Step 1: Click New Project, then select Visual C# on the left, then Windows and then select Windows Forms Application. Name your project "COM" and then click OK
Step 2: Design your form as below

Step 3: Add code to button click event handler as below
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO.Ports;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace COM
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
//Get all ports
string[] ports = SerialPort.GetPortNames();
cboPort.Items.AddRange(ports);
cboPort.SelectedIndex = 0;
btnClose.Enabled = false;
}
private void btnOpen_Click(object sender, EventArgs e)
{
btnOpen.Enabled = false;
btnClose.Enabled = true;
try
{
//Open port
serialPort1.PortName = cboPort.Text;
serialPort1.Open();
}
catch(Exception ex)
{
MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnSend_Click(object sender, EventArgs e)
{
try
{
if (serialPort1.IsOpen)
{
//Send text to port
serialPort1.WriteLine(txtMessage.Text + Environment.NewLine);
txtMessage.Clear();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnClose_Click(object sender, EventArgs e)
{
btnOpen.Enabled = true;
btnClose.Enabled = false;
try
{
serialPort1.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnReceive_Click(object sender, EventArgs e)
{
try
{
if (serialPort1.IsOpen)
{
//Read text from port
txtReceive.Text = serialPort1.ReadExisting();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
if (serialPort1.IsOpen)
serialPort1.Close();
}
}
}
VIDEO TUTORIALS