VC++ API串口通讯只能发送一次数据，无法接受

[zhouyj-csdn]

本人接触这个不久，问题可能有点小儿科，是这样的，我仿照CSerialPort类写了一个类，可是有很多问题，我是用串口通讯助手来测试发送接收数据的。
1， ClosePort 中SetEvent(m_hShutdownEvent);为什么不能直接触发ThreadPro_C1中的MsgWaitForMultipleObjects。
2，只能发送一次，第二次发送没反应。
希望有大神可以帮我指出我的错误，谢谢了。

CCom_C1::CCom_C1(void)
	: m_strData(_T(""))
	,m_nTimeOut(10000)
	,m_bSending(FALSE)
	, m_hWnd(NULL)
{
	hComm = NULL;
	m_nPort= 0;
	m_nBaud= 0;
	m_nData= 0;
	m_nParity= 0;
	m_nStop = 0;

	m_bComOpen= FALSE;
	m_bThreadAlive = FALSE;
	///初始化异步结构体
	m_ov.Offset = 0;
	m_ov.OffsetHigh = 0;

	// create events
	m_ov.hEvent = NULL;
	m_hWriteEvent = NULL;
	m_hShutdownEvent = NULL;
	// create events
	m_ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
	m_hWriteEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
	m_hShutdownEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

	m_hEventArray[0] = m_hShutdownEvent;	// highest priority
	m_hEventArray[1] = m_hWriteEvent;
	m_hEventArray[2] = m_ov.hEvent;

	InitializeCriticalSection(&m_csCommunicationSync);  
}

CCom_C1::~CCom_C1(void)
{
// close Handles  
	if (m_hShutdownEvent != NULL)
	{
		CloseHandle(m_hShutdownEvent);
	}
	if (m_ov.hEvent != NULL)
	{
		CloseHandle(m_ov.hEvent);
	}
	if (m_hWriteEvent != NULL)
	{
		CloseHandle(m_hWriteEvent);
	}
	//释放临界资源
	DeleteCriticalSection(&m_csCommunicationSync);
}

BOOL CCom_C1::OpenPort(HWND hWnd)
{
	if(!IsWindow(hWnd)) return false;
	if (IsOpen())
	{
		return true;
	}

	m_hWnd = hWnd;
	m_bSending = FALSE;
	m_strData = _T("");
	m_strData.Empty();



	//进入临界区
	EnterCriticalSection(&m_csCommunicationSync);
	CString szCom; 
	szCom.Format(_T("\\\\.\\COM%d"), m_nPort);
	hComm = CreateFile(szCom.GetBuffer(50),
		GENERIC_READ | GENERIC_WRITE,
		0,
		NULL,
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL|  
		FILE_FLAG_OVERLAPPED,			// Async I/O
		NULL);
	if(hComm==INVALID_HANDLE_VALUE)
	{
		DWORD dwErr= GetLastError();
		::MessageBox(NULL,_T("Cannot Open Communication Port.Please Check Communication Port Setting Whether Correctly."),_T("PLC Com Port Error"),MB_OK+MB_ICONERROR);
		m_bComOpen=false;
		return FALSE;
	}

	DCB m_dcb;
	memset(&m_dcb,0,sizeof(m_dcb));
	if(GetCommDCB(&m_dcb))///获取当前DCB参数
	{
		if (!SetCommDCB(&m_dcb))//设置新参数
		{
			//错误处理
			CloseHandle(hComm);
			hComm=NULL;
			m_bComOpen =false;
			return FALSE;
		}
	}
	else//错误处理，不能获取当前配置
	{
		CloseHandle(hComm);
		hComm=NULL;
		m_bComOpen =false;
		return FALSE;
	}

	COMMTIMEOUTS  m_CommTimeouts;
	if(GetCommTimeouts(hComm, &m_CommTimeouts)) 
	{
		m_CommTimeouts.ReadIntervalTimeout =MAXDWORD;//指定了在接收字符间的最大时间，如果超过了这个时间，ReadFile立即返回
		m_CommTimeouts.ReadTotalTimeoutConstant = 0;//表示读数据总时间常量
		m_CommTimeouts.ReadTotalTimeoutMultiplier = 0;//表示平均读一个字节的时间上限
		m_CommTimeouts.WriteTotalTimeoutConstant = 2000;//表示写数据总超时常量
		m_CommTimeouts.WriteTotalTimeoutMultiplier =50;//表示平均写一个字节的时间上限
	}
	else
	{
		m_bComOpen =false;
		return FALSE;
	}
	//给定串口读与操作限时
	if(!SetCommTimeouts(hComm, &m_CommTimeouts))
	{
		TRACE(_T("SetCommTimeouts  Error!"));
		CloseHandle(hComm);
		hComm=NULL;
		m_bComOpen =false;
		return FALSE;
	}
	// 设置串口缓冲区,输入/输出大小(字节数)
	SetupComm(hComm, 1024, 1024);
	// 用来指定程序接收特定的串口事件_收到字符放入缓冲区
	SetCommMask(hComm, EV_RXCHAR) ;//监视串口中有无数据，一旦就激活WaitCommEvent。（设置我们关心的事件）
	//刷清缓冲区,终止读写并清空接收和发送
	PurgeComm(hComm, PURGE_TXABORT | PURGE_RXABORT | PURGE_TXCLEAR | PURGE_RXCLEAR ) ;
	LeaveCriticalSection(&m_csCommunicationSync);  

