串口编程 - windows如何枚举串口|获取活跃串口号

「爱情、让人受尽委屈。」 2022-10-25 04:49 428阅读 0赞

# 串口编程 - windows如何枚举串口|获取活跃串口号 #

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如需转载请标明出处：[http://blog.csdn.net/itas109 ][http_blog.csdn.net_itas109]  
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### 文章目录 ###

*  串口编程 - windows如何枚举串口|获取活跃串口号
 *   *  前言
     *  1. windows枚举设备简介
     *  2. windows枚举串口代码实现
     *   *  2.1 CreateFile函数遍历
         *  2.2 注册表
         *  2.3 setupapi(GUID\_DEVINTERFACE\_COMPORT && SetupDiEnumDeviceInfo)

环境：  
OS: windows 10  
compiler: VS2019

## 前言 ##

进行串口通信，首先会面临串口枚举的问题。本文将介绍windows如何枚举串口。

## 1. windows枚举设备简介 ##

一般而言，windows下枚举的串口可以分为如下几种类型：

*  物理串口：RS232
 *  虚拟串口：com0com 或 ELTIMA Virtual Serial Port 等
 *  蓝牙转串口
 *  USB转串口
 *  STM32虚拟COM端口 (设备管理器显示 `STMicroelectronics Virtual COM Port`)(未测试)

## 2. windows枚举串口代码实现 ##

以下以三种主流方式实现枚举串口，包括CreateFile函数遍历、注册表和setupapi三种方式。

<table> 
 <thead> 
  <tr> 
   <th align="left">串口</th> 
   <th align="left">友好名称</th> 
   <th align="left">物理设备对象名称</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">COM1</td> 
   <td align="left">ELTIMA Virtual Serial Port</td> 
   <td align="left">\Device\VSerial7_0</td> 
  </tr> 
  <tr> 
   <td align="left">COM2</td> 
   <td align="left">ELTIMA Virtual Serial Port</td> 
   <td align="left">\Device\VSerial7_1</td> 
  </tr> 
  <tr> 
   <td align="left">COM4</td> 
   <td align="left">Prolific USB-to-Serial Comm Port</td> 
   <td align="left">\Device\ProlificSerial0</td> 
  </tr> 
  <tr> 
   <td align="left">COM5</td> 
   <td align="left">Standard Serial over Bluetooth link</td> 
   <td align="left">\Device\BthModem0</td> 
  </tr> 
  <tr> 
   <td align="left">COM6</td> 
   <td align="left">com0com - serial port emulator</td> 
   <td align="left">\Device\com0com11</td> 
  </tr> 
  <tr> 
   <td align="left">COM7</td> 
   <td align="left">com0com - serial port emulator</td> 
   <td align="left">\Device\com0com21</td> 
  </tr> 
  <tr> 
   <td align="left">CNCA0</td> 
   <td align="left">com0com - serial port emulator CNCA0</td> 
   <td align="left">\Device\com0com10</td> 
  </tr> 
  <tr> 
   <td align="left">CNCB0</td> 
   <td align="left">com0com - serial port emulator CNCB0</td> 
   <td align="left">\Device\com0com20</td> 
  </tr> 
 </tbody> 
</table>

测试结果：

*  COMxxx遍历

0 - COM1
    1 - COM2
    2 - COM4
    3 - COM5
    4 - COM6
    5 - COM7
    time : 375 ms

*  注册表

0 - CNCA0
    1 - CNCB0
    2 - COM1
    3 - COM2
    4 - COM5
    5 - COM6
    6 - COM7
    7 - COM4
    time : 0 ms

*  setupapi

0 - COM6 com0com - serial port emulator
    1 - COM4 Prolific USB-to-Serial Comm Port
    2 - COM1 ELTIMA Virtual Serial Port
    3 - CNCA0 com0com - serial port emulator CNCA0 (CNCA0)
    4 - COM7 com0com - serial port emulator
    5 - COM5 Standard Serial over Bluetooth link
    6 - COM2 ELTIMA Virtual Serial Port
    7 - CNCB0 com0com - serial port emulator CNCB0 (CNCB0)
    time : 0 ms

