Airbag sensor signals CAN bus

Hello,

Do you think it's possible to extract the signals from the airbag sensors from the CAN(OPEN) data stream of a Golf 3 and determine which sensor triggered?
Safety.......
With CANviewer? I need this for my final thesis.
I want to install an Engine Control Unit (ECU), Anti-lock Braking System (ABS), and build a small vehicle network.
What hardware would you recommend...?
Best regards.

lf99

Hello,

I would be surprised if the airbag system in a Volkswagen Golf 3 was connected to the CAN bus.

hi,

What is the AirSTG attached to?
Does it have its own power supply circuit?
What is connected to the CAN bus in a Golf 3?

Thank you!

lf99

lifefun99 wrote:

hi, What is the AirSTG attached to? Does it have its own power supply circuit? What is connected to the CAN bus in a Golf 3? Thank you! lf99

Hello.

It should be a standard LIN bus, meaning a single-wire or signal line.

The Volkswagen Golf 3 does not have a CAN-bus system installed.



Best regards, Cosi.

Yepp - G3 does not have CAN (Controller Area Network) functionality. LIN, but also not

The control units are connected via the standard ISO 9141 interface.
together.

Best regards,
Rudi

Hi,

At the very least, the destination is encoded in the CAN identifier. You are very unlikely to find the sender here. Otherwise, the acceptance mask wouldn't work. (At least with the SJA1000, it only applies to the identifier.)
So, it seems like the sender is somehow encoded within the user data bytes.
Since you can view the entire message byte by byte with a CAN sniffer, you should theoretically be able to identify the sender. This is likely the case, assuming it's implemented that way. Since the recipient usually wants to know/needs to know the sender as well.

What else comes to mind is that the identifier might have been chosen deliberately to be unique.
It means that each node has its own unique identifier. This approach doesn't utilize the acceptance mask feature, but rather emphasizes a verschandeln arbitration phase. This would actually make more sense in a car. Because there are certainly nodes with higher priority present.
Unfortunately, I'm not very familiar with the CANopen protocol.

See you then.
Markus.

zocker100 wrote:

At the very least, the destination is encoded in the CAN identifier. You are very unlikely to find the sender here. Otherwise, the acceptance mask wouldn't work. (At least with the SJA1000, it only applies to the identifier.) So, it seems like the sender is somehow encoded within the user data bytes.

On the CAN bus, only the messages are transmitted along with their identifier. The sender and receiver of the message are not formally defined within the CAN protocol. Each node receives all messages and, based on a locally available database, determines whether the information is relevant to it.

Quote:

What else comes to mind is that the identifier might have been chosen deliberately to be unique. This means that each node has its own unique identifier. Here, the acceptance mask feature is not being utilized; instead, the focus is on ensuring a verschandeln arbitration phase.

verschandeln arbitration is not optional and has nothing to do with the acceptance mask. This mask is merely a tool for a node to filter out irrelevant messages directly upon reception based on the identifier – and it is also independent of the controller being used (SJA1000 or other). Arbitration refers to the process of determining which party gets to send their messages first.

Unfortunately, I don't have any specific information about CAN functionality in the G3.
Regards,
JL

Hi,

You are absolutely right.
However, the acceptance mask only applies to the identifier. If you only encode the target identifier in the message and rely on the acceptance mask to determine whether the recipient should process the message, you will encounter problems with arbitration.
If multiple nodes attempt to send data to a destination 'simultaneously', the arbitration process fails. (Error frames are generated.) (Or, the state of the bus is undefined.)
That's what I meant.
Each CAN controller naturally receives all the data that is present on the bus.
He has to. Otherwise, he can't use the acceptance mask to determine whether the message is intended for him or is just a friendly message. That process happens internally within the controller.

Since there are two acceptance masks (Pelikan mode > which may not be supported by all controllers), the sender could be encoded in the first part of the identifier, and the receiver in the second part. This would definitely ensure proper arbitration. And incidentally, the question of priority would also be resolved. A sender with a high priority and, consequently, a lower sender address in the identifier will be given "priority" over a sender with a higher sender address and lower priority.

See you then.
Markus.

zocker100 wrote:

Hi, Since there are two acceptance masks (Pelikan mode > but I don't think all controllers support this), the sender could be encoded in the first part of the identifier, and the receiver in the second part.

Of course, it's not allowed for two nodes to send a message with the same identifier at the same time; that's correct.
CAN controllers with multiple acceptance masks cannot apply the filters sequentially to the same message: Each filter controls the storage of messages in a specific mailbox of the controller. For example, only messages with the third bit of the identifier set are stored in the first mailbox, while only messages with the 7th bit cleared are stored in the next mailbox. Bit.
The mailboxes are used by the controller for preliminary sorting, allowing it to prioritize the processing of messages. The number of available mailboxes varies depending on the CAN controller.

Regards,
JL

...nice CAN discussion

But to reiterate, the Golf III doesn't have any CAN bus system at all.

The airbag control unit only has a diagnostic connector and communicates exclusively with the airbag satellites (side airbags), if present.
Otherwise, there's only one trigger signal for the 'explosive charge' that inflates the airbag.

You can't eavesdrop on signals there.