串口异步同步通讯 - c语言编程

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OVERLAPPED m_osWrite;
memset(&m_osWrite,0,sizeof(OVERLAPPED));
m_osWrite.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);

char lpOutBuffer[7];
memset(lpOutBuffer,''\0'',7);
lpOutBuffer[0]=''\x11'';
lpOutBuffer[1]=''0'';
lpOutBuffer[2]=''0'';
lpOutBuffer[3]=''1'';
lpOutBuffer[4]=''0'';
lpOutBuffer[5]=''1'';
lpOutBuffer[6]=''\x03'';

DWORD dwBytesWrite=7;
COMSTAT ComStat;
DWORD dwErrorFlags;
BOOL bWriteStat;
ClearCommError(hCom,&dwErrorFlags,&ComStat);
bWriteStat=WriteFile(hCom,lpOutBuffer,
dwBytesWrite,& dwBytesWrite,&m_osWrite);

if(!bWriteStat)
{
if(GetLastError()==ERROR_IO_PENDING)
{
WaitForSingleObject(m_osWrite.hEvent,1000);
}
}

}

void CRS485CommDlg::OnReceive()
{
// TODO: Add your control notification handler code here
OVERLAPPED m_osRead;
memset(&m_osRead,0,sizeof(OVERLAPPED));
m_osRead.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);

COMSTAT ComStat;
DWORD dwErrorFlags;

char str[100];
memset(str,''\0'',100);
DWORD dwBytesRead=100;//读取的字节数
BOOL bReadStat;

ClearCommError(hCom,&dwErrorFlags,&ComStat);
dwBytesRead=min(dwBytesRead, (DWORD)ComStat.cbInQue);
bReadStat=ReadFile(hCom,str,
dwBytesRead,&dwBytesRead,&m_osRead);
if(!bReadStat)
{
if(GetLastError()==ERROR_IO_PENDING) //GetLastError()函数返回ERROR_IO_PENDING,表明串口正在进行读操作
{
WaitForSingleObject(m_osRead.hEvent,2000);
//使用WaitForSingleObject函数等待，直到读操作完成或延时已达到2秒钟
//当串口读操作进行完毕后，m_osRead的hEvent事件会变为有信号
}
}

PurgeComm(hCom, PURGE_TXABORT|
PURGE_RXABORT|PURGE_TXCLEAR|PURGE_RXCLEAR);
m_disp=str;
UpdateData(FALSE);
}

//打开ClassWizard,为静态文本框IDC_DISP添加CString类型变量m_disp，同时添加WM_CLOSE的相应函数：

void CRS485CommDlg::OnClose()
{
// TODO: Add your message handler code here and/or call default
CloseHandle(hCom); //程序退出时关闭串口
CDialog::OnClose();
}

//您可以仔细对照这两个例程，细心体会串口同步操作和异步操作的区别。

作者“情っ㈠颗欲枯草丶 ”

串口异步同步通讯(三)