<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> System.IO.Ports.SerialPort SerialPort1 = new System.IO.Ports.SerialPort(); protected void Page_Load(object sender, EventArgs e) { this.SerialPort1.PortName = "COM1"; if (!this.SerialPort1.IsOpen) { this.SerialPort1.Open(); } this.SerialPort1.Write("Hello World"); this.SerialPort1.Close(); } </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <div> </div> </form> </body> </html>