C#

//if you are to set different time intervals?
//say 100ms to ON state and 400ms to OFF state?
//Here is the answer!   ...and the final finished code!

//all other usings +
using System.IO.Ports;

private  SerialPort port = new SerialPort("COM3", 9600, Parity.Odd, 8, StopBits.One);

        public Form1()
        {
            InitializeComponent();  port.Open();
        }


        private void buttonSS_Click(object sender, EventArgs e)
        {
            if (buttonSS.BackColor==Color.Transparent)
            {
                buttonSS.BackColor = Color.GreenYellow; port.DtrEnable = true;
                timer1.Start(); //timer1.Enabled = !timer1.Enabled;
            }
            else
            {
                buttonSS.BackColor = Color.Transparent;port.DtrEnable = false;
                timer1.Stop(); label1ShowPort.Text = "Closed";
            } 
                
            
        }


        
        private void timer1_Tick(object sender, EventArgs e)
        {
            port.DtrEnable = !port.DtrEnable;

            if (port.DtrEnable)
            {
                timer1.Interval = (int)numericUpDown1.Value;
                label1ShowPort.Text = "sending...";
                label1ShowPort.BackColor = Color.OrangeRed;
            }
            else
            {
                timer1.Interval = (int)numericUpDown2.Value;
                label1ShowPort.BackColor = Color.DarkRed;
                label1ShowPort.Text = "";
            }
        }
      




        private void numericUpDown1_ValueChanged(object sender, EventArgs e)
        {
            timer1.Interval = (int)numericUpDown1.Value;
        }

//pin4 and pin5 are the right connections(DTR+Grd) + 
//+ 1k resistor + 1 bright LED.

//                                 ~Teodor~  

idan_bismut wrote:

a bit change on some array that is updated with changes

Qendro wrote:

its not nessesary to do it by writitng code