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Start communication in KWP2000 Fast init (ISO14230)

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  • Start communication in KWP2000 Fast init (ISO14230)

    Hello everybody!!
    When we work with the KWP2000, the tester sends to vehicule "wake up" from 50 ms long (25ms low and 25 ms high) followed inmediately by start communication request (C1 33 F1 81 66).
    Do they start bit and end bit of each?

    Example: START_BIT C1 STOP_BIT START_BIT 33_STOP_BIT ....

    or Is there just one start bit and a bit of order?

    START_BIT C1 33... STOP_BIT

    Thanks!!!

  • #2
    Fast init (ISO14230)

    I have checked it with an oscilloscope.

    I used an ELM327 v1.4 interface.
    Wakeup is 25ms low then 25 ms high.
    The data is send as 5 complete frames of 10 bits, start-8data-stop.
    The stop bits are not very vissible because there are long gaps between the frames.(approx 5mSec.)

    regards from hans

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    • #3
      Each byte should have a start bit and stop bit.

      In some cases you may need to wait up to 10ms after a fast init. So if you discover problems you may want to relax this timing.

      Also make sure that you have a checksum at the end or the message will be ignored.
      Hack your car's CAN BUS at www.canbushack.com

      Comment


      • #4
        Thanks to ones two for the info

        ---------- Post added at 02:16 PM ---------- Previous post was at 01:12 PM ----------

        The KWP fast init works correctly in my ECU simulator, but when I received the first data frame from tester C2 33 F1 01 00 (MODE 1 PID 00) I response with 86 F1 10 41 00 98 00 00 00 cs (cs is checksum) but the tester no interpret anything.

        Why would this happen?

        Chewwtoy this time that you say (up to 10ms after a fast init). Could be related? I have tried to send 86 F1 10 41 00 98 00 00 00 cs with a pause of 10 miliseconds but the problem continues.

        Thanks!!!
        Last edited by proyectanteATE; 03-30-2011, 07:20 AM.

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        • #5
          Timing between KWP fast init and first trasmission

          Hello everybody! I hope you can help me.

          Does anyone know how time is necessary between the ECU transmits startcommunication response and the ECU receives the first data request (MODE 01 PID 00) from tester?

          Thanks you!!!

          Comment


          • #6
            Admittedly I'm not a HUGE KWP 2K expert, but I'm not at all familiar with the header bytes (C2 33 F1 -or- 86 F1 10). In my experience the Tester sends 68 6A F0 and the node responds with 48 6B XX (where XX is variable node ID). Not sure if your protocol is correct or not?
            Hack your car's CAN BUS at www.canbushack.com

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