How to open a serial port by friendly name?

Question

friendly name = the name that appears in "Device Manager" under "Ports (COM & LPT).

EDIT: two solutions provided below. One with WMI and another with SetupAPI.

Answer 1

Posting tonight's code, for everybody's enjoyment:

public class SetupDiWrap {     static public string ComPortNameFromFriendlyNamePrefix(string friendlyNamePrefix)     {         const string className = "Ports";         Guid[] guids = GetClassGUIDs(className);          System.Text.RegularExpressions.Regex friendlyNameToComPort =             new System.Text.RegularExpressions.Regex(@".? \((COM\d+)\)$");  // "..... (COMxxx)" -> COMxxxx          foreach (Guid guid in guids)         {             // We start at the "root" of the device tree and look for all             // devices that match the interface GUID of a disk             Guid guidClone = guid;             IntPtr h = SetupDiGetClassDevs(ref guidClone, IntPtr.Zero, IntPtr.Zero, DIGCF_PRESENT | DIGCF_PROFILE);             if (h.ToInt32() != INVALID_HANDLE_VALUE)             {                 int nDevice = 0;                 while (true)                 {                     SP_DEVINFO_DATA da = new SP_DEVINFO_DATA();                     da.cbSize = (uint)Marshal.SizeOf(da);                      if (0 == SetupDiEnumDeviceInfo(h, nDevice++, ref da))                         break;                      uint RegType;                     byte[] ptrBuf = new byte[BUFFER_SIZE];                     uint RequiredSize;                     if (SetupDiGetDeviceRegistryProperty(h, ref da,                         (uint)SPDRP.FRIENDLYNAME, out RegType, ptrBuf,                         BUFFER_SIZE, out RequiredSize))                     {                         const int utf16terminatorSize_bytes = 2;                         string friendlyName = System.Text.UnicodeEncoding.Unicode.GetString(ptrBuf, 0, (int)RequiredSize - utf16terminatorSize_bytes);                          if (!friendlyName.StartsWith(friendlyNamePrefix))                             continue;                          if (!friendlyNameToComPort.IsMatch(friendlyName))                             continue;                          return friendlyNameToComPort.Match(friendlyName).Groups[1].Value;                     }                 } // devices                 SetupDiDestroyDeviceInfoList(h);             }         } // class guids          return null;     }      /// <summary>     /// The SP_DEVINFO_DATA structure defines a device instance that is a member of a device information set.     /// </summary>     [StructLayout(LayoutKind.Sequential)]     private struct SP_DEVINFO_DATA     {         /// <summary>Size of the structure, in bytes.</summary>         public uint cbSize;         /// <summary>GUID of the device interface class.</summary>         public Guid ClassGuid;         /// <summary>Handle to this device instance.</summary>         public uint DevInst;         /// <summary>Reserved; do not use.</summary>         public uint Reserved;     }      [StructLayout(LayoutKind.Sequential)]     private struct SP_DEVICE_INTERFACE_DATA     {         public Int32 cbSize;         public Guid interfaceClassGuid;         public Int32 flags;         private UIntPtr reserved;     }      const int BUFFER_SIZE = 1024;      [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]     private struct SP_DEVICE_INTERFACE_DETAIL_DATA     {         public int cbSize;         [MarshalAs(UnmanagedType.ByValTStr, SizeConst = BUFFER_SIZE)]         public string DevicePath;     }      private enum SPDRP     {         DEVICEDESC = 0x00000000,         HARDWAREID = 0x00000001,         COMPATIBLEIDS = 0x00000002,         NTDEVICEPATHS = 0x00000003,         SERVICE = 0x00000004,         CONFIGURATION = 0x00000005,         CONFIGURATIONVECTOR = 0x00000006,         CLASS = 0x00000007,         CLASSGUID = 0x00000008,         DRIVER = 0x00000009,         CONFIGFLAGS = 0x0000000A,         MFG = 0x0000000B,         FRIENDLYNAME = 0x0000000C,         LOCATION_INFORMATION = 0x0000000D,         PHYSICAL_DEVICE_OBJECT_NAME = 0x0000000E,         CAPABILITIES = 0x0000000F,         UI_NUMBER = 0x00000010,         UPPERFILTERS = 0x00000011,         LOWERFILTERS = 0x00000012,         MAXIMUM_PROPERTY = 0x00000013,     }      [DllImport("setupapi.dll", SetLastError = true)]     static extern bool SetupDiClassGuidsFromName(string ClassName,         ref Guid ClassGuidArray1stItem, UInt32 ClassGuidArraySize,         out UInt32 RequiredSize);      [DllImport("setupapi.dll")]     internal static extern IntPtr