Schematic of a GM ALDL -> PC converter

[John Faubion]

> The level shifting from ALDL levels to RS-232 must be the problem. Async 
> communications is very forgiving of clock speed mismatches. It has to be.

The levels? Like in the voltage levels on the lines? I would think the ECM
would have a max of +12VDC. Since RS-232 is supposed to comply with a plus
or minus 15VDC that shouldn't be a problem. I guess I could check it out on
my scope to see.

John Faubion
jfaubion at beaches.net