How do I get the friendly name of a COM port in Windows?

Question

I have a GSM modem connected via USB. The modem creates 2 serial ports. The first is automatically attached to the modem, the second shows in Device Manager as \"HUAWEI Mo

Answer 1

Used the method posted by LiGenChen. The method ComPortSetupAPISetupDiClassGuids gave the best time and friendly name.

Answer 2

The information posted by Will Dean was most helpful. This is the code that eventually worked for me. Everything in the PInvoke class was taken verbatim from http://www.pinvoke.net . I did have to change a data type here or there to make it work (like when using an enum instead of a uint) but it should be easy to figure out.

internal static string GetComPortByDescription(string Description)
{
    string Result = string.Empty;
    Guid guid = PInvoke.GUID_DEVCLASS_PORTS;
    uint nDevice = 0;
    uint nBytes = 300;
    byte[] retval = new byte[nBytes];
    uint RequiredSize = 0;
    uint PropertyRegDataType = 0;

    PInvoke.SP_DEVINFO_DATA devInfoData = new PInvoke.SP_DEVINFO_DATA();
    devInfoData.cbSize = Marshal.SizeOf(typeof(PInvoke.SP_DEVINFO_DATA));

    IntPtr hDeviceInfo = PInvoke.SetupDiGetClassDevs(
        ref guid, 
        null, 
        IntPtr.Zero, 
        PInvoke.DIGCF.DIGCF_PRESENT);

    while (PInvoke.SetupDiEnumDeviceInfo(hDeviceInfo, nDevice++, ref devInfoData))
    {
        if (PInvoke.SetupDiGetDeviceRegistryProperty(
                hDeviceInfo, 
                ref devInfoData, 
                PInvoke.SPDRP.SPDRP_FRIENDLYNAME,
                out PropertyRegDataType, 
                retval, 
                nBytes, 
                out RequiredSize))
        {
            if (System.Text.Encoding.Unicode.GetString(retval).Substring(0, Description.Length).ToLower() ==
                Description.ToLower())
            {
                string tmpstring = System.Text.Encoding.Unicode.GetString(retval);
                Result = tmpstring.Substring(tmpstring.IndexOf("COM"),tmpstring.IndexOf(')') - tmpstring.IndexOf("COM"));
            } // if retval == description
        } // if (PInvoke.SetupDiGetDeviceRegistryProperty( ... SPDRP_FRIENDLYNAME ...
    } // while (PInvoke.SetupDiEnumDeviceInfo(hDeviceInfo, nDevice++, ref devInfoData))

    PInvoke.SetupDiDestroyDeviceInfoList(hDeviceInfo);
    return Result;
}

I think the line Result = tmpstring.Substring(tmpstring.IndexOf("COM"),tmpstring.IndexOf(')') - tmpstring.IndexOf("COM")); is a little clumsy, suggestions on how to clean it up would be appreciated.

Thanks for your help with this matter Will, without you, I'd still be searching google.