OBDLink MX Wifi update too slow error

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ItsRossTime
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OBDLink MX Wifi update too slow error

Postby ItsRossTime » Tue May 26, 2015 1:42 pm

First off - awesome app, Harry. This is a great tool to get some insights in to lapping at a reasonable price.

I purchased an OBDLink MX Wifi adapter so I could add throttle/RPM data to my sessions, but I'm having trouble getting it to work. When I go to view the real time data, I get the error that the OBD sensor's update rate is slow (even through this is the fastest adapter you've tested?). I'm using this with a 2005 BMW M3.

When I go to the sensor information, I get some odd (non-standard?) PIDs. See attached picture.

Can anyone help?
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Harry
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Re: OBDLink MX Wifi update too slow error

Postby Harry » Tue May 26, 2015 2:33 pm

This are the initialization commands, not any PID. The rate is considered too low because it is 0 currently - no conversion going on.

The older M3s are known for their buggy OBD II implementation and often create issues. I have added plenty of OBD tweaks over time but I can't recall which one fixes the issue for the M3 (at least one does). In case someone can add a hint here - welcome. I'd suggest to start with setting the OBD Protocol explicitly (instead of Automatic) initially. To do this, you need to find out which bus protocol is used for the M3/2005 and set it in LapTimer's Expert Settings / OBD Tweaks.

- Harry


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ItsRossTime
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Re: OBDLink MX Wifi update too slow error

Postby ItsRossTime » Wed May 27, 2015 2:02 am

Harry, thanks so much for the tip & quick response.

The dongle works perfectly fine with the supplied OBDLink iOS app. I noticed from the connection display on that it is doing so via ISO 9141-2, so I set your app to force that protocol, and I can get it to connect, but it still shows the update at 0 Hz. I've tried toggling:
    Ignore NO DATA
    CAN Multi Requests
    Auto Exclude PIDs
but none of this has improved the refresh rate. Sometimes I'll get data, then it looks like the app loses connection (the name of the connector and the car disappears).

What I really don't get is this adapter works fine with their own app. There has to be some setting I'm missing to get things to work properly.

Here's the list of PIDs when it would actually connect. Image Anyone else figured this out already?


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Re: OBDLink MX Wifi update too slow error

Postby Harry » Wed May 27, 2015 7:11 am

LapTimer's parser is more picky then that for most other tools. This is by design because it allows higher update rates once it works (every error ignored adds a lag to updates, not recognizing this seems to be a bad option).

- Keep the ISO 9141-2 protocol setting instead of Automatic
- You must not turn on CAN Multi Requests for the ISO 9141-2 protocol.
- Ignore NO DATA is a release in pickiness :-)
- Auto Exclude PIDs - please turn it off

The above snapshot shows there is some initial communication on now, but it stops early (and will result in a reconnect with OBD going off and on again).

Before going into a detailed logging, please try the following settings:

- Set "Adaptive Timing" to "Enabled".

In case this works, reduce "Reply Timeout" to something smaller than 1.02, at most down to 0.20. Once the connection drops again, increase it a bit.

Please let us know if this works. If not, we need to check the communication in detail: viewtopic.php?f=20&t=1500

- Harry


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ItsRossTime
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Re: OBDLink MX Wifi update too slow error

Postby ItsRossTime » Fri Jun 12, 2015 4:29 pm

Harry - was so excited to see the update hit my phone yesterday. I tried it out today and it looks like there is still a problem.

I sent another log file (though I don't think GPS buddy got the same update, so not sure if it's helpful) and was hoping there was some other correction I could use.

I had the expert settings defaulted (I think, it appears the "reset" functionality doesn't actually reset the settings, so I copied values from a fresh install of GPS buddy), except for the protocol set to ISO 9141-2.

Is there any chance that excluding some unnecessary PIDs would reduce the slow connection rate? I'm the most interested in RPM, throttle position, and wheel speed (water temp would be nice, but is low priority). Will auto-exclude PIDs work, or should I enter all received PIDs into the exclusion and start troubleshooting?

When PID troubleshooting, does the connection have to be reset between changes, or is it done immediately? Meaning: if the update rate is low and I add a PID, should it happen immediately, or do I have to power down the connector and re-connect for the exclusion (or any other OBD expert tweak) to take effect?

I also saw a reference somewhere about initializing using STIAT0 to disable "adaptive interbyte timing" which, apparently, has fixed some of the communication issues with BMW ECUs (see here: https://www.scantool.net/forum/index.ph ... 1#msg19391). Any chance that adding this would help?
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Re: OBDLink MX Wifi update too slow error

Postby Harry » Fri Jun 12, 2015 6:11 pm

The reasons an adapter is working with one app and not another can be many. There are quite different strategies one can implement to request data, and they come with different pros and cons. The LapTimer strategy is focussed on highest update speeds while others are more focussed on resilience with wrong behaving adapters and car busses. Once we get it working, you will see that LapTimer can pull data a magnitude faster than the OBDLink app, but it is more sensible too.

I have Buddy submitted to Apple in parallel with LapTimer, but it seems it got lower priority. Once it gets available, we can check the log again. Till then, please try the following settings:

Default Protocol ‣ your protocol
Adaptive Timing ‣ Enabled
Reply Timeout ‣ 0.3
Ignore NO DATA ‣ ON
CAN Multi Requests ‣ OFF
Auto Exclude PIDs ‣ OFF
Exclude PIDs ‣ empty

Please understand the low update rate message as "error occur while communicating". In case LapTimer thinks it cannot recover, it will close the connection and try again. This will make the rate drop to 0, the sensor disappear / re-appear etc.

- Harry


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