Как управлять Входами RS-232

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.IO;
using System.IO.Ports;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
 
namespace COMPORT
{
    public partial class Form1 : Form
    {
   
        public Form1()
        {
 
            InitializeComponent();
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
           
            serialPort1.RtsEnable = true;
        }
 
        private void button2_Click(object sender, EventArgs e)
        {
            serialPort1.RtsEnable=false;
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
          serialPort1.Open();
        }
 
        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            serialPort1.Close();
        }
 
}
}

var p = new SerialPort(portname, baudrate) { Parity = Parity.None, Handshake = Handshake.None };

byte[] data = new byte[]{1, 2, 3};
p.Write(data, 0, data.Count());

int count = p.BytesToRead;
byte[] data = new byte[count];
int readBytesCount = p.Read(data, 0, count);