KIWI WIFI ODBII DATA

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devas72
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KIWI WIFI ODBII DATA

Post by devas72 » Thu Jun 16, 2011 4:29 pm

Hi all,
first of all thanks to Harry for the app, it's really pretty good.

I noticed that the data coming from the OBD are not in real time.
What you think, is this an PLX' device issue, software settings or,maybe, the ECU protocol data speed ?

I have a BMW 330Cd of 2006.

Cheers all

Ale
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Harry
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Re: KIWI WIFI ODBII DATA

Post by Harry » Thu Jun 16, 2011 4:49 pm

Hi,

The process is as follows:

1. LT request a piece of data (PID)
2. WLAN latency + transmission time
3. KiwiWifi sends the request to the car's bus
4. any ECU on the bus will answer and send the data
5. KiwiWifi receives it and sends a piece of data
6. WLAN latency + transmission time
7. LT receives the data, unpacks it and stores the data
8. LT displays data at 5Hz display update rate

You can check response times for individual pieces of data while you have LT connected to your Kiwi. Goto the vehicle details at this time and check the list of PIDs. Those with a number in brackets show the time (in milliseconds) for steps #1 to #7. Important: at #4, there is not information how old the data is already, this may add additional latency. As the last remark, the newer the cars, the faster the busses - you can see this here:

2005 Porsche 911 C2 - 1.4Hz
2011 Porsche 911 GTS - 7.0Hz
2007 Volvo C30 2.0d - 6.0Hz
2005 Clio Sport - 0.8Hz
2006 Renault Clio C - 10.0Hz
2011 BMW 335i - 8.0Hz
2005 Lotus Elise - 2.0Hz
2001 BMW 325Ci - 1.3Hz
2009 Corvette - 8.0Hz
2003 Honda S2000 - 1.5 Hz

The update rates results from a high frequency request of two PIDs plus low frequency requests for some others.

- Harry
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devas72
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Re: KIWI WIFI ODBII DATA

Post by devas72 » Thu Jun 16, 2011 10:54 pm

Hi Harry,
I open a support ticket at PLX, below the question and answer.


Subject: Slow data polling

Ticket Thread
Thu, Jun 16 2011 6:31am
Dear,
I have a question regarding the wifi Kiwi connected to my Iphone, I receive the data from OBD II ECU from my BMW 330 but the polling is very slow, for example the the RPM data or SPEED data is not in realtime.

Have you any idea ?

My car is a BMW 330 Diesel engine
Production year 2006
Iphone 3G
Whit harry's lap timer pro

cheers

Ale
Thu, Jun 16 2011 8:12am - staff
Unfortunately, that is a limitation of the protocol used by your vehicle. The BMW 3-series before model year 2008 use the protocol ISO 9141, which is one of the slowest OBDII protocol. The BMW 3-series from model year 2008 and onwards use ISO-15765 (CAN), which is the fastest available protocol.



Do you know the frequency rate of the ISO 9141 Protocol ?

Cheers

Ale
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Re: KIWI WIFI ODBII DATA

Post by Harry » Thu Jun 16, 2011 11:43 pm

Hi again,

yes, these affects steps #3 to #5. I have no idea on the protocols exact speed. However, as stated above, LapTimer can measure the overall request time for #1 to #7 - which includes #3 to #5. Here is an example of a 2005 Porsche 911 delivering an update rate between 1.0 and 1.4 Hz (which is pretty weak compared to later years):
Image

As you can see, steps #1 to #7 take 256ms for requesting RPM only (which effectively means a theoretical max update rate of 3.9 Hz in case we are interested in RPM only). As RPM, VSS, TPS are requested at the same frequency, these three make up 873ms, which results in an update rate of 1.2Hz.

Please connect, start your engine, and goto the Vehicle Details screen. Check the values and let me know.

- Harry
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Re: KIWI WIFI ODBII DATA

Post by devas72 » Fri Jun 17, 2011 8:32 pm

Hi again,

Sure Harry i will connect the car to Iphone then I send you the results as soon as possible.

Cheers...
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Re: KIWI WIFI ODBII DATA

Post by devas72 » Fri Jun 17, 2011 10:44 pm

Harry,
There is a problem.

I havent the obd data displayed in the image that you post.

I think the VIN is not recognized, so I attach an image that I take a bit ago

I can't send image to forum from iPhone... I send you later
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Re: KIWI WIFI ODBII DATA

Post by slntsam » Mon Jun 20, 2011 3:19 pm

I have a very similar issue and I'm wondering if it's related.

I have a 2003 Mazda MX-5 Miata and the laptimer seems to have issues with my kiwi wifi.

LT reports that my OBD rate is 1.2-1.6 but then it will go to 0.0 or nothing at all.

When I am getting data and start recording video, it only works for a short while (a few seconds) and then fails to show any data.

Last night I tried it out with my 2007 Hyundai Tucson where I'm getting a ODB rate of 5.4 or 5.6...something much greater than with the Miata.

Same thing happens with video, it works for a few moments and then fails to show anything about throttle position/rpm and speed.

However when I use Dash Command, the connection is solid and it always shows information for either car.

This is on a 4g iPod touch.
The Tucson sends the VIN number but the Miata does not.

Thanks!
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Re: KIWI WIFI ODBII DATA

Post by Harry » Mon Jun 20, 2011 7:43 pm

Hi,

Here you can see that the update rates are really different for different cars and bus protocols supported.

On the missing data / disconnects: this is definitively an issue with the KiwiWifi's WLAN connection. Please check their forum for help on this: http://www.plxdevices.com/forum/ The recommendation is to use some special connection setting and go for the flight mode to improve stability. The later one will disable GPS which is not a good idea for LapTimer... In case you have a TomTom, you can go with flight mode, all devices (including the internal sensor) that go through Apple's Location Service will not work in flight mode...

- Harry
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Re: KIWI WIFI ODBII DATA

Post by slntsam » Tue Jul 05, 2011 2:42 pm

I don't think it's the kiwiwifi. I've tested with airplane mode and what not as well.

If I use DashCommand, I can log all the data for quite a while (over 10 mins I've tried).

it stops after a while with laptimer, and obdwiz (wired connection for that).

I think the answer lies somwhere within reply #7 in this link.

http://www.obdpros.com/yabb/YaBB.pl?num=1229314951

If what he's saying is true, then something is making my OBD not send anymore. I might test with the hyperterminal connection he's talking about.
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Re: KIWI WIFI ODBII DATA

Post by Harry » Tue Jul 05, 2011 8:24 pm

--> Please read if you followed the link and still feel comfortable :-) Skip it otherwise as it is getting very technical.

Hi,

It might be that certain cars do not comply to OBD II completely and run into problems like this. LapTimer regularly checks if NO DATA is responded and resets in this case to at least make it work again.

LapTimer queries both $01 and $09 PID availability and will not request PIDs not available. I can hardly believe that the $0100 request blocks the ECU (because this should be a very common request), on the $0900 I'm not sure. You may enable logging in LapTimer (Settings->Expert Settings->Enable Logging; send LT to the background and bring it to foreground again; you should see a recording symbol in the footer now; log as long as you think it makes sense; send to background again; bring to foreground again; send the message including the log file to yourself for analysis). Filter this log to lines including OBDSENSORS and check the OBD dialog.

- Harry
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