General questions about CAN protocols

Hello everyone,

I'm quite new to the field of CAN-Bus and vehicle diagnostics, so please excuse me if I ask 'silly' questions .

For your information, here's a list of the hardware and software I have access to.

Bosch KTS 670
Vector CANcard XL, 2x CANcab 251 opto.
Vector CANalyzer, CANoe.
ETAS Busmaster 1.3.0
AGV4000 Expert Interface.
NI LabView 2011
can tool.
VCDS Lite

I have the following vehicles available, among others:
VW Passat B6, type 3C, manufactured in 2008 or later -> Diagnostic capabilities via CAN bus.
Audi A4 8E/B6, year 2003 -> Diagnosis via K-Line.

To the best of my knowledge, these protocols exist.
SAE J1850.
KW1281 (Volkswagen proprietary)
ISO 9141.
ISO 14230 (KWP2000)
ISO 15765 / SAE J2480 (CAN ISO-TP)

Regarding the question: KWP2000 doesn't specify the bus, does it? Could it be that a vehicle expects a KWP2000 or KW1281 protocol on the CAN bus, or does that correspond to CAN ISO-TP?

I have done the above. Sent the following message on the CAN bus from the Passat.
7DF 02 01 0C so the request for the motor speed.

I understand the structure of this message and the function of the SIP and PID.

I'm also getting the expected response! But what protocol is this referring to? Am I assuming correctly that it's ISO 15765?

2. Question: The ECU responds to the functional CAN ID 7DF and returns the physical ID + data!
Is this approach also possible for other control units, such as ABS, speedometer, etc.? If so, which ID must be sent?

Hi,

You are only describing the OBD-2 protocol; the manufacturer-specific diagnostic system works differently.

Best regards, Rainer.