C#串口通讯

网上的原版的串口通讯类N年前就出了的：
using System;
using System.Runtime.InteropServices;

namespace JustinIO {
   class CommPort {

      public string PortNum; 
      public int BaudRate;
      public byte ByteSize;
      public byte Parity; // 0-4=no,odd,even,mark,space 
      public byte StopBits; // 0,1,2 = 1, 1.5, 2 
      public int ReadTimeout;
      
      //comm port win32 file handle
      private int hComm = -1;
      
      public bool Opened = false;
       
      //win32 api constants
        private const uint GENERIC_READ = 0x80000000;
        private const uint GENERIC_WRITE = 0x40000000;
        private const int OPEN_EXISTING = 3;      
        private const int INVALID_HANDLE_VALUE = -1;
      
      [StructLayout(LayoutKind.Sequential)]
      public struct DCB {
         //taken from c struct in platform sdk 
         public int DCBlength;           // sizeof(DCB) 
         public int BaudRate;            // 指定当前波特率 current baud rate
         // these are the c struct bit fields, bit twiddle flag to set
         public int fBinary;          // 指定是否允许二进制模式,在windows95中必须主TRUE binary mode, no EOF check 
         public int fParity;          // 指定是否允许奇偶校验 enable parity checking 
         public int fOutxCtsFlow;      // 指定CTS是否用于检测发送控制，当为TRUE是CTS为OFF，发送将被挂起。 CTS output flow control 
         public int fOutxDsrFlow;      // 指定CTS是否用于检测发送控制 DSR output flow control 
         public int fDtrControl;       // DTR_CONTROL_DISABLE值将DTR置为OFF, DTR_CONTROL_ENABLE值将DTR置为ON, DTR_CONTROL_HANDSHAKE允许DTR"握手" DTR flow control type 
         public int fDsrSensitivity;   // 当该值为TRUE时DSR为OFF时接收的字节被忽略 DSR sensitivity 
         public int fTXContinueOnXoff; // 指定当接收缓冲区已满,并且驱动程序已经发送出XoffChar字符时发送是否停止。TRUE时，在接收缓冲区接收到缓冲区已满的字节XoffLim且驱动程序已经发送出XoffChar字符中止接收字节之后，发送继续进行。　FALSE时，在接收缓冲区接收到代表缓冲区已空的字节XonChar且驱动程序已经发送出恢复发送的XonChar之后，发送继续进行。XOFF continues Tx 
         public int fOutX;          // TRUE时，接收到XoffChar之后便停止发送接收到XonChar之后将重新开始 XON/XOFF out flow control 
         public int fInX;           // TRUE时，接收缓冲区接收到代表缓冲区满的XoffLim之后，XoffChar发送出去接收缓冲区接收到代表缓冲区空的XonLim之后，XonChar发送出去 XON/XOFF in flow control 
         public int fErrorChar;     // 该值为TRUE且fParity为TRUE时，用ErrorChar 成员指定的字符代替奇偶校验错误的接收字符 enable error replacement 
         public int fNull;          // eTRUE时，接收时去掉空（0值）字节 enable null stripping 
         public int fRtsControl;     // RTS flow control 
                                 /*RTS_CONTROL_DISABLE时,RTS置为OFF
         　                        RTS_CONTROL_ENABLE时, RTS置为ON
　　                              RTS_CONTROL_HANDSHAKE时,
　　                              当接收缓冲区小于半满时RTS为ON
　         　                        当接收缓冲区超过四分之三满时RTS为OFF
　　                              RTS_CONTROL_TOGGLE时,
　　                              当接收缓冲区仍有剩余字节时RTS为ON ,否则缺省为OFF*/

         public int fAbortOnError;   // TRUE时,有错误发生时中止读和写操作 abort on error 
         public int fDummy2;        // 未使用 reserved 
         
