Get List of Connected Ports using C# .Net

Here I have created sample that will help you out.

HTML

<div>
    <asp:DropDownList ID="ddlDevices" runat="server">
    </asp:DropDownList>
</div>

C#

protected void Page_Load(object sender, EventArgs e)
{
    List<USBDeviceInfo> devices = GetUSBDevices();
    ddlDevices.DataSource = devices;
    ddlDevices.DataTextField = "DeviceID";
    ddlDevices.DataValueField = "DeviceID";
    ddlDevices.DataBind();
}

public static List<USBDeviceInfo> GetUSBDevices()
{
    List<USBDeviceInfo> devices = new List<USBDeviceInfo>();

    ManagementObjectCollection collection;
    using (var searcher = new ManagementObjectSearcher(@"Select * From Win32_USBHub"))
        collection = searcher.Get();
    foreach (var device in collection)
    {
        devices.Add(new USBDeviceInfo()
        {
            DeviceID = (string)device.GetPropertyValue("DeviceID"),
            DeviceDescription = (string)device.GetPropertyValue("Description"),
            PnpDeviceID = (string)device.GetPropertyValue("PNPDeviceID")
        });
    }
    collection.Dispose();
    return devices;
}

USBDeviceInfo class

public class USBDeviceInfo
{
    public string DeviceID { get; set; }
    public string DeviceDescription { get; set; }
    public string PnpDeviceID { get; set; }
}

Screenshot