how to trigger event when a com device is connected in c#
/*
Headers to be used:-
using System;
using System.Runtime.InteropServices;
*/
public Form1()
{
InitializeComponent();
UsbNotification.RegisterUsbDeviceNotification(this.Handle);
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == UsbNotification.WmDevicechange)
{
switch ((int)m.WParam)
{
case UsbNotification.DbtDeviceremovecomplete:
Usb_DeviceRemoved(); // this is where you do your magic
break;
case UsbNotification.DbtDevicearrival:
Usb_DeviceAdded(); // this is where you do your magic
break;
}
}
}
internal static class UsbNotification
{
public const int DbtDevicearrival = 0x8000; // system detected a new device
public const int DbtDeviceremovecomplete = 0x8004; // device is gone
public const int WmDevicechange = 0x0219; // device change event
private const int DbtDevtypDeviceinterface = 5;
private static readonly Guid GuidDevinterfaceUSBDevice = new Guid("A5DCBF10-6530-11D2-901F-00C04FB951ED"); // USB devices
private static IntPtr notificationHandle;
/// <summary>
/// Registers a window to receive notifications when USB devices are plugged or unplugged.
/// </summary>
/// <param name="windowHandle">Handle to the window receiving notifications.</param>
public static void RegisterUsbDeviceNotification(IntPtr windowHandle)
{
DevBroadcastDeviceinterface dbi = new DevBroadcastDeviceinterface
{
DeviceType = DbtDevtypDeviceinterface,
Reserved = 0,
ClassGuid = GuidDevinterfaceUSBDevice,
Name = 0
};
dbi.Size = Marshal.SizeOf(dbi);
IntPtr buffer = Marshal.AllocHGlobal(dbi.Size);
Marshal.StructureToPtr(dbi, buffer, true);
notificationHandle = RegisterDeviceNotification(windowHandle, buffer, 0);
}
/// <summary>
/// Unregisters the window for USB device notifications
/// </summary>
public static void UnregisterUsbDeviceNotification()
{
UnregisterDeviceNotification(notificationHandle);
}
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr RegisterDeviceNotification(IntPtr recipient, IntPtr notificationFilter, int flags);
[DllImport("user32.dll")]
private static extern bool UnregisterDeviceNotification(IntPtr handle);
[StructLayout(LayoutKind.Sequential)]
private struct DevBroadcastDeviceinterface
{
internal int Size;
internal int DeviceType;
internal int Reserved;
internal Guid ClassGuid;
internal short Name;
}
}