[HOWTO] Debugging OBD Communication

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froggy47
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Re: [HOWTO] Debugging OBD Communication

Postby froggy47 » Tue Mar 03, 2015 12:11 am

Any help?

Thanks!


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Re: [HOWTO] Debugging OBD Communication

Postby Harry » Tue Mar 03, 2015 6:26 pm

@froggy47,

I cannot provide more help than I did. For a non CAN bus car, update rates around 2 Hz are what you can get. There is not a lot one can do here. One option is to connect sensors directly and work around OBD completely, and the other one is to buy a new car :-) If there would be a known option to increase speed, I'd provide it anyway, so no, there are no hidden settings to improve the rate. Btw. if acceleration shows up with 10 Hz, it is too low and you likely changed another Expert Setting. Maybe you want to try to delete and reinstall the app to get rid of wrong settings.

- Harry


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Re: [HOWTO] Debugging OBD Communication

Postby gplracerx » Tue Mar 03, 2015 9:08 pm

I'll second the 10Hz accelerometer update rate is too slow, especially for autocross. I set mine at the maximum, ~100Hz. Even 30 Hz ends up being over smoothed, in my opinion, as the cutoff frequency of the filter is directly proportional to the accelerometer update rate.

There's an option to reset expert settings to default at the bottom of the expert settings page. If I remember correctly, the default accelerometer update rate is 30Hz.
Last edited by gplracerx on Tue Mar 03, 2015 9:09 pm, edited 1 time in total.


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[HOWTO] Debugging OBD Communication

Postby Harry » Tue Mar 03, 2015 9:09 pm

Yes, but this option does not cover all settings - it is not safe.


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Re: [HOWTO] Debugging OBD Communication

Postby gplracerx » Tue Mar 03, 2015 9:10 pm

Harry wrote:Yes, but this option does not cover all settings - it is not safe.


Good to know.


froggy47
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Re: [HOWTO] Debugging OBD Communication

Postby froggy47 » Tue Mar 03, 2015 10:36 pm

gplracerx wrote:I'll second the 10Hz accelerometer update rate is too slow, especially for autocross. I set mine at the maximum, ~100Hz. Even 30 Hz ends up being over smoothed, in my opinion, as the cutoff frequency of the filter is directly proportional to the accelerometer update rate.

There's an option to reset expert settings to default at the bottom of the expert settings page. If I remember correctly, the default accelerometer update rate is 30Hz.


I never touched accelerometer settings, I would have no way of knowing what is good or not regarding these update speeds.

Unfortunately I am finding the app (HLT) only works on my car and my phone with extensive expert guidance & I thank you Harry as you are VERY responsive on the forum, really among the best I have every "worked with".

So far as the disconnects I still have, only with the obd dongle, should I just expect that random disconnects will always happen?

My previous question, is wifi obd2 mx better at staying connected and update speed? My android phone does wifi also.

Thanks.


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Re: [HOWTO] Debugging OBD Communication

Postby Harry » Tue Mar 03, 2015 10:44 pm

Well, the good thing is most users do not experience that kind of issues :-) Both BT and WiFi connections can be disturbed - that's the nature of wireless connections. WiFi is more fragile in my experience, and more complicated to configure. But that's a my personal experience and not representative.

- Harry


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froggy47
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Re: [HOWTO] Debugging OBD Communication

Postby froggy47 » Sat Mar 07, 2015 11:54 pm

I tried the VGate obd2 BT dongle with good results, it "likes" the "special" settings that we ended up with while trouble shooting the connection issues with the ScanTool obd2 MX BT.

It paired & connected for 5 -6 min KOEO and then I started the engine and it stayed connected, not a blink.

Also Dual 160 stayed green the whole time.

For the accelerometer It was set to 10 (never touched by me) and I changed it to 20, then the Hz went from 9/10 to 18/19 so an improvement there. Should I change it higher? What will be the effect/benefit?

Posting all this so others who look at the thread will gain some info on obd trouble shooting.


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Re: [HOWTO] Debugging OBD Communication

Postby gplracerx » Mon Mar 09, 2015 3:20 pm

I set my accelerometer update rate to 100Hz. It shows up as 91Hz on the accelerometer display. At 20Hz, the filter time constant is too low for autocross, in my opinion. YMMV. If I get time, I'll put up some graphs to show the effect. I've got to prep the car for the Dixie National Tour event this weekend.


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Re: [HOWTO] Debugging OBD Communication

Postby Harry » Mon Mar 09, 2015 3:28 pm

froggy47 wrote:For the accelerometer It was set to 10 (never touched by me) and I changed it to 20, then the Hz went from 9/10 to 18/19 so an improvement there. Should I change it higher? What will be the effect/benefit?

The default rate predefined in LapTimer is 30 Hz.

- Harry


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