SetupDiGetClassDevsEx(IntPtr ClassGuid,         [MarshalAs(UnmanagedType.LPStr)]String enumerator,         IntPtr hwndParent, Int32 Flags, IntPtr DeviceInfoSet,         [MarshalAs(UnmanagedType.LPStr)]String MachineName, IntPtr Reserved);      [DllImport("setupapi.dll")]     internal static extern Int32 SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);      [DllImport(@"setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]     private static extern Boolean SetupDiEnumDeviceInterfaces(        IntPtr hDevInfo,        IntPtr optionalCrap, //ref SP_DEVINFO_DATA devInfo,        ref Guid interfaceClassGuid,        UInt32 memberIndex,        ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData     );      [DllImport("setupapi.dll")]     private static extern Int32 SetupDiEnumDeviceInfo(IntPtr DeviceInfoSet,         Int32 MemberIndex, ref SP_DEVINFO_DATA DeviceInterfaceData);      [DllImport("setupapi.dll")]     private static extern Int32 SetupDiClassNameFromGuid(ref Guid ClassGuid,         StringBuilder className, Int32 ClassNameSize, ref Int32 RequiredSize);      [DllImport("setupapi.dll")]     private static extern Int32 SetupDiGetClassDescription(ref Guid ClassGuid,         StringBuilder classDescription, Int32 ClassDescriptionSize, ref Int32 RequiredSize);      [DllImport("setupapi.dll")]     private static extern Int32 SetupDiGetDeviceInstanceId(IntPtr DeviceInfoSet,         ref SP_DEVINFO_DATA DeviceInfoData,         StringBuilder DeviceInstanceId, Int32 DeviceInstanceIdSize, ref Int32 RequiredSize);      [DllImport("setupapi.dll", CharSet = CharSet.Auto)]     static extern IntPtr SetupDiGetClassDevs(           // 1st form using a ClassGUID only, with null Enumerator        ref Guid ClassGuid,        IntPtr Enumerator,        IntPtr hwndParent,        int Flags     );      [DllImport(@"setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]     private static extern Boolean SetupDiGetDeviceInterfaceDetail(        IntPtr hDevInfo,        ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData,        ref SP_DEVICE_INTERFACE_DETAIL_DATA deviceInterfaceDetailData,        UInt32 deviceInterfaceDetailDataSize,        out UInt32 requiredSize,        ref SP_DEVINFO_DATA deviceInfoData     );      /// <summary>     /// The SetupDiGetDeviceRegistryProperty function retrieves the specified device property.     /// This handle is typically returned by the SetupDiGetClassDevs or SetupDiGetClassDevsEx function.     /// </summary>     /// <param Name="DeviceInfoSet">Handle to the device information set that contains the interface and its underlying device.</param>     /// <param Name="DeviceInfoData">Pointer to an SP_DEVINFO_DATA structure that defines the device instance.</param>     /// <param Name="Property">Device property to be retrieved. SEE MSDN</param>     /// <param Name="PropertyRegDataType">Pointer to a variable that receives the registry data Type. This parameter can be NULL.</param>     /// <param Name="PropertyBuffer">Pointer to a buffer that receives the requested device property.</param>     /// <param Name="PropertyBufferSize">Size of the buffer, in bytes.</param>     /// <param Name="RequiredSize">Pointer to a variable that receives the required buffer size, in bytes. This parameter can be NULL.</param>     /// <returns>If the function succeeds, the return value is nonzero.</returns>     [DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]     private static extern bool SetupDiGetDeviceRegistryProperty(         IntPtr DeviceInfoSet,         ref SP_DEVINFO_DATA DeviceInfoData,         uint Property,         out UInt32 PropertyRegDataType,         byte[] PropertyBuffer,         uint PropertyBufferSize,         out UInt32 RequiredSize);       const int DIGCF_DEFAULT = 0x1;     const int DIGCF_PRESENT = 0x2;     const int DIGCF_ALLCLASSES = 0x4;     const int DIGCF_PROFILE = 0x8;     const int DIGCF_DEVICEINTERFACE = 0x10;     const int INVALID_HANDLE_VALUE = -1;      private static Guid[] GetClassGUIDs(string className)     {         UInt32 requiredSize = 0;         Guid[] guidArray = new Guid[1];          bool status = SetupDiClassGuidsFromName(className, ref guidArray[0], 1, out requiredSize);         if (true == status)         {             if (1 < requiredSize)             {                 guidArray = new Guid[requiredSize];                 SetupDiClassGuidsFromName(className, ref guidArray[0], requiredSize, out requiredSize);             }         }         else             throw new System.ComponentModel.Win32Exception();          return guidArray;     }   } 

