How to catch the return of a serial port after sending a command? The return is OK. How do i read?
I tried using readLine () and ReadExisting () did not work.

```
        serialPort.PortName = "COM1";
            serialPort.BaudRate = 115200;
            serialPort.Open();
            if (serialPort.IsOpen)
            {
                // Send command
                serialPort.Write("at");

                // string data = portaSerial.ReadLine();

                // Close serial port
                serialPort.Close();
            }

```