Very basic VB.Net & Serial IO issue - vb.net

Question

After searching around I am still having issues with reading data from a serial port in VB.Net/VS2010. I know the Serial Port works, I can write to the port fine but when reading from it, nothing happens. I have only been programming for the last 3 weeks so am still trying to get my head around it all.
The program must run to capture data from a door logger, I will then be outputting the data to a database (not yet implemented - I want to get this part sorted first).
I have tried using several terminal programs as well as another device which outputs data onto the serial line, with nothing displaying in the textbox tbxIn.
Any help would be greatly appreciated.
Code is below:
Imports System.IO.Ports
Imports System.IO.Ports.SerialPort
Public Class Form1
Dim comPort As IO.Ports.SerialPort = Nothing
Dim sComPort As String = ""
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
GetSerialPortNames()
End Sub
Sub GetSerialPortNames()
' Show all available COM ports.
For Each sp As String In My.Computer.Ports.SerialPortNames
lstPorts.Items.Add(sp)
Next
End Sub
Private Sub lstPorts_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstPorts.SelectedIndexChanged
sComPort = lstPorts.SelectedItem
Button1.Enabled = True
End Sub
Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
' Open the serial port using the OpenSerialPort method
Button1.Enabled = False
Button2.Enabled = True
Try
comPort = My.Computer.Ports.OpenSerialPort(sComPort, 9600, IO.Ports.Parity.None, 8, 1)
' comPort.DtrEnable = True
comPort.ReadTimeout = 500
Do
comPort.WriteLine("Go")
Dim sIncomming As String = comPort.ReadLine()
tbxIn.Text = sIncomming & vbCrLf
Loop
Catch ex As TimeoutException
tbxIn.Text &= "Error: Serial Port Read Timeout" & vbCrLf
End Try
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
comPort.Close()
Button1.Enabled = True
Button2.Enabled = False
End Sub
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
tbxIn.Text = e.ToString
End Sub
End Class

Answer 1

PRetty sure this will get you what you need. You DON't need the Serial1 component on the designer. Remove that and use this code:
Private comPort As IO.Ports.SerialPort = Nothing
Private sComPort As String = ""
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)
GetSerialPortNames()
End Sub
Sub GetSerialPortNames()
' Show all available COM ports.
For Each sp As String In My.Computer.Ports.SerialPortNames
lstPorts.Items.Add(sp)
Next
End Sub
Private Sub lstPorts_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstPorts.SelectedIndexChanged
sComPort = lstPorts.SelectedItem
Button1.Enabled = True
End Sub
Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
' Open the serial port using the OpenSerialPort method
Button1.Enabled = False
Button2.Enabled = True
Try
comPort = My.Computer.Ports.OpenSerialPort(sComPort, 9600, IO.Ports.Parity.None, 8, 1)
' comPort.DtrEnable = True
'must add handler
AddHandler comPort.DataReceived, AddressOf SerialPort1_DataReceived
comPort.ReadTimeout = 500
Do
comPort.WriteLine("Go")
Dim sIncomming As String = comPort.ReadLine()
tbxIn.Text = sIncomming & vbCrLf
Loop
Catch ex As TimeoutException
tbxIn.Text &= "Error: Serial Port Read Timeout" & vbCrLf
End Try
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
comPort.Close()
'remove handler
RemoveHandler comPort.DataReceived, AddressOf SerialPort1_DataReceived
Button1.Enabled = True
Button2.Enabled = False
End Sub
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs)
tbxIn.Text = e.ToString
End Sub