C# code fails to read serial input from Arduino - c#-4.0

Question

Hi I am trying to read serial input from my Arduino but I am having no luck. I believe I am opening and closing the connection correctly but do not appear to be having much success!
I'm sure the Arduino is outputting data because I can see it in the serial terminal.
The code for my C# program is below, I was wondering if anyone could spot any mistakes I may have missed.
Also this is an example of the serial data I should receive "12.2,1111,332,233"
namespace FridgeProtectionDeviceMonitor
{
public partial class Online_mode : Form
{
public Online_mode()
{
InitializeComponent();
}
private void Online_mode_Load(object sender, EventArgs e)
{
cmbPortSelection.DataSource = SerialPort.GetPortNames();
cmbChartSelection.SelectedIndex = 0;
}
string x = "";
SerialPort port;
private void btnFindPorts_Click(object sender, EventArgs e)
{
var ports = SerialPort.GetPortNames();
cmbPortSelection.DataSource = ports;
}
private void btnOpenPort_Click(object sender, EventArgs e)
{
if (cmbPortSelection.SelectedIndex > -1)
{
port = new SerialPort(cmbPortSelection.Text);
try
{
if (!port.IsOpen)
{
port.BaudRate = 9600;
port.Open();
}
}
catch (Exception)
{
MessageBox.Show("Serial connection request denied: Port is in use!");
}
}
else
{
MessageBox.Show("Serial connection request denied: No port selected!");
}
}
private void btnClosePort_Click(object sender, EventArgs ex)
{
try
{
port.Close();
}
catch (Exception)
{
MessageBox.Show("Serial close connection request denied: ", ex.ToString());
}
}
private void update(object sender, EventArgs e)
{
txtSaveLocation.Text = x;
}
private void port_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
x = port.ReadLine().ToString();
MessageBox.Show(x);
this.Invoke(new EventHandler(update));
}
}
}

Answer 1

I was just working on the same thing as you, you'll have to modify it if you want to use it for your purposes, but here's the code I use that works. The only problem is that for me I need it to read very quickly because it's for a speedometer and it sort of lags (anyone know why?) but anyways here's my code that works for me.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public void Form1_Load(object sender, EventArgs e)
{
try
{
if (arduinoCom.IsOpen == false)
{
arduinoCom.Open();
}
}
catch
{
MessageBox.Show("Serial Error: Is your serial plugged in?");
}
}
private void refresh_Tick(object sender, EventArgs e)
{
string speedReading = arduinoCom.ReadLine();
speed.Text = speedReading;
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
arduinoCom.Close();
}
}
}

Answer 2

I've got a USB to serial converter linked to an XBee wireless bridge linked to PIC micro-controllers and i've found that running the serial port read functions in a separate thread increases communication speeds something chronic!
The readline blocks the code until the newline character is received, therefore blocking your main thread. Before i moved it to another thread my GUI became un-responsive etc.
By the way I'm using ReadByte().
I'm continuously reading bytes from the serial buffer in a backgroundworker and storing them in a thread safe queue. Then checking the queue for my communication start bits and analyzing the packet from there. Using manual reset events I'm syncing everything.
In my experience the port_datareceived event is a nice addition to the serialport class but unfortunately it is relatively useless for fast communications. I'm running at 12900 baud.
If you want code snippets i can provide them.
Regards,
Pete
P.S. I'm using an ATS5004D 4 channel differential oscilloscope with multichannel software. multichannel software can analyse the voltage signal into serial data through it's built in serial analyzer block. That way you can see what's actually being discussed on the serial comms lines!! cutting out all the BS other serial terminals add...

Answer 3

#michael b I'd start by looking at what the actual communication is doing i.e. scope the TX RX lines to see what the arduino board is putting out. I have only little experience with arduino but its predecessor the PICAXE system had a debug function which slowed everything down heaps, is something like this going on?
How many times per second do you want to update the speedo?
The SAE J1939 automotive serial communication standard says that RPM only needs to be updated once every 100ms. The human eye usually can't see/react faster than 300ms. 9600 baud gives you one 8bit byte per millisecond approx.
Personally I wouldn't use the timer to get the updates and instead do everything on a separate thread from main, and let it run as fast/slow as it wants.
this thread shows you roughly how i've set up my communications System.IO.IOException: A device attached to the system is not functioning C# .NET 4.0
hope it helps,
pete