Receiving >1 byte over serial

[VBNovice96]

so i have an optris ct IR sensor and you can find the list of commands in this link below
https://www.google.co.uk/url?sa=t&rc...OnGD4-8Yo2Cprg

So I want to send the command 01 and hopefully I will receive "04 D3" if you have a look in the examples section of the pdf above.

I have tried to use the code in the follwing link
http://mikrotronics.blogspot.co.uk/2...VqkH1vrZWHtD8H

However nothing appears in the text box and I'm not sure what is happening

Last thing, when I put in some breakpoints and step into the function and go line by line I get an error message on the line SerialPort1.Write(outdata, 0, 1) in the ScrollDAta_Scroll private function which reads
" Invalid operation exception was unhandled; the port is closed"

Not sure what to do

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

Thanks