<StructLayout(LayoutKind.Sequential)> _
    Structure PRINTER_DEFAULTS
        Public pDatatype As IntPtr
        Public pDevMode As IntPtr
        Public DesiredAccess As Integer
    End Structure
 
 
    <DllImport("winspool.drv", EntryPoint:="OpenPrinterA", ExactSpelling:=True, _
              SetLastError:=True, CallingConvention:=CallingConvention.StdCall, _
              CharSet:=CharSet.Ansi)> _
    Private Shared Function OpenPrinter(ByVal pPrinterName As String, _
             ByRef hPrinter As IntPtr, ByRef pDefault As PRINTER_DEFAULTS) As _
             Boolean
    End Function

 Dim hprinter As System.IntPtr
 Dim pd As New PRINTER_DEFAULTS
 
 Dim ok As Boolean = OpenPrinter(<Printername>, hprinter, pd)