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Chat Area => General Car Chat => Topic started by: JamesV6CDX on 05 March 2010, 13:36:29

Title: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 13:36:29
I have an ELM 327 with a USB lead

Trouble is, can't get it to work.

It's installed a "virtual" com port, Com5. The software can see port 5 and it's all configured on correct baud rate etc.

When you tell it to connect to the car - it sucesfully opens the com port, but then says "cannot detect interface".

Any ideas?  :-/
Title: Re: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 13:36:44
Just to add, the car IS OBD2 compliant.
Title: Re: ELM 327 Code Read problems
Post by: Entwood on 05 March 2010, 13:41:12
When I tried the ELM327 I seem to remember a major "faff" changing/configuring ports until I found one that worked ....  one reason I changed to the Maxscan .. :)
Title: Re: ELM 327 Code Read problems
Post by: Jimbob on 05 March 2010, 13:44:22
using some bits like that, Ive had to force the virtual port to be port 1, then worked ok.
Title: Re: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 13:46:13
Quote
using some bits like that, Ive had to force the virtual port to be port 1, then worked ok.

I will play in more depth tonight.

Essentially then - disable com1 in the bios, and try again?  :y
Title: Re: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 13:46:58
Thing is - the lead remains red when plugged into the car - does this indicate for whatever reason, it's not getting any power from the ODB2 socket?
Title: Re: ELM 327 Code Read problems
Post by: Jimbob on 05 March 2010, 13:49:28
what currently has com1?
My bet is nothing.

shouldnt need to go to bios level, unless it was to disable the existing serial port 'com1' in which case you wouldnt be using an adapter in the 1st place.

device manager and the ports section should be all you need.

if something like a modem has com1....redirect that furher down the list.
Title: Re: ELM 327 Code Read problems
Post by: Kevin Wood on 05 March 2010, 14:22:03
If you open that COM port with (e.g.) Hyperterminal you should get an AT-command style interface similar to a modem (remember them?).

Set the right BAUD rate and see of you can ping it with AT and get an OK response back. This will prove that the USB interface is OK and the ELM chip is working.

Some adaptors power the USB to serial chip from the USB port but the ELM chip is powered from the Diag socket so it won't be recognised unless plugged into a car.

ELM327 chips can default to one of 2 BAUD rates depending on how they are bootstrapped. (9600 BAUD or 38400 BAUD IIRC.) Worth trying both of those.

Kevin
Title: Re: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 14:47:09
The laptop has a physical  9pin serial port , shock horror
Title: Re: ELM 327 Code Read problems
Post by: Jimbob on 05 March 2010, 14:48:12
Quote
The laptop has a physical  9pin serial port , shock horror


use it then! and file the adaptor away  :y
Title: Re: ELM 327 Code Read problems
Post by: TheBoy on 05 March 2010, 14:48:37
Most of the freebie apps need it to be on Com1-com4.

COM4 rarely conflicts on any laptop, so thats a good start
Title: Re: ELM 327 Code Read problems
Post by: TheBoy on 05 March 2010, 14:49:32
Most lappies:

COM1 - 9 pin serial (if it exists - beware it may exist in chipset, but no connector!)
COM2 - Infrared
COM3 - Modem
COM4 - free
Title: Re: ELM 327 Code Read problems
Post by: Kevin Wood on 05 March 2010, 14:56:53
Quote
Quote
The laptop has a physical  9pin serial port , shock horror


use it then! and file the adaptor away  :y

I'm guessing the ELM lead has a built in USB-to-serial chip. Mine has (but it works flawlessly)  :-/

Kevin
Title: Re: ELM 327 Code Read problems
Post by: TheBoy on 05 March 2010, 15:35:39
Quote
Quote
Quote
The laptop has a physical  9pin serial port , shock horror


use it then! and file the adaptor away  :y

I'm guessing the ELM lead has a built in USB-to-serial chip. Mine has (but it works flawlessly)  :-/

Kevin
Believe they do.  The one in my kitchen that doesn't belong to me ::) has usb to serial built on the board
Title: Re: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 15:49:30
mine only has a USB end on it
Title: Re: ELM 327 Code Read problems
Post by: JamesV6CDX on 05 March 2010, 22:42:07
disabled the "real" com port in BIOS, USB one now as Com1. Tried all manner of configs. It will not see the device  >:(