.WriteLine("Mappings:")
    For Each item As KeyValuePair(Of UOM, UOM) In group.Mappings
        Console.WriteLine("    {0} ==> {1}", item.Key, item.Value)
    Next
Next

' Perform some conversions
Dim origAFValue As New AFValue(55.3, AFTime.Now, myDB.UOMs("mi"))
Dim mappedValue As Double = MyCustomGroup.Convert(100.0, myDB.UOMs("yd"))
Console.WriteLine("Convert 100.0 ft ==> {0}", mappedValue)
Dim mappedAFValue As AFValue = origAFValue.Convert(MyCustomGroup)
Console.WriteLine("Convert {0} {1} ==> {2} {3}",
    origAFValue.Value, origAFValue.UOM, mappedAFValue.Value, mappedAFValue.UOM)

' Display attribute value using Display UOM
myDB.DisplayUOMGroup = MyCustomGroup
origAFValue = MyAttr.GetValue()
mappedAFValue = MyAttr.GetValue(MyAttr.DisplayUOM)
Console.WriteLine("GetValue {0} {1} ==> {2} {3}",
    origAFValue.Value, origAFValue.UOM, mappedAFValue.Value, mappedAFValue.UOM)

No code example is currently available or this language may not be supported.

Version Information

AFSDK

Supported in: 3.1.1, 3.1.0, 3.0.2, 3.0.1, 3.0.0, 2.10.11, 2.10.5, 2.10.0, 2.10, 2.9.5

AF SDK Reference