本文主要是讲述如何通过C# .net1.1平台调用API操作串口，.net2.0已经内置串口操作类！
通常，在C#中实现串口通信，我们有四种方法：
第一：通过MSCOMM控件这是最简单的，最方便的方法。可功能上很难做到控制自如，同时这个控件并不是系统本身所带，所以还得注册。可以访问
http://www.devhood.com/tutorials/tutorial_details.aspx?tutorial_id=320
一个外国人写的教程
第二：微软在.NET新推出了一个串口控件，基于.NET的P/Invoke调用方法实现，详细的可以访问微软网站
Serial Comm
Use P/Invoke to Develop a .NET Base Class Library for Serial
Device Communications
http://msdn.microsoft.com/msdnmag/issues/02/10/netserialcomm/
第三：就是用第三方控件啦，可一般都要付费的，不太合实际，何况楼主不喜欢，不作考虑
第四：自己用API写串口通信，这样难度高点，但对于我们来说，可以方便实现自己想要的各种功能。
我们采用第四种方法来实现串口通信，用现成的已经封装好的类库，常见两个串口操作类是JustinIO和SerialStreamReader。介绍JustinIO的使用方法：
打开串口：
函数原型：public void Open()
说明：打开事先设置好的端口
示例：
using JustinIO;
static JustinIO.CommPort ss_port = new
JustinIO.CommPort();
ss_port.PortNum = COM1; //端口号
ss_port.BaudRate =
19200; //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
}
else
{
ss_port.Open();//打开串口
}
return true;
}
catch(Exception e)
{
MessageBox.Show("错误：" + e.Message);
return false;
}
写串口：
函数原型：public void Write(byte[]
WriteBytes)
WriteBytes 就是你的写入的字节，注意，字符串要转换成字节数组才能进行通信
示例：
ss_port.Write(Encoding.ASCII.GetBytes("AT+CGMI\r")); //获取手机品牌
读串口：
函数原型：public byte[] Read(int NumBytes)
NumBytes
读入缓存数，注意读取来的是字节数组，要实际应用中要进行字符转换
示例：
string response =
Encoding.ASCII.GetString(ss_port.Read(128)); //读取128个字节缓存
关闭串口：
函数原型：ss_port.Close()
示例：
ss_port.Close();
整合代码：
using System;
using System.Runtime.InteropServices;
namespace
JustinIO {
class CommPort {
public int 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; // current baud rate
/* these are the c
struct bit fields, bit twiddle flag to set
public int fBinary; // binary
mode, no EOF check
public int fParity; // enable parity checking
public
int fOutxCtsFlow; // CTS output flow control
public int fOutxDsrFlow; // DSR
output flow control
public int fDtrControl; // DTR flow control type
public int fDsrSensitivity; // DSR sensitivity
public int
fTXContinueOnXoff; // XOFF continues Tx
public int fOutX; // XON/XOFF out
flow control
public int fInX; // XON/XOFF in flow control
public int
fErrorChar; // enable error replacement
public int fNull; // enable null
stripping
public int fRtsControl; // RTS flow control
public int
fAbortOnError; // abort on error
public int fDummy2; // reserved
*/
public uint flags;
public ushort wReserved; // not currently used
public ushort XonLim; // transmit XON threshold
public ushort XoffLim;
// transmit XOFF threshold
public byte ByteSize; // number of bits/byte, 4-8
public byte Parity; // 0-4=no,odd,even,mark,space
public byte StopBits;
// 0,1,2 = 1, 1.5, 2
public char XonChar; // Tx and Rx XON character
public char XoffChar; // Tx and Rx XOFF character
public char ErrorChar;
// error replacement character
public char EofChar; // end of input
character
public char EvtChar; // received event character
public ushort
wReserved1; // 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, // file name
uint dwDesiredAccess, // access mode
int dwShareMode, // share mode
int lpSecurityAttributes, // SD
int
dwCreationDisposition, // how to create
int dwFlagsAndAttributes, // file
attributes
int hTemplateFile // handle to template file
);
[DllImport("kernel32.dll")]
private static extern bool GetCommState(
int hFile, // handle to communications device
ref DCB lpDCB //
device-control block
);
[DllImport("kernel32.dll")]
private static
extern bool BuildCommDCB(
string lpDef, // device-control string
ref DCB
lpDCB // device-control block
);
[DllImport("kernel32.dll")]
private
static extern bool SetCommState(
int hFile, // handle to communications
device
ref DCB lpDCB // device-control block
);
[DllImport("kernel32.dll")]
private static extern bool GetCommTimeouts(
int hFile, // handle to comm device
ref COMMTIMEOUTS lpCommTimeouts //
time-out values
);
[DllImport("kernel32.dll")]
private static extern
bool SetCommTimeouts(
int hFile, // handle to comm device
ref
COMMTIMEOUTS lpCommTimeouts // time-out values
);
[DllImport("kernel32.dll")]
private static extern bool ReadFile(
int
hFile, // handle to file
byte[] lpBuffer, // data buffer
int
nNumberOfBytesToRead, // number of bytes to read
ref int
lpNumberOfBytesRead, // number of bytes read
ref OVERLAPPED lpOverlapped //
overlapped buffer
);
[DllImport("kernel32.dll")]
private static
extern bool WriteFile(
int hFile, // handle to file
byte[] lpBuffer, //
data buffer
int nNumberOfBytesToWrite, // number of bytes to write
ref
int lpNumberOfBytesWritten, // number of bytes written
ref OVERLAPPED
lpOverlapped // 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();
// OPEN
THE COMM PORT.
hComm = CreateFile("COM" + PortNum ,GENERIC_READ |
GENERIC_WRITE,0, 0,OPEN_EXISTING,0,0);
// IF THE PORT CANNOT BE OPENED,
BAIL OUT.
if(hComm == INVALID_HANDLE_VALUE) {
throw(new
ApplicationException("Comm Port Can Not Be Opened"));
}
// SET THE
COMM TIMEOUTS.
GetCommTimeouts(hComm,ref ctoCommPort);
ctoCommPort.ReadTotalTimeoutConstant = ReadTimeout;
ctoCommPort.ReadTotalTimeoutMultiplier = 0;
ctoCommPort.WriteTotalTimeoutMultiplier = 0;
ctoCommPort.WriteTotalTimeoutConstant = 0;
SetCommTimeouts(hComm,ref
ctoCommPort);
// 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("Comm Port Can Not Be Opened"));
}
//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("Comm Port Not Open"));
}
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("Comm Port Not Open"));
}
}
}
}
}
由于篇幅，以及串口通信涉及内容广泛，我在这里只讲这些。