Debasish Das Gupta Debasish Das Gupta - 1 month ago 18
Vb.net Question

How to detect gsm modem using vb.net

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

Answer

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.