OBD-II UART Speed

Inquiry and support for Freematics products
dsmith658
Posts: 7
Joined: Sun Jun 18, 2017 8:05 am

OBD-II UART Speed

Postby dsmith658 » Fri Jul 28, 2017 8:14 am

I am polling 8 PIDs most with only 2 byte responses. It takes 400ms+ to return responses for all 8 PIDS. I tried speeding things up with changing the baud rate to 115200 but the results were exactly the same, so I don't think it's just serial speed issue.

I use other devices to data log my ECU with much faster data returns (~20ms - ~100ms)

I really need to poll faster. Can you suggest any changes to fix this issue? Can anyone comment if the I2C version is having better performance?

dsmith658
Posts: 7
Joined: Sun Jun 18, 2017 8:05 am

Re: OBD-II UART Speed

Postby dsmith658 » Sun Jul 30, 2017 6:07 am

Just an update on this. Using the Sparkfun UART I was able to increase speed significantly by turning off adaptive timing and lowering the timeout to 1

AT AT0
AT ST 01

However when I tried these commands with the freematics they were not recognized. Most other AT commands work fine with the Freematics. I would really prefer continuing working with the freematics I just need a little help overcoming this obstacle. Thanks for your help.

protomor
Posts: 99
Joined: Wed Oct 14, 2015 9:17 am

Re: OBD-II UART Speed

Postby protomor » Mon Jul 31, 2017 8:43 pm

What year/model car are you polling? Older care are always just plain slower. 400ms isn't an abnormal return time for a single PID from an early 2000s car. Even some later 2000s cars.

The chip used by the freematics unit is the same as the sparkfun (ELM327 IIRC). So the commands should be available. You simply need to code it into the hardware calls on the unit itself instead of into your main sketch. If you're already doing that, then I'm not sure. What do you mean "not recognized"? The ELM sends back some form of a byte response.

dsmith658
Posts: 7
Joined: Sun Jun 18, 2017 8:05 am

Re: OBD-II UART Speed

Postby dsmith658 » Tue Aug 01, 2017 2:43 am

protomor wrote:
> What year/model car are you polling? Older care are always just plain
> slower. 400ms isn't an abnormal return time for a single PID from an early
> 2000s car. Even some later 2000s cars.
>
> The chip used by the freematics unit is the same as the sparkfun (ELM327
> IIRC). So the commands should be available. You simply need to code it into
> the hardware calls on the unit itself instead of into your main sketch. If
> you're already doing that, then I'm not sure. What do you mean "not
> recognized"? The ELM sends back some form of a byte response.

Since I'm able to poll it quickly with the sparkfun I don't think my issue is vehicle, but only with the freematics, and likely only settings related.

I assumed this was based on the ELM327 too but when you request version it does not give the ELM typical response. Which makes me think they are emulating the 327.

When I send a command like AT AT0 or AT ST 01 to the freematics I get a "?" response. Most commands work, but not those, and others. I need to modify those timeouts and modes to solve my issue like I have with the sparkfun version. When I send those commands to the sparkfun version I get the "OK" response indicating the command took effect. It was only after turning off adaptive timing and reducing the timeout that the sparkfun UART gave me good performance.

rrsilver
Posts: 7
Joined: Wed Sep 06, 2017 6:45 am

Re: OBD-II UART Speed

Postby rrsilver » Wed Sep 06, 2017 6:49 am

Hello friends

I'm using this library and I have the same problem, when I consult only one pid gets pretty fast, but querying 10 pid's gets pretty slow, I'm trying the ATST command to download the time but it did not work out, I'll try a few more things here and I find out how to improve this time share with you.
Forgive my English.

stanley
Site Admin
Posts: 769
Joined: Sat Mar 01, 2014 3:15 am

Re: OBD-II UART Speed

Postby stanley » Wed Sep 06, 2017 11:51 am

There is not much can be done for older cars.

rrsilver
Posts: 7
Joined: Wed Sep 06, 2017 6:45 am

Re: OBD-II UART Speed

Postby rrsilver » Tue Sep 12, 2017 2:10 am

Hi Dsmith, did you get any results? I tried to pass the ATST parameter in the obd.init function but it does not seem to work, I also tried directly using serial.write but it also seems not to accept, I'm thinking of using an arduino due to see if I have faster answers but I do not know if it will solve, Could you give us any tips?
the car in question is from the year 2015 and uses the CAN and when I use only a pid it responds quickly, but when increase the amount of pid slows down.

rrsilver
Posts: 7
Joined: Wed Sep 06, 2017 6:45 am

Re: OBD-II UART Speed

Postby rrsilver » Tue Sep 12, 2017 10:53 pm

Hello everyone
I did a test yesterday and would like your comment about the results.
https://youtu.be/CX1E-s9I9Ps
Thank you very much in advance.

stanley
Site Admin
Posts: 769
Joined: Sat Mar 01, 2014 3:15 am

Re: OBD-II UART Speed

Postby stanley » Sun Oct 01, 2017 10:23 pm

Very impressive GUI.

rrsilver
Posts: 7
Joined: Wed Sep 06, 2017 6:45 am

Re: OBD-II UART Speed

Postby rrsilver » Wed Oct 04, 2017 2:24 am

Thanks Stanley, but your work with this library is fantastic, very very good even the result that it presents, I know that adjustments are missing to get more speed because I saw some videos on youtube with this library with faster answers, I would like to buy your scanner and I even sent an email asking if you would send it to Brazil but I know it must be very busy and you still have not answered me. I am very grateful to have shared your work with everyone.


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