         public uint flags;
         public ushort wReserved;          // 未使用,必须为0 not currently used 
         public ushort XonLim;             // 指定在XON字符发送这前接收缓冲区中可允许的最小字节数 transmit XON threshold 
         public ushort XoffLim;            // 指定在XOFF字符发送这前接收缓冲区中可允许的最小字节数 transmit XOFF threshold 
         public byte ByteSize;           // 指定端口当前使用的数据位   number of bits/byte, 4-8 
         public byte Parity;             // 指定端口当前使用的奇偶校验方法,可能为:EVENPARITY,MARKPARITY,NOPARITY,ODDPARITY  0-4=no,odd,even,mark,space 
         public byte StopBits;           // 指定端口当前使用的停止位数,可能为:ONESTOPBIT,ONE5STOPBITS,TWOSTOPBITS  0,1,2 = 1, 1.5, 2 
         public char XonChar;            // 指定用于发送和接收字符XON的值 Tx and Rx XON character 
         public char XoffChar;           // 指定用于发送和接收字符XOFF值 Tx and Rx XOFF character 
         public char ErrorChar;          // 本字符用来代替接收到的奇偶校验发生错误时的值 error replacement character 
         public char EofChar;            // 当没有使用二进制模式时,本字符可用来指示数据的结束 end of input character 
         public char EvtChar;            // 当接收到此字符时,会产生一个事件 received event character 
         public ushort wReserved1;         // 未使用 reserved; do not use 
      }

      [StructLayout(LayoutKind.Sequential)]
      private struct COMMTIMEOUTS {  
        public int ReadIntervalTimeout; 
        public int ReadTotalTimeoutMultiplier; 
        public int ReadTotalTimeoutConstant; 
        public int WriteTotalTimeoutMultiplier; 
        public int WriteTotalTimeoutConstant; 
      }    

      [StructLayout(LayoutKind.Sequential)]   
      private struct OVERLAPPED { 
          public int  Internal; 
          public int  InternalHigh; 
          public int  Offset; 
          public int  OffsetHigh; 
          public int hEvent; 
      }  
      
      [DllImport("kernel32.dll")]
      private static extern int CreateFile(
        string lpFileName,                         // 要打开的串口名称
        uint dwDesiredAccess,                      // 指定串口的访问方式，一般设置为可读可写方式
        int dwShareMode,                          // 指定串口的共享模式，串口不能共享，所以设置为0
        int lpSecurityAttributes, // 设置串口的安全属性，WIN9X下不支持，应设为NULL
        int dwCreationDisposition,                // 对于串口通信，创建方式只能为OPEN_EXISTING
        int dwFlagsAndAttributes,                 // 指定串口属性与标志，设置为FILE_FLAG_OVERLAPPED(重叠I/O操作)，指定串口以异步方式通信
        int hTemplateFile                        // 对于串口通信必须设置为NULL
      );
      [DllImport("kernel32.dll")]
      private static extern bool GetCommState(
        int hFile,  //通信设备句柄
        ref DCB lpDCB    // 设备控制块DCB
      );   
      [DllImport("kernel32.dll")]
      private static extern bool BuildCommDCB(
        string lpDef,  // 设备控制字符串
        ref DCB lpDCB     // 设备控制块
      );
      [DllImport("kernel32.dll")]
      private static extern bool SetCommState(
        int hFile,  // 通信设备句柄
        ref DCB lpDCB    // 设备控制块
      );
      [DllImport("kernel32.dll")]
      private static extern bool GetCommTimeouts(
        int hFile,                  // 通信设备句柄 handle to comm device
        ref COMMTIMEOUTS lpCommTimeouts  // 超时时间 time-out values
      );   
      [DllImport("kernel32.dll")]   
      private static extern bool SetCommTimeouts(
        int hFile,                  // 通信设备句柄 handle to comm device
        ref COMMTIMEOUTS lpCommTimeouts  // 超时时间 time-out values
      );
      [DllImport("kernel32.dll")]
      private static extern bool ReadFile(
        int hFile,                // 通信设备句柄 handle to file
        byte[] lpBuffer,             // 数据缓冲区 data buffer
        int nNumberOfBytesToRead,  // 多少字节等待读取 number of bytes to read
        ref int lpNumberOfBytesRead, // 读取多少字节 number of bytes read
        ref OVERLAPPED lpOverlapped    // 溢出缓冲区 overlapped buffer
      );
      [DllImport("kernel32.dll")]   
      private static extern bool WriteFile(
        int hFile,                    // 通信设备句柄 handle to file
        byte[] lpBuffer,                // 数据缓冲区 data buffer
        int nNumberOfBytesToWrite,     // 多少字节等待写入 number of bytes to write
        ref int lpNumberOfBytesWritten,  // 已经写入多少字节 number of bytes written
        ref OVERLAPPED lpOverlapped        // 溢出缓冲区 overlapped buffer
      );
      [DllImport("kernel32.dll")]
      private static extern bool CloseHandle(
        int hObject   // handle to object
      );
      [DllImport("kernel32.dll")]
      private static extern uint GetLastError();
      
      public void Open()
      {
      
            DCB dcbCommPort = new DCB();
            COMMTIMEOUTS ctoCommPort = new COMMTIMEOUTS();   
           
