Inventor API: using UnitsOfMeasure.ConvertUnits

Solution:
Below is a quick example that you can use to do the units detection and conversion in your code.

Here is the basic function. It uses the document's length units and centimeters to determine the conversion factor, and displays this in a message box to return the conversion factor.

DimoUOMAsUnitsOfMeasure
oUOM = ThisDoc.Document.UnitsOfMeasure
oLenUnits = oUOM.GetStringFromType(UnitsTypeEnum.kDefaultDisplayLengthUnits)
oInvUnits = UnitsTypeEnum.kCentimeterLengthUnits
oInvUnitString = oUOM.GetStringFromType(oInvUnits)
oConversion = oUOM.ConvertUnits(1, oUOM.LengthUnits, oInvUnits)

MsgBox("Document Units = "& oLenUnits& vbLf& _
"Inventor Internal Units = "& oInvUnitString& vbLf& _
"Conversion factor = "& oConversion, , "Inventor")

Here a sketch dimension/parameter named length is set to 70 mm, even though the part file is using Inches. And because our code is using the API to get the parameter value, we know that it's going to be returned in centimeters. 

Without the conversion factor, the code returns 7, which is the value in Inventor's internal units of centimeters.

So we use the UnitsOfMeasure.ConvertUnits function to handle all of this and return the expected value in the document units. 






With the conversion code, it returns 2.756, which is the value in inches.

Here's the working example:

DimoUOMAsUnitsOfMeasure
oUOM = ThisDoc.Document.UnitsOfMeasure
oConversion = oUOM.ConvertUnits(1, oUOM.LengthUnits, _
UnitsTypeEnum.kCentimeterLengthUnits)

oMsg = "Select a sketch dimension(Press Esc to continue)"

WhileTrue
DimoDimensionAsDimensionConstraint
oDimension = ThisApplication.CommandManager.Pick(
SelectionFilterEnum.kSketchDimConstraintFilter, oMsg)

' If nothing gets selected then we're done	
IfIsNothing(oDimension) ThenExitWhile
oParam = oDimension.Parameter
oParamVal = Round(oParam.Value() / oConversion, 3)

MsgBox(oParamVal,,"Inventor")	
EndWhile