请问一下WinCE串口通讯的有关问题,大侠们一看估计就知道原因,但困扰小弟我了

//串口打开函数
BOOL OpenPort(HWND hWnd)
{
    DWORD dwError;

    //打开串口
    hSerPort=CreateFile(TEXT("COM1:"),
                        GENERIC_READ | GENERIC_WRITE,
                        0,
                        NULL,
                        OPEN_EXISTING,
                        0,
                        NULL);

    if(hSerPort == INVALID_HANDLE_VALUE)
    {
        dwError = GetLastError();
        MessageBox(hWnd, _T("Open Port (COM1:) Error!"), _T("ERROR"), 0);
        return FALSE;
    }
    
    //设置串口输入输出缓冲区大小
    //SetupComm(hSerPort, _InQue, _OutQue);

    //设置串口事件掩码
    //SetCommMask(hSerPort, 0);

    //设置串口属性
    if(ConfigComm())
    {
        fContinue = TRUE;
        return TRUE;
    }
    else
    {
        MessageBox(hWnd, TEXT("Config COM1: error!"), TEXT("ERROR"), 0);
        CloseHandle(hSerPort);
        return FALSE;
    }
}

//串口设置函数
BOOL ConfigComm()
{
    DCB dcb;
    COMMTIMEOUTS tmOuts;

    //获取串口原始属性
    GetCommState(hSerPort, &dcb);

    dcb.BaudRate = 19200;        // 设置波特率
    dcb.ByteSize = 8;            // 数据位,范围:4-8 
    dcb.Parity   = NOPARITY;    // 校验模式:无校验
    dcb.StopBits = ONESTOPBIT;    // 停止位: 1位
    dcb.fParity  = FALSE;        // 不支持奇偶校验
    //dcb.fBinary  = TRUE;        // 设置二进制模式，此处必须设置TRUE
    dcb.fNull    = FALSE;        // Disable null stripping 

    /*以下这些设置了之后有用么???
    dcb.fOutxCtsFlow  = FALSE;    // No CTS output flow control 
    dcb.fOutxDsrFlow  = FALSE;    // No DSR output flow control 
    dcb.fDtrControl   = DTR_CONTROL_DISABLE;    //启用流量控制

    // DTR flow control type
    dcb.fDsrSensitivity   = FALSE;    // DSR sensitivity 
    dcb.fTXContinueOnXoff = TRUE;    // XOFF continues Tx 
    dcb.fOutX             = FALSE;    // No XON/XOFF out flow control 
    dcb.fInX              = FALSE;    // No XON/XOFF in flow control 
    dcb.fErrorChar        = FALSE;    // Disable error replacement 

    dcb.fRtsControl       = RTS_CONTROL_ENABLE;    // RTS flow control
    dcb.fAbortOnError     = FALSE;    // 当串口发生错误，并不终止串口读写
    */

    if(!SetCommState(hSerPort, &dcb))
    {
        return FALSE;
    }

    //设置串口超时时间,[color=#FF0000]这样设置有问题吗?超时的设置是不是跟波特率有关才行?[/color]
    GetCommTimeouts(hSerPort, &tmOuts);
    tmOuts.ReadIntervalTimeout = 0;
    tmOuts.ReadTotalTimeoutConstant = 0;
    tmOuts.ReadTotalTimeoutMultiplier = 0;
    tmOuts.WriteTotalTimeoutConstant = 0;
    tmOuts.WriteTotalTimeoutMultiplier = 0;

    if(!SetCommTimeouts(hSerPort, &tmOuts))
    {
        return FALSE;
    }

    //指定端口监测的事件集
    //SetCommMask (hSerPort, EV_RXCHAR);
    
    //分配设备缓冲区
    //SetupComm(hSerPort, 10, 10);

    //初始化缓冲区中的信息
    PurgeComm(hSerPort, PURGE_TXCLEAR | PURGE_RXCLEAR);
    return TRUE;
}

