Private Declare Function MeineAPI Lib "MeineDLL.dll" (ByVal Parameter As Any) _
  As Long
 
Private Type MeinDatentyp
  Wert As Integer
End Type
 
Private Sub TesteAPI()
  Dim Var As MeinDatentyp
  Dim Result As Long
 
  Var.Wert = 2
 
  Result = MeineAPI(Var)
 
  MsgBox Result
End Sub

Private Declare Function MeineAPI Lib "MeineDLL.dll" (ByVal Parameter As _
  MeinDatentyp) As Integer
 
Private Structure MeinDatentyp
  Dim Wert As Short
End Structure
 
Private Sub TesteAPI()
  Dim Var As MeinDatentyp
  Dim Result As Integer
 
  Var.Wert = 2
 
  Result = MeineAPI(Var)
 
  MsgBox(Result)
End Sub