WinAPI 操作串口

public class CommPort
    {
        /// <summary>
        /// 端口名称(COM1,COM2...COM4...)
        /// </summary>
        public string Port = "COM1:";
        /// <summary>
        /// 波特率9600
        /// </summary>
        public int BaudRate = 9600;
        /// <summary>
        /// 数据位4-8
        /// </summary>
        public byte ByteSize = 8; //4-8
        /// <summary>
        /// 奇偶校验0-4=no,odd,even,mark,space
        /// </summary>
        public byte Parity = 0;   //0-4=no,odd,even,mark,space
        /// <summary>
        /// 停止位
        /// </summary>
        public byte StopBits = 0;   //0,1,2 = 1, 1.5, 2
        /// <summary>
        /// 超时长
        /// </summary>
        public int ReadTimeout = 200;
        /// <summary>
        /// 串口是否已经打开
        /// </summary>
        public bool Opened = false;
        /// <summary>
        /// COM口句柄
        /// </summary>
        private int hComm = -1;

        #region "API相关定义"
        private const string DLLPATH = "\\windows\\coredll.dll"; // "kernel32";

        /// <summary>
        /// WINAPI常量,写标志
        /// </summary>
        private const uint GENERIC_READ = 0x80000000;
        /// <summary>
        /// WINAPI常量,读标志
        /// </summary>
        private const uint GENERIC_WRITE = 0x40000000;
        /// <summary>
        /// WINAPI常量,打开已存在
        /// </summary>
        private const int OPEN_EXISTING = 3;
        /// <summary>
        /// WINAPI常量,无效句柄
        /// </summary>
        private const int INVALID_HANDLE_VALUE = -1;

        private const int PURGE_RXABORT = 0x2;
        private const int PURGE_RXCLEAR = 0x8;
        private const int PURGE_TXABORT = 0x1;
        private const int PURGE_TXCLEAR = 0x4;

        /// <summary>
        /// 设备控制块结构体类型
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DCB
        {
            /// <summary>
            /// DCB长度
            /// </summary>
            public int DCBlength;
            /// <summary>
            /// 指定当前波特率
            /// </summary>
            public int BaudRate;
            #region "标志"
            ///// <summary>
            ///// 指定是否允许二进制模式
            ///// </summary>
            //public int fBinary;
            ///// <summary>
            ///// 指定是否允许奇偶校验
            ///// </summary>
            //public int fParity;
            ///// <summary>
            ///// 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。
            ///// </summary>
            //public int fOutxCtsFlow;
            ///// <summary>
            ///// 指定CTS是否用于检测发送控制
            ///// </summary>
            //public int fOutxDsrFlow;
            ///// <summary>
            ///// 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"
            ///// </summary>
            //public int fDtrControl;
            ///// <summary>
            ///// 当该值为TRUE时DSR为OFF时接收的字节被忽略
            ///// </summary>
            //public int fDsrSensitivity;
            ///// <summary>
            ///// 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
            ///// </summary>
            //public int fTXContinueOnXoff;
            ///// <summary>
            ///// 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
            ///// </summary>
            //public int fOutX;
            ///// <summary>
            ///// 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
            ///// </summary>
            //public int fInX;
            ///// <summary>
            ///// 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
            ///// </summary>
            //public int fErrorChar;
            ///// <summary>
            ///// eTRUE时，接收时去掉空（0值）字节 enable null stripping
            ///// </summary>
            //public int fNull;
            ///// <summary>
            ///// 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
            ///// </summary>
            //public int fRtsControl;
            ///// <summary>
            ///// TRUE时,有错误发生时中止读和写操作 abort on error
            ///// </summary>
            //public int fAbortOnError;
            ///// <summary>
            ///// 未使用
            ///// </summary>
            //public int fDummy2;
            #endregion
            /// <summary>
            /// 标志位
            /// </summary>
            public uint flags;
            /// <summary>
            /// 未使用,必须为0
            /// </summary>
            public ushort wReserved;
            /// <summary>
            /// 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
            /// </summary>
            public ushort XonLim;
            /// <summary>
            /// 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
            /// </summary>
            public ushort XoffLim;
            /// <summary>
            /// 指定端口当前使用的数据位
            /// </summary>
            public byte ByteSize;
            /// <summary>
            /// 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
            /// </summary>
            public byte Parity;
            /// <summary>
            /// 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
            /// </summary>
            public byte StopBits;
            /// <summary>
            /// 指定用于发送和接收字符XON的值 Tx and Rx XON character
            /// </summary>
            public byte XonChar;
            /// <summary>
            /// 指定用于发送和接收字符XOFF值 Tx and Rx XOFF character
            /// </summary>
            public byte XoffChar;
            /// <summary>
            /// 本字符用来代替接收到的奇偶校验发生错误时的值
            /// </summary>
            public byte ErrorChar;
            /// <summary>
            /// 当没有使用二进制模式时,本字符可用来指示数据的结束
            /// </summary>
            public byte EofChar;
            /// <summary>
            /// 当接收到此字符时,会产生一个事件
            /// </summary>
            public byte EvtChar;
            /// <summary>
            /// 未使用
            /// </summary>
            public ushort wReserved1;