	m_bComOpen=true;
	m_Thread = ::CreateThread(NULL, 0, ThreadProc_C1, this, 0, NULL);
	m_bThreadAlive=TRUE;

	return TRUE;
}

void CCom_C1::ClosePort()
{
	MSG message;

	if (!IsOpen())//当端口未打开时
	{
		return;
	}
	m_bSending = FALSE;
	m_bThreadAlive=FALSE;

	//设置所有事件无效无效  
	SetCommMask(hComm, 0);  
	//清空所有将要读的数据  
	PurgeComm( hComm,  PURGE_RXCLEAR |PURGE_RXABORT|PURGE_TXCLEAR|PURGE_TXABORT); 

	if (SuspendThread(m_Thread)!=-1)
	{
		ResumeThread(m_Thread);
	}
	do
	{
		SetEvent(m_hShutdownEvent);//通知关闭系统
		Sleep(1000);
		if (::PeekMessage(&message, m_hWnd, 0, 0, PM_REMOVE))
		{
			::TranslateMessage(&message);
			::DispatchMessage(&message);
		}
	} while (m_bThreadAlive);


	//关闭串口句柄
	if(hComm = INVALID_HANDLE_VALUE)
	{
		m_bComOpen =false;
	}
	else  
	{
		CloseHandle(hComm);
		hComm = NULL;
	}

	
}

void CCom_C1::WriteChar(CCom_C1* pThis)
{
	DWORD dwStartTime = 0;
	while(pThis->m_bThreadAlive)
	{
			PC1_CMD_SEND_INFO pCmdInfo = pThis->GetNextCmd();
			if(pCmdInfo)
			{
				pThis->m_nCmdSending = pCmdInfo->nCmd;

				PBYTE sendData=(LPBYTE)pCmdInfo->szCmd;
				int sendLen= strlen(pCmdInfo->szCmd);
				DWORD   BytesSend=0;
				DWORD dwError;
				COMSTAT m_comstat;
				EnterCriticalSection(&pThis->m_csCommunicationSync);
				ResetEvent(pThis->m_hWriteEvent);
				// Initailize variables
				pThis->m_ov.Offset = 0;
				pThis->m_ov.OffsetHigh = 0;

				PurgeComm(pThis->hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
				ClearCommError(pThis->hComm,&dwError,&m_comstat);
				if (!WriteFile(pThis->hComm,sendData,	sendLen,&BytesSend,&pThis->m_ov))
				{
					DWORD dwError = GetLastError();
				}
				GetOverlappedResult(pThis->hComm,&pThis->m_ov,&BytesSend,TRUE); 			// Wait flag
				LeaveCriticalSection(&pThis->m_csCommunicationSync);
				delete []pCmdInfo->szCmd;
				pCmdInfo->szCmd = NULL;
				delete pCmdInfo;
			}
	}
}

//响应函数
void CCom_C1::ReceiveStr(CCom_C1* pThis)
{
	DWORD dwRealRead;
	DWORD dwError;
	DWORD dwWantRead;
	COMSTAT m_comstat;

	for (;;)
	{
		EnterCriticalSection(&pThis->m_csCommunicationSync);
		//防止死锁
		if (WaitForSingleObject(pThis->m_hShutdownEvent, 0) == WAIT_OBJECT_0)
			return;

		if(pThis->m_nCmdSending == C1_No)//此时没有任何指令
		{
			pThis->ClearReadBuffer();		
			return;
		}
		pThis->m_bSending = true;//发送接受进行时
		ClearCommError(pThis->hComm,&dwError,&m_comstat);
		dwWantRead=m_comstat.cbInQue;
		if (m_comstat.cbInQue == 0 || m_comstat.cbInQue == 0xcccccccc)
		{
			break;
		}
		//如果遇到'\0'，那么数据会被截断，实际数据全部读取只是没有显示完全，这个时候使用memcpy才能全部获取
		char RXBuff[512];
		memset(RXBuff,0,sizeof(char)*512);
		dwWantRead = min(dwWantRead,512);
		RXBuff[dwWantRead] = '\0';//附加字符串结束符
		ReadFile(pThis->hComm,RXBuff,dwWantRead,&dwRealRead,&pThis->m_ov);
		pThis->m_strData += RXBuff;
		GetOverlappedResult(pThis->hComm,&pThis->m_ov,&dwRealRead,TRUE);
		::PostMessage(pThis->m_hWnd , WM_PEEKCOMDATA, MAKEWPARAM(0,pThis->m_nCmdSending), 1);  //工作线程中不要修改主界面，发送消息响应
		LeaveCriticalSection(&pThis->m_csCommunicationSync);

		pThis->ClearReadBuffer();
		pThis->m_strData = _T("");
		pThis->m_bSending = false;
	}
}

