Send/route CAN telegrams via diagnostic CAN

Hello, dear CANHack community!

I would like to know if it is possible to send simple CAN messages via the diagnostic interface (VAG, diagnostic CAN, J533), or if there is a way to inform the gateway that the upcoming messages, which are intended for a specific bus (e.g., CAN infotainment), should be routed via the diagnostic CAN.
Dies wäre für einfache Vortests sehr hilfreich, oder stelle ich mir das zu einfach vor?

Sure, here's the translation:

'Example of a desired process:'

- Analyze, for example, the steering wheel controls via the steering column electronics using VCDS (e.g., by examining measured values) and a CAN analyzer.
- Received message: ID 776 / Data length 8 / MSG: 07 62 1F XX XX 00 00 4A (XX represents the variable data portion, which changes depending on which button is pressed).
- Prepare the test application via the diagnostic connector to send the previously analyzed data: Inform the gateway that data should be sent on a specific bus and then send the data.

I've only discovered that the UDS protocol includes a 'Write Data by Common ID' function with mode 0x2E, but unfortunately, I have no idea whether and how this is implemented in VAG vehicles, let alone whether I'm even on the right track.

Data for my gateway J533:

Part number: 5Q0907530AC
Part: GW MQB High 1281204
Company number: 790 WSC 73430

Für eure Hilfe wäre ich sehr dankbar. FRaw Christmas!

Best, Dobby!

The routing, which specifies which information from which bus should be sent to which bus, is configured within the gateway. If the routing is not pre-defined, there is no mechanism in UDS to inform a gateway which bus a signal should be routed to.

Hello postman,

zunächst mal danke für die Antwort! Wenn ich dich richtig verstehe, habe ich überhaupt keine Chance CAN-Telegramme über die Diag-Schnittstelle zu versenden, außer sie betreffen die üblichen Diag-Protokolle. Oder Are there other ways?
I accidentally discovered that there's a coding option for the gateway in VCDS that allows you to 'enable and disable all development messages.'

Best regards,

Dobby!

If the routing is not intended by the manufacturer, the gateway will not route traffic, and this can only be changed in the gateway's software. Activating and deactivating the developer messages, as far as I know, only enables or disables the corresponding XCP or CCP messages. This allows the transmission of data from the control units.

Hello everyone. Did you know that the diagnostic session can be initiated from other CAN buses (e.g., infotainment)? That's something new to me.

majonez wrote:

Hello everyone. Did you know that the diagnostic session can be initiated by other CAN buses (e.g., infotainment)? That's something new to me.

Hello,

Is that a statement or a question? With some engine control units, I know that diagnostics can be performed normally via the CAN bus, and you don't need a separate gateway control unit for that.

Best regards, Rainer.

Hallo, es ist eine Feststellung. Ich habe dies realisiert, wenn ich versehentlich eine Setup-Meldung mit ID 0x200 von Infotainment-Bus gesendet. Die Botschaft war 200 01 C0 00 10 00 03 01 so dass das angeforderte Ziel das Motor Modul war, das auf Motor-Bus ist. Dann bekam ich Antwort von ID 0x201 auf Infotainment-Bus. So ist es klar, dass das Gateway eine Diagnoseaufbaumeldung von Infotainment zum Motor-Bus geleitet. I never knew that was possible.
Sure, here's the translation:

"PS: Sorry for using a translator."

Ok

I can confirm that a diagnostic session can be initiated from the infotainment bus.

It is therefore easily possible, for example, to access the engine control unit via the OBD protocol to query the data blocks.
Currently, I'm using a small, self-developed module with an STM32F4 microcontroller that is connected to the (separated) Infobus before the Audi RNS-E. This module acts as a CAN router, passing all CAN messages in both directions, except for IDs 0x363 and 0x365 originating from the radio. These two IDs are responsible for the upper lines displayed in the FIS (driver information system).
The module establishes an OBD session with ECU 01 if necessary, periodically reads the corresponding diagnostic trouble codes (DTCs), and displays the oil temperature in the instrument cluster (FIS).

Vehicle: Audi A3 8PA, manufactured in May 2011, mileage 932 km, with a white FIS (instrument cluster).

User Givertech has posted here -> http://www.canhack.de/en/viewtopic.php?t=1951#4901
posted that it's also easier to retrieve data from another bus. This would be very helpful for many things.
Unfortunately, he is no longer active on this forum, and he has not provided further details about this.

Perhaps he or someone else will read this and be able to help!