//Add the NameSpace fo serialPort
using System.Io.ports;
Write the below code in a Button Click :-
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SerilaPort sp=new SerialPort();
sp.PortName="COM1";
sp.BaudRate=9600
sp.DataBits=8;
sp.Open();
textWieght.Text=sp.ReadLine().ToString();
sp.Close();By the help of this code you can connect port in windows application.
