Windows Forms: Serial Communication in C#

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();
        }
    }
}

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