如何用API实现串口通讯

1.新建一个CommPort.cs文件

代码如下:

using System;
using System.Runtime.InteropServices;

namespace CommPortDemo
{
 /// <summary>
 /// CommPort 的摘要说明。
 /// </summary>
 public 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
   // 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
   ref COMMTIMEOUTS lpCommTimeouts // 超时时间
   );
  [DllImport("kernel32.dll")]
  private static extern bool SetCommTimeouts(
   int hFile, // 通信设备句柄
   ref COMMTIMEOUTS lpCommTimeouts // 超时时间
   );
  [DllImport("kernel32.dll")]
  private static extern bool ReadFile(
   int hFile, // 通信设备句柄
   byte[] lpBuffer, // 数据缓冲区
   int nNumberOfBytesToRead, // 多少字节等待读取
   ref int lpNumberOfBytesRead, // 读取多少字节
   ref OVERLAPPED lpOverlapped // 溢出缓冲区
   );
  [DllImport("kernel32.dll")]
  private static extern bool WriteFile(
   int hFile, // 通信设备句柄
   byte[] lpBuffer, // 数据缓冲区
   int nNumberOfBytesToWrite, // 多少字节等待写入
   ref int lpNumberOfBytesWritten, // 已经写入多少字节
   ref OVERLAPPED lpOverlapped // 溢出缓冲区
   );
  [DllImport("kernel32.dll")]
  private static extern bool CloseHandle(
   int hObject // handle to object
   );
  [DllImport("kernel32.dll")]
  private static extern uint GetLastError();

  /// <summary>
  /// 打开串口
  /// </summary>
  public void Open()
  {
   DCB dcbCommPort = new DCB();
   COMMTIMEOUTS ctoCommPort = new COMMTIMEOUTS();

   // 打开串口
   hComm = CreateFile(PortNum ,GENERIC_READ | GENERIC_WRITE,0, 0,OPEN_EXISTING,0,0);
   
   // 如果串口没有打开
   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
   GetCommTimeouts(hComm,ref ctoCommPort);
   ctoCommPort.ReadTotalTimeoutConstant = ReadTimeout;
   ctoCommPort.ReadTotalTimeoutMultiplier = 0;
   ctoCommPort.WriteTotalTimeoutMultiplier = 0;
   ctoCommPort.WriteTotalTimeoutConstant = 0;
   SetCommTimeouts(hComm,ref ctoCommPort);

   // 设置串口
   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！"));
   }
  }
 }
}
 2.下面是一个DEMO源码

using System;

using System.Threading;

namespace CommPortDemo
{
 /// <summary>
 /// Class1 的摘要说明。
 /// </summary>
 class Class1
 {

  /// <summary>
  /// 应用程序的主入口点。
  /// </summary>
  [STAThread]
  static void Main(string[] args)
  {
   CommPort ss_port = new CommPort();
   
   ss_port.PortNum = "COM3"; //端口号
   ss_port.BaudRate = 384000; //串口通信波特率
   ss_port.ByteSize = 8; //数据位
   ss_port.Parity = 0; //奇偶校验
   ss_port.StopBits = 1;//停止位
   ss_port.ReadTimeout = 1000; //读超时
   
   try
   {
    if (ss_port.Opened)
　    {
　　    ss_port.Close();
　　    ss_port.Open(); //打开串口

     Console.WriteLine("===>>the port is opened !");
　    }
    else
    {
　　    ss_port.Open();//打开串口

     Console.WriteLine("===>>the port is opened !");
    }
   }
   catch(Exception ex)
   {
    Console.WriteLine("===>>An error occurred while open the com port : "+ex.Message);
   }

   while(true)
   {
    try
    {
     //发送的数据
     byte[] outByte = new byte[2];
     outByte[0] = 0x01;
     outByte[1] = 0x02;
     ss_port.Write(outByte);
     
     string sendData = HexCon.ByteToString(outByte);
    
     Console.WriteLine("===>> send Data : "+sendData);

     if(outByte.Length>0)
     {
      //接收的数据
      byte[] inByte = new byte[2];
      inByte = (byte[])ss_port.Read(inByte.Length);
      string receData = HexCon.ByteToString(inByte);

      Console.WriteLine("===>> receive Data : "+receData);
     }

     Thread.Sleep(2000); //延时2S

    }
    catch(Exception er)
    {
     Console.WriteLine("===>>An error occurred while send data : "+er.Message);
    }
   }
  }
 }
}