用WriteFile（）写串口不成功的问题。。。

CreateFile时正确得到了hCom句柄，但在WriteFile时却是句柄无效，写不进去，问题I出在那里啊？源程序如下,帮忙看一下，谢谢 HANDLE hCom;
DWORD dwError;
DCB dcb;
COMMTIMEOUTS TimeOuts;
hCom=CreateFile("COM3",           //文件名
GENERIC_READ | GENERIC_WRITE, // 允许读和写
0,                            // 独占方式
NULL,
OPEN_EXISTING,                 //打开而不是创建
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, // 重叠方式
NULL
);

if(hCom == INVALID_HANDLE_VALUE)
{
dwError=GetLastError( );// 处理错误
}
SetupComm( hCom, 1024, 1024);//缓冲区的大小为1024

TimeOuts. ReadIntervalTimeout=1000;
TimeOuts.ReadTotalTimeoutMultiplier=500;
TimeOuts.ReadTotalTimeoutConstant=5000;
TimeOuts.WriteTotalTimeoutMultiplier=500;
TimeOuts.WriteTotalTimeoutConstant=5000;

SetCommTimeouts(hCom, &TimeOuts); // 设置超时

GetCommState(hCom, &dcb);
dcb.BaudRate=2400; // 波特率为2400
dcb.ByteSize=8; // 每个字符有8位
dcb.Parity=NOPARITY; //无校验
dcb.StopBits=ONESTOPBIT; //一个停止位
SetCommState(hCom, &dcb);

char buf[20]="ATDT823\r";
int i=strlen(buf);
DWORD dwBytesWritten;
OVERLAPPED write_os; BOOL bRtn=WriteFile(hCom,buf,i,&dwBytesWritten,&write_os);
if(!bRtn)
{
dwError=GetLastError();
}

解决方案 »

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你定义的DCB结构可以直接用，不要加&
DCB dcb;
        COMMTIMEOUTS CommTimeOuts;
        BOOL fSuccess;
        hCom = CreateFile(FormMain->ComboBox1->Text.c_str(),
                GENERIC_READ | GENERIC_WRITE,
                0,    //必须
                NULL, //无安全属性
                OPEN_EXISTING, //必须用OPEN_EXISTING
                FILE_FLAG_OVERLAPPED,  //重叠I/O操作
                NULL  //对通信设备必须是NULL
                );
        if (hCom == INVALID_HANDLE_VALUE) {
                MessageBox(NULL,"打开通信设备文件失败！","错        误",MB_OK);
        return false;
        }        if(!SetupComm(hCom,BLOCK_LENGTH,BLOCK_LENGTH))
        {
                MessageBox(NULL,"设置串行口内部输入、输出缓冲区长度操作异常！","错误",MB_OK);
        return false;
        }        fSuccess = GetCommState(hCom, &dcb);
        if (!fSuccess) {
                MessageBox(NULL,"获取通信设备控制块数据结构操作异常！","错误",MB_OK);
        return false;
        }
        //填充要改变的串行口控制（配置）块数据结构的有关成员
        dcb.DCBlength=sizeof(DCB);
        //dcb.BaudRate=9600;
        dcb.Parity=1;
        dcb.ByteSize=8;
        dcb.StopBits=2;
        BuildCommDCB("9600,N,8,1",&dcb);

