C#向并口设备发送指令以获取并口设备的状态

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;

 
namespace ParallelPort
{
    public partial class Form1 : Form
    {
        const uint GENERIC_READ = 0x80000000;
        const uint GENERIC_WRITE = 0x40000000;
        const uint FILE_ATTRIBUTE_NORMAL = 0x80;
 
        #region win32 API
        [DllImport("kernel32.dll ")]
        private static extern int CreateFile(
            string lpFileName,
            uint dwDesiredAccess,
            int dwShareMode,
            int lpSecurityAttributes,
            int dwCreationDisposition,
            uint dwFlagsAndAttributes,
            int hTemplateFile
           );
 
        [DllImport("kernel32.dll ")]
        private static extern bool WriteFile(
            int hFile,
            byte[] lpBuffer,
            int nNumberOfBytesToWrite,
            ref int lpNumberOfBytesWritten,
            int lpOverlapped
           );
 
        [DllImport("kernel32.dll ")]
        private static extern bool DefineDosDevice(
        int dwFlags,
        string lpDeviceName,
        string lpTargetPath);
 
        [DllImport("kernel32.dll ")]
        private static extern bool CloseHandle(
            int hObject
           );
        [DllImport("kernel32.dll ")]
        private static extern bool ReadFile(
            int hFile,
            byte[] lpBuffer,
            int nNumberOfBytesToRead,
            ref int lpNumberOfBytesRead,
            int lpOverlapped
           );
       #endregion

 
        public Form1()
        {
           InitializeComponent();
        }
 

        private void button1_Click(object sender, EventArgs e)
        {
            int iHandle = -1;
            try
            {
               int i = 0;
               //创建实例
               DefineDosDevice(0x00000001, "LptPortName",@"DeviceParallel0");
               iHandle = CreateFile(@"\.LptPortName",GENERIC_READ | GENERIC_WRITE, 0, 0, 3, FILE_ATTRIBUTE_NORMAL, 0);
               if (iHandle !=-1)
               {
                   byte[] mybyte = new byte[3]{ 0x12, 0x14, 0x14 };//要发送的命令（16进制）
                   WriteFile(iHandle, mybyte, mybyte.Length, ref i, 0);
                   byte[] mybyte1 = new byte[3];
                   string content = String.Empty;
                   int j = 0;
                   ReadFile(iHandle, mybyte1, 3, ref j,  0);
                   if (mybyte1 != null)
                   {
                        foreach(var tempByte in mybyte1)
                        {
                            content += tempByte.ToString();
                        }
                   }                               
                   MessageBox.Show(content);//获取的状态值
               }
               else
               {
                   MessageBox.Show("创建文件失败!");
               }
            }
            catch(Exception ex)
            {
               MessageBox.Show(ex.Message);
            }
            finally
            {
               if (iHandle > 0)
               {
                   CloseHandle(iHandle);
               }
            }
        }
    }
}