Yet Another OBDII VB6 Class

Erorus · 02-16-2005, 07:31 PM

Here's my version, folks.. it's a class so you make it an object and use its functions/subs/events to communicate with it in your application. Practically plug-and-play.

Works with the ELM323 chip found in scantool.net's OBD devices. The 323 is the ISO version, but I bet this exact code will also work with the other ELM chips (ELM320 and ELM322).

http://www.apeirokalia.com/elm323/

stevieg · 02-17-2005, 07:28 AM

Quote: Originally Posted by Erorus

Here's my version, folks.. it's a class so you make it an object and use its functions/subs/events to communicate with it in your application. Practically plug-and-play.

Works with the ELM323 chip found in scantool.net's OBD devices. The 323 is the ISO version, but I bet this exact code will also work with the other ELM chips (ELM320 and ELM322).

http://www.apeirokalia.com/elm323/

Thanks... Looks good.

So basically, once the inital setup is done, you fire a command to it and an event comes back with the data?

stevieg · 02-17-2005, 07:29 AM

by the way... Yet another VB6 elm class? Where are all the others???? I thought this was the first?

EDIT:
I would like to use this to finish off my MPG meter.. Do you have a sample app to give me a better idea of how to use the class?

Erorus · 02-17-2005, 08:36 AM

Quote:

Thanks... Looks good.

So basically, once the inital setup is done, you fire a command to it and an event comes back with the data?

That's the idea exactly.

Quote:

by the way... Yet another VB6 elm class? Where are all the others???? I thought this was the first?

EDIT:
I would like to use this to finish off my MPG meter.. Do you have a sample app to give me a better idea of how to use the class?

Well, I see a lot of VB code on this so I tacked "Yet Another" on the subject line.

The thing I like about the class is it isn't fully embedded in a form that you have to take apart to figure out how to use.

I don't have a sample app for ya, sorry. Maybe if I get bored in the next few days.

takissd · 02-17-2005, 09:48 AM

great! will that work with vb.net??? if yes, how?

Erorus · 02-17-2005, 09:52 AM

Quote: Originally Posted by takissd

great! will that work with vb.net??? if yes, how?

No idea, I don't have VB.net. Worth a shot, tho.

kocke · 03-12-2005, 11:22 AM

I can't download the class

can you send it me?

thanks and regards

Erorus · 03-12-2005, 11:56 AM

Please try it again from the webpage, I changed the URL. When you download it, just cut off the .txt extension.

kocke · 03-12-2005, 01:08 PM

thanks, now it works

Kind Regards

blaster · 03-22-2005, 08:23 PM

can I use VAG TWIN COM with it?

Erorus · 03-22-2005, 09:45 PM

Probably not.

carabuser · 04-07-2005, 08:22 PM

So anyone used it yet?

stevieg · 04-08-2005, 04:40 AM

Quote: Originally Posted by carabuser

So anyone used it yet?

Yes!!!

I'm using it! It works - My app isn't finished yet, but it's a re-hash of this:

http://www.mp3car.com/vbulletin/showthread.php?t=32692

The OBDII stuff is working very well. I've successfully had it running for hours on end pulling out the data. My MPG calculations seem to be a bit iffy though - I am having trouble finding a comprehensive list of all the basic formulas for temp, mass air flow etc for when I'm converting from the output long to it's 'real' value! I found one a long time ago when I first started on this, before your VB6 class, but can't find it now, so having a little trouble double checking everything.

I haven't tested standby/resume properly yet - my only try resulted in failure but I was thinking about polling for the standby system call and disconnecting, then on resume reconnecting if it causes any issues - my main thing is getting the instant MPG quick and reliable.

But yes... It works!

knubile · 08-28-2005, 10:28 AM

Any progress on this? I'm wondering if MPG calculations are possible using OBD-II.

Erorus · 08-28-2005, 05:07 PM

Quote: Originally Posted by knubile

Any progress on this? I'm wondering if MPG calculations are possible using OBD-II.

PHP Code:


  
   
Function GetMPG(tMAF As Variant, tSpeed As Variant, tLTFuelTrim As Variant) As Variant



''MAF is maf_air_flow sensor. To convert from what the OBD returns, value=OBDData * 0.01

''tSpeed is vehicle speed in MPH. To convert from what the OBD returns, value=OBDData * 0.621371192

''tLTFuelTrim is long-term fuel trim. To convert from what the OBD returns, value=0.7812 * (OBDData - 128)

    

    If IsNull(tMAF) Or IsNull(tSpeed) Or IsNull(tLTFuelTrim) Then

        GetMPG = Null

        Exit Function

    End If



    Dim tMPG As String



    '' Do MAF over an hour

    tMAF = tMAF * 60

    tMAF = tMAF * 60



    '' Turn into KG/litre equivalent

    tMAF = tMAF / 1000



    '' Get petrol flow based on 14.7:1

    tMAF = tMAF / 14.7



    '' convert litres to gallons

    tMAF = tMAF * 0.219969157



    '' convert long term fuel trim to percentage

        tLTFuelTrim = (tLTFuelTrim / 100) + 1



    '' Calculate MPG

    tMPG = (tSpeed / tMAF) * tLTFuelTrim



    GetMPG = FormatNumber(tMPG, 1, True, False, False)

End Function

The problem I have with this is the air flow sensor is very optimistic, and you probably run richer than this formula indicates. It says I average around 60-90MPG when cruising on the hwy and up to 200+ MPG when coasting. However, it does change when you have the pedal down, etc. I forget where I stole this code from.