        dcb.fInX =  true;
        dcb.fOutX =  true;
        dcb.XonLim =  1;
        dcb.XoffLim =  1;        //回写DCB数据块
        fSuccess = SetCommState(hCom, &dcb);
        if (!fSuccess) {
                MessageBox(NULL,"设置通信设备控制块数据结构操作异常！","错误",MB_OK);
        return false;
        }
        //清除接收缓冲区
        PurgeComm(hCom,PURGE_RXCLEAR);
        GetCommTimeouts(hCom, &CommTimeOuts);
            CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
        CommTimeOuts.WriteTotalTimeoutConstant = 5000;         SetCommTimeouts(hCom, &CommTimeOuts);
            memset(&osRead, 0, sizeof(OVERLAPPED));
                memset(&osWrite, 0, sizeof(OVERLAPPED));
                osRead.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
            osWrite.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);        BufferOffset=0;
        return true;还要对重叠操作的数据结构初始化，建立信号态。
如果你用的是2000的话，设一下write_os.offset和write_os.offsethigh都为零
osWrite.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);还有将osWrite.offset和osWrite.offsehigh设为零。
估计是你的OVERLAPPED的成员变量hEvent没有初始化吧
write_os.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
然后看看行不行
// 打开串行口并建立辅助工作线程
BOOL CNcfileCtrlDlg::OpenConnection()
{
COMMTIMEOUTS TimeOuts;
m_hTermWnd = GetSafeHwnd();
if(m_bConnected)
return FALSE;
m_hCom = CreateFile(m_sPort, GENERIC_READ | GENERIC_WRITE, 0, NULL,
                      OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
                      NULL); // 重叠方式
if(m_hCom == INVALID_HANDLE_VALUE)
return FALSE;
SetupComm(m_hCom,MAXBLOCK,MAXBLOCK);
// SetCommMask(m_hCom, EV_RXCHAR);/////////////////////////////////////////////////////////////////////
//测试代码
// DWORD lpEvtMask;
// GetCommMask(m_hCom,&lpEvtMask);
// if(lpEvtMask & EV_RXCHAR == EV_RXCHAR)
// AfxMessageBox("EV_RXCHAR!");
// SetCommMask(m_hCom,0);
// GetCommMask(m_hCom,&lpEvtMask);
// if(lpEvtMask & EV_RXCHAR == EV_RXCHAR)
// AfxMessageBox("EV_RXCHAR!");
// else
// AfxMessageBox("NO EV_RXCHAR!");
//////////////////////////////////////////////////////////////////// // 把间隔超时设为最大，把总超时设为0将导致ReadFile立即返回并完成操作
TimeOuts.ReadIntervalTimeout = MAXDWORD;
    TimeOuts.ReadTotalTimeoutMultiplier = 0;
TimeOuts.ReadTotalTimeoutConstant = 0;
/* 设置写超时以指定WriteComm成员函数中的
    GetOverlappedResult函数的等待时间*/
TimeOuts.WriteTotalTimeoutMultiplier = 50;
TimeOuts.WriteTotalTimeoutConstant = 2000;
SetCommTimeouts(m_hCom, &TimeOuts);
if(ConfigConnection())
{
m_pThread = AfxBeginThread(CommProc, this, THREAD_PRIORITY_NORMAL,
0, CREATE_SUSPENDED, NULL); // 创建并挂起接收线程
