With this sample code, you can identify the available serial port on the PC. Running a ForEach iteration on the SerialPortNames property in vb.net and GetPortNames method in C#.

Sample code for C#:

private void BtnFindSerialPort_Click(object sender, EventArgs e)
{
     foreach (string ports in System.IO.Ports.SerialPort.GetPortNames())
     {
         MessageBox.Show("Serial port avialible" + " " + ports);
     }
}