MP3Car.com - View Single Post

takeda · 04-30-2006, 12:01 PM

The available ISO (?) OBD Interfaces are

OBD-II Signal Protocols

There are five protocols in use with the OBD-II interface, and often it is possible to make an educated guess about the protocol in use based on which pins are present on the J1962 connector:

* SAE J1850 PWM (41.6 kbaud, standard of the Ford Motor Company)
o pin 2: Bus-
o pin 10: Bus+
o High voltage is +5V
o Message length is restricted to 12 bytes, including CRC
o Employs a multi-master arbitration scheme called 'Carrier Sense Multiple Access with Non-Destructive Arbitration' (CSMA/NDA)
* SAE J1850 VPW (Variable Pulse Width) (10.4/41.6 kbaud, standard of General Motors)
o pin 2: Bus+
o Bus idles low
o High voltage is +7V
o Decision point is +3.5V
o Message length is restricted to 12 bytes, including CRC
o Employs CSMA/NDA
* ISO 9141-2. This protocol has a data rate of 10.4 kbaud, and is similar to RS-232. ISO 9141-2 is primarily used in Chrysler, European, and Asian vehicles.
o pin 7: K-line
o pin 15: L-line (optional)
o UART signaling (though not RS-232 voltage levels)
o K-line idles high
o High voltage is Vbatt
o Message length is restricted to 12 bytes, including CRC
* ISO 14230 KWP2000 (Keyword Protocol 2000)
o pin 7: K-line
o pin 15: L-line (optional)
o Physical layer identical to ISO 9141-2
o Data rate 1.2 to 10.4 kbaud
o Message may contain up to 255 bytes in the data field
* ISO 15765 CAN (250kbit/sec or 500kbit/sec)
o pin 6: CAN High
o pin 14: CAN Low

Note that pins 4 (battery ground) and 16 (battery positive) are present in all configurations. Also, ISO 9141 and ISO 14230 use the same pinout, thus you cannot distinguish between the two simply by examining the connector.

I think BMW does not use can at all.

Can you tell, the ELM based cables like

http://www.mp3car.com/vbulletin/show...734#post200734

which of those interfaces implement?

Two programs that look nice for livedata analysis are the Dyno-Scan and DigiMoto

1. Are any of them compatible with the above BMW Engines/Cars (I mean purchasing the kit DynoScan/DigiMoto without DIY kits)
2. Is there any schematics or info for the hardware used by either of them?

04-30-2006, 12:01 PM	#2
takeda Newbie Join Date: Apr 2006 Posts: 21	The available ISO (?) OBD Interfaces are OBD-II Signal Protocols There are five protocols in use with the OBD-II interface, and often it is possible to make an educated guess about the protocol in use based on which pins are present on the J1962 connector: * SAE J1850 PWM (41.6 kbaud, standard of the Ford Motor Company) o pin 2: Bus- o pin 10: Bus+ o High voltage is +5V o Message length is restricted to 12 bytes, including CRC o Employs a multi-master arbitration scheme called 'Carrier Sense Multiple Access with Non-Destructive Arbitration' (CSMA/NDA) * SAE J1850 VPW (Variable Pulse Width) (10.4/41.6 kbaud, standard of General Motors) o pin 2: Bus+ o Bus idles low o High voltage is +7V o Decision point is +3.5V o Message length is restricted to 12 bytes, including CRC o Employs CSMA/NDA * ISO 9141-2. This protocol has a data rate of 10.4 kbaud, and is similar to RS-232. ISO 9141-2 is primarily used in Chrysler, European, and Asian vehicles. o pin 7: K-line o pin 15: L-line (optional) o UART signaling (though not RS-232 voltage levels) o K-line idles high o High voltage is Vbatt o Message length is restricted to 12 bytes, including CRC * ISO 14230 KWP2000 (Keyword Protocol 2000) o pin 7: K-line o pin 15: L-line (optional) o Physical layer identical to ISO 9141-2 o Data rate 1.2 to 10.4 kbaud o Message may contain up to 255 bytes in the data field * ISO 15765 CAN (250kbit/sec or 500kbit/sec) o pin 6: CAN High o pin 14: CAN Low Note that pins 4 (battery ground) and 16 (battery positive) are present in all configurations. Also, ISO 9141 and ISO 14230 use the same pinout, thus you cannot distinguish between the two simply by examining the connector. I think BMW does not use can at all. Can you tell, the ELM based cables like http://www.mp3car.com/vbulletin/show...734#post200734 which of those interfaces implement? Two programs that look nice for livedata analysis are the Dyno-Scan and DigiMoto 1. Are any of them compatible with the above BMW Engines/Cars (I mean purchasing the kit DynoScan/DigiMoto without DIY kits) 2. Is there any schematics or info for the hardware used by either of them? Last edited by takeda; 04-30-2006 at 12:12 PM.