Hi Guys, this is my first post and below are the description of project in C#, using the basic of SerialPort . I created a program using write and read. With a Texbox you write anything you want and click a button "Send", and this message is send through serial Communication (RS232, RS485, RS422, TTL). Everytime, who the event of timer1 is active, will call the read of portSerial, and will show the message in textbox ( Form1).