读卡器的Win32 Dll调用

unsafe class Program
{
    [DllImport("mwhrf_bj.dll")]
    public static extern int rf_card(int icdev, Byte _Mode, UInt64* _Snr);

    [DllImport("mwhrf_bj.dll")]
    public static extern int Open_USB();

    [DllImport("mwhrf_bj.dll")]
    public static extern int Close_USB(int icdev);

    [DllImport("mwhrf_bj.dll")]
    public static extern int rf_beep(int icdev, UInt32 _Msec);

    static void Main(string[] args)
    {
        int devID = Open_USB();
        Console.WriteLine("打开端口成功");
        while (true)
        {
            UInt64 cardSN;
            int flag= rf_card(devID, (Byte)0x00, &cardSN);//寻一次卡 然后卡片必须拿开
            //int flag= rf_card(devID, (Byte)0x00, &cardSN);//在卡片不拿走的情况连续询卡
            if (flag != 1)
            {
                rf_beep(devID, 10);
                Console.WriteLine("寻卡成功，卡号是{0}", cardSN);
            }
            Thread.Sleep(1000);
        }
        Close_USB(devID);
        Console.WriteLine("关闭端口成功");
    }
}