# GigE Vision Events

**URL:** <https://forum.commonvisionblox.com/t/gige-vision-events/190>\
**Category:** C-style API\
**Tags:** acquisition, genicam, gigevision, c\
**Created:** [August 4, 2017, 8:24am UTC](https://forum.commonvisionblox.com/t/gige-vision-events/190 "2017-08-04T08:24:52Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![parsd](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/parsd/32/7_2.png) [@parsd](https://forum.commonvisionblox.com/u/parsd)\
**Post date:** [August 7, 2017, 9:17am UTC](https://forum.commonvisionblox.com/t/gige-vision-events/190/3 "2017-08-07T09:17:13Z")

</div>

The second way, if the camera’s GenApi node map does not support it, is the :cvb: `INotify` interface:

First we create this harness:

```auto
  IMG hCamera = NULL;
  if(const char *cvbDir = getenv("CVB"))
  {
    char genicamPath[_MAX_PATH] = { 0 };
    snprintf(genicamPath, _MAX_PATH, "%sDrivers\\GenICam.vin", cvbDir);
    hCamera = OpenDriverPort(genicamPath, 0);
  }

  // here we will put the code from below

  ReleaseObject(hCamera);

```

Using `OpenDriverPort` from here:

[https://forum.commonvisionblox.com/t/old-image-broken-after-setting-new-camport/66/5?u=parsd](https://forum.commonvisionblox.com/t/old-image-broken-after-setting-new-camport/66/5)

This code simply opens the first available configured camera and frees it.

If I call this function in the section marked by the comment above:

```auto
void ListINotifyEvents(IMG hCamera)
{
  assert(CanNotify(hCamera));

  size_t numEvents = 0;
  NOGetNumSupported(hCamera, numEvents);
  for(size_t eventIndex = 0; eventIndex < numEvents; ++eventIndex)
  {
    char descriptionBuffer[128] = { 0 }; // this should suffice
    size_t desciptionBufferSize = sizeof(descriptionBuffer);
    CVNotifyEvent_t eventId = -1;
    NOGetDescription(hCamera, eventIndex, descriptionBuffer, desciptionBufferSize, eventId);
    printf("- %s: %i\n", descriptionBuffer, eventId);
  }
}

```

I get the following output (:cvb: 2017/13.00.00x):

- `Disconnect`: 2
- `Reconnect`: 3
- `LinkLoss`: 1000
- `CCPLoss`: 1001
- `DevEvent`: 1003
- `Test`: 10000

What we want here is the `DevEvent` (device event) which then is the GEV event in our case. We also need a callback function:

```auto
void __stdcall CameraEvent(CVNotifyEvent_t eventID, void *pBuffer, size_t bufferSize, CVNotifyDatatype_t bufferDataType, void *pPrivate);

```

which we then register:

```auto
  intptr_t cameraEventToken = -1;
  cvbres_t result = NORegister(hCamera, 1003, &CameraEvent, NULL, cameraEventToken);
  if(result < 0)
    ; // error handling

```

The data delivered via `CameraEvent` is **transport technology dependent**. In case of a GigE Vision event data, the event ID can be found in the second `WORD`:

```auto
void __stdcall CameraEvent(CVNotifyEvent_t eventID, void *pBuffer, size_t bufferSize, CVNotifyDatatype_t bufferDataType, void *pPrivate)
{
  assert(bufferSize >= 4);
  const uint16_t *pWords = reinterpret_cast<const uint16_t *>(pBuffer);
  uint16_t eventId = pWords[1];

  // ...
}

```

So, this is how you can get the event id via `INotify`. I find this a) more complicated and b) it is transport technology dependent. Thus if you have a U3V device, the `pBuffer` interpretation is different.

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