using System.IO.Ports
 
namespace Test
{
     class SerialPortTest
     {
          public SerialPortTest()
          {
               // com port("COM1") , baud rate, parity bit, number of bits for data , stop bits 
               SerialPort serialPort = new SerialPort(comPort,9600,Parity.None, 8, StopBits.One);
               serialPort.open();
 
               byte[] temp = new byte[1];
               temp[0] = 0;
               //the data in a byte array to write,starting index in the array, the size of the array in bytes
               serialPort.Write(temp,0,1);
          }
     }
}