Sending a double via serial communication from arduino to vb.net application

Question

I'm trying to make an application in vb.net which can read the temperature from an arduino over a serial communication (USB).

I want that it is possible to only read the temperature when a user clicks on a button.

I have posted my code below. When I click on the button 'BtnManueel_Click' I first send a command to the arduino. When the arduino receives this command, it will read the temperature end send it to the PC. This works perfectly when I use a serial monitor. But when I run my application with the code below, I don't get the value in vb.net.

What am I doing wrong and/or why isn't it working?

I don't have much experience with vb.net and serial communication and I was hoping you could help me out with this.

Thanks in advance.

kind regards.

vb.net code:

Imports System
Imports System.IO.Ports
Imports System.Windows.Forms

Public Class Form1
    Dim serielepoort As New SerialPort
    Dim celsius As Double

    Private Sub BtnVerbinden_Click(sender As Object, e As EventArgs) Handles BtnVerbinden.Click
        Try
            serielepoort.PortName = "COM8"
            serielepoort.BaudRate = 9600
            serielepoort.DataBits = 8
            serielepoort.Parity = Parity.None
            serielepoort.StopBits = StopBits.One
            serielepoort.Handshake = Handshake.None
            serielepoort.Encoding = System.Text.Encoding.Default
            serielepoort.ReadTimeout = 10000
            serielepoort.Open()

        Catch ex As Exception

            MessageBox.Show(ex.Message, "fout bij verbinden!", MessageBoxButtons.OK, MessageBoxIcon.Error)

        End Try
    End Sub


    Private Sub BtnVerbindingVerbreken_Click(sender As Object, e As EventArgs) Handles BtnVerbindingVerbreken.Click

        serielepoort.Close()

    End Sub


    Private Sub Form1_FormClosed(sender As Object, e As FormClosedEventArgs) Handles Me.FormClosed

        BtnVerbindingVerbreken_Click(sender, e)

    End Sub


    Private Sub BtnManueel_Click(sender As Object, e As EventArgs) Handles BtnManueel.Click

        If (serielepoort.IsOpen) Then
            serielepoort.Write("t")            
        End If

    End Sub


    Private Sub serialPort_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs)

        celsius = serielepoort.ReadLine()
        LblTempWaarde.Text = celsius

    End Sub

End Class

Code in arduino:

nt pinLM335 = 0;


void setup() 
{
  Serial.begin(9600);

}

void loop() {
  if(Serial.available() >0)
  {
   String val = Serial.readStringUntil('\n');
   if (val == "t")
   { int waarde = analogRead(pinLM335);
   double spanning =(waarde / 1024.0)*5;
   double Kelvin = (spanning) * 1000 / 10;
   double celsius = Kelvin - 273.15;

   Serial.println(celsius);
  }
  }

}

Mikes3ds Mikes3ds · Accepted Answer · 2016-04-08T17:19:11

Try this, and see if you get any data when constantly sending? Then add the post.

Imports System
Imports System.IO.Ports
Class PortDataReceived
    Public Shared Sub Main()
        Dim mySerialPort As New SerialPort("COM1")

        mySerialPort.BaudRate = 9600
        mySerialPort.Parity = Parity.None
        mySerialPort.StopBits = StopBits.One
        mySerialPort.DataBits = 8
        mySerialPort.Handshake = Handshake.None
        mySerialPort.RtsEnable = True

        AddHandler mySerialPort.DataReceived, AddressOf DataReceivedHandler

        mySerialPort.Open()

        Console.WriteLine("Press any key to continue...")
        Console.WriteLine()
        Console.ReadKey()
        mySerialPort.Close()
    End Sub

    Private Shared Sub DataReceivedHandler(
                        sender As Object,
                        e As SerialDataReceivedEventArgs)
        Dim sp As SerialPort = CType(sender, SerialPort)
        Dim indata As String = sp.ReadExisting()
        Console.WriteLine("Data Received:")
        Console.Write(indata)
    End Sub
End Class

Sending a double via serial communication from arduino to vb.net application

1 Answers