If you are here you are trying to talk to your EU/US E36 with INPA and don't know what adaptor to buy and why they are different. If you are not looking for an explanation of the interfaces as described in the thread title and are looking for an INPA quickstart guide go to this thread by dailydoggy.
Your E36 has a 20 pin socket under the bonnet. It is enabled with OBD1 for all models globally. If you have a US 96+ car, post 09/99 EU Z3 or compact you additionally have a mixed OBD1/OBD2 interface on pin 17 in the 20 pin socket. With the 20 pin cap in place, the 16 pin OBD2 socket under the dash is connected and ready to use. You will not use OBD2 16 pin port for INPA, 20 pin has more modules.
First the software.
Please disconnect in your mind the adaptor and the software. It is the software that issues commands in any langauge it feels like, and the adaptor, OBD2 sticker or otherwise, simply converts from PC compatible signals to car compatible signals.
INPA speaks a language called D2 (aka DS2) to your E36, for all models; globally. It is more advanced in the number of commands it supports than OBD2.
Heres a simplified example:
OBD2: There is a an ABS Error
D2: There is an ABS error on speed sensor 3, measured 5 times, speed was 30 MPH, sticky reading 50% lower than other wheels, intermittant fault.
The program EDIABAS is the translator for INPA. It allows several programs to share the COM port. It converts messages to D2 ready for broadcast to the car. It handles the oddties of the adaptor you use. It can support several adaptor types, including LAN.
In summary: The software speaks an advanced language called D2 that all E36 globally will respond to. Whilst it might send out the odd OBD2 message to check for general fault codes, it is not exclusively OBD2, no matter what E36 you connect to.
Second the adaptor.
There are two types. Both have the same job. Convert PC compatible signals (serial over RS232 or USB) to car compatible signals (K line, 12V idle, 0V active). Baud is set by EDIABAS.
USB-OBD2 adaptor (£6 eBay) with 16 to 20 pin adaptor (£6 eBay). This contains one USB to K line tranciever. The only thing OBD2 about it is the shape and that it does 12V/0V on pin OBD2.7.
ADS adaptor (£55). This contains one RS232 to K line tranciever, plus a switch to route K line data to the L line based on the DTR line (+12V/-12V) of the RS232 port.
Why are there two types?
Old tech in the car. 80% of E36 modules need one bi directional k line (TxD), just like the modern cars. Others (KOMBI, ASC/ABS) need a seperate RxD and TxD becuase they are old.
With a USB OBD2 adaptor you get the K line interface to talk to 80% of modules, including DME, airbag, PDC, ZKE. If you want the other 2 or 3 modules, you need to go old school with ADS.
So you want every module don't you?
Well to use an ADS adaptor you need a laptop with a proper harware serial port. Why? Because of the DTR line support, and because of a quirk in EDIABAS that means the Interface = ADS* adaptor must be on COM1/IRQ11/3F38h address. Some laptops might allow you to enter into BIOS and change a PCMCIA adaptor IRQ and address (mine doesn't), but windows XP onwards overides those settings (!), and you must disable ACHI to regain control, which requires a format and OS install.
So you have bought an adaptor, and you have installed the INPA software, what do you change in EDIABAS?
In c:\ediabas\bin is a file called ediabas.ini
You can see the options for the different adaptor
Interface = STD:OBD
Interface = ADS
Why do you need to change this?
If you use ADS, there is a D2 echo that comes back on the Rx path when DTR is -12V. EDIABAS gets upset if it sees this echo with STD:OBD and throws errors.
I hope this clears up the two adaptor types for INPA on E36, and helps you to ignore OBD2 - the language and OBD2 - the socket; and focus on the K line transciever that resides in the adaptors. That should be the focus of your purchasing.
[Note ADS adaptors also offers +12V igniton sensing on the car. This simply lights a black circle in INPA, and performs no further functions. It is not essential to have this feature because if the ignition is off, modules will not respond to any command at all.]
If you want to read more about the software installation and configuration, read here.
Given time and inclination, it may be possible to use USB-RS232 with ADS. The probelm to solve would be the COM port address and D2 echo. Making changes to obd.ini it may be possible to use COM2 in ADS mode. This will allow newer laptops without a serial port to use ADS adaptors. I will update this thread if that does prove possible.
All E36 94-99 with unmodifled VAGCOM cable (Interface=STD:OBD Hadware = USB or OBD) plus 16 to 20 pin adaptor you can access
DME Joylove Yes 1997 328i Anon Yes 1995 328i
ZKE Joylove Yes 1997 328i Anon Yes 1995 328i
PDC Joylove Yes 1997 328i
HVAC Joylove Yes 1997 328i
KOMBI Tonyday - No 1999 323i Joylove No 1997 328i
ABS/ASC Tonyday - No 1999 323i Joylove No 1997 328i IanS- Yes 1996 EVO
Cabrio module Can't remember
Airbag Can't remember Tonyday - Yes 1999 323i
RAD Joylove No CD43
OBC Never tried
EGS (Auto cars) Never tried
Not tried any other modules.
*EDIABAS.ini Interface = OBD and in the OBD.ini file Hardware=ADS & Port=COM1,2,3... is supported for USB->RS232->ADS connections.
ADS detailed in technical terms
How to use a Resler interface with INPA
What adaptor should I buy for INPA
INPA Idiots guide