Private WithEvents objPort As SerialPort
 
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
  Handles MyBase.Load
 
objPort = New SerialPort("COM3", 9600)
 
objPort.ReceivedBytesThreshold = 1024
 
objPort.Open()
 
End Sub
 
Private Sub objPort_DataReceived(ByVal sender As Object, ByVal e As _
  System.IO.Ports.SerialDataReceivedEventArgs) Handles objPort.DataReceived, _
  SerialPort.DataReceived
 
Dim strSerialPortData As String = objPort.ReadExisting
 
End Sub
 
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button2.Click
 
Dim strSerialPortData As String = objPort.ReadExisting
 
textBox1.Text = strSerialPortData
 
End Sub
 
 
End Class