### 2.1 CreateFile函数遍历 ###

使用CreateFile函数遍历COM1-COM255，如果返回结果正确或错误为被占用，则认为是活跃串口。但是该方式只能针对串口名称为COMxxx格式的串口。

代码：

### 2.2 注册表 ###

注册表`HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM`查询，可以实时获取活跃串口

代码：

#include <iostream>
    
    #include <string>
    #include <vector>
    
    #include "windows.h" // CreateFile GetTickCount64
    #include "tchar.h" // _sntprintf _T 
    
    using namespace std;
    
    struct SerialPortInfo
    {
    	std::string portName;
    	std::string description;
    };
    
    std::string wstringToString(const std::wstring& wstr)
    {
    	// https://stackoverflow.com/questions/4804298/how-to-convert-wstring-into-string
    	if (wstr.empty())
    	{
    		return std::string();
    	}
    
    	int size = WideCharToMultiByte(CP_ACP, 0, &wstr[0], (int)wstr.size(), NULL, 0, NULL, NULL);
    	std::string ret = std::string(size, 0);
    	WideCharToMultiByte(CP_ACP, 0, &wstr[0], (int)wstr.size(), &ret[0], size, NULL, NULL); // CP_UTF8
    
    	return ret;
    }
    
    bool enumDetailsSerialPorts(vector<SerialPortInfo>& portInfoList)
    {
    	//https://msdn.microsoft.com/en-us/library/ms724256
    
    #define MAX_KEY_LENGTH 255
    #define MAX_VALUE_NAME 16383
    
    	HKEY hKey;
    
    	TCHAR		achValue[MAX_VALUE_NAME];					// buffer for subkey name
    	DWORD		cchValue = MAX_VALUE_NAME;					// size of name string
    	TCHAR		achClass[MAX_PATH] = _T("");				// buffer for class name
    	DWORD		cchClassName = MAX_PATH;					// size of class string
    	DWORD		cSubKeys = 0;								// number of subkeys
    	DWORD		cbMaxSubKey;								// longest subkey size
    	DWORD		cchMaxClass;								// longest class string
    	DWORD		cKeyNum;									// number of values for key
    	DWORD		cchMaxValue;								// longest value name
    	DWORD		cbMaxValueData;								// longest value data
    	DWORD		cbSecurityDescriptor;						// size of security descriptor
    	FILETIME	ftLastWriteTime;							// last write time
    
    	int iRet = -1;
    	bool bRet = false;
    
    	std::string strPortName;
    	SerialPortInfo m_serialPortInfo;
    
    	TCHAR strDSName[MAX_VALUE_NAME];
    	memset(strDSName, 0, MAX_VALUE_NAME);
    	DWORD nValueType = 0;
    	DWORD nBuffLen = 10;
    
    	if (ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("HARDWARE\\DEVICEMAP\\SERIALCOMM"), 0, KEY_READ, &hKey))
    	{
    		// Get the class name and the value count.
    		iRet = RegQueryInfoKey(
    			hKey,                    // key handle
    			achClass,                // buffer for class name
    			&cchClassName,           // size of class string
    			NULL,                    // reserved
    			&cSubKeys,               // number of subkeys
    			&cbMaxSubKey,            // longest subkey size
    			&cchMaxClass,            // longest class string
    			&cKeyNum,                // number of values for this key
    			&cchMaxValue,            // longest value name
    			&cbMaxValueData,         // longest value data
    			&cbSecurityDescriptor,   // security descriptor
    			&ftLastWriteTime);       // last write time
    
    		if (!portInfoList.empty())
    		{
    			portInfoList.clear();
    		}
    
    		// Enumerate the key values.
    		if (cKeyNum > 0 && ERROR_SUCCESS == iRet)
    		{
    			for (int i = 0; i < (int)cKeyNum; i++)
    			{
    				cchValue = MAX_VALUE_NAME;
    				achValue[0] = '\0';
    				nBuffLen = MAX_KEY_LENGTH;//防止 ERROR_MORE_DATA 234L 错误
    
    				if (ERROR_SUCCESS == RegEnumValue(hKey, i, achValue, &cchValue, NULL, NULL, (LPBYTE)strDSName, &nBuffLen))
    				{
    
