Serial port communication problem

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

namespace PortChat
{
    public class PortChat
    {
       // private static StreamWriter sw = new StreamWriter("filename.txt");
        static bool _continue;
        static SerialPort _serialPort;
        
        public static void Main(string[] args)
        {
            string name;
            string message;
            //string path = "";
            //// Write
            //string path = "example.txt";
            //string[] myMenu = { "A", "B", "C" };
            //File.WriteAllLines(path, myMenu);

            //// Read
            //string[] readMenu = File.ReadAllLines(path);
            StringComparer stringComparer = StringComparer.OrdinalIgnoreCase;
            Thread readThread = new Thread(Read);
            
            // Create a new SerialPort object with default settings.
            _serialPort = new SerialPort();

            // Allow the user to set the appropriate properties.
            _serialPort.PortName = SetPortName(_serialPort.PortName);
            _serialPort.BaudRate = SetPortBaudRate(_serialPort.BaudRate);
            _serialPort.Parity = SetPortParity(_serialPort.Parity);
            _serialPort.DataBits = SetPortDataBits(_serialPort.DataBits);
            _serialPort.StopBits = SetPortStopBits(_serialPort.StopBits);
            _serialPort.Handshake = SetPortHandshake(_serialPort.Handshake);

            // Set the read/write timeouts
            _serialPort.ReadTimeout = 500;
            _serialPort.WriteTimeout = 500;

            _serialPort.DataReceived += new SerialDataReceivedEventHandler(_serialPort_DataReceived);
            _serialPort.Open();
            _continue = true;
            readThread.Start();

            //_serialPort.WriteLine("$");//Command to start Data Stream
            //// Wait for data or user input to continue.
            //Console.ReadLine();
           // Console.WriteLine("FILEPATH");
           // path = Console.ReadLine();
            Console.Write("Name: ");
            name = Console.ReadLine();
            Console.WriteLine("Type QUIT to exit");
            while (_continue)
            {
                message = Console.ReadLine();

                if (stringComparer.Equals("quit", message))
                {
                    _continue = false;
                }
                else
                {
                    _serialPort.WriteLine(
                        String.Format("<{0}>: {1}", name, message));
                }
            }

            readThread.Join();
            _serialPort.Close();
        }
        static void _serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            SerialPort _serialPort = (SerialPort)sender;
            Console.WriteLine(_serialPort.ReadExisting());
        }

        public static void Read()
        {
            while (_continue)
            {
                try
                {
        
                    string message = _serialPort.ReadLine();
                    Console.WriteLine(message);
                }
                catch (TimeoutException) { }
            }
        }
        public static string SetPortName(string defaultPortName)
        {
            string portName="";

            Console.WriteLine("Available Ports:");
            foreach (string s in SerialPort.GetPortNames())
            {
                Console.WriteLine("   {0}", s);
                portName = s;
            }
            //my code
            _serialPort.PortName = portName;
            defaultPortName = portName;
            Console.Write("COM port({0}): ", defaultPortName);
            portName = Console.ReadLine();

            if (portName == "")
            {
                portName = defaultPortName;
            }
            return portName;
        }
        public static int SetPortBaudRate(int defaultPortBaudRate)
        {
            string baudRate;

            Console.Write("Baud Rate({0}): ", defaultPortBaudRate);
            baudRate = Console.ReadLine();

            if (baudRate == "")
            {
                baudRate = defaultPortBaudRate.ToString();
            }

            return int.Parse(baudRate);
        }
        public static Parity SetPortParity(Parity defaultPortParity)
        {
            string parity;

            Console.WriteLine("Available Parity options:");
            foreach (string s in Enum.GetNames(typeof(Parity)))
            {
                Console.WriteLine("   {0}", s);
            }

            Console.Write("Parity({0}):", defaultPortParity.ToString());
            parity = Console.ReadLine();

            if (parity == "")
            {
                parity = defaultPortParity.ToString();
            }

            return (Parity)Enum.Parse(typeof(Parity), parity);
        }
        
        public static int SetPortDataBits(int defaultPortDataBits)
        {
            string dataBits;

            Console.Write("Data Bits({0}): ", defaultPortDataBits);
            dataBits = Console.ReadLine();

            if (dataBits == "")
            {
                dataBits = defaultPortDataBits.ToString();
            }

                return int.Parse(dataBits);
        }
        public static StopBits SetPortStopBits(StopBits defaultPortStopBits)
        {
            string stopBits;

            Console.WriteLine("Available Stop Bits options:");
            foreach (string s in Enum.GetNames(typeof(StopBits)))
            {
                Console.WriteLine("   {0}", s);
            }

            Console.Write("Stop Bits({0}):", defaultPortStopBits.ToString());
            stopBits = Console.ReadLine();

            if (stopBits == "")
            {
                stopBits = defaultPortStopBits.ToString();
            }

            return (StopBits)Enum.Parse(typeof(StopBits), stopBits);
        }
        public static Handshake SetPortHandshake(Handshake defaultPortHandshake)
        {
            string handshake;

            Console.WriteLine("Available Handshake options:");
            foreach (string s in Enum.GetNames(typeof(Handshake)))
            {
                Console.WriteLine("   {0}", s);
            }

            Console.Write("Handshake({0}):", defaultPortHandshake.ToString());
            handshake = Console.ReadLine();

            if (handshake == "")
            {
                handshake = defaultPortHandshake.ToString();
            }

            return (Handshake)Enum.Parse(typeof(Handshake), handshake);
        }
    }
}