Set up serial port and write string to it : COM Port SerialPort : Development C# Examples

    
using  System;
using  System.IO.Ports;

static  class  MainClass
{
        static  void  Main(string[]  args)
        {
                using  (SerialPort  port  =  new  SerialPort("COM1"))
                {
                        //  Set  the  properties.
                        port.BaudRate  =  9600;
                        port.Parity  =  Parity.None;
                        port.ReadTimeout  =  10;
                        port.StopBits  =  StopBits.One;

                        //  Write  a  message  into  the  port.
                        port.Open();
                        port.Write("Hello  world!");

                        Console.WriteLine("Wrote  to  the  port.");
                }
        }
}