        }

        /// <summary>
        /// 串口超时时间结构体类型
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        private struct COMMTIMEOUTS
        {
            public int ReadIntervalTimeout;
            public int ReadTotalTimeoutMultiplier;
            public int ReadTotalTimeoutConstant;
            public int WriteTotalTimeoutMultiplier;
            public int WriteTotalTimeoutConstant;
        }

        /// <summary>
        /// 溢出缓冲区结构体类型
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        private struct OVERLAPPED
        {
            public int Internal;
            public int InternalHigh;
            public int Offset;
            public int OffsetHigh;
            public int hEvent;
        }

        /// <summary>
        /// 打开串口
        /// </summary>
        /// <param name="lpFileName">要打开的串口名称</param>
        /// <param name="dwDesiredAccess">指定串口的访问方式，一般设置为可读可写方式</param>
        /// <param name="dwShareMode">指定串口的共享模式，串口不能共享，所以设置为0</param>
        /// <param name="lpSecurityAttributes">设置串口的安全属性，WIN9X下不支持，应设为NULL</param>
        /// <param name="dwCreationDisposition">对于串口通信，创建方式只能为OPEN_EXISTING</param>
        /// <param name="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</param>
        /// <param name="hTemplateFile">对于串口通信必须设置为NULL</param>
        [DllImport(DLLPATH)]
        private static extern int CreateFile(string lpFileName, uint dwDesiredAccess, int dwShareMode,
        int lpSecurityAttributes, int dwCreationDisposition, int dwFlagsAndAttributes, int hTemplateFile);

        /// <summary>
        /// 得到串口状态
        /// </summary>
        /// <param name="hFile">通信设备句柄</param>
        /// <param name="lpDCB">设备控制块DCB</param>
        [DllImport(DLLPATH)]
        private static extern bool GetCommState(int hFile, ref DCB lpDCB);

        /// <summary>
        /// 建立串口设备控制块(嵌入版没有)
        /// </summary>
        /// <param name="lpDef">设备控制字符串</param>
        /// <param name="lpDCB">设备控制块</param>
        //[DllImport(DLLPATH)]
        //private static extern bool BuildCommDCB(string lpDef, ref DCB lpDCB);

        /// <summary>
        /// 设置串口状态
        /// </summary>
        /// <param name="hFile">通信设备句柄</param>
        /// <param name="lpDCB">设备控制块</param>
        [DllImport(DLLPATH)]
        private static extern bool SetCommState(int hFile, ref DCB lpDCB);

        /// <summary>
        /// 读取串口超时时间
        /// </summary>
        /// <param name="hFile">通信设备句柄</param>
        /// <param name="lpCommTimeouts">超时时间</param>
        [DllImport(DLLPATH)]
        private static extern bool GetCommTimeouts(int hFile, ref COMMTIMEOUTS lpCommTimeouts);

        /// <summary>
        /// 设置串口超时时间
        /// </summary>
        /// <param name="hFile">通信设备句柄</param>
        /// <param name="lpCommTimeouts">超时时间</param>
        [DllImport(DLLPATH)]
        private static extern bool SetCommTimeouts(int hFile, ref COMMTIMEOUTS lpCommTimeouts);

