Odd Baud Rate 8192

[72455]

Does anyone know how to change the com port speed from 9600 to 8192 in Win XP?
I need to link up with my 1989 Lotus Esprit automobile computer. It has a General Motors ECU which needs a communication speed of 8192.
I think it can been done in the regit edit mode.
I have been told to set the speed at 115200, then take 115200/65536. Something about a divisor of 14. the 8 th register bit must be high for UART to slow the com speed from 9600 to 8192 or close enough to 8192 for communication to take place. I've been told that a GM Saturn has the same 8192 com rate.
HELP
Thank you

 

[strongm]

Presumably you are aware that the ECU produces a proprietary data stream running over a proprietary serial protocol all on a proprietary interface, collectively known as Assembly Line Data Link that is not directly compatible with a PC's comm ports (whether physical serial connectors or USB)?

So you presumably have at least a hardware interface to allow the ECU to actually connect to the comm port (these days that would be an ECU to USB cable). If so, normally those converters would come with both driver and configuration software.

>I have been told to set the speed at 115200, then take 115200/65536. Something about a divisor of 14

Let's hope a GM ECU expert turns up to explain what this advice means, as it doesn't make much sense to me. For a start, which registry entry have you been advised to modify?

 

[72455]

Thank you. Yes, I bought a special usb to aldl cable the guys made to communicate with Freescan and Espritmon the two that will communicate with the Lotus Esprit ECU. I don't know which register, but it just says Register, First port 0X3F8 then second port 0X2F8, then reg=16 bits wide, to access the register the 8 th bit of line control register needs to be high then the registercan be programed via the first and second. 1111111111111111 = 65536 ( or the speed 115200/65536 = 1.7 baud) 0000000000000001 = 1 or the speed 115200/1 =115200. then it talks about interrupt enable, interrupt status, fifo control, line control, modem control, line status. WOW
Thank you

 

[edfair]

Have you looked at what is available on google with regards to reading the unit?

PC serial communications are not set up to use the same voltage swings as provided by the ECU and the timing issues you are facing would normally require matching a special crystal to whatever communications chip you use.

One possible way to get the readings is by building an interface:

http://lukeskaff.com/?page_id=305

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[strongm]

Well, as I say, such cables should come with the appropriate driver. And/or proper documentation.

The info you have then been given, however, relates to some very low-level configuration of a PC's physical hardware serial port controller (specifically referencing COM1 and COM2 and the UART). The register that is being talked about is the UART's line control register (not any sort of registry entry, and thus absolutely nothing to do with regedit). Which means you need to be a low-level hardware programmer in order to make any changes

Except it won't do you any good, because, as I say, this is all for physical hardware serial ports. Which your ALDL-to-USB cable is not.

I think you need to question 'the guys' further.

 

[xwb]

Have you tried just connecting at 9600?

You could try Erik4's solution in

http://www.thelotusforums.com/forums/topic/32501-cannot-establish-connection/

 

[72455]

Yes, I found a cable that will do the conversion.
Thank you

 

[strongm]

Hurrah!