    #ifdef UNICODE
    					strPortName = wstringToString(strDSName);
    #else
    					strPortName = std::string(strDSName);
    #endif
    					m_serialPortInfo.portName = strPortName;
    					portInfoList.push_back(m_serialPortInfo);
    				}
    			}
    		}
    		else
    		{
    
    		}
    	}
    
    	if (portInfoList.empty())
    	{
    		bRet = false;
    	}
    	else
    	{
    		bRet = true;
    	}
    
    
    	RegCloseKey(hKey);
    
    	return bRet;
    }
    
    int main()
    {
    	ULONGLONG startTick = 0;
    	startTick = GetTickCount64();
    
    	vector<SerialPortInfo> spInfo;
    	enumDetailsSerialPorts(spInfo);
    	for (int i = 0; i < spInfo.size(); i++)
    	{
    		std::cout << i << " - " << spInfo[i].portName << " " << spInfo[i].description << std::endl;
    	}
    
    	_tprintf(_T("time : %I64u ms"), GetTickCount64() - startTick);
    
    	return 0;
    }

### 2.3 setupapi(GUID\_DEVINTERFACE\_COMPORT && SetupDiEnumDeviceInfo) ###

setupapi可以遍历设备管理器，因此可以用来枚举串口(包括友好名称、物理设备对象名称等)，其本质上也是操作注册表。

代码：

// https://github.com/itas109/CSerialPort/blob/master/src/SerialPortInfoWinBase.cpp
    
    #include <iostream>
    
    #include <string>
    #include <vector>
    
    #include "windows.h" // CreateFile GetTickCount64
    #include "tchar.h" // _sntprintf _T 
    
    #include <Setupapi.h> //SetupDiGetClassDevs Setup*
    #include <initguid.h> //GUID
    
    #pragma comment (lib, "setupapi.lib")
    
    using namespace std;
    
    #ifndef GUID_DEVINTERFACE_COMPORT
    DEFINE_GUID(GUID_DEVINTERFACE_COMPORT, 0x86E0D1E0L, 0x8089, 0x11D0, 0x9C, 0xE4, 0x08, 0x00, 0x3E, 0x30, 0x1F, 0x73);
    #endif
    
    struct SerialPortInfo
    {
    	std::string portName;
    	std::string description;
    };
    
    std::string wstringToString(const std::wstring& wstr)
    {
    	// https://stackoverflow.com/questions/4804298/how-to-convert-wstring-into-string
    	if (wstr.empty())
    	{
    		return std::string();
    	}
    
    	int size = WideCharToMultiByte(CP_ACP, 0, &wstr[0], (int)wstr.size(), NULL, 0, NULL, NULL);
    	std::string ret = std::string(size, 0);
    	WideCharToMultiByte(CP_ACP, 0, &wstr[0], (int)wstr.size(), &ret[0], size, NULL, NULL); // CP_UTF8
    
    	return ret;
    }
    
    bool enumDetailsSerialPorts(vector<SerialPortInfo>& portInfoList)
    {
    	// https://docs.microsoft.com/en-us/windows/win32/api/setupapi/nf-setupapi-setupdienumdeviceinfo
    
    	bool bRet = false;
    	SerialPortInfo m_serialPortInfo;
    
    	std::string strFriendlyName;
    	std::string strPortName;
    
    	HDEVINFO hDevInfo = INVALID_HANDLE_VALUE;
    
