using System.IO.Ports;

string portName = "COM3";

    // Create serial port instance (9600 baud rate is default standard)
    using (SerialPort port = new SerialPort(portName, 9600))
    {
        try
        {
            port.Open();
            Console.WriteLine($"Successfully opened {portName}.\n");

            // --- Step 1: DTR High, RTS Low ---
            Console.WriteLine("Step 1: Setting DTR = HIGH, RTS = LOW");
            port.DtrEnable = true;
            port.RtsEnable = false;
            PrintStatus(port);
            Thread.Sleep(1000);

            // --- Step 2: DTR Low, RTS High ---
            Console.WriteLine("\nStep 2: Setting DTR = LOW, RTS = HIGH");
            port.DtrEnable = false;
            port.RtsEnable = true;
            PrintStatus(port);
            Thread.Sleep(1000);

            // --- Step 3: Both DTR and RTS High ---
            Console.WriteLine("\nStep 3: Setting DTR = HIGH, RTS = HIGH");
            port.DtrEnable = true;
            port.RtsEnable = true;
            PrintStatus(port);
            Thread.Sleep(1000);

            // --- Step 4: Both DTR and RTS Low ---
            Console.WriteLine("\nStep 4: Setting DTR = LOW, RTS = LOW");
            port.DtrEnable = false;
            port.RtsEnable = false;
            PrintStatus(port);
            Thread.Sleep(1000);

            port.Close();
            Console.WriteLine("\nDone. Port closed successfully.");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }


static void PrintStatus(SerialPort port)
{
    // Outputs (driven by PC)
    Console.WriteLine($"  [Driven Outputs] DTR: {port.DtrEnable} | RTS: {port.RtsEnable}");

    // Inputs (read from connected hardware)
    Console.WriteLine($"  [Hardware Inputs] CTS: {port.CtsHolding} | DSR: {port.DsrHolding} | CD: {port.CDHolding}");
}