根据PID和VID得到USB转串口的串口号

 /*******************************************************************************
  *
  *  FindAppUART.cpp - PC command line utility for enumerating MSP430 EVM's
  *                    Application UARTs.
  *
  *  Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/
  *
  *  Redistribution and use in source and binary forms, with or without
  *  modification, are permitted provided that the following conditions
  *  are met:
  *
  *    Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  *    Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the
  *    distribution.
  *
  *    Neither the name of Texas Instruments Incorporated nor the names of
  *    its contributors may be used to endorse or promote products derived
  *    from this software without specific prior written permission.
  *
  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************/

 //------------------------------------------------------------------------------
 // Desc: PC command line utility for enumerating MSP430 EVM's Application UARTs.
 //       The application returns the COM port number of the first UART that is
 //       found. If this is successful the error code is set to '0'. In case of
 //       the UART string could not be determined '1' is returned.
 //
 //       The code was developed with the Express Edition of Visual C++ 2008
 //       http://www.microsoft.com/express/
 //
 // Ver.: 0.1 (February 2011)
 //       - Alpha version
 //
 // Auth: Andreas Dannenberg
 //       MSP430 Applications
 //       Texas Instruments, Inc.
 //------------------------------------------------------------------------------

 // Windows Header Files
 #define WIN32_LEAN_AND_MEAN                        // Exclude rarely-used stuff
                                                 // from Windows headers
 #include <windows.h>
 #include <tchar.h>
 #include <shellapi.h>
 #include <setupapi.h>                            // "setupapi.lib" must be linked
                                                 // to the project
 // C Runtime Header Files
 #include <stdlib.h>
 #include <malloc.h>
 #include <memory.h>

 //------------------------------------------------------------------------------
 // DWORD WINAPI EnumComPorts(DWORD dwIndex, LPTSTR lptszName,
 //      DWORD dwNumOfElements)
 //
 // User-mode code fragment to identify attached VCP COMnn port[s] with a
 // specific device instance ID based on USB VID and PID and returns the COMnn
 // port that the OS embeds into the device instance ID. When called with
 // dwIndex = 0, the function will enumerate all COMPORT class devices and
 // return the name of the first one that was found. Subsequent calls using an
 // incremented dwIndex parameter can be performed until ERROR_NO_MORE_ITEMS
 // is returned.
 //
 // IN:  dwIndex               COMPORT class device # 0, 1, 2, ... to check
 //      dwNumOfElements       The size of the lptszName buffer
 // OUT: lptszName             COMnn name of given device #
 //      return()              ERROR_SUCCESS - lpszName is valid
 //                            ERROR_NO_MORE_ITEMS - End of device list reached
 //------------------------------------------------------------------------------
 DWORD WINAPI EnumComPorts(DWORD dwIndex, LPTSTR lptszName, DWORD dwNumOfElements)
 {
     HDEVINFO hDevInfo;
     SP_DEVINFO_DATA DeviceInfoData;
     DWORD i;
     TCHAR *pcParse;

     // Create a HDEVINFO with all present devices
     hDevInfo = SetupDiGetClassDevs(
                     NULL,
                     , // Enumerator
                     ,
                     DIGCF_PRESENT | DIGCF_ALLCLASSES);

     if (INVALID_HANDLE_VALUE == hDevInfo)
     {
         return GetLastError();
     }

     // Enumerate through all devices in set
     DeviceInfoData.cbSize = sizeof(SP_DEVINFO_DATA);

     for (i = ; SetupDiEnumDeviceInfo(hDevInfo, i, &DeviceInfoData); i++)
     {
         LPTSTR buffer     = NULL;
         DWORD  buffersize = ;

         // Get the device instance ID that is associated with the device information element
         while (!SetupDiGetDeviceInstanceId(
                     hDevInfo,
                     &DeviceInfoData,
                     buffer,
                     buffersize,
                     &buffersize))
         {
             if (buffer)
             {
                LocalFree(buffer);
             }

             if (ERROR_INSUFFICIENT_BUFFER == GetLastError())
             {
                 // Change the buffer size. Double the size to avoid problems on
                 // W2K MBCS systems per KB 888609.
                 buffer = (LPTSTR)LocalAlloc(LPTR, buffersize * );
             }
             else
             {
                 // Error: could not get device instance ID
                 // Cleanup and return error code
                 SetupDiDestroyDeviceInfoList(hDevInfo);
                 return GetLastError();
             }
         }

         if (buffer)
         {
             // Look for the "Application UART" of common MSP430 EVMs. The application UART
             // has an USB VID of 0x0451 (Texas Instruments) and an PID of 0xF432.
             const TCHAR testval[] = _T("USB\\VID_0451&PID_F432&MI_00");

             if (NULL != _tcsstr(buffer, testval))
             {
                 TCHAR szFriendlyName[MAX_PATH];

                 if (SetupDiGetDeviceRegistryProperty(
                     hDevInfo,
                     &DeviceInfoData,
                     SPDRP_FRIENDLYNAME,
                     NULL,
                     (PBYTE)szFriendlyName,
                     sizeof(szFriendlyName) - ,
                     NULL))
                 {
                     // Check if we have reached the dwIndex-th element, if not keep looking
                     if (dwIndex == )
                     {
                         // Find pointer to "COM" substring (secure)
                         szFriendlyName[sizeof(szFriendlyName) - ] = 0x00;
                         pcParse = _tcsstr(szFriendlyName, _T("COM"));

                         if (pcParse != NULL)
                         {
                             // Zero-terminate COM port string after last digit
                             if (!isdigit(pcParse[])) {
                                 pcParse[] = ;
                             }
                             else if (!isdigit(pcParse[])) {
                                 pcParse[] = ;
                             }
                             else {
                                 pcParse[] = ;
                             }

                             // Pass string to the return parameter
                             _tcscpy_s(lptszName, dwNumOfElements, pcParse);

                             // Cleanup
                             SetupDiDestroyDeviceInfoList(hDevInfo);

                             return ERROR_SUCCESS;
                         }
                     }
                     else
                     {
                         dwIndex--;
                     }
                 }
             }
         }
     }

     //  Cleanup
     SetupDiDestroyDeviceInfoList(hDevInfo);

     return ERROR_NO_MORE_ITEMS;
 }

 //------------------------------------------------------------------------------
 // Main application entry point. Simply return the first Application UART
 // COM port that was found to STDOUT.
 //------------------------------------------------------------------------------
 int _tmain(int argc, _TCHAR* argv[])
 {
     TCHAR szDeviceName[MAX_PATH];
     DWORD dwReturnValue;

     dwReturnValue = EnumComPorts(, szDeviceName, _countof(szDeviceName));

     if (dwReturnValue == ERROR_SUCCESS) {
         _ftprintf_s(stdout, _T("%s\r\n"), szDeviceName);
         return ;
     }

     return ;
 }