C语言编程：如何同时打开多个串口进行通信？
可以两个方式：
1、如果是 MSComm控件方式可以加入三个控件分别控制；在OnComm事件里面接收数据；用m_Comm.SetOutput(COleVariant(m_SendData));发送数据；
2、把 MSComm控件 打包在一个类里面，自己写初始化和发送接收函数；
如何利用C语言，C++语言打开USB串口，然後对其发送信号？ 跪求回答！ 可行比加分！！
openfile和createfile，就可以，可以打开串口号的，创建接收信息，发送。。。
c语言串口通讯过程?
分接收端和发送端。
接收端:
1·打开com1端口
fd=fopen(“/dev/ttys0”,方式);
2·取得当前串口值，保存到结构体变量oldtio
tcgetattr(fd,oldtio);
3·串口结构体变量newtio清0.
bzero(newtio,sizeof(newtio))
4·设置串口参数
主要设置比特率、是否忽略奇偶校验错误，启用正规模式等等。
接收端
1·打开com端口
2·取得当前串口值
3·串口结构体变量清0
4·设置串口参数。
如何用C语言控制计算机串口
基本方法是使用CreateFile来建立一个串口文件，然后用overlap的方式进行读写
#define SERAIL_PORT_BUF_MAX (1024*8)
typedef HRESULT (*PFN_CMD_PARSE_DATA)(HANDLE hParseApp, LPCSTR szRspCmd, int nCmdLen);
class CUsbSrvApp// : public CWinApp
{
public:
CUsbSrvApp();
~CUsbSrvApp();
BOOL OnSendData(const char *szBuf, int nLen);// 发送数据
int ComConnect(CString strPort); // 连接COM口
HANDLE OpenComPort(CString strPort, int nBaudRate, int nDataBits, int nStopBits, int nParity, int nFlowCtrlType); // 打开串口
void Close(); // 关闭串口
HANDLE m_hCom;
BOOL m_bConnected;
OVERLAPPED m_OverlappedRead;
OVERLAPPED m_OverlappedWrite;
CWinThread *m_pThread;
PFN_CMD_PARSE_DATA m_pRspCmdFunc; // 用来处理接受数据的CALLBACK
HANDLE m_hParseApp;
};
CUsbSrvApp::CUsbSrvApp()
{
// TODO: add construction code here,
// Place all significant initialization in InitInstance
m_bConnected = false;
m_hCom = NULL;
m_pRspCmdFunc = NULL;
}
CUsbSrvApp::~CUsbSrvApp()
{
}
//打开串口通信，并返回串口句柄
HANDLE CUsbSrvApp::OpenComPort(CString strPortName,
int nBaudRate,
int nDataBits,
int nStopBits,
int nParity,
int nFlowCtrlType)
{
DCB dcb;
COMMTIMEOUTS CommTimeOuts ;
COMMCONFIG ComConfig;
HANDLE hComPort;
CString strPort;
strPort.Format(“\\\\.\\%s”,strPortName); // COM口的文件名应该是 \\.\COMXX
//打开窗口其实就是创建一个文件
hComPort = CreateFile(strPort,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED,
NULL);
if (INVALID_HANDLE_VALUE == hComPort)
return INVALID_HANDLE_VALUE;
// 设置一些COM口通讯参数和OVERLAP
CommTimeOuts.ReadIntervalTimeout = -1;
CommTimeOuts.ReadTotalTimeoutConstant = 0;
CommTimeOuts.ReadTotalTimeoutMultiplier = 0;
CommTimeOuts.WriteTotalTimeoutConstant = 0;
CommTimeOuts.WriteTotalTimeoutMultiplier = 0x1388;
SetCommTimeouts( m_hCom, CommTimeOuts ) ;
SetDefaultCommConfig(strPortName, ComConfig, sizeof(COMMCONFIG));
GetCommState(m_hCom, dcb ) ;
dcb.BaudRate = nBaudRate;
dcb.ByteSize = nDataBits;
dcb.StopBits = nStopBits;
dcb.fParity = (NOPARITY != nParity);
dcb.Parity = nParity;
//set the receive char
dcb.EvtChar = 0x0D;
switch(nFlowCtrlType)
{
case 0: //no flow control
break;
case 1://HARD_FLOW_CTRL:
dcb.fOutxCtsFlow = TRUE;
dcb.fOutxDsrFlow = TRUE;
dcb.fDtrControl = DTR_CONTROL_DISABLE;
dcb.fDsrSensitivity = TRUE;
dcb.fRtsControl = RTS_CONTROL_TOGGLE;
break;
case 2://SOFT_FLOW_CTRL:
dcb.fOutX = TRUE;
dcb.fInX = TRUE;
break;
}
BuildCommDCB(_T(“baud=115200 parity=N data=8 stop=1”),dcb);
SetCommState(hComPort, dcb ) ;
SetCommMask(hComPort, 0);
SetCommMask(hComPort, EV_RXCHAR|EV_CTS|EV_DSR|EV_RLSD|EV_RING);
SetupComm( hComPort, SERAIL_PORT_BUF_MAX,SERAIL_PORT_BUF_MAX) ;
//clear read and write buffer
PurgeComm( hComPort, PURGE_TXABORT | PURGE_RXABORT | PURGE_TXCLEAR | PURGE_RXCLEAR );
return hComPort;
}
void CUsbSrvApp::Close()
{
if(m_bConnected)
{
m_bConnected = false;
CloseHandle(m_hCom);
m_hCom = NULL;
}
}
// 这个线程是监视串口数据，一旦有数据则读取并调用CALLBACK通知客户端
UINT ReceiveComData(LPVOID pParam)
{
CUsbSrvApp *pUsbSrv = (CUsbSrvApp *)pParam;
HANDLE hComPort = pUsbSrv-m_hCom;
DWORD dwEvtMask=0;
DWORD dwErrorFlags;
SetCommMask( hComPort, EV_RXCHAR);
OVERLAPPED osRead;
osRead.hEvent = CreateEvent(NULL,FALSE,FALSE,NULL);
