Serial data outputs nonsense

[Peter Swinkels]

Hi guys,

I'm attempting at just displaying the raw values from a COM serial port from a sensor, which gives around 4000 rows of data per cycle.

Here's the code:

Imports System
Imports System.IO.Ports
Imports System.Threading

Public Class Form1

    Dim readThread As Thread = New Thread(AddressOf ReadFromCom)
    Dim abortThread As Boolean

    Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        SerialPort2.Open()
        readThread.Start()

    End Sub

    Public Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        With SerialPort2
            .PortName = "COM9"
            .BaudRate = 2000000
            .Parity = Parity.None
            .DataBits = 8
            .StopBits = 1
            .ReadTimeout = Nothing
            .DtrEnable = True
            .RtsEnable = True
        End With
    End Sub

    Public Sub ReadFromCom()

        While abortThread = False
            Try
                Dim message As String = SerialPort2.ReadExisting
                updateStatus("Received: " & message)
            Catch ex As TimeoutException
                updateStatus(ex.ToString)
            End Try
        End While
    End Sub

    Public Delegate Sub updateStatusDelegate(ByVal newStatus As String)

    Public Sub updateStatus(ByVal newStatus As String)
        If Me.InvokeRequired Then
            Dim upbd As New updateStatusDelegate(AddressOf updateStatus)
            Me.Invoke(upbd, New Object() {newStatus})
        Else
            TextBox1.Text = newStatus & vbCrLf & vbCrLf & TextBox1.Text
        End If
    End Sub
End Class

The output textbox gives out a string of ????????? most of the time, sometimes numerical. Sometimes it's nothing.

Anything I should read more into? It seems not many thread discusses this at length so I'm tweaking about other people's code hoping for the best.

Anyhow an independent Python code with MatPlotLib, with the same settings for the serial port outputs the data quite nicely.

Thanks.
Vizier87

Hello Vizier87,

What kind of data are you expecting from that sensor? If it is plain text, your problem might be an encoding issue. If it isn't plain text you probably shouldn't be reading it straight into a string but rather a byte array and display it's contents as a series of hexadecimal values. Try this page: https://social.msdn.microsoft.com/Fo...orum=vbgeneral

yours,
Peter Swinkels

EDIT:
Perhaps you could upload that Python code? It would make understanding the issue easier.