display text from serial port

using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.IO.Ports;
using System.IO;
using System.Windows.Forms;
using System.Globalization;
using System.Threading;
using System.Resources;


namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        
        public Form1()
        {
           
            InitializeComponent();
            if (!mySerialport.IsOpen)
            {
                mySerialport.Open();
                tbRX.Text = "port opened   :)";
            }
            else {
                tbRX.Text = "port busy :(";           
                       
            }
        }
        private string rxstring;
   
        private void Form1_Load(object sender, EventArgs e)
        {
        
        }
       

        private void mySerialport_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            rxstring = mySerialport.ReadExisting();
            this.Invoke(new EventHandler(dsiplayTEXT));
        }
        private void dsiplayTEXT(object o, EventArgs e)
        {
            tbRX.AppendText(rxstring);        
        
        }
    }
}