have a read thru how-to-get-the-best-out-of-this-forum
in particular avoid posting images of code - they waste space, are difficult ro read and imposible to copy a segment of code to test
you C# serialport code looks similar to mine so no idea why it does not work
e.g. my Form1.cs may give you some ideas
using System;
using System.Windows.Forms;
using System.IO.Ports;
namespace CsharpTerminal
{
public partial class Form1 : Form
{
// delegate to transfer received data to TextBox
public delegate void AddDataDelegate(String myString);
public AddDataDelegate myDelegate;
public Form1()
{
InitializeComponent();
this.myDelegate = new AddDataDelegate(AddDataMethod);
// Get a list of serial port names.
string[] ports = SerialPort.GetPortNames();
textBox1.AppendText("The following serial ports were found:");
// Display each port name to the console.
foreach (string port in ports)
{
textBox1.AppendText(" " + port);
ToolStripMenuItem item = new ToolStripMenuItem(port); // create a new menu item
item.Click += comPortsStripMenuItem_Click; // add event handler
comPortsStripMenuItem.DropDownItems.Add(item); // add to the menu of COM ports
}
// scan for COM ports and add to menu item if found
/* for (int port = 0; port <= 20; port++)
{
serialPort1.PortName = "COM" + port.ToString();
try
{
serialPort1.Open(); // attempt to open serial port
serialPort1.BaudRate=115200;
textBox1.AppendText("Found " + serialPort1.PortName + "\n");
Console.WriteLine("serial port open OK {0}", serialPort1.PortName);
serialPort1.Close() ; //open OK, close it
ToolStripMenuItem item = new ToolStripMenuItem(serialPort1.PortName); // create a new menu item
item.Click += comPortsStripMenuItem_Click; // add event handler
comPortsStripMenuItem.DropDownItems.Add(item); // add to the menu of COM ports
}
catch ( Exception ex)
{ Console.WriteLine("serial port open fail {0} ", serialPort1.PortName, ex); }
}
Console.WriteLine("COM ports found {0} ", comPortsStripMenuItem.DropDownItems.Count);
textBox1.AppendText(String.Format("{0} COM ports found - select from COM ports menu\r\n\r\n", comPortsStripMenuItem.DropDownItems.Count));
*/
// if no COM ports were found display message
if(comPortsStripMenuItem.DropDownItems.Count == 0 )
textBox1.AppendText("\r\n No COM ports found\r\n");
else textBox1.AppendText("\r\n Found " + comPortsStripMenuItem.DropDownItems.Count + " COM ports \n");
}
// key on textbox pressed, read key and transmit down serial line
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if(echoOFFToolStripMenuItem.Text == "Echo ON") e.Handled = true; // if echo is off don't display on textbox
if( serialPort1.IsOpen)
serialPort1.Write(e.KeyChar.ToString());
else
textBox1.AppendText("No COM port open" + Environment.NewLine);
}
// data received from serial port - display on textbox
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
//textBox1.AppendText(serialPort1.ReadExisting()); // not thread safe
string s = serialPort1.ReadExisting();
textBox1.Invoke(this.myDelegate, new Object[] { s });
}
// display seral data on textbox
public void AddDataMethod(String myString)
{
textBox1.AppendText(myString);
}
// COM port selected
private void comPortsStripMenuItem_Click(object sender, EventArgs e)
{
try
{
Console.WriteLine("item selected {0} {1}", e.ToString(), sender.ToString());
serialPort1.Close();
serialPort1.PortName = sender.ToString();
serialPort1.Open();
textBox1.AppendText("Opened Port " + sender.ToString() + " baud rate " + serialPort1.BaudRate.ToString() + "\r\n");
Text = "Port " + sender.ToString() + " baud rate " + serialPort1.BaudRate.ToString();
}
catch (Exception e1)
//{ textBox1.AppendText("Failed to open Port " + sender.ToString() + "\r\n" + e1 + "\r\n"); }
{ textBox1.AppendText("Failed to open Port " + sender.ToString() +
"\r\n Is it already open in another program?? \r\n"); }
// serialPort1.RtsEnable = true;
// serialPort1.Handshake = Handshake.RequestToSend;
}
// baud rate selected
private void baudRateToolStripMenuItem_Click(object sender, EventArgs e)
{
Console.WriteLine("item selected {0} {1}", e.ToString(), sender.ToString());
serialPort1.BaudRate = Convert.ToInt32(sender.ToString());
textBox1.AppendText('\n' + " baud rate " + serialPort1.BaudRate.ToString() + '\n');
Text = "Port " + serialPort1.PortName.ToString() + " baud rate " + serialPort1.BaudRate.ToString();
}
// echo selected
private void echoONToolStripMenuItem_Click(object sender, EventArgs e)
{
// invert echo ON/OFF display
if(echoOFFToolStripMenuItem.Text == "Echo ON")
echoOFFToolStripMenuItem.Text = "Echo OFF";
else
echoOFFToolStripMenuItem.Text = "Echo ON";
}
private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
serialPort1.Close();
}
// handshake mode selected
private void handShakeNone(object sender, EventArgs e)
{
serialPort1.Handshake = Handshake.None;
}
private void handShakeRequestToSend(object sender, EventArgs e)
{
serialPort1.Handshake = Handshake.RequestToSend;
}
private void handShakeXonXoff(object sender, EventArgs e)
{
serialPort1.Handshake = Handshake.XOnXOff;
}
private void handShakeRequestXonXoff(object sender, EventArgs e)
{
serialPort1.Handshake = Handshake.RequestToSendXOnXOff;
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
}
}
the code running
I scan the COM ports , list them under Com Ports menu item and then selected COM11
you can see the output of an Arduini Mega