        /// <summary>
        /// 读取串口数据
        /// </summary>
        /// <param name="hFile">通信设备句柄</param>
        /// <param name="lpBuffer">数据缓冲区</param>
        /// <param name="nNumberOfBytesToRead">多少字节等待读取</param>
        /// <param name="lpNumberOfBytesRead">读取多少字节</param>
        /// <param name="lpOverlapped">溢出缓冲区</param>
        [DllImport(DLLPATH)]
        private static extern bool ReadFile(int hFile, byte[] lpBuffer, int nNumberOfBytesToRead,
        ref int lpNumberOfBytesRead, ref OVERLAPPED lpOverlapped);

        /// <summary>
        /// 写串口数据
        /// </summary>
        /// <param name="hFile">通信设备句柄</param>
        /// <param name="lpBuffer">数据缓冲区</param>
        /// <param name="nNumberOfBytesToWrite">多少字节等待写入</param>
        /// <param name="lpNumberOfBytesWritten">已经写入多少字节</param>
        /// <param name="lpOverlapped">溢出缓冲区</param>
        [DllImport(DLLPATH)]
        private static extern bool WriteFile(int hFile, byte[] lpBuffer, int nNumberOfBytesToWrite,
        ref int lpNumberOfBytesWritten, ref OVERLAPPED lpOverlapped);

        [DllImport(DLLPATH, SetLastError = true)]
        private static extern bool FlushFileBuffers(int hFile);

        [DllImport(DLLPATH, SetLastError = true)]
        private static extern bool PurgeComm(int hFile, uint dwFlags);

        /// <summary>
        /// 关闭串口
        /// </summary>
        /// <param name="hObject">通信设备句柄</param>
        [DllImport(DLLPATH)]
        private static extern bool CloseHandle(int hObject);

        /// <summary>
        /// 得到串口最后一次返回的错误
        /// </summary>
        [DllImport(DLLPATH)]
        private static extern uint GetLastError();
        #endregion

        /// <summary>
        /// 设置DCB标志位
        /// </summary>
        /// <param name="whichFlag"></param>
        /// <param name="setting"></param>
        /// <param name="dcb"></param>
        internal void SetDcbFlag(int whichFlag, int setting, DCB dcb)
        {
            uint num;
            setting = setting << whichFlag;
            if ((whichFlag == 4) || (whichFlag == 12))
            {
                num = 3;
            }
            else if (whichFlag == 15)
            {
                num = 0x1ffff;
            }
            else
            {
                num = 1;
            }
            dcb.flags &= ~(num << whichFlag);
            dcb.flags |= (uint)setting;
        }

        /// <summary>
        /// 建立与串口的连接
        /// </summary>
        public int Open()
        {
            DCB dcb = new DCB();
            COMMTIMEOUTS ctoCommPort = new COMMTIMEOUTS();

            // 打开串口
            hComm = CreateFile(Port, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
            if (hComm == INVALID_HANDLE_VALUE)
            {
                return -1;
            }

            // 设置通信超时时间
            GetCommTimeouts(hComm, ref ctoCommPort);
            ctoCommPort.ReadTotalTimeoutConstant = ReadTimeout;
            ctoCommPort.ReadTotalTimeoutMultiplier = 0;
            ctoCommPort.WriteTotalTimeoutMultiplier = 0;
            ctoCommPort.WriteTotalTimeoutConstant = 0;
            SetCommTimeouts(hComm, ref ctoCommPort);

            //设置串口参数
            GetCommState(hComm, ref dcb);
            dcb.DCBlength = Marshal.SizeOf(dcb);
            dcb.BaudRate = BaudRate;
            dcb.flags = 0;
            dcb.ByteSize = (byte)ByteSize;
            dcb.StopBits = StopBits;
            dcb.Parity = (byte)Parity;

