You have probaly noticed that if you go into the the system properties then you can load the port settings for the LPT and CoM ports. You can display these properties dialog boxes by using the ConfigurePort API. For more information you can subscribe to my Visual basic journal which will explain this in much more detail. Start a new standard-EXE project and and add a Command button to form1 and type the following code into the code window of form1: Private Declare Function ConfigurePort _ Lib "winspool.drv" Alias "ConfigurePortA" _ (ByVal pName As String, ByVal hwnd As Long, _ ByVal pPortName As String) As Long Private Sub Command1_Click() MsgBox ConfigurePort("", Me.hwnd, "COM4") MsgBox ConfigurePort("", Me.hwnd, "LPT1") End Sub Run the project (F5) and click on the command button the properties for the COM$ and LPT1 ports will be displayed as well as a message box that will display 1 ofr success and 0 if an error has occured.