How to read more than 1 bytes from serial port

 Dim outData As Byte() = New Byte(0) {}

Private Function HextoByte(ByVal msg As String) As Byte()
        msg = msg.Replace(" ", "")

        Dim combuffer As Byte() = New Byte(msg.Length \ 2 - 1) {}
        For i As Integer = 0 To msg.Length - 1 Step 2
            combuffer(i \ 2) = CByte(Convert.ToByte(msg.Substring(i, 2), 16))
        Next

        Return combuffer
    End Function

Private Function BytetoHex(ByVal comByte As Byte()) As String
        Dim builder As New StringBuilder(comByte.Length * 3)
        For Each data As Byte In comByte
            builder.Append((Convert.ToString(data, 16).PadLeft(2, "0")))
        Next
        Return builder.ToString().ToUpper()
    End Function

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lblDataValue.Text = ScrollData.Value.ToString()
        ScrollData.Enabled = False
        ScrollData.Maximum = 255
        ScrollData.LargeChange = 1
        btnDisconnect.Enabled = False
        tbRx.Text = "00"

        Dim Portnames as String() = SerialPOrt.GetPortNames
        IF Portnames is nothing then
            msgbox("No ports detected")
            me.close()
        End If
        cbComPort.Items.AddRange(Portnames)
        cbComPort.Text = Portnames(0)
    End Sub

Private Sub btnConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnect.Click

        outData(0) = Convert.ToByte(lblDataValue.Text)

        Try
            SerialPort1.PortName = cboCOMPorts.Items(cboCOMPorts.SelectedIndex).ToString()
            SerialPort1.BaudRate = 9600
            SerialPort1.Open()
            SerialPort1.Write(outData, 0, 1)
            btnDisconnect.Enabled = True
            ScrollData.Enabled = True
            btnConnect.Enabled = False
        Catch ex As Exception
            btnDisconnect.PerformClick()
        End Try
    End Sub

 Private Sub btnDisconnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisconnect.Click
        Try
            SerialPort1.DiscardInBuffer()
            SerialPort1.DiscardOutBuffer()
            SerialPort1.Close()
            ScrollData.Value = 0
            ScrollData.Enabled = False
            btnConnect.Enabled = True
            btnDisconnect.Enabled = False
        Catch ex As Exception

        End Try
    End Sub

Private Sub ScrollData_Scroll(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ScrollEventArgs) Handles ScrollData.Scroll
        lblDataValue.Text = ScrollData.Value.ToString("X")

        outData(0) = Convert.ToByte(ScrollData.Value)
        SerialPort1.Write(outData, 0, 1)
    End Sub

Private Delegate Sub DisplayDelegate(ByVal displayChar As String)

    Private Sub DisplayCharacter(ByVal displayChar As String)
        tbRx.Text = displayChar
    End Sub

    Private Sub serialPort1_DataReceived(ByVal sender As Object, ByVal e As SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        Dim rx As Integer
        rx = SerialPort1.BytesToRead
        Dim comBuff As Byte() = New Byte(rx - 1) {}
        SerialPort1.Read(comBuff, 0, rx)
        tbRx.Invoke(New DisplayDelegate(AddressOf DisplayCharacter), New Object() {BytetoHex(comBuff)})
    End Sub