Importing data from OBD2?

Advanced Central Logging System including Versatile Input Modules

Importing data from OBD2?

Postby Holmz on Sat May 30, 2009 4:21 pm

I have an ACL that is doing multiple duties, and am going give it some work on the car when not being used for the non-automotive projects.

But I have an OBD2 running data around the car.
Example- The dash unit and ECU (Rover K 1800cc engine) are factory, and use OBD2.

Is there a way to get the OBD2 data into the ACL?

From http://en.wikipedia.org/wiki/On-Board_Diagnostics, it looks like it is 500kHz rate...
But not sure if is just as simple as splicing the wires into CAN bus?
(and then figuring out the data messages.)
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Re: Importing data from OBD2?

Postby JamieA on Mon Jun 01, 2009 11:21 am

no, it is not that simple. OBDII is a request based system. It doesnt send anything unless specifically asked for. So if you want to know the current RPM, you have to send a request for it, then you get one instance of RPM. If you want it again, you ask again. It does not stream out data. you also have to be able to contro lthe flow of data, as you have to request the next RPM, only after you have recieved the previous RPM data.

It is not that difficult for a dedicated PC application to do this, but is it not as straightforward as it seems like it should be to connect to a logger.

Many have tried to do this, but I havent seen a working example of this yet, where you have a box that takes the OBDII information and turns it into streaming CAN or RS232 data. If you find one, let me know..

thanks.

-Jamie
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Re: Importing data from OBD2?

Postby Holmz on Mon Jun 01, 2009 12:48 pm

Thanks Jamie,

It (OBD2) supposedly sends the RPM, water temp, and fuel data to the dash at 100mS intervals - without a request (I think initiated from the ECU sending the data to the Dash).
And it is unclear to me but is either an OBD2 or OBD2b operating at either 500kHz, or 1MHz respectively.
Sounds like I have some work cut out in catching this data midstream...

What are the other options?
I suspect that the inputs are hi impedance (sensor outputs lo impedance), so can I splice into each wire I want to get data from and run that into a VIM?
Sound non-optimal, but maybe the easiest option.

R
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Re: Importing data from OBD2?

Postby JamieA on Wed Jun 10, 2009 9:59 am

Data to the factory dash is often K line (bikes, jet ski's etc), or factory CAN bus (most cars) rather than OBDII. OBDII is generally used for diagnostics, and nothing else as far as I know. I am happy for someone with more knowledge of OEM communications to let me know otherwise.

I would think that your best option may be to install extra sensors for this task, depending on what you are intending to measure. The other option would be to use a canalyzer to scan the factory bus, and try to grab the channels off there, but this will be far more involved..

regards

-Jamie
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Re: Importing data from OBD2?

Postby GaryA on Mon Aug 22, 2011 4:45 pm

Hi Guys,

I would also like to log some data from the ECU Via the OBD-2 port (or even another method which would require little modification). I was wondering if there has been any advancements in this? The main information i would like to log would be speed, followed by anything else that would be easy to log.

I noticed this topic has been dead for a few years so i thought i might try and resurrect it rather than start a new one.

Thanks
Gary
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Re: Importing data from OBD2?

Postby JamieA on Thu Oct 20, 2011 9:25 am

We have implemented some specific OBD-II code in the new CDL3 product.

This allows us to get a selection of channels from most 2007+ cars.

this will be ported up to SDL3, ADL3 and ACL over the next few weeks.

regards,

Jamie
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