最近搞了PDA 和GPS相结合的一个项目，在写串口程序的时候遇到了一点问题，困饶了好几天都没有解决。最后是因为测试的方法不对引起的。我测试的时候是现在一台机器上面写一个字符串，然后读取，结果啥都没读到，后来连了串口线进行测试就对了，就是用串口线把计算机和pda连接起来，然后在pda上部署一个简单的测试程序，在计算机上通过串口调试助手不断的发数据，然后pda点接收按钮，哈哈，就有数据了哦！
串口操作的过程实现打开串口，然后读取，然后关闭。
PDA要接收GPS发来的信息。我用的开发工具是c#.net、compact framework 2003、PDA 模拟器
.net2003并没有提供相应的操作串口的类，所以要自己调用windows的api，具体的代码如下:
using System;
using System.Collections;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.IO;
namespace Port
{
public class Port
{
public byte[] OutBytes;
public byte[] mbytTxBuffer;
public int strNum;
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("coredll.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("coredll.dll")]
private static extern int GetCommState(
int hFile, //通信设备句柄
ref DCB lpDCB // 设备控制块DCB
);
[DllImport("coredll.dll")]
private static extern bool BuildCommDCB(
string lpDef, // 设备控制字符串
ref DCB lpDCB // 设备控制块
);
[DllImport("coredll.dll")]
private static extern bool SetCommState(
int hFile, // 通信设备句柄
ref DCB lpDCB // 设备控制块
);
[DllImport("coredll.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("coredll.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("coredll.dll")]
private static extern int 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("coredll.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("coredll.dll")]
private static extern bool CloseHandle(
int hObject // handle to object
);
[DllImport("coredll.dll")]
private static extern uint GetLastError();
[DllImport("coredll.dll")]
private static extern int PurgeComm(int hFile,int dwFlags);
//打开串口的程序；
public void Open()
{
DCB dcbCommPort = new DCB();
COMMTIMEOUTS ctoCommPort = new COMMTIMEOUTS();
hComm = CreateFile(PortNum, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
MessageBox.Show("hComm is :"+hComm);
// 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 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;
dcbCommPort.flags |= 1;
if (Parity > 0)
{
dcbCommPort.flags |= 2;
}
dcbCommPort.Parity = Parity;
dcbCommPort.ByteSize = ByteSize;
dcbCommPort.StopBits = StopBits;
if (!SetCommState(hComm, ref dcbCommPort))
{
throw (new ApplicationException("非法操作，不能打开串口！"));
}
Opened = true;
}
public void Close()
{
if (hComm != INVALID_HANDLE_VALUE)
{
CloseHandle(hComm);
}
}
//读数据
public byte[] Read(int NumBytes)
{
byte[] 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,0,OutBytes,0,BytesRead);
strNum = BytesRead;
}
else
{
throw (new ApplicationException("串口未打开！"));
}
MessageBox.Show("OutBytes.length is :"+OutBytes.Length);
return OutBytes;
}
//来源自.net compact framework 技术内幕第11章串行通信第347页
//用的就是这个方法来读的
public string Input(int BytesToRead)
{
string result="";
int intResult;
ASCIIEncoding objEncoder=new ASCIIEncoding();
int lpNumberOfBytesRead=0;
OVERLAPPED lpOverlapped;
if(BytesToRead==0)
BytesToRead=512;
if(hComm!=-1)
{
OutBytes=new byte[BytesToRead];
lpOverlapped=new OVERLAPPED();
intResult=ReadFile(hComm, OutBytes, BytesToRead, ref lpNumberOfBytesRead, ref lpOverlapped);
if(intResult==0)
{
hComm=-1;
throw (new ApplicationException("串口未打开！"));
}
else
{
result=objEncoder.GetString(OutBytes,0,BytesToRead);
MessageBox.Show("result is :"+result);
}
}
return result;
}
//这个方法是把数据写到串口上的，来源自.net compact framework 技术内幕第11章串行通信第347页
//没有用到这个方法暂时
public void Output(string Value)
{
int lpNumberOfBytesWritten=0;
OVERLAPPED lpOverlapped=new OVERLAPPED();
ASCIIEncoding objEncoder=new ASCIIEncoding();
MessageBox.Show("hComm is :"+hComm);
if(hComm!=-1)
{
mbytTxBuffer=new byte[Value.Length];
mbytTxBuffer=objEncoder.GetBytes(Value);
bool m_boo=false;
m_boo=WriteFile(hComm,mbytTxBuffer,mbytTxBuffer.Length,ref lpNumberOfBytesWritten,ref lpOverlapped);
if(m_boo==true)
{
MessageBox.Show("写成功了");
}
else
{
MessageBox.Show("没有成功！!");
}
}
}
// 这个方法也是写数据到串口的
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！"));
}
}
}
public 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];
for (int i = 0; i <= ByteStrings.Length - 1; i++)
{
ByteOut[i] = Convert.ToByte(ByteStrings[i], 16);
}
return ByteOut;
}
}
}
原文: http://blog.csdn.net/zhiyuzhe/archive/2006/12/15/1444313.aspx