Change API Reference at runtime VB.NET 3.5 - vb.net

Question

I'm writing an application for a device running Windows XP. There are 2 versions of the device and each version has its own API to communicate with the device's software. The application I'm writing needs to pull the same data from the API. My question is how to write a application that will detect at runtime which version of the device it is on and use the appropriate API. I've figured out how to read the registry to determine the device.
I've created an interface containing all of the common methods and also classes for each device that implement the interface. Now I need to know how to activate the correct one at runtime.
Public Interface IAPI
Sub InitializeMachine()
Function GetActiveProgram() As String
Function GetActiveGCodes() As String
Function GetCurrentBlockNumber() As Integer
''#etc...
End Interface
''#Mill API
Public Class CMAPI : Implements IAPI
Private ObjMachine As Okuma.CMDATAPI.DataAPI.CMachine
Private ObjPgm As Okuma.CMDATAPI.DataAPI.CProgram
Public Sub New()
End Sub
Public Function GetActiveGCodes() As String Implements IAPI.GetActiveGCodes
Try
Return ObjPgm.GetGCodes
Catch ex As Exception
Throw ex
End Try
End Function
Public Function GetActiveProgram() As String Implements IAPI.GetActiveProgram
Try
Return ObjPgm.GetActiveProgramName
Catch ex As Exception
Throw ex
End Try
End Function
Public Function GetCurrentBlockNumber() As Integer Implements IAPI.GetCurrentBlockNumber
Try
Return ObjPgm.GetCurrentBlockNumber
Catch ex As Exception
Throw ex
End Try
End Function
''#....
End Class
''#Lathe API
Public Class CLAPI : Implements IAPI
Private ObjMachine As Okuma.CLDATAPI.DataAPI.CMachine
Private ObjPgm As Okuma.CLDATAPI.DataAPI.CProgram
Public Sub New()
End Sub
Public Function GetActiveGCodes() As String Implements IAPI.GetActiveGCodes
Try
Return ObjPgm.GetGCodes
Catch ex As Exception
Throw ex
End Try
End Function
Public Function GetActiveProgram() As String Implements IAPI.GetActiveProgram
Try
Return ObjPgm.GetActiveProgramName
Catch ex As Exception
Throw ex
End Try
End Function
''#...
End Class

Answer 1

Untested, theory is right - there just might be typos :P
Dim rightAPI As IAPI
If CheckForTypeCMAPI() = true Then ' You said you can determine which device youre on, replace this with the right function
rightAPI = new CMAPI()
Else
rightAPI = new CLAPI()
End If
' Use rightAPI wherever you need it
MessageBox.Show(rightAPI.GetActiveProgram())

Answer 2

I would use a factory method:
Dim rightAPI As IAPI
rightAPI = APIFactory.GetAPI(HowYouDistinguishDevice)
' Use rightAPI wherever you need it
MessageBox.Show(rightAPI.GetActiveProgram())
public class APIFactory
public shared function GetAPI(string HowYouDistinguishDevice) as IAPI
dim oAPI as IAPI
'do whatever it is you need to do to determine which api to use
if CMAPI then oAPI = new CMAPI
if CLAPI then oAPI = new CLAPI
'or you could use select, whatever
return oAPI
end function
end class