    	// Return only devices that are currently present in a system
    	// The GUID_DEVINTERFACE_COMPORT device interface class is defined for COM ports. GUID
    	// {86E0D1E0-8089-11D0-9CE4-08003E301F73}
    	hDevInfo = SetupDiGetClassDevs(&GUID_DEVINTERFACE_COMPORT, NULL, NULL, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
    
    	if (INVALID_HANDLE_VALUE != hDevInfo)
    	{
    		SP_DEVINFO_DATA devInfoData;
    		// The caller must set DeviceInfoData.cbSize to sizeof(SP_DEVINFO_DATA)
    		devInfoData.cbSize = sizeof(SP_DEVINFO_DATA);
    
    		for (DWORD i = 0; SetupDiEnumDeviceInfo(hDevInfo, i, &devInfoData); i++)
    		{
    			// get port name
    			TCHAR portName[256];
    			HKEY hDevKey = SetupDiOpenDevRegKey(hDevInfo, &devInfoData, DICS_FLAG_GLOBAL, 0, DIREG_DEV, KEY_READ);
    			if (INVALID_HANDLE_VALUE != hDevKey)
    			{
    				DWORD dwCount = 255; // DEV_NAME_MAX_LEN
    				RegQueryValueEx(hDevKey, _T("PortName"), NULL, NULL, (BYTE*)portName, &dwCount);
    				RegCloseKey(hDevKey);
    			}
    
    			// get friendly name
    			TCHAR fname[256];
    			SetupDiGetDeviceRegistryProperty(hDevInfo, &devInfoData, SPDRP_FRIENDLYNAME, NULL, (PBYTE)fname,
    				sizeof(fname), NULL);
    
    #ifdef UNICODE
    			strPortName = wstringToString(portName);
    			strFriendlyName = wstringToString(fname);
    #else
    			strPortName = std::string(portName);
    			strFriendlyName = std::string(fname);
    #endif
    			// remove (COMxx)
    			strFriendlyName = strFriendlyName.substr(0, strFriendlyName.find(("(COM")));
    
    			m_serialPortInfo.portName = strPortName;
    			m_serialPortInfo.description = strFriendlyName;
    			portInfoList.push_back(m_serialPortInfo);
    		}
    
    		if (ERROR_NO_MORE_ITEMS == GetLastError())
    		{
    			bRet = true; // no more item
    		}
    	}
    
    	SetupDiDestroyDeviceInfoList(hDevInfo);
    
    	return bRet;
    }
    
    int main()
    {
    	ULONGLONG startTick = 0;
    	startTick = GetTickCount64();
    
    	vector<SerialPortInfo> spInfo;
    	enumDetailsSerialPorts(spInfo);
    	for (int i = 0; i < spInfo.size(); i++)
    	{
    		std::cout << i << " - " << spInfo[i].portName << " " << spInfo[i].description << std::endl;
    	}
    
    	_tprintf(_T("time : %I64u ms"), GetTickCount64() - startTick);
    
    	return 0;
    }

注意：  
使用`SetupDiGetDeviceInterfaceDetail`替代`SetupDiEnumDeviceInfo`也能达到效果。参考：https://github.com/itas109/CSerialPort/issues/41

--------------------

**License**

[*License under CC BY-NC-ND 4.0: 署名-非商业使用-禁止演绎*][License under CC BY-NC-ND 4.0_ _-_-]

如需转载请标明出处：[http://blog.csdn.net/itas109 ][http_blog.csdn.net_itas109]  
QQ技术交流群：[129518033][]

--------------------

Refrence：

1.  https://github.com/itas109/CSerialPort
2.  http://www.naughter.com/enumser.html

[http_blog.csdn.net_itas109]: http://blog.csdn.net/itas109
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[License under CC BY-NC-ND 4.0_ _-_-]: https://creativecommons.org/licenses/by-nc-nd/4.0/deed.zh