Serial xfer of data

static bool cancel = false;
        static void sendFile(string fileName, string portName, int baudRate, int lineDelay)
        {
            using (SerialPort serialPort = new SerialPort(portName, baudRate))
            {
                StreamReader stream = new StreamReader(new MemoryStream(File.ReadAllBytes(fileName)));

                serialPort.Open();
                while (!cancel)
                {
                    stream.BaseStream.Seek(0, SeekOrigin.Begin);    // start from the beginning

                    while (!stream.EndOfStream)
                    {
                        string line = stream.ReadLine();
                        if (line != null)
                        {
                            serialPort.Write(line);
                            System.Threading.Thread.Sleep(lineDelay);
                        }
                    }
                }
                serialPort.Close();
            }
        }

port.Handshake = Handshake.RequestToSend;