Re: Noise on K line?

Hi Bole,

First the protocol is KWP1281 not KWP2000 (It will be easy in
KWP2000 because of the longer timeout).
Then I only have the problem when I'm testing on the car with the
engine ON. In my desktop or in the car with the engine OFF the
problem doesn't exist and the program runs for hours without error.
Moreover, the actual design in mounted on a protoboard, so perhaps
it's noise, on the K line or on the Supply Line.

I don't think it's a problem of busy ECU, because my father's
scanner (which cost him thousands of dollars) display Block
information on a PC and without this problem. The refresh of the RPM
info is quite fast (it seems as fast as my program when it's
running).

Does anybody know if I can ask the ECU only the RPM info and not the
whole block? This will speed up my program.

Thanks and Bye
Ezequiel

--- In opendiag@yahoogroups.com, "Veselinovic Bozidar"
<vescomp@v...> wrote:
> Hi Ezequiel,
>
> I don't think that's any noise on the K_Line, could be the timing.
> If ECU is busy, your request can remain unanswered (remember, it
is VW - software is writen in kindergarden).
> So:
> a) set time _till_ecu_answer to 450mS ( ** see 1 **)
> b) repeat request min. 3 times
> c) if, after 3 times your request still remains unanswered, send
TesterPresent Message
> d) if your TesterPresent message remains unanswered,
communication is broken, do new InitSequence.
>
> 1. Some ECU's have max. InterMessageTime of 500mS, instead of
5000mS.
>
> bye,
> bole
>
>
>
> ----- Original Message -----
> From: acetoel
> To: opendiag@yahoogroups.com
> Sent: Tuesday, September 30, 2003 02:50
> Subject: [opendiag] Noise on K line?
>
>
> Hello,
>
> I'm trying to make my own scanner with an AVR and my own version
of
> Jeff's interfase. I can stablish a communication to a VW GOL
Diesel
> Pump ECU.
>
> If I ask the ECU for the RPM data with the Engine ON, in a
ramdom
> moment the program halts. I can halt when the RPM reach an
elevated
> number or when just started.
>
> I think is a kind of noise but don't know if it's on the K Line
or
> in the Supply. All the components are on a protoboard, and I
know
> this is not good for noise reduction. Can I filter the K Line
with a
> 0.1uF capacitor? or something like that.
>
> Thanks
> Ezequiel
>
>
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>
>
> [Non-text portions of this message have been removed]

 
Received on Fri Oct 03 03:52:52 2003