System.IO.Ports.SerialPort 应用-没完成

using System;
using System.Collections.Generic;
using System.Text;
using System.IO.Ports;

namespace SerialTest
{
public class NM4BPort
{
private SerialPort sp;

public NM4BPort(string portName)
{
sp = new SerialPort(portName, 115200, Parity.Space, 8);
sp.ReadTimeout = 5000;
sp.WriteTimeout = 5000;
}
public void Open()
{
if(sp != null)
sp.Open();
}

public void Close()
{
if (sp != null)
sp.Close();
}

private void SendCommandID(byte chCMD)
{
WriteByte(0x3F);
WriteByte(chCMD);
ReadByte();
ReadByte();
}

private byte ReadByte()
{
byte ret = (byte)sp.ReadByte();

byte[] buf = { 0x2E };
sp.Write(buf,0, 1);
return ret;
}

private bool WriteByte(byte dat)
{
byte[] buf = { dat };
sp.Write(buf, 0, 1);
byte ret = (byte)sp.ReadByte();
return (ret == (byte)0x2E);
}

private int ReadInt()
{
int ret = 0;

ReadByte();

for(int i=0; i<4; i++)
ret = (ret << 8) + ReadByte();
return ret;
}

private string ReadString(int nMax)
{
byte[] buf = new byte[nMax];

ReadByte();
for(int i=0; i<nMax; i++)
buf[i] = ReadByte();

ASCIIEncoding ascii = new ASCIIEncoding();
string decoded = ascii.GetString(buf);

return decoded;
}

public string GetDriverNames()
{
SendCommandID(0x03);
int nLen = ReadInt();

return ReadString(nLen);
}

}

class Program
{
static void Main(string[] args)
{
NM4BPort port = new NM4BPort("COM2");
try
{
port.Open();

string driverNames = port.GetDriverNames();
Console.WriteLine(driverNames);

port.Close();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
finally
{
port.Close();
Console.ReadKey();
}
}
}
}