if(m_pThread == NULL)
{
MessageBox("创建接收数据线程失败!","警告", MB_ICONWARNING | MB_OK);
CloseHandle(m_hCom);
return FALSE;
} ReceiveThread = TRUE;
m_bConnected = TRUE;
}
else
{
CloseHandle(m_hCom);
return FALSE;
}
return TRUE;
}// 结束工作者线程，关闭串行口
void CNcfileCtrlDlg::CloseConnection()
{
// 结束事件监视线程
if(!m_bConnected) return;
m_bConnected = FALSE; // 结束CommProc线程中WaitSingleObject函数的等待
SetEvent(m_hPostMsgEvent); // 结束CommProc线程中WaitCommEvent的等待
SetCommMask(m_hCom, 0); if(ReceiveThread)//判断接收线程是否退出
{
if(!TerminateThread(m_pThread->m_hThread,0))
MessageBox("终止接收数据线程失败!","警告", MB_ICONWARNING | MB_OK);
}
if(BeginThread)      //判断发送线程是否退出
{
if(!TerminateThread(m_pThreadT->m_hThread,0))
MessageBox("终止发送数据线程失败!","警告", MB_ICONWARNING | MB_OK);
} if(EventThread)      //判断事件监视线程是否退出
{
if(!TerminateThread(m_pThreadEvent->m_hThread,0))
MessageBox("终止事件监视线程失败!","警告", MB_ICONWARNING | MB_OK);
} CloseHandle(m_hCom);
}
// 从串行口输入缓冲区(m_hCom通信设备)中读入指定数量的字符
DWORD CNcfileCtrlDlg::ReadComm(char *buf, DWORD dwLength)
{
DWORD length = 0;
COMSTAT ComStat; // 串口设备状态结构
DWORD dwErrorFlags;
ClearCommError(m_hCom,&dwErrorFlags,&ComStat); // 读取串口设备的当前状态
length = min(dwLength, ComStat.cbInQue); // 应该读取的数据长度
ReadFile(m_hCom,buf,length,&length,&m_osRead); // 读取数据
return length;
}// 将指定数量的字符从串行口输出,在调用该函数时，实际dwLength都为1
DWORD CNcfileCtrlDlg::WriteComm(char* buf, DWORD dwLength)
{
BOOL fState;
DWORD length = dwLength;  //成功写入缓冲区的字符数
COMSTAT ComStat;
DWORD dwErrorFlags;
ClearCommError(m_hCom,&dwErrorFlags,&ComStat);
fState = WriteFile(m_hCom,buf,dwLength,&length,&m_osWrite);
if(!fState){
if(GetLastError() == ERROR_IO_PENDING)   //写操作被挂起
{
if(!GetOverlappedResult(m_hCom,&m_osWrite,&length,TRUE)) //写操作没有成功完成
{
MessageBox("发送代码出现错误!","错误", MB_ICONERROR | MB_OK);
}
}
else
length = 0;
} return length;
}
// 配置串行口
BOOL CNcfileCtrlDlg::ConfigConnection()
{
DCB dcb;
if(!GetCommState(m_hCom, &dcb)) // 获取缺省的dcb结构的值
return FALSE; dcb.fOutX = 0;
dcb.fInX = 0;
dcb.fOutxCtsFlow = 0;
dcb.fOutxDsrFlow = 0;
dcb.fBinary = TRUE;
dcb.BaudRate = m_nBaud; // 波特率
dcb.ByteSize = m_nDataBits; // 每字节位数
dcb.fParity = TRUE;
switch(m_nParity) // 校验设置
{
case 0: dcb.Parity = NOPARITY;
break;
case 1: dcb.Parity = ODDPARITY;
break;
case 2: dcb.Parity = EVENPARITY;
break;
case 3: dcb.Parity = MARKPARITY;
break;
        case 4: dcb.Parity = SPACEPARITY;
break;
default:;
}
switch(m_nStopBits) // 停止位
{
case 0: dcb.StopBits = ONESTOPBIT;
break;
// case 1: dcb.StopBits = ONE5STOPBITS;
// break;
case 1: dcb.StopBits = TWOSTOPBITS;
break;
default:;
}
// 硬件流控制设置

