How to detect gsm modem using vb.net

Question

I am a newbee in vb.net. Want to know how to get port of a connected gsm modem programmatically using vb.net

Dim MgmtSearch As ManagementObjectSearcher

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    For Each queryObj As ManagementObject In MgmtSearch.Get()
        If queryObj("Status") = "OK" Then
            ListBox1.Items.Add(queryObj("Description"))
        End If
    Next
End Sub

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
    MgmtSearch = New ManagementObjectSearcher("root\\CIMV2", "SELECT * FROM Win32_POTSModem ")
End Sub

The above code I am using but getting An unhandled exception of type 'System.NullReferenceException' occurred in Serial Port Project.exe error when clicking button.

I am using Dlink Modem and vb.net 2015

Read this article for help on debugging null reference exceptions. http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it. — FloatingKiwi, Oct 23 '16 at 08:25
i know what the error means,but need to know the cause of such errors... — Debasish Das Gupta, Oct 23 '16 at 10:04
Then read the section on debugging. If you need more help then let us know which line the exception occurs on. — FloatingKiwi, Oct 23 '16 at 10:09
For Each queryObj As ManagementObject In MgmtSearch.Get() ---line generates the error — Debasish Das Gupta, Oct 23 '16 at 10:11

score 1 · Accepted Answer · answered Oct 23 '16 at 10:21

1

This line is failing on my machine with an "Invalid Parameters" exception:

MgmtSearch = New ManagementObjectSearcher("root\\CIMV2", "SELECT * FROM Win32_POTSModem ")

This is due to the double slash replace it with "root\CIMV2" instead and it will start working.

I'm not sure how the form continued to load after this exception occurred but the result is that MgmtSearch is null.

answered Oct 23 '16 at 10:21

FloatingKiwi

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Here's some info on why it's not catching that exception: http://stackoverflow.com/questions/4933958/vs2010-does-not-show-unhandled-exception-message-in-a-winforms-application-on-a/4934010#4934010 – FloatingKiwi Oct 23 '16 at 10:24

How to detect gsm modem using vb.net

1 Answers1