RKS+CAN for CAN sniffing and sending

Hello,

I'm starting a new project related to vehicles again, and this time it involves the CAN bus .

First of all, the question is: how can I even sniff the CAN bus?

In my Audi A6 4F test vehicle, I want to monitor the data being transmitted on the CAN bus and potentially send my own commands. Is this possible using a RKS+CAN USB interface? What other options do I have for sniffing the CAN bus? Are there pre-built controllers that can be connected "in between"? I'm particularly interested in what exactly happens when the vehicle is turned off, and the telestart module activates the auxiliary heater.
I can't quite imagine that all the CAN buses are connected to the diagnostic connector, or that the CAN gateway outputs everything through the diagnostic port. Are the individual CAN systems (e.g., powertrain, comfort) physically separated and "routed" via the gateway, or are all CAN buses fundamentally present at every point in the system and simply tagged with IDs and filtered accordingly?

My goal is first to better understand; in the distant future, I might build something beautiful, but for now, I'm going to do some "research" .

Hello,

Quote:

Kann mir irgendwie nicht vorstellen, das auf dem Diagnose-Anschluss alle CAN anliegen bzw. das das CAN-Gateway alles über den Diagnoseport ausgibt.

The RKS+CAN has an OBD2 connector because it allows you to use it for other things on the OBD2 port (diagnostic port) without needing a separate adapter or connector.
Die meisten CAN-Sniffer haben einen SUB-D9 Anschluss, was im Hinblick auf den Diagnoseport recht sinnlos ist. Zum Anschluss am fahrzeuginternen CAN (oder einer Maschine etc.) braucht man dann sowieso einen zusätzlichen Anschlussstecker und ob das ein SUB-D9 oder eine OBD2-Buchse ist, spielt dann ja auch nicht wirklich eine Rolle.

Quote:

Are the individual CAN systems (drive, comfort, etc.) physically separated and are they routed through the gateway?

For the Audi A6 4F: yes. You can find the diagnostic gateway by removing the glove compartment (the procedure is the same as when replacing the pollen filter), located in the upper right corner. All CAN buses are connected there.

Best regards, Rainer.