    if (m_bRts)
dcb.fRtsControl = RTS_CONTROL_HANDSHAKE ;
else
dcb.fRtsControl = RTS_CONTROL_ENABLE ;
// XON/XOFF流控制设置，软件流控制
if (m_bXon)
{
dcb.fInX = dcb.fOutX = 1;
dcb.XonChar = XON;
dcb.XoffChar = XOFF;
dcb.XonLim = 50;
dcb.XoffLim = 50;
}
    //硬件流控制设置
if (m_bDsr)
dcb.fDtrControl = DTR_CONTROL_HANDSHAKE ;
else
dcb.fDtrControl = DTR_CONTROL_ENABLE ; //输出流信号监控
if(m_bOutxCtsFlow)
dcb.fOutxCtsFlow = 1;
if(m_bOutxDsrFlow)
dcb.fOutxDsrFlow = 1; return SetCommState(m_hCom, &dcb);
}void CNcfileCtrlDlg::OnQuery()
{
BeginWaitCursor();
UpdateData();
pPartSet = new CPartSet;
pNcprogramSet = new CNcprogramSet; if(m_PartDrawCode == "")
{
MessageBox("零件图号不能为空，请输入!!!","提示", MB_ICONINFORMATION | MB_OK);
return;
}
else
{
/* CString tempSqlStr;
tempSqlStr="select PROCESS_ROUTE.* from PROCESS_ROUTE,NC_PROGRAM_LIB where NC_PROGRAM_LIB.NC_PROGRAM_NAME=PROCESS_ROUTE.NC_PROGRAM_NAME and PROCESS_ROUTE.DRAWING_NUMBER='";//
tempSqlStr+=m_PartDrawCode;
tempSqlStr+="'";
if(!pProcessSet->IsOpen() && !pPartSet->IsOpen())
{
pProcessSet->Open(AFX_DB_USE_DEFAULT_TYPE,tempSqlStr,CRecordset::none);
pPartSet->Open(AFX_DB_USE_DEFAULT_TYPE,tempSqlStr,CRecordset::none);
}*/
if(!pPartSet->IsOpen())
pPartSet->Open();
pPartSet->MoveFirst();
while(!pPartSet->IsEOF())
{
if(pPartSet->m_PART_DRAW_CODE == m_PartDrawCode)
{
m_partname = pPartSet->m_PART_NAME;
UpdateData(false);
}
pPartSet->MoveNext();
}
if(m_partname == "")
{
MessageBox("输入的零件图号不存在或错误，请核实!","警告",MB_ICONWARNING | MB_OK);
}
pPartSet->Close();
if(!pNcprogramSet->IsOpen ())
pNcprogramSet->Open ();
m_cOperationCode.ResetContent();
        pNcprogramSet->MoveFirst ();
while(!pNcprogramSet->IsEOF())
{
            if(pNcprogramSet->m_PART_DRAW_CODE == m_PartDrawCode)
{
m_cOperationCode.AddString(pNcprogramSet->m_OPERATION_NO);
m_cOperationCode.GetLBText(0,m_sOperationCode);
UpdateData(false);
}
pNcprogramSet->MoveNext();
}
pNcprogramSet->Close();
}
m_sNcFile = "";
m_sProgramCode = "";
m_sState = "";
m_sVersion = "";
m_sStart = "";
m_sEnd = "";
UpdateData(false);
EndWaitCursor();
}
// 打开串行口并建立辅助工作线程
BOOL CNcfileCtrlDlg::OpenConnection()
{
COMMTIMEOUTS TimeOuts;
m_hTermWnd = GetSafeHwnd();
if(m_bConnected)
return FALSE;
m_hCom = CreateFile(m_sPort, GENERIC_READ | GENERIC_WRITE, 0, NULL,
                      OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
                      NULL); // 重叠方式
if(m_hCom == INVALID_HANDLE_VALUE)
return FALSE;
SetupComm(m_hCom,MAXBLOCK,MAXBLOCK);
// SetCommMask(m_hCom, EV_RXCHAR);/////////////////////////////////////////////////////////////////////
//测试代码
// DWORD lpEvtMask;
// GetCommMask(m_hCom,&lpEvtMask);
// if(lpEvtMask & EV_RXCHAR == EV_RXCHAR)
// AfxMessageBox("EV_RXCHAR!");
// SetCommMask(m_hCom,0);
// GetCommMask(m_hCom,&lpEvtMask);
// if(lpEvtMask & EV_RXCHAR == EV_RXCHAR)
// AfxMessageBox("EV_RXCHAR!");
// else
// AfxMessageBox("NO EV_RXCHAR!");
//////////////////////////////////////////////////////////////////// // 把间隔超时设为最大，把总超时设为0将导致ReadFile立即返回并完成操作