DWORD SendThread (PVOID pArg)
{
    TCHAR szText[TEXTSIZE];
    TCHAR szDlg[128];
    DWORD dwLen;
    BOOL stat, start;
    HWND hWnd = (HWND)pArg;

    start = TRUE;
    while(1)
    {
        Sleep(5000);
        if(fContinue)
        {
            if(!fContinue)//这句话是浪费的,大家不用管
                break;

            if(start)
            {
                lstrcat(szText, TEXT("ATE0\r"));
                start = FALSE;
                wsprintf(szDlg, TEXT("Sended ATE0. \r\n"));
                UpdateHistory((LPARAM)szDlg);
            }
            else
            {
                lstrcat(szText, TEXT("AT\r"));
                //显示发送的数据
                wsprintf(szDlg, TEXT("Sended AT.\r\n"));
                UpdateHistory((LPARAM)szDlg);
            }

            PurgeComm(hSerPort, PURGE_TXCLEAR | PURGE_RXCLEAR);    //发送之前先清空输入输出缓冲区
            stat = WriteFile (hSerPort, szText, lstrlen (szText)*sizeof (TCHAR), &dwLen, 0);

            if(!stat)
            {
                wsprintf(szDlg, TEXT("Send ERROR!!\r\n"));
                UpdateHistory((LPARAM)szDlg);
                return 0;
            }
        }
        else
            break;
    }
    return 0;
}

DWORD ReadThread (PVOID pArg)
{
    //BYTE szText[TEXTSIZE];
    //COMSTAT comstat;

    //SetCommMask (hSerPort, EV_RXCHAR); 
    while (fContinue)
    {
        /*
        if(ReadFile(hSerPort, szText, 10, &dwLength, NULL))
        {
            if(dwLength != 0)
            {
                TCHAR dlg[128];
                wsprintf(dlg, TEXT("received %d bytes.\r\n"), dwLength);
                UpdateHistory((LPARAM)dlg);
                UpdateHistory((LPARAM)szText);
            }
        }*/

        /*************************************************
        DWORD dwError, dwLength;
        COMSTAT comstat;

        ClearCommError(hSerPort, &dwError, &comstat);
        if(comstat.cbInQue > 0)
        {
            ReadFile(hSerPort, &szText, comstat.cbInQue, &dwLength, 0);
            
            //保存数据
            TCHAR *tmp = new TCHAR[iCount + 1];
            if(tmp == NULL)
                return -1;

            TCHAR dlg[128];
            wsprintf(dlg, TEXT("received %d bytes.\r\n"), comstat.cbInQue);
            UpdateHistory((LPARAM)dlg);
            memcpy(tmp, szText, iCount);
            lstrcat(tmp, TEXT("\r\n"));
            UpdateHistory((LPARAM)tmp);
            PurgeComm(hSerPort, PURGE_RXCLEAR);
        }
        
        Sleep(1);*/
        //**************************************************/
        //DWORD dwCommStatus;
        //WaitCommEvent(hSerPort, &dwCommStatus, 0);
        //SetCommMask (hSerPort, EV_RXCHAR);
        //PurgeComm(hSerPort, PURGE_RXCLEAR);
        //memset(szText, 0, sizeof(szText));
        TCHAR szText[TEXTSIZE];
        BYTE rByte;    //接收到的一个字节
        DWORD dwLength;    //实际接收的字节数
        INT iCount=0;
        TCHAR tch;

        do
        {
            ReadFile(hSerPort, &rByte, 1, &dwLength, 0);
            if(dwLength == 1)
            {
                szText[iCount] = rByte;
                iCount ++;

                tch = (tch << 8) & 0xff00;
                if (tch == TEXT ('\n'))
                    break;
                //if(iCount >= TEXTSIZE)
                //{
                //    return -1;//缓冲区满
                //}
            }
        }while(dwLength == 1);

        //ClearCommError(hSerPort,&dwReadErrors,&cmState);//清除错误标志并得到串口状态

        //PurgeComm(hSerPort, PURGE_RXCLEAR);

        if(iCount == 0)
        {
            //Sleep(100);
            continue;    //没接收到数据,继续下次循环
        }

        //保存数据
        TCHAR dlg[128];
        wsprintf(dlg, TEXT("received %d bytes.\r\n"), iCount);
        UpdateHistory((LPARAM)dlg);

        TCHAR *tmp = new TCHAR[iCount + 1];
        if(tmp == NULL)
            return -1;

        memcpy(tmp, szText, iCount);
        lstrcat(tmp, TEXT("\r\n"));
        UpdateHistory((LPARAM)tmp);

        //iCount = 0;
        //Sleep(100);
    }
    return 0;
}