[Ovmsdev] Multi frame query

Michael Balzer dexter at expeedo.de
Mon Mar 29 01:39:22 HKT 2021


the PID scanner normally works perfectly with multi frame responses, but 
I haven't had a response that long yet.

For 1503 bytes, 215 consecutive frames need to be transmitted. The PID 
scanner requests these to be sent with 25 ms separation time, so they 
should need 5.375 seconds.

Maybe some frame gets lost, or maybe the device doesn't allow a 
separation time that high for a transmission that huge.

Your log quote wasn't from the re-pid component but from obd2ecu, which 
has nothing to do with the RE tools. You should raise the log level for 
re-pid to see more info. Another tracing option is to use the CAN log 

Btw, you should never need 30 seconds timeout for a PID poll, as the 
scanner checks against the last frame reception.


Am 28.03.21 um 17:52 schrieb didier at ernotte.com:
> I am investigating some PID with very long data. I am using the PID 
> scanner for this.
> When I turn on the log level debug , I can see this as the first repy
> D (1456677) obd2ecu: Rcv 7ec: 8 (15 df 62 48 83 0 0 0)
> From the Canbus doc, I understand that the first "1x (15)" tells me 
> that this is the first frame of a multi frame, and the length is "5df" 
> . The Pid scanner seems to return only "df", not "5df" data, and I can 
> see in the log that I have around 1500 byte returned, not 220. Any 
> explanation ? anyone see this problem as well ? The scan command is (I 
> had to hack the code to allow timeout > 10sec)
> re obdii scan start 1 7e4 4883 4883 -r500-7ff -t22 -x30

Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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