            //------------------------------
            SetDcbFlag(0, 1, dcb);            //二进制方式
            SetDcbFlag(1, (Parity == 0) ? 0 : 1, dcb);
            SetDcbFlag(2, 0, dcb);            //不用CTS检测发送流控制
            SetDcbFlag(3, 0, dcb);            //不用DSR检测发送流控制
            SetDcbFlag(4, 0, dcb);            //禁止DTR流量控制
            SetDcbFlag(6, 0, dcb);            //对DTR信号线不敏感
            SetDcbFlag(9, 1, dcb);            //检测接收缓冲区
            SetDcbFlag(8, 0, dcb);            //不做发送字符控制
            SetDcbFlag(10, 0, dcb);           //是否用指定字符替换校验错的字符
            SetDcbFlag(11, 0, dcb);           //保留NULL字符
            SetDcbFlag(12, 0, dcb);           //允许RTS流量控制
            SetDcbFlag(14, 0, dcb);           //发送错误后，继续进行下面的读写操作
            //--------------------------------
            dcb.wReserved = 0;                       //没有使用，必须为0  
            dcb.XonLim = 0;                          //指定在XOFF字符发送之前接收到缓冲区中可允许的最小字节数
            dcb.XoffLim = 0;                         //指定在XOFF字符发送之前缓冲区中可允许的最小可用字节数
            dcb.XonChar = 0;                         //发送和接收的XON字符
            dcb.XoffChar = 0;                        //发送和接收的XOFF字符
            dcb.ErrorChar = 0;                       //代替接收到奇偶校验错误的字符
            dcb.EofChar = 0;                         //用来表示数据的结束  
            dcb.EvtChar = 0;                         //事件字符，接收到此字符时，会产生一个事件  
            dcb.wReserved1 = 0;                      //没有使用

            if (!SetCommState(hComm, ref dcb))
            {
                return -2;
            }
            Opened = true;
            return 0;
        }

        /// <summary>
        /// 关闭串口,结束通讯
        /// </summary>
        public void Close()
        {
            if (hComm != INVALID_HANDLE_VALUE)
            {
                CloseHandle(hComm);
            }
        }

        /// <summary>
        /// 读取串口返回的数据
        /// </summary>
        /// <param name="NumBytes">数据长度</param>
        public int Read(ref byte[] bytData, int NumBytes)
        {
            if (hComm != INVALID_HANDLE_VALUE)
            {
                OVERLAPPED ovlCommPort = new OVERLAPPED();
                int BytesRead = 0;
                ReadFile(hComm, bytData, NumBytes, ref BytesRead, ref ovlCommPort);
                return BytesRead;
            }
            else
            {
                return -1;
            }
        }

        /// <summary>
        /// 向串口写数据
        /// </summary>
        /// <param name="WriteBytes">数据数组</param>
        public int Write(byte[] WriteBytes, int intSize)
        {
            if (hComm != INVALID_HANDLE_VALUE)
            {
                OVERLAPPED ovlCommPort = new OVERLAPPED();
                int BytesWritten = 0;
                WriteFile(hComm, WriteBytes, intSize, ref BytesWritten, ref ovlCommPort);
                return BytesWritten;
            }
            else
            {
                return -1;
            }
        }

        /// <summary>
        /// 清除接收缓冲区
        /// </summary>
        /// <returns></returns>
        public void ClearReceiveBuf()
        {
            if (hComm != INVALID_HANDLE_VALUE)
            {
                PurgeComm(hComm, PURGE_RXABORT | PURGE_RXCLEAR);
            }
        }

        /// <summary>
        /// 清除发送缓冲区
        /// </summary>
        public void ClearSendBuf()
        {
            if (hComm != INVALID_HANDLE_VALUE)
            {
                PurgeComm(hComm, PURGE_TXABORT | PURGE_TXCLEAR);
            }
        }

        /// <summary>
        /// 发送命令
        /// </summary>
        /// <param name="SendData"></param>
        /// <param name="ReceiveData"></param>
        /// <param name="Overtime"></param>
        /// <returns></returns>
        public int SendCommand(byte[] SendData, ref  byte[] ReceiveData, int Overtime)
        {
            if (hComm != INVALID_HANDLE_VALUE)
            {
                COMMTIMEOUTS ctoCommPort = new COMMTIMEOUTS();
                // 设置通信超时时间
                GetCommTimeouts(hComm, ref ctoCommPort);
                ctoCommPort.ReadTotalTimeoutConstant = Overtime;
                ctoCommPort.ReadTotalTimeoutMultiplier = 0;
                ctoCommPort.WriteTotalTimeoutMultiplier = 0;
                ctoCommPort.WriteTotalTimeoutConstant = 200;  //叶帆 2007年11月21日
                SetCommTimeouts(hComm, ref ctoCommPort);

                ClearSendBuf();
                ClearReceiveBuf();

                Write(SendData, SendData.Length);
                return Read(ref ReceiveData, ReceiveData.Length);
            }
            return -1;
        }
    }