[CAN-FD] Vehicle Diagnostic Communication Part 86 [Overview 2]

Click here for back issues.
https://www.simulationroom999.com/blog/diagnostic-communication-en-back-issue/

Introduction.
Steps to simulation implementation
Intuition for CAN-FD control by python-can
Intuition for CAN-FD diagnostic communication (ISO15765-2) with can-isotp
CAN-FD diagnostic communication with AUTOSAR-CanTp (ISO15765-2)
CAN-FD diagnostic communication with AUTOSAR-Dcm (ISO14229-1)
Conclusion

Introduction.

This article will be toward a vehicle diagnostic communication simulation of CAN-FD.

Steps to simulation implementation

Following the steps of CAN, we will start from the lower layers.
It is possible to finish the simulation in one shot by playing with AUTOSAR-dcm and can-isotp at once, but it is better to clear it one layer at a time.
Therefore, the following is the flow.

(1) CAN-FD control by python-can
(2) CAN-FD diagnostic communication by can-isotp (ISO15765-2)
(3) CAN-FD diagnostic communication with AUTOSAR-CanTp (ISO15765-2)
(4) CAN-FD diagnostic communication with AUTOSAR-Dcm (ISO14229-1)

First, let me give you a rough idea.

Intuition for CAN-FD control by python-can

The intuition of CAN-FD control by python-can is as follows.

Control of flags associated with CAN-FD frames
- FDF (FD Format Indicator): Flag to indicate CAN-FD
- BRS (Bit Rate Switch): Flag that is FlexDataRate. (FDF must be enabled)

This is the flag specification unique to CAN-FD, as reported in the previous article.

Intuition for CAN-FD diagnostic communication (ISO15765-2) with can-isotp

The intuition of CAN-FD diagnostic communication (ISO15765-2) with can-isotp is as follows.

Frames exceeding 8[bytes]
- Single frames exceeding 7[bytes] messages are possible.
Messages exceeding 4095 [bytes]

In the case of CAN, the maximum value of one frame was 8[bytes], so a single frame exceeding 7[bytes] was impossible, but in the case of CAN-FD, the maximum value is 64[bytes], so it is possible.

Note that the maximum message can exceed 4095[bytes], and this is achieved by extending the frame structure.

CAN-FD diagnostic communication with AUTOSAR-CanTp (ISO15765-2)

This is the same as ISO15765-2 above.
Well, it is not surprising since can-isotp is a Python library to realize ISO15765-2.

CAN-FD diagnostic communication with AUTOSAR-Dcm (ISO14229-1)

The content here will be just a simple check to see how each service works.
The message itself is the same, so the main thing is to check what is happening on the CAN-FD line.

This is meant to check the advantage of good abstraction at the lower layers.

Conclusion

Simulation procedure and intuition explanation.
- CAN-FD control with python-can.
- CAN-FD diagnostic communication with can-isotp (ISO15765-2).
- CAN-FD diagnostic communication with AUTOSAR-CanTp (ISO15765-2).
- AUTOSAR-Dcm for CAN-FD diagnostic communication (ISO14229-1).

Click here for back issues.