DWORD  WINAPI  CCom_C1::ThreadProc_C1(LPVOID lParam)//LPVOID没有类型的指针
{
	CCom_C1 * pThis = (CCom_C1 *) lParam;
	DWORD BytesTransfered = 0;
	DWORD Event;
	DWORD CommEvent;
	DWORD dwError = 0;
	COMSTAT comstat;

	BOOL  bResult = TRUE;

	if (pThis->hComm)		// check if the port is opened
	{
		PurgeComm(pThis->hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
	}

	for (;;)
	{
		bResult = WaitCommEvent(pThis->hComm, &Event, &pThis->m_ov);///表示该函数是异步的
		if (!bResult)
		{
			switch (dwError = GetLastError())
			{
			case ERROR_IO_PENDING: 	///正常情况，没有字符可读 erroe code:997
				{
					break;
				}
			case ERROR_INVALID_PARAMETER:///系统错误 erroe code:87
				{
					break;
				}
			case ERROR_ACCESS_DENIED:///拒绝访问 erroe code:5
				{
					pThis->hComm = INVALID_HANDLE_VALUE;
					TCHAR Temp[200] = { 0 };
					_stprintf_s(Temp, 200, _T("COM%d ERROR_ACCESS_DENIED，WaitCommEvent() Error Code:%d"), pThis->m_nPort, GetLastError());
					::MessageBox(NULL, Temp, _T("COM WaitCommEvent Error"), MB_ICONERROR);
					break;
				}
			case ERROR_INVALID_HANDLE:///打开串口失败 erroe code:6
				{
					pThis->hComm = INVALID_HANDLE_VALUE;
					::MessageBox(NULL, _T("Open COM Failed"), _T("COM Error"), MB_ICONERROR);
					break;
				}
			case ERROR_BAD_COMMAND:///连接过程中非法断开 erroe code:22
				{
					pThis->hComm = INVALID_HANDLE_VALUE;
					TCHAR Temp[200] = {0};
					_stprintf_s(Temp, 200, _T("COM%d ERROR_BAD_COMMAND，WaitCommEvent() Error Code:%d"), pThis->m_nPort, GetLastError());
					::MessageBox(NULL, Temp, _T("COM WaitCommEvent Error"), MB_ICONERROR);
					break;
				}
			default:///发生其他错误，其中有串口读写中断开串口连接的错误（错误22）
				{
					//发生错误时，将串口句柄置为无效句柄
					pThis->hComm = INVALID_HANDLE_VALUE;
					::MessageBox(NULL, _T("COM Other Problem"), _T("COM Error"), MB_ICONERROR);
					break;
				}
			}
		}
		else	///WaitCommEvent()能正确返回
		{
			bResult = ClearCommError(pThis->hComm, &dwError, &comstat);
			if (comstat.cbInQue == 0)
				continue;

		}	// end if bResult

		Event = MsgWaitForMultipleObjects(3, ///3个事件
			pThis->m_hEventArray, ///事件数组
			FALSE, ///有一个事件发生就返回
			INFINITE,
			QS_ALLEVENTS);///超时时间

		if (Event >= WAIT_OBJECT_0 && Event < WAIT_OBJECT_0 + 3)
		{
			for (int i = Event - WAIT_OBJECT_0 - 1; i < 3; i++)
			{
				if (WaitForSingleObject(pThis->m_hEventArray[i], 0) == WAIT_OBJECT_0)
				{
					switch (Event)
					{
					case WAIT_OBJECT_0 + 0:
						{
							///关断事件，关闭串口
							CloseHandle(pThis->hComm);
							pThis->hComm = NULL;
							pThis->m_bThreadAlive = FALSE;
							pThis->m_bComOpen=false;
							pThis->RemoveAllCmdFromList();
							::ExitThread(1000);

							break;
						}
					case WAIT_OBJECT_0 + 1: // write event 发送数据
						{
							// Write character event from port
							WriteChar(pThis);
							break;
						}
					case WAIT_OBJECT_0 + 2:	// read event 将定义的各种消息发送出去
						{
							GetCommMask(pThis->hComm, &CommEvent);
							if (CommEvent & EV_RXCHAR) //接收到字符，并置于输入缓冲区中
							{
								ReceiveStr(pThis);
							}
							break;
						}
					} // end switch
				}
			}
		}
	} 
	return 0;
}

[赵4老师]

百度搜相关关键字。

[新人码农]

CSerialPort没试过，我用的是Win32API函数，https://blog.csdn.net/cjdxzy2010/article/details/6120391

[tiger波波]

ClosePort 中SetEvent(m_hShutdownEvent);为什么不能直接触发ThreadPro_C1中的MsgWaitForMultipleObjects。 -------------------- 你的程序是不是占用CPU很高？你的for循环里边没有Sleep，貌似别的线程插不进去手。你试下加个Sleep试试。 for(...) { ..... ..... Sleep(10); }

[这不是鸭头]

串口类都烂大街了还用自己写？

[sevancheng]

WaitForMultipleObjects