Как преобразовать Hex в ASCII на основе этого кода?

Основной вопрос здесь Как вывести вес с весов в текстовое поле через последовательный порт RS-232 или usb-конвертер?

Теперь я пытаюсь получить шестнадцатеричное значение, преобразовать его в ascii и отобразить.

Основной код это

public partial class MainForm : Form
{
    private SerialPort _serialPort; // formda kullanilacak degisken
    private const int BaudRate = 9600; // BaudRate Constant. default 9600 ile oynanabilir 
    public MainForm()
    {
        InitializeComponent();
    }

    private void MainForm_Load(object sender, EventArgs e)
    {
        this.MinimizeBox = false;
        string[] portNames = SerialPort.GetPortNames(); // bütün kullanilabilecek com portlari okur
        foreach (var portName in portNames)
        {
            comboBox1.Items.Add(portName); // Adds Ports to combobox
        }
        if (comboBox1.SelectedIndex != -1)
        {
            comboBox1.SelectedIndex = 0; // Selects first entry (convenience purposes)
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        // This block ensures that no exceptions happen
        if (_serialPort != null && _serialPort.IsOpen)
            _serialPort.Close();
        if (_serialPort != null)
            _serialPort.Dispose();
        // End of Block

        _serialPort = new SerialPort(comboBox1.Text, BaudRate, Parity.None, 8, StopBits.One);  //<-- Creates new SerialPort using the name selected in the combobox

        _serialPort.DataReceived += SerialPortOnDataReceived; //<-- this event happens everytime when new data is received by the ComPort
        _serialPort.Open(); //<-- make the comport listen
        textBox1.Text = string.Format("Listening on {0}...", comboBox1.Text);

    //here i am trying @Adam Casey 's code and serialReceived thing doesn't work.
         byte[] serialReceived;
         string reading = Encoding.UTF8.GetString(serialReceived);
         textBox2.Text = reading.Substring(13);
    }
    private delegate void Closure();
    private void SerialPortOnDataReceived(object sender, SerialDataReceivedEventArgs serialDataReceivedEventArgs)
    {
        if (InvokeRequired)     //<-- Makes sure the function is invoked to work properly in the UI-Thread
            BeginInvoke(new Closure(() => { SerialPortOnDataReceived(sender, serialDataReceivedEventArgs); }));     //<-- Function invokes itself
        else
        {
            while (_serialPort.BytesToRead > 0) //<-- repeats until the In-Buffer is empty
            {
                textBox1.Text += string.Format("{0:X2} ", _serialPort.ReadByte()); //<-- bytewise adds inbuffer to textbox
            }
        }
    }