Unhandled Exception Null :(

[drancill]

Okay I've managed to figure out its something to do with this subroutine....

I've also shown the DIM's and other headers, as I have a funny feeling I may not of Dim'd correctly as its to do with something reporting as null exception

Any ideas?

Thanks in advance for anyone who can tell me whats wrong!

Imports System.IO.Ports
Imports System.Text
Imports System

Public Class Form1
    Dim comPort As IO.Ports.SerialPort
    Dim returnStr As String = ""
    Dim Incoming As String = ""
    Dim n As Integer
    Dim sn As Integer
    Dim cpnames As System.Object
    Dim uport As String = ""
    Dim uportstate As Integer
    Dim Phnum As String = ""
    Dim ex As String = ""
    Dim sp As String = ""

Sub GetSerialPortNames()
        ' Show all available COM ports.
        uport = ListBox1.Text
        ListBox1.Items.Clear()
        cpnames = My.Computer.Ports.SerialPortNames
        ' MsgBox(uport)
        uportstate = 1
        For Each sp As String In cpnames
            ListBox1.Items.Add(sp)
            'TextBox1.Text &= sp & "--- " & uport & vbCrLf
            If sp = uport Then

                ListBox1.SelectedIndex = ListBox1.Items.Count - 1
                uportstate = 0
            End If

            If sn <> 1 Then
                Try
                    comPort = My.Computer.Ports.OpenSerialPort(sp, 240)
                    sn = 1
                    TextBox1.Text &= vbCrLf & "** OPENING " & sp & " ***" & vbCrLf
                Catch ex As Exception
                    'MsgBox(ex.ToString & " PORT FAIL")
                    TextBox1.Text &= vbCrLf & "** CANNOT OPEN " & sp & " ***" & vbCrLf
                End Try
                TextBox1.SelectionStart = TextBox1.Text.Length
                TextBox1.ScrollToCaret()


            End If
        Next
        If uportstate = 1 Then
            comPort.ReadTimeout = 500
            TextBox1.Text &= vbCrLf & "** CLOSING PORT NO LONGER AVAIL ***" & vbCrLf
            TextBox1.SelectionStart = TextBox1.Text.Length
            TextBox1.ScrollToCaret()
            Try
                ListBox1.SelectedIndex = 0
            Catch
                '
            End Try
            Try
                comPort.Close()
            Catch
                '
            End Try
        End If
    End Sub

 

[Invisionsoft]

What line is the error occuring on?