c# - Identify COM port using VID and PID for USB device attached to x64

Question

As following i able to get usb com port names attached to 32bit win7OS machine, by given pid and vid,but when running in x64 it stuck in the following line:

comports.Add((string)rk6.GetValue("PortName"));

This is my code

static List<string> ComPortNames(String VID, String PID)
    {
        String pattern = String.Format("^VID_{0}.PID_{1}", VID, PID);
        Regex _rx = new Regex(pattern, RegexOptions.IgnoreCase);
        List<string> comports = new List<string>();

        RegistryKey rk1 = Registry.LocalMachine;
        RegistryKey rk2 = rk1.OpenSubKey("SYSTEM\CurrentControlSet\Enum");

        foreach (String s3 in rk2.GetSubKeyNames())
        {

            RegistryKey rk3 = rk2.OpenSubKey(s3);
            foreach (String s in rk3.GetSubKeyNames())
            {
                if (_rx.Match(s).Success)
                {
                    RegistryKey rk4 = rk3.OpenSubKey(s);
                    foreach (String s2 in rk4.GetSubKeyNames())
                    {
                        RegistryKey rk5 = rk4.OpenSubKey(s2);
                        RegistryKey rk6 = rk5.OpenSubKey("Device Parameters");
                        comports.Add((string)rk6.GetValue("PortName"));
                    }
                }
            }
        }
        return comports;
    }

actual code get here, So how to get com port names in x64, any suggestion?

Answer 1

While I was testing the answer from Youkko under Windows 10 x64 I was getting some strange results and looking at the registry on my machine the LocationInformation keys contained strings such as Port_#0002.Hub_#0003so they are related to the USB hub / port the device is connected to not the COM port allocated by Windows.

So in my case I was getting COM2 included which is a hardware port on my motherboard and it skipped the COM5 port I was expecting but that was located under the PortName registry key. I'm not sure if something has changed since the version of Windows you were using but I think your main problem might have been not checking for null values on the keys.

The following slightly modified version seems to work fine on a variety or Windows 7 / 10 and x32 / 64 systems and I've also added a to check of SerialPort.GetPortNames() to make sure the device is available and plugged into the system before returning it:

static List<string> ComPortNames(String VID, String PID)
{
    String pattern = String.Format("^VID_{0}.PID_{1}", VID, PID);
    Regex _rx = new Regex(pattern, RegexOptions.IgnoreCase);
    List<string> comports = new List<string>();

    RegistryKey rk1 = Registry.LocalMachine;
    RegistryKey rk2 = rk1.OpenSubKey("SYSTEM\CurrentControlSet\Enum");

    foreach (String s3 in rk2.GetSubKeyNames())
    {
        RegistryKey rk3 = rk2.OpenSubKey(s3);
        foreach (String s in rk3.GetSubKeyNames())
        {
            if (_rx.Match(s).Success)
            {
                RegistryKey rk4 = rk3.OpenSubKey(s);
                foreach (String s2 in rk4.GetSubKeyNames())
                {
                    RegistryKey rk5 = rk4.OpenSubKey(s2);
                    string location = (string)rk5.GetValue("LocationInformation");
                    RegistryKey rk6 = rk5.OpenSubKey("Device Parameters");
                    string portName = (string)rk6.GetValue("PortName");
                    if (!String.IsNullOrEmpty(portName) && SerialPort.GetPortNames().Contains(portName))
                        comports.Add((string)rk6.GetValue("PortName"));
                }
            }
        }
    }
    return comports;
}