[obdgpslogger] ELM327 interface "hanging" with NO DATA condition after a random amount of time (Toyota Corolla)

[Maciej Grela]

Hi,

I've been trying out obdgpslogger today with an ELM327 cable connected
to a Toyota Corolla and I noticed strange behaviour - after a while of
logging using obdgpslogger the interface "locks up" and the tool can
no longer receive data from the OBD-II bus. In the output it looks
like this:

temp=86.000000
rpm=1100.000000
vss=17.000000
maf=8.720000
throttlepos=2.745098
temp=86.000000
>BD reported NO DATA for 01 0C: NO DATA
Ending current trip
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA

<...>
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>BD reported NO DATA for 01 05: NO DATA
>COBD reported NO DATA for 01 05: NO DATA

The funny thing is that it seems to be the chip hanging. If you stop
the logger and restart again it resumes without any problems:

kraken ~ # obdgpslogger --spam-stdout --serial /dev/ttyUSB0
--samplerate 10 --db ./obdgpslogger7.db
Opening serial port /dev/ttyUSB0, this can take a while
Successfully connected to serial port. Will log obd data
temp=87.000000
rpm=1185.000000
vss=18.000000
maf=8.690000

This happens at a random time after startup of obdgpslogger, sometimes
it's 2 minutes and sometimes it can run for an hour.

One additional thing I've noticed, is that when this happens the "RX"
led on the OBD side of my interface stops blinking - as if the ECU
stopped responding. This may very well be the case but why it
"unfreezes" when I restart the obdgpslogger ? Is there some special
command sequence sent to the ECU "resetting" the interface when
obdgpslogger starts ? Or is this a buggy ELM327 clone ?

I would very much like to hear your opinion.

Best regards,
Maciej Grela