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Information about power train CAN communications?

Discussion in 'Model S: Driving Dynamics' started by HH007, Mar 11, 2015.

  1. HH007

    HH007 Member

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    Hi guys,

    we are facing an exciting duty: We are trying to run the drive unit of a Model S stand-alone outside the car. Emulating the analog signals shouldn't be that big problem - what makes us worry about is the CAN communication. For gathering some messages we installed a measuring box directly to the drive unit. As a first approach we will gather some data on an ordinary ride where we try to minimize all kind of determining factors. Then the difficult task - decoding the messages. We expect this to be rather complex but we are willing to face this challenge.

    Did anyone of you already gain experiences in this area? Or is someone maybe interested in working together at this question?

    Best regards from Germany!
     
  2. scottm

    scottm Active Member

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    If you are serious about CAN, contact your friends in Stuttgart Vector Group Contact Info

    They probably educated the engineers who developed that CAN system that dropped into the Model S.
     
  3. glhs272

    glhs272 Unnamed plug faced villian

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    I would be surprised if the CAN bus is not encrypted. I work with CAN every day, but we don't bother with encryption and our systems don't support it. If it's not encrypted, I would think it would be possible to use a can bus sniffer and decipher the traffic. I hope you succeed and share your results.
     
  4. vvanders

    vvanders Member

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    It'd be surprised if they used CAN Bus at all. It's a pretty limiting bus in a lot of ways. I could have sworn I saw a teardown where the majority of the interconnect was actually CAT5 based.
     
  5. HH007

    HH007 Member

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    The Model S definitely uses at least four different CAN networks.


    If we read the CAN communication, how can we recognize encrypted traffic? Will the frames be completly different to the ordinary structure or are just the identifier or data fields modified somehow for example?
     
  6. Martini

    Martini Member

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    Check out this guy;

    Stretchla Blog | Stretched Vanagon Westfalia shell on a Tesla platform

     
  7. GSP

    GSP Member

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  8. Johan

    Johan Took a TSLA bear test. Came back negative.

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    May I ask what you are trying to do by doing this? Will you put it in another car? For testing purposes? For other applications than running a car?
     
  9. HH007

    HH007 Member

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    #9 HH007, Mar 12, 2015
    Last edited: Mar 12, 2015
    For a start, we want to do some testing. As the next step, we would like to install it in another car.
     
  10. glhs272

    glhs272 Unnamed plug faced villian

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    #10 glhs272, Mar 12, 2015
    Last edited: Mar 12, 2015
    If you are at least able to see the CAN frames and their respective IDs, that is a important start. At that point it takes a bit of study to analyze the messages as you change certain conditions (go from park to drive or reverse, etc.). Obviously it would be very important and helpful to get a lot of data logged for analysis with a complete and working vehicle. Things like pre-charging the capacitors are very important to keep from frying components.

    The hardware I work with is not capable of encryption (at the hardware level), so other tricks must be used on the software side. I have no idea what Tesla's hardware is capable of. If it is anything like what I work with then it should be possible to figure this out. I know where Tesla was using a LIN bus (suspension position sensors, radiator flap position sensors and controllers, etc.), there was no special encryption going on (see Otmar's work on the Vanagon).
     

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