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squat · 05-31-2006, 08:01 AM

Quote: Originally Posted by Tippa

Yes, i think so... At last service they connected some kind on scanner to this plug, under the hud:

Attachment 29429
Attachment 29432
Attachment 29430

Mine E36 325i -91 uses this protocol (i think)
• 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.

Hi

I like Tippa's information provided... Just a few things to say:

If you wish to make a converter from RS232 to ISO 9141-2 (K-line), please consider the following:
- Transceiver IC's of both standards exist, you can simply hook them together and get a "dumb" converter. This is OK, provided you either write your own software or find some software that supports this... bringing about a problem:
- RS232 standard does not (normally) support 10.4Kbaud. The closest speed is 9600, but it is not close enough. I have written software before that does this... its simply done by using a non-standard divisor of the RS232 clock (115200 / 11 = close enough to 10400). Think it's a hack? well that's what is used extensively in OEM... main difference is they write their own software to do exactly what they need.
- Transmitted messages from a PC are received simultaneously as the K-line has a shared Tx/Rx line
- Alternatively, you could use that bloody ELM 323 chip that is supported by lots of software, just costs a fair bit of $.

Anyway my point is this:
For my 1991 BMW e36 (which I believe has K-line), I have made a dumb transceiver as explained, and I am trying to get some sense out of my car. The pics Tippa provided match my car exactly, but I want to find out the following:

Tippa, where did you get these pics from???? Also, what protocol is used for this communication, it doesnt seem like K-line, as it shares Tx and Rx lines and your diagrams have separate.

I am desperately trying to get this working, I will post any info if i get it working as it's hard to find.

05-31-2006, 08:01 AM	#21
squat Newbie Join Date: May 2006 Location: Melb, Australia Posts: 1	Quote: Originally Posted by Tippa Yes, i think so... At last service they connected some kind on scanner to this plug, under the hud: Attachment 29429 Attachment 29432 Attachment 29430 Mine E36 325i -91 uses this protocol (i think) • 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. Hi I like Tippa's information provided... Just a few things to say: If you wish to make a converter from RS232 to ISO 9141-2 (K-line), please consider the following: - Transceiver IC's of both standards exist, you can simply hook them together and get a "dumb" converter. This is OK, provided you either write your own software or find some software that supports this... bringing about a problem: - RS232 standard does not (normally) support 10.4Kbaud. The closest speed is 9600, but it is not close enough. I have written software before that does this... its simply done by using a non-standard divisor of the RS232 clock (115200 / 11 = close enough to 10400). Think it's a hack? well that's what is used extensively in OEM... main difference is they write their own software to do exactly what they need. - Transmitted messages from a PC are received simultaneously as the K-line has a shared Tx/Rx line - Alternatively, you could use that bloody ELM 323 chip that is supported by lots of software, just costs a fair bit of $. Anyway my point is this: For my 1991 BMW e36 (which I believe has K-line), I have made a dumb transceiver as explained, and I am trying to get some sense out of my car. The pics Tippa provided match my car exactly, but I want to find out the following: Tippa, where did you get these pics from???? Also, what protocol is used for this communication, it doesnt seem like K-line, as it shares Tx and Rx lines and your diagrams have separate. I am desperately trying to get this working, I will post any info if i get it working as it's hard to find.