TimeOuts.ReadIntervalTimeout = MAXDWORD;
    TimeOuts.ReadTotalTimeoutMultiplier = 0;
TimeOuts.ReadTotalTimeoutConstant = 0;
/* 设置写超时以指定WriteComm成员函数中的
    GetOverlappedResult函数的等待时间*/
TimeOuts.WriteTotalTimeoutMultiplier = 50;
TimeOuts.WriteTotalTimeoutConstant = 2000;
SetCommTimeouts(m_hCom, &TimeOuts);
if(ConfigConnection())
{
m_pThread = AfxBeginThread(CommProc, this, THREAD_PRIORITY_NORMAL,
0, CREATE_SUSPENDED, NULL); // 创建并挂起接收线程
if(m_pThread == NULL)
{
MessageBox("创建接收数据线程失败!","警告", MB_ICONWARNING | MB_OK);
CloseHandle(m_hCom);
return FALSE;
} ReceiveThread = TRUE;
m_bConnected = TRUE;
}
else
{
CloseHandle(m_hCom);
return FALSE;
}
return TRUE;
}// 结束工作者线程，关闭串行口
void CNcfileCtrlDlg::CloseConnection()
{
// 结束事件监视线程
if(!m_bConnected) return;
m_bConnected = FALSE; // 结束CommProc线程中WaitSingleObject函数的等待
SetEvent(m_hPostMsgEvent); // 结束CommProc线程中WaitCommEvent的等待
SetCommMask(m_hCom, 0); if(ReceiveThread)//判断接收线程是否退出
{
if(!TerminateThread(m_pThread->m_hThread,0))
MessageBox("终止接收数据线程失败!","警告", MB_ICONWARNING | MB_OK);
}
if(BeginThread)      //判断发送线程是否退出
{
if(!TerminateThread(m_pThreadT->m_hThread,0))
MessageBox("终止发送数据线程失败!","警告", MB_ICONWARNING | MB_OK);
} if(EventThread)      //判断事件监视线程是否退出
{
if(!TerminateThread(m_pThreadEvent->m_hThread,0))
MessageBox("终止事件监视线程失败!","警告", MB_ICONWARNING | MB_OK);
} CloseHandle(m_hCom);
}
// 从串行口输入缓冲区(m_hCom通信设备)中读入指定数量的字符
DWORD CNcfileCtrlDlg::ReadComm(char *buf, DWORD dwLength)
{
DWORD length = 0;
COMSTAT ComStat; // 串口设备状态结构
DWORD dwErrorFlags;
ClearCommError(m_hCom,&dwErrorFlags,&ComStat); // 读取串口设备的当前状态
length = min(dwLength, ComStat.cbInQue); // 应该读取的数据长度
ReadFile(m_hCom,buf,length,&length,&m_osRead); // 读取数据
return length;
}// 将指定数量的字符从串行口输出,在调用该函数时，实际dwLength都为1
DWORD CNcfileCtrlDlg::WriteComm(char* buf, DWORD dwLength)
{
BOOL fState;
DWORD length = dwLength;  //成功写入缓冲区的字符数
COMSTAT ComStat;
DWORD dwErrorFlags;
ClearCommError(m_hCom,&dwErrorFlags,&ComStat);
fState = WriteFile(m_hCom,buf,dwLength,&length,&m_osWrite);
if(!fState){
if(GetLastError() == ERROR_IO_PENDING)   //写操作被挂起
{
if(!GetOverlappedResult(m_hCom,&m_osWrite,&length,TRUE)) //写操作没有成功完成
{
MessageBox("发送代码出现错误!","错误", MB_ICONERROR | MB_OK);
}
}
else
length = 0;
} return length;
}
// 配置串行口
BOOL CNcfileCtrlDlg::ConfigConnection()
{
DCB dcb;
if(!GetCommState(m_hCom, &dcb)) // 获取缺省的dcb结构的值
return FALSE; dcb.fOutX = 0;
dcb.fInX = 0;
dcb.fOutxCtsFlow = 0;
dcb.fOutxDsrFlow = 0;
dcb.fBinary = TRUE;
dcb.BaudRate = m_nBaud; // 波特率
dcb.ByteSize = m_nDataBits; // 每字节位数
dcb.fParity = TRUE;
switch(m_nParity) // 校验设置
{
case 0: dcb.Parity = NOPARITY;
break;
case 1: dcb.Parity = ODDPARITY;
break;
case 2: dcb.Parity = EVENPARITY;
break;
case 3: dcb.Parity = MARKPARITY;
break;
        case 4: dcb.Parity = SPACEPARITY;
break;
default:;
}
switch(m_nStopBits) // 停止位
{
case 0: dcb.StopBits = ONESTOPBIT;
break;
// case 1: dcb.StopBits = ONE5STOPBITS;
// break;
case 1: dcb.StopBits = TWOSTOPBITS;
break;
default:;
}
// 硬件流控制设置