          // 打开串口 OPEN THE COMM PORT.
            hComm = CreateFile(PortNum ,GENERIC_READ | GENERIC_WRITE,0, 0,OPEN_EXISTING,0,0);
          // 如果串口没有打开，就打开 IF THE PORT CANNOT BE OPENED, BAIL OUT.
         if(hComm == INVALID_HANDLE_VALUE) 
         {
              throw(new ApplicationException("非法操作，不能打开串口！"));
         }
      
         // 设置通信超时时间 SET THE COMM TIMEOUTS.
         GetCommTimeouts(hComm,ref ctoCommPort);
         ctoCommPort.ReadTotalTimeoutConstant = ReadTimeout;
         ctoCommPort.ReadTotalTimeoutMultiplier = 0;
         ctoCommPort.WriteTotalTimeoutMultiplier = 0;
         ctoCommPort.WriteTotalTimeoutConstant = 0;  
         SetCommTimeouts(hComm,ref ctoCommPort);
      
         // 设置串口 SET BAUD RATE, PARITY, WORD SIZE, AND STOP BITS.
         GetCommState(hComm, ref dcbCommPort);
         dcbCommPort.BaudRate=BaudRate;
         dcbCommPort.flags=0;
         //dcb.fBinary=1;
         dcbCommPort.flags|=1;
         if (Parity>0)
         {
            //dcb.fParity=1
            dcbCommPort.flags|=2;
         }
         dcbCommPort.Parity=Parity;
         dcbCommPort.ByteSize=ByteSize;
         dcbCommPort.StopBits=StopBits;
         if (!SetCommState(hComm, ref dcbCommPort))
         {
          //uint ErrorNum=GetLastError();
           throw(new ApplicationException("非法操作，不能打开串口！"));
         }
        //unremark to see if setting took correctly
        //DCB dcbCommPort2 = new DCB();
        //GetCommState(hComm, ref dcbCommPort2);
         Opened = true;
      }
      
      public void Close() {
         if (hComm!=INVALID_HANDLE_VALUE) {
            CloseHandle(hComm);
         }
      }
      
      public byte[] Read(int NumBytes) {
         byte[] BufBytes;
         byte[] OutBytes;
         BufBytes = new byte[NumBytes];
         if (hComm!=INVALID_HANDLE_VALUE) {
            OVERLAPPED ovlCommPort = new OVERLAPPED();
            int BytesRead=0;
            ReadFile(hComm,BufBytes,NumBytes,ref BytesRead,ref ovlCommPort);
            OutBytes = new byte[BytesRead];
            Array.Copy(BufBytes,OutBytes,BytesRead);
         } 
         else {
            throw(new ApplicationException("串口未打开！"));
         }
         return OutBytes;
      }
      
      public void Write(byte[] WriteBytes) {
         if (hComm!=INVALID_HANDLE_VALUE) {
            OVERLAPPED ovlCommPort = new OVERLAPPED();
            int BytesWritten = 0;
            WriteFile(hComm,WriteBytes,WriteBytes.Length,ref BytesWritten,ref ovlCommPort);
         }
         else {
            throw(new ApplicationException("串口未打开！"));
         }      
      }
   }

   class HexCon {
   // 把十六进制字符串转换成字节型和把字节型转换成十六进制字符串 converter hex string to byte and byte to hex string
      public static string ByteToString(byte[] InBytes) {
         string StringOut="";
         foreach (byte InByte in InBytes) {
            StringOut=StringOut + String.Format("{0:X2} ",InByte);
         }
         return StringOut; 
      }
      public static byte[] StringToByte(string InString) {
         string[] ByteStrings;
         ByteStrings = InString.Split(" ".ToCharArray());
         byte[] ByteOut;
         ByteOut = new byte[ByteStrings.Length-1];
         for (int i = 0;i==ByteStrings.Length-1;i++) {
            ByteOut[i] = Convert.ToByte(("0x" + ByteStrings[i]));
         } 
         return ByteOut;
      }
   }
}