用vs2010 c++编写收银机开钱箱

1.环境 Windows7 vs2010
2.语言 c++
3.设备 钱箱与打印机的LPT1口相连
4.控制指令  27 112 7（十进制）
5.代码

CString sPort;
    //sPort.Format(_T("\\\\.\\LPT1"));//两种方法都行
    sPort.Format(_T("LPT1"));
#if 1
    //设置为重叠 异步IO
    HANDLE hPort = CreateFile(sPort,GENERIC_READ | GENERIC_WRITE,0,NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);//创建文件
    if (hPort == INVALID_HANDLE_VALUE || hPort == (HANDLE)ERROR_INVALID_HANDLE)
    {
        CString lsreturn = L"open fail";
        ExecutePrint(rect,LogFont,pDC,lsreturn.GetBuffer(0),lsreturn.GetLength(),DT_CENTER | DT_BOTTOM | DT_SINGLELINE);
        return false;
    }
    char lco[4];

    lco[0] = 27;
    lco[1] = 112;
    lco[2] = 7;
    lco[3] = '\0';

    DWORD writebyte = 0;
    DWORD writecount = 4;

    OVERLAPPED* pOverlapped = new OVERLAPPED;
    ZeroMemory(pOverlapped, sizeof(OVERLAPPED));
    pOverlapped->Offset = 0;
    pOverlapped->OffsetHigh = 0;
    pOverlapped->hEvent = 0;
    //pOverlapped->hEvent = (HANDLE) this;
    int lret = 0;
    lret = WriteFile(hPort,lco,writecount,&writebyte,pOverlapped);//向文件中直接写命令
    if (lret == 0)
    {
        int err = GetLastError();
        if (GetLastError() == ERROR_IO_PENDING)//重叠IO进行中
        {
            GetOverlappedResult(hPort,pOverlapped,&writebyte,true);
        }
        else//其他的错误
        {
            delete pOverlapped;
            CloseHandle(hPort);
            CString lsreturn = L"Failed to write";
            ExecutePrint(rect,LogFont,pDC,lsreturn.GetBuffer(0),lsreturn.GetLength(),DT_CENTER | DT_BOTTOM | DT_SINGLELINE);
            return false;
        }
    }
#endif

#if 0
    //同步IO 2种方法都可以
    HANDLE hPort = CreateFile(sPort,GENERIC_READ | GENERIC_WRITE,0,NULL, OPEN_EXISTING, 0, NULL);
    if (hPort == INVALID_HANDLE_VALUE || hPort == (HANDLE)ERROR_INVALID_HANDLE)
    {
        CString lsreturn = L"open fail";
        ExecutePrint(rect,LogFont,pDC,lsreturn.GetBuffer(0),lsreturn.GetLength(),DT_CENTER | DT_BOTTOM | DT_SINGLELINE);
        return false;
    }
    char lco[4];
    lco[0] = 27;
    lco[1] = 112;
    lco[2] = 7;
    lco[3] = '\0';

    DWORD writebyte = 0;
    DWORD writecount = 4;
    int lret = 0;
    lret = WriteFile(hPort,lco,writecount,&writebyte,NULL);
    if (lret == 0)
    {
        int err = GetLastError();
        CloseHandle(hPort);
        CString lsreturn = L"Failed to write";
        ExecutePrint(rect,LogFont,pDC,lsreturn.GetBuffer(0),lsreturn.GetLength(),DT_CENTER | DT_BOTTOM | DT_SINGLELINE);
        return false;
    }
#endif
    CloseHandle(hPort);

打开LPT1文件
向文件中写入命令
关闭文件

另外，在网上还查到一些别的指令，如 27 112 0 60 225（十进制的）。但是中间的那个0会被看成空字符，指令会被截断，不知道用什么方法解决。