Displaying raw data hex-bytes from SerialPort.DataReceived method

Hi,
how can I display data, I received on SerialPort, in a raw hex byte format ?

It took me several approaches to convert the data basically, but there still seems to be an ASCII / UTF7 / UTF8 problem. I am now using a byte array instead of a former char-array, but still I don't get any value larger than 127 dec (0x7F). When sending decimal 128, I receive 0x3F on RX-Side.

Here's the current DataReceiveHandler:

 void PortBDataReceived(object sender, SerialDataReceivedEventArgs e)

        {

            Thread.Sleep(200);

            string bytestr = "";

            bytestr = _portB.ReadExisting();

            bytestr = bytestr.Replace("\r", "");

            UTF8Encoding utf = new UTF8Encoding();           

            byte[] myarray = utf.GetBytes(bytestr);           

            string hexvalues = "";

            foreach (byte b in myarray)

            {

                hexvalues = hexvalues + (b.ToString("X2")) + " ";

            }

            UpdGuiEvent.Invoke(hexvalues);

        }

Does anybody know how to display the hex values for incoming bytes from 0x80 up to 0xFF ?

OK, I guess I got it.
I have to use

public int ReadByte() instead of public string ReadExisting()

Here's the code:

void PortBDataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            Thread.Sleep(200);
            string bytestr = "";

            int numbytes = _portB.BytesToRead;
            byte[] rxbytearray = new byte[numbytes];

            for(int i = 0; i             {
                rxbytearray[i] = (byte)_portB.ReadByte();
            }

            string hexvalues = "";
            foreach (byte b in rxbytearray)
            {
                if(b != '\r')
                hexvalues = hexvalues + (b.ToString("X2")) + " ";
            }
            UpdGuiEvent.Invoke(hexvalues);
        }