Questo è il codice dell'applicazione:

codice:
Public Class Form1

    Dim inputData As String = ""
    Dim s As String = ""

    Public Event DataReceived As IO.Ports.SerialDataReceivedEventHandler

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        'Set values for some properties

        SerialPort1.PortName = "COM1"

        SerialPort1.BaudRate = 19200

        SerialPort1.Parity = IO.Ports.Parity.None

        SerialPort1.DataBits = 8

        SerialPort1.StopBits = IO.Ports.StopBits.One

        SerialPort1.Handshake = IO.Ports.Handshake.None

        SerialPort1.RtsEnable = True

        ' Open the Serial Port

        SerialPort1.Open()

        'Writes data to the Serial Port output buffer 

        If SerialPort1.IsOpen = True Then

            SerialPort1.Write("PC Pronto")
            ListBox1.Items.Add("PC Pronto")            
        End If

    End Sub

    ' Receive data from the Serial Port

    Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

        inputData = SerialPort1.ReadExisting 'or SerialPort1.ReadLine

        Me.Invoke(New EventHandler(AddressOf DoUpdate))

    End Sub


    'Show received data on UI controls and do something

    Public Sub DoUpdate()
        s = inputData

        ListBox2.Items.Add(s)
        TextBox1.Text = s
    End Sub


    Private Sub Form1_FormClosed(ByVal sender As System.Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles MyBase.FormClosed

        ' Close the Serial Port

        SerialPort1.Close()

    End Sub


    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        ListBox2.Items.Clear()
    End Sub

    Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
        ListBox1.Items.Clear()
    End Sub
    'Invia testo alla seriale
    
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        If SerialPort1.IsOpen = True Then
            SerialPort1.Write(TextBox2.Text)
            ListBox1.Items.Add(TextBox2.Text)
        Else
            MsgBox("Porta seriale non aperta", vbExclamation)
        End If
    End Sub
End Class