    if (m_bRts)
dcb.fRtsControl = RTS_CONTROL_HANDSHAKE ;
else
dcb.fRtsControl = RTS_CONTROL_ENABLE ;
// XON/XOFF流控制设置，软件流控制
if (m_bXon)
{
dcb.fInX = dcb.fOutX = 1;
dcb.XonChar = XON;
dcb.XoffChar = XOFF;
dcb.XonLim = 50;
dcb.XoffLim = 50;
}
    //硬件流控制设置
if (m_bDsr)
dcb.fDtrControl = DTR_CONTROL_HANDSHAKE ;
else
dcb.fDtrControl = DTR_CONTROL_ENABLE ; //输出流信号监控
if(m_bOutxCtsFlow)
dcb.fOutxCtsFlow = 1;
if(m_bOutxDsrFlow)
dcb.fOutxDsrFlow = 1; return SetCommState(m_hCom, &dcb);
}void CNcfileCtrlDlg::OnQuery()
{
BeginWaitCursor();
UpdateData();
pPartSet = new CPartSet;
pNcprogramSet = new CNcprogramSet; if(m_PartDrawCode == "")
{
MessageBox("零件图号不能为空，请输入!!!","提示", MB_ICONINFORMATION | MB_OK);
return;
}
else
{
/* CString tempSqlStr;
tempSqlStr="select PROCESS_ROUTE.* from PROCESS_ROUTE,NC_PROGRAM_LIB where NC_PROGRAM_LIB.NC_PROGRAM_NAME=PROCESS_ROUTE.NC_PROGRAM_NAME and PROCESS_ROUTE.DRAWING_NUMBER='";//
tempSqlStr+=m_PartDrawCode;
tempSqlStr+="'";
if(!pProcessSet->IsOpen() && !pPartSet->IsOpen())
{
pProcessSet->Open(AFX_DB_USE_DEFAULT_TYPE,tempSqlStr,CRecordset::none);
pPartSet->Open(AFX_DB_USE_DEFAULT_TYPE,tempSqlStr,CRecordset::none);
}*/
if(!pPartSet->IsOpen())
pPartSet->Open();
pPartSet->MoveFirst();
while(!pPartSet->IsEOF())
{
if(pPartSet->m_PART_DRAW_CODE == m_PartDrawCode)
{
m_partname = pPartSet->m_PART_NAME;
UpdateData(false);
}
pPartSet->MoveNext();
}
if(m_partname == "")
{
MessageBox("输入的零件图号不存在或错误，请核实!","警告",MB_ICONWARNING | MB_OK);
}
pPartSet->Close();
if(!pNcprogramSet->IsOpen ())
pNcprogramSet->Open ();
m_cOperationCode.ResetContent();
        pNcprogramSet->MoveFirst ();
while(!pNcprogramSet->IsEOF())
{
            if(pNcprogramSet->m_PART_DRAW_CODE == m_PartDrawCode)
{
m_cOperationCode.AddString(pNcprogramSet->m_OPERATION_NO);
m_cOperationCode.GetLBText(0,m_sOperationCode);
UpdateData(false);
}
pNcprogramSet->MoveNext();
}
pNcprogramSet->Close();
}
m_sNcFile = "";
m_sProgramCode = "";
m_sState = "";
m_sVersion = "";
m_sStart = "";
m_sEnd = "";
UpdateData(false);
EndWaitCursor();
}