Answer 2

This article's code did the job for me (he links to this post, but doesn't seem to have provided an answer here himself). Here's the author's code:

using System.Management; internal class ProcessConnection {      public static ConnectionOptions ProcessConnectionOptions()    {      ConnectionOptions options = new ConnectionOptions();      options.Impersonation = ImpersonationLevel.Impersonate;      options.Authentication = AuthenticationLevel.Default;      options.EnablePrivileges = true;      return options;    }     public static ManagementScope ConnectionScope(string machineName, ConnectionOptions options, string path)    {      ManagementScope connectScope = new ManagementScope();      connectScope.Path = new ManagementPath(@"\\" + machineName + path);      connectScope.Options = options;      connectScope.Connect();      return connectScope;    } }  public class COMPortInfo {    public string Name { get; set; }    public string Description { get; set; }     public COMPortInfo() { }          public static List<COMPortInfo> GetCOMPortsInfo()    {      List<COMPortInfo> comPortInfoList = new List<COMPortInfo>();       ConnectionOptions options = ProcessConnection.ProcessConnectionOptions();      ManagementScope connectionScope = ProcessConnection.ConnectionScope(Environment.MachineName, options, @"\root\CIMV2");       ObjectQuery objectQuery = new ObjectQuery("SELECT * FROM Win32_PnPEntity WHERE ConfigManagerErrorCode = 0");      ManagementObjectSearcher comPortSearcher = new ManagementObjectSearcher(connectionScope, objectQuery);       using (comPortSearcher)      {        string caption = null;        foreach (ManagementObject obj in comPortSearcher.Get())        {          if (obj != null)          {            object captionObj = obj["Caption"];            if (captionObj != null)            {               caption = captionObj.ToString();               if (caption.Contains("(COM"))               {                 COMPortInfo comPortInfo = new COMPortInfo();                 comPortInfo.Name = caption.Substring(caption.LastIndexOf("(COM")).Replace("(", string.Empty).Replace(")",                                                      string.Empty);                 comPortInfo.Description = caption;                 comPortInfoList.Add(comPortInfo);               }            }          }        }      }       return comPortInfoList;    }  } 

Usage:

foreach (COMPortInfo comPort in COMPortInfo.GetCOMPortsInfo()) {   Console.WriteLine(string.Format("{0} – {1}", comPort.Name, comPort.Description)); }