How do I get serial Port device id?

Question

In this program I\'m first trying to connect to availalbe port. When found and connected, I want to read the connected USB device ID and vendor ID, How do I do that?

Answer 1

I finally got this sorted out myself a couple days ago. There are two parts, one to check the registry and another to check the vid/pid of the device.

The registry method I use just to make sure I don't capture a null modem emulator like com0com.

    /// <summary>
    /// Removes any comm ports that are not explicitly defined as allowed in ALLOWED_TYPES
    /// </summary>
    /// <param name="allPorts">reference to List that will be checked</param>
    /// <returns></returns>
    private static void nullModemCheck(ref List<string> allPorts)
    {
        // Open registry to get the COM Ports available with the system
        RegistryKey regKey = Registry.LocalMachine;

        // Defined as: private const string REG_COM_STRING ="HARDWARE\DEVICEMAP\SERIALCOMM";
        regKey = regKey.OpenSubKey(REG_COM_STRING);

        Dictionary<string, string> tempDict = new Dictionary<string, string>();
        foreach (string p in allPorts)
            tempDict.Add(p, p);

        // This holds any matches we may find
        string match = "";
        foreach (string subKey in regKey.GetValueNames())
        {
            // Name must contain either VCP or Seial to be valid. Process any entries NOT matching
            // Compare to subKey (name of RegKey entry)
            if (!(subKey.Contains("Serial") || subKey.Contains("VCP")))
            {
                // Okay, this might be an illegal port.
                // Peek in the dictionary, do we have this key? Compare to regKey.GetValue(subKey)
                if(tempDict.TryGetValue(regKey.GetValue(subKey).ToString(), out match))         
                {
                    // Kill it!
                    allPorts.Remove(match);

                    // Reset our output string
                    match = "";
                }

            }

        }

        regKey.Close();
    }

The vid/pid portion was gleaned from techinpro

    /// <summary>
    /// Compile an array of COM port names associated with given VID and PID
    /// </summary>
    /// <param name="VID">string representing the vendor id of the USB/Serial convertor</param>
    /// <param name="PID">string representing the product id of the USB/Serial convertor</param>
    /// <returns></returns>
    private static List<string> getPortByVPid(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;
    }