Ora funziona.. Cioè facendo la readline in questo modo non capisco cosa mi restituisce, cioè quale riga mi resituisce.

Come faccio a digli quale prendere?? Cioè la risposta al comando AT (inquesto caso)

codice:
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim readThread As Thread = New Thread(AddressOf Read)


        ' Set the read/write timeouts
        SerialPort1.ReadTimeout = 500
        SerialPort1.WriteTimeout = 500

        SerialPort1.WriteLine("AT" & vbCrLf)

        readThread.Start()
    End Sub

    Public Sub Read()
            Try
                Dim message As String = SerialPort1.ReadLine()
            MessageBox.Show(message)
            Catch ex As TimeoutException
                ' Do nothing
            End Try
    End Sub