DWORD dwTransfer = 0;
while(pUsbSrv-m_bConnected)
{
if( !WaitCommEvent( hComPort, dwEvtMask,osRead))
{
if( GetLastError()== ERROR_IO_PENDING)
{
WaitForSingleObject(osRead.hEvent, INFINITE);
if(dwEvtMaskEV_RXCHAR==EV_RXCHAR)
{
COMSTAT ComStat={0} ;
DWORD dwReadLen = 0;
DWORD dwBytesRead = 0;
DWORD dwTotalLen = 0;
ClearCommError(hComPort, dwErrorFlags, ComStat );
dwTotalLen = ComStat.cbInQue;
dwReadLen = (SERAIL_PORT_BUF_MAX dwTotalLen)?dwTotalLen:SERAIL_PORT_BUF_MAX;
BYTE *pBuf = new BYTE[dwTotalLen+1];
memset(pBuf, 0 , dwTotalLen+1);
DWORD nReadBufLen=0;
while(dwTotalLen0)
{
if(FALSE == ReadFile( hComPort, pBuf+nReadBufLen,dwReadLen, dwBytesRead,pUsbSrv-m_OverlappedRead))
{
if(GetLastError() == ERROR_IO_PENDING)
{
GetOverlappedResult(hComPort,osRead, dwTransfer, TRUE );
}
break;
}
nReadBufLen +=dwBytesRead;
dwTotalLen -=dwBytesRead;
dwReadLen -= dwBytesRead;
dwReadLen = (SERAIL_PORT_BUF_MAXdwReadLen)?dwReadLen:SERAIL_PORT_BUF_MAX;
}
if(pUsbSrv-m_pRspCmdFunc!=NULLnReadBufLen!=0)
{
pUsbSrv-m_pRspCmdFunc(pUsbSrv-m_hParseApp, (char*)pBuf,nReadBufLen);
}
delete pBuf;
ClearCommError(hComPort, dwErrorFlags, ComStat );
int len =0;//= m_retList.GetSize();
}//endif if(dwEvtMaskEV_RXCHAR==EV_RXCHAR)
}//endif if( GetLastError()== ERROR_IO_PENDING)
}//endif if( !WaitCommEvent( hComPort, dwEvtMask,o))
else
{
if(GetLastError() == ERROR_IO_PENDING) {
GetOverlappedResult(hComPort, osRead, dwTransfer, TRUE ); // sleep thread
}
}
Sleep(1);
} //endwhile while(m_bConnected)
return 0;
}
int CUsbSrvApp::ComConnect(CString strPort)
{
int nBaudRate = 115200;
int nDataBits = 8;
int nStopBits = 1;
int nParity = 0;
int nFlowCtrl = 1;
if (NULL != m_hCom || m_bConnected)
{
return 0;
}
m_hCom = OpenComPort(strPort,nBaudRate,nDataBits,nStopBits,nParity,nFlowCtrl);
if( INVALID_HANDLE_VALUE == m_hCom)
{
m_hCom = NULL;
return 0;
}
memset( m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
memset( m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );
m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
m_pThread = AfxBeginThread( ReceiveComData,(void*)this,THREAD_PRIORITY_NORMAL,0,CREATE_SUSPENDED ,NULL );
if( NULL == m_pThread )
{
CloseHandle( m_hCom );
m_hCom = NULL;
return FALSE;
}
else
{
m_bConnected = TRUE;
m_pThread-ResumeThread( );
}
return TRUE;
}
int CUsbSrvApp::OnSendData(const char *szBuf, int nLen)
{
BOOL bWriteStat;
BOOL bWrite = TRUE;
DWORD dwBytesWrite = 0;
DWORD dwBytesWritten = 0;
int dwByteswrittenTotal = 0;
if (NULL == m_hCom)
return 0;
int nSentTimes=0;
while(dwByteswrittenTotalnLennSentTimes10)
{
nSentTimes++;
dwBytesWrite = nLen-dwByteswrittenTotal;
bWriteStat = WriteFile( m_hCom, szBuf+dwByteswrittenTotal, dwBytesWrite, dwBytesWritten, m_OverlappedWrite );
if( !bWriteStat)
{
if ( GetLastError() == ERROR_IO_PENDING )
{
dwBytesWritten = 0;
bWrite = FALSE;
}
}
if (!bWrite)
{
bWrite = TRUE;
bWriteStat = GetOverlappedResult(m_hCom, // Handle to COMM port
m_OverlappedWrite, // Overlapped structure
dwBytesWritten, // Stores number of bytes sent
TRUE); // Wait flag
//deal with the error code
}
dwByteswrittenTotal += dwBytesWritten;
}
if(dwByteswrittenTotalnLen)
return 0;
else
return 1;
}
C语言打开串口报错。
你申请的char字段comname 存文件名肯定有问题哦，我给你修改了一下，可以运行通过了。
FILE *usart;
int i = 10;
char comname[100];
printf(“请输入串口号：”);
scanf(“%s”, comname);
if ((usart = fopen(comname, “r”)) == NULL)
printf(“无法连接%s \n”, comname);
else
printf(“串口连接成功!\n”);
fclose(usart);
return 0;
C语言中如何对串口进行操作
C语言会有操作串口的库函数的，按照串口库函数标识实现调用就可以了。
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