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18/12/2017 by Kvaser

Kvaser Leaf Light V2 w/ CAN Callbacks in C# (.NET)

I have developed a suite of applications designed to use a USB CAN interface and have adapted the CAN interface to work with a few different USB CAN adapters for testing/evaluation to see which is the most robust and reliable in the long run.

One quirk I am running into with the CANlib SDK is when reading CAN frames using the Canlib.canRead call, I am receiving duplicate frames in my callback function.

I have setup my callback function like so:

private void GetDataCallback(int handle, IntPtr context, UInt32 notifyEvent)
{
if (notifyEvent == Canlib.canNOTIFY_RX)
{
_mutex.WaitOne();
byte[] data = new byte[8];

while (Canlib.canRead(handle, out int id, data, out int dlc, out int flags, out long timestamp) == Canlib.canStatus.canOK)
{
CanRxService.Instance.QueueFrame(new CanFrame((uint)id, data, (byte)dlc, flags));
//Thread.Sleep(1);
}
_mutex.ReleaseMutex();
}
}

Note: _mutex is a, you guessed it, Mutex

It seems the issue occurs less when I include the call to Thread.Sleep but it still isn’t quite consistent. Another CAN-USB adapter I am using supports callbacks and I don’t have this issue at all.

Is this the proper way to read data from the callback function, or should I just read one CAN frame each time the callback function is called or what?

In every other way, this CAN USB adapter is the most reliable, aside from this one issue which seems rather sporadic.

On a side note, I also can’t get the acceptance filter to work:

This does not work:
Canlib.canSetAcceptanceFilter(_handle, ((Can.BOARD_ID_MASTER << 21) | (Can.NODE_ID_MASTER << 17)), 0x1FF0000, 1);

This does work (doing it myself in software):
if ((id & 0x1FF0000) != ((Can.BOARD_ID_MASTER << 21) | (Can.NODE_ID_MASTER << 17))) continue;

Thanks and best regards,
– Rick

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