New here: CAN beginner with a basic question.

Hello everyone, I'm the new one here ).

I don't have much technical knowledge about the CAN bus topic, so I'd like to learn more here.

I am familiar with various systems (e.g., drive, comfort, etc.) and I know that they differ in terms of voltages and speeds. I also know what is dominant and recessive ).
Well, they have some basic knowledge...

I have also made several modifications and connected to the CAN bus, and everything seems to be working fine so far.

I have a question about that.

If I install another CAN control unit (let's say, an AHK) and the control unit is already programmed, then everything should work fine right away (the lights).
That means the SG (Sensor Gateway) is already working on the CAN bus.

Could someone please explain to me why the steering gear (SG) is always adjusted using an SCN or SVM code (e.g., can ESP or the motor steering gear still use the information on the bus from the trailer steering gear (AHK SG))?

Why does a retrofitted SG need to be registered with the gateway, especially since communication is already working (and this is not related to the previous question)?


Sure, no problem.

Looking forward to a great collaboration.

Best regards,
Micha

Hi Micha,

The information that a control unit makes available on the bus is generally valid for the CAN system. This means that, in principle, all participants in a network can see and work with this information. However, since not all information is relevant to every participant, filters are used in the CAN system. Therefore, all information is present on the CAN bus, but a control unit filters out the CAN messages that it actually needs.

If you want to retrofit a trailer control module, for example, the instrument cluster needs to know that the trailer indicator light needs to be activated. The lighting control module needs to know that there are two additional turn signals. The rear fog light may need to be disabled on the towing vehicle, etc. Regardless of the information, the control modules need to know what to do. This is achieved by programming the control modules. I'm happy to explain it to the interns; it's kind of like when a new feature is unlocked in an app (like in-app purchases).

Registration with the gateway is required for network management. Because the CAN bus is subject to certain rules that vary depending on the "operating system" (OSEK, AUTOSAR, etc.), all bus participants, for example, must connect to form a ring in an OSEK environment. This is the only way to detect the failure of a bus participant (due to a missing "alive" message). In AUTOSAR, it is crucial that all bus participants register at least with their `RepeateMessageTime` after bus start. This allows them to use their Network Management ID (NM_ID) to determine which participant maintains network management during bus load reduction.

Another reason is that this approach can prevent the arbitrary installation of aftermarket solutions. For example, if the manufacturer, such as Porsche, does not allow a trailer hitch to be installed on a 911, simply prevent the corresponding coding from being enabled.

Sure, here is the translation of the text from German to English:

"cu Postmann"

Hello mailman...

Thank you for your great answer.

How can I get a more precise understanding of what network management is?

Are these specific rules that EVERY CAN bus has, and are there different "management" systems for them?

Could you please send me a link to a resource where I, as a beginner, can read about this in a way that is easy to understand?

I still don't fully understand the real meaning of the build list encoding in the gateway.

I would appreciate any information.

Best regards,
Micha