serial RS232 Get Data

Public Class Form1
    Dim readbuffer As String = String.Empty
    Dim Bytenumber As Integer
    Dim ByteToRead As Integer
    Dim byteEnd(2) As Char

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If Button1.Text = "Connect" Then
            AddHandler SerialPort1.DataReceived, AddressOf DataReceivedHandler
            SerialPort1.Open()
            Button1.Text = "Disconnect"
            Timer1.Enabled = True

        Else
            Button1.Text = "Connect"
            SerialPort1.Close()
            Timer1.Enabled = False
        End If
    End Sub

    Sub DataReceivedHandler(ByVal sender As Object, ByVal e As IO.Ports.SerialDataReceivedEventArgs)
        'byteEnd = SerialPort1.NewLine.ToCharArray
        '   Bytenumber = SerialPort1.BytesToRead
        readBuffer = SerialPort1.ReadLine
        Me.Invoke(New EventHandler(AddressOf DoUpdate))
    End Sub

   Public Sub DoUpdate(ByVal sender As Object, ByVal e As System.EventArgs)
        TextBox1.Text = readBuffer
    End Sub