在vc串口通讯程序中,当4个com口同时通信时表现串口很不稳定,请问各位应怎么处理?

在vc串口通讯程序中,当4个com口同时通信时表现串口很不稳定,请问各位应怎么处理?
谢谢各位

14 个解决方案

#1

那应该是你自己的线程设计不够好，或是共享资源没有互斥吧

#2

谢谢，能够说详细一点吗
我用的是CreateFile（）ReadFile（） WriteFile（）同步实现的

#3

现在就是串口不稳定，一会正常一会丢失，很急求大侠帮忙

#4

4个com口同时通信时,降低波特率试试。

#5

你用多线程做的吗？每个线程处理一个串口？

#6

降低波特率不行呀

#7

这个我读串口的程序
HANDLE CComRW::CreateCom()
{
DWORD dwError;
// TODO: Add extra validation here
/*
// m_hCom=INVALID_HANDLE_VALUE;
if (m_hCom!=INVALID_HANDLE_VALUE)
{
CloseHandle(m_hCom);
HANDLE m_hCom =INVALID_HANDLE_VALUE;
}
*/
// DWORD dwError=0;
dwError=0;
BOOL fSuccess=FALSE;

char com[100];
//sprintf(com,"\\\.\\COM%d",m_nComSel);
sprintf(com,"COM%d",m_nComSel);
HANDLE hCom = CreateFile(com,
GENERIC_READ | GENERIC_WRITE,
0,    // comm devices must be opened w/exclusive-access
NULL, // no security attributes
OPEN_EXISTING, // comm devices must use OPEN_EXISTING
0,    // not overlapped I/O
NULL  // hTemplate must be NULL for comm devices
);

if (hCom == INVALID_HANDLE_VALUE)
{
dwError = GetLastError();
LOGINFO(0,"%s 无法打开！错误码=%d",com,dwError);
return INVALID_HANDLE_VALUE;
    // handle error
}

// Omit the call to SetupComm to use the default queue sizes.
// Get the current configuration.
DCB dcb;
fSuccess = GetCommState(hCom, &dcb);

if (!fSuccess)
{
dwError = GetLastError();
LOGINFO(0,"%s GetCommState erorr code=%d",com,dwError);
CloseHandle(hCom);
return INVALID_HANDLE_VALUE;
    // Handle the error.
}

// Fill in the DCB: baud=9600, 8 data bits, no parity, 1 stop bit.

dcb.BaudRate = m_nBPS;
// dcb.BaudRate = CBR_57600;
dcb.ByteSize = 8;
// dcb.Parity = ODDPARITY;
dcb.Parity = checka[m_nParity];
// dcb.Parity = NOPARITY;
dcb.StopBits = stopa[m_nStopBit];
// dcb.StopBits = ONESTOPBIT;
fSuccess = SetCommState(hCom, &dcb);

if (!fSuccess)
{
dwError = GetLastError();
LOGINFO(0,"%s SetCommState code=%d",com,dwError);
CloseHandle(hCom);
return INVALID_HANDLE_VALUE;
    // Handle the error.
}

COMMTIMEOUTS CommTimeouts;

fSuccess = GetCommTimeouts(hCom,&CommTimeouts);
if (!fSuccess)
{
dwError = GetLastError();
LOGINFO(0,"%s GetCommTimeouts code=%d",com,dwError);
CloseHandle(hCom);
return INVALID_HANDLE_VALUE;
    // Handle the error.
}
CommTimeouts.ReadIntervalTimeout=MAXDWORD;
CommTimeouts.ReadTotalTimeoutConstant=0; //0.3 seconds
CommTimeouts.ReadTotalTimeoutMultiplier=0;
fSuccess = SetCommTimeouts(hCom,&CommTimeouts);
if (!fSuccess)
{
dwError = GetLastError();
LOGINFO(0,"%s SetCommTimeouts code=%d",com,dwError);
CloseHandle(hCom);
return INVALID_HANDLE_VALUE;
    // Handle the error.
}

LOGINFO(0,"%s open bps=%d handle=%x",com,dcb.BaudRate,hCom);
// m_hCom=hCom;
ResetRunData();

m_hCom=hCom;
return hCom;

}

void CComRW::CloseCom()
{
if (m_hCom!=INVALID_HANDLE_VALUE)
{
CloseHandle(m_hCom);
m_hCom=INVALID_HANDLE_VALUE;
}
ResetRunData();
}

void CComRW::FlushRead()
{
if (m_hCom==INVALID_HANDLE_VALUE)
{
return;
}

BYTE tmp[1024];
BOOL ret;
for(;;)
{
DWORD rn=0;
ret=ReadFile(m_hCom,tmp,sizeof(tmp),&rn,NULL);
if (!ret || !rn)
{
return;
}
}
}

void CComRW::ReadCom()
{
if (m_hCom==INVALID_HANDLE_VALUE)
{
return;
}

DWORD dw=0;
BOOL ret=ReadFile(m_hCom,m_abyComData+m_nTotalRead,sizeof(m_abyComData)-m_nTotalRead,&dw,NULL);
if (!ret)
{
LOGINFO(0,"com read error=%d",GetLastError());
return;
}

if (dw==0)
{
m_nIdleNbr++;
if (m_nIdleNbr>=m_nProcessAfterIdleNbr)
{
if (m_nTotalRead>0)
{
ProcessMsg();
}
m_nIdleNbr=0;
}
return;
}
else
{
LOGSIG(LL_UDP,m_abyComData+m_nTotalRead,dw,"READ COM %d bytes",dw);
m_nTotalRead+=dw;
m_nIdleNbr=0;
}

}

void CComRW::WriteCom(void* p,int len)
{
DWORD wn=0;
BOOL ret=WriteFile(m_hCom,p,len,&wn,NULL);
LOGSIG(LL_UDP,p,len,"WRIT COM %d bytes ret=%d wn=%d",len,ret,wn);
if (!ret)
{
LOGINFO(0,"write error=%d",GetLastError());
return;
}
if (wn!=len)
{
LOGINFO(0,"write error1=%d",GetLastError());
}
}

#8

BOOL ret=ReadFile(m_hCom,m_abyComData+m_nTotalRead,sizeof(m_abyComData)-m_nTotalRead,&dw,NULL);
阻塞式的读？
BOOL ret=WriteFile(m_hCom,p,len,&wn,NULL);
如何区分4个 com？

#9

先问楼主1个问题：
你读取串口数据的机制是怎样设计的？是主程序中设计好了固定的时间间隔，然后定时到串口的缓存中取数；还是主程序中的串口通信控件响应接收事件，当检测到有数据发过来之后再去取数？

#10

1.每个串口都有一个ID
2.采用固定时间间隔去轮询

#11

关注一下我们马上也要用到。

#12

你的timeout好像有点短，
我的一个案例：
COMMTIMEOUTS timeout;
timeout.ReadIntervalTimeout=2;
timeout.ReadTotalTimeoutMultiplier=2;
timeout.ReadTotalTimeoutConstant=50;
timeout.WriteTotalTimeoutMultiplier=1;
timeout.WriteTotalTimeoutConstant=50;
另外DCB的XonLim和XoffLim也检查一下

#13

还是使用事件触发吧！

#14

谢谢大家已经解决

#1