View source for UsbRegisterChangeNotification

==Description==
Registers semaphores for generic attach/detach notification of USB devices.

==Syntax==
<pre>
ulrc = UsbRegisterChangeNotification(pNotifyID,hDeviceAdded,hDeviceRemoved)
</pre>

==Parameters==
; pNotifyID : the address of the variable to receive the Notification Identifier.

; hDeviceAdded : the handle of the event semaphore to be posted on device attach.

; hDeviceRemoved : the handle of the event semaphore to be posted on device detach.

==Return Code==
<pre>
0x0000 - NO_ERROR
</pre>
===Errors===
<pre>
0x0006 - ERROR_INVALID_HANDLE
0x0057 - ERROR_INVALID_PARAMETER
0x005F - ERROR_INTERRUPT
0x0067 - ERROR_TOO_MANY_SEM_REQUESTS
0x0069 - ERROR_SEM_OWNER_DIED
0x1B58 - USB_NOT_INIT
0x1B59 - USB_ERROR_NO_MORE_NOTIFICATTIONS
0xFF06 - ERROR_INVALID_HANDLE
0xFF1F - ERROR_GEN_FAILURE
0xFF57 - ERROR_INVALID_PARAMETER
0xFF64 - ERROR_TOO_MANY_SEMAPHORES
</pre>
==Remarks==

==Example Code==
<pre>
//Code Snippet - UsbRegisterChangeNotification
{
  APIRET ulrc;
  HEV hDeviceAdded;
  HEV hDeviceRemoved;
  PHEV phDeviceAdded;
  PHEV phDeviceRemoved;
  PUSBNOTIFY pNotifyID;
  ULONG ulTimeout = 8000;
  USBNOTIFY NotifyID;

  //acquire semaphores
  phDeviceAdded = &hDeviceAdded;
  ulrc = DosCreateEventSem(NULL,phDeviceAdded,DC_SEM_SHARED,FALSE);
  printf("\nDosCreateEventSem - ulrc: 0x%04X (%hu)",ulrc,ulrc);
  phDeviceRemoved = &hDeviceRemoved;
  ulrc = DosCreateEventSem(NULL,phDeviceRemoved,DC_SEM_SHARED,FALSE);
  printf("\nDosCreateEventSem - ulrc: 0x%04X (%hu)",ulrc,ulrc);

  pNotifyID = &NotifyID;
  ulrc = UsbRegisterChangeNotification(pNotifyID,hDeviceAdded,hDeviceRemoved);
  printf("\nUsbRegisterChangeNotification - ulrc: 0x%04X (%hu)",ulrc,ulrc);

  //await attach device event
  ulrc = DosWaitEventSem(hDeviceAdded,ulTimeout);
  printf("\nDosWaitEventSem - ulrc: 0x%04X (%hu)",ulrc,ulrc);
  if (!ulrc) //success
  {
    printf(" - obtained Attach Notification");
  }

  //await detach device event
  ulrc = DosWaitEventSem(hDeviceRemoved,ulTimeout);
  printf("\nDosWaitEventSem - ulrc: 0x%04X (%hu)",ulrc,ulrc);
  if (!ulrc) //success
  {
    printf(" - obtained Detach Notification");
  }
}
</pre>

==Related Functions==
* [[UsbRegisterDeviceNotification]]
* [[UsbDeregisterNotification]]
* [[UsbOpen]]

[[Category:USBCalls]]