ALDL stuff

[PHXSYS at aol.com]

 Barry

Thanks for the help. I am mainly looking for TPS, MAP, O2, RPM, SPEED, BLM, 
INT.
I am not sure what or how  to  send for a request message to the serial port. 
I don't have a problem with the serial rs232 interface to a PIC.

Are there different interface modes ie slow or fast?

Is the data just sent in consecutive bytes and I filter the bytes I want or 
can I request the data I am looking for?

I think the 94 TBI truck does use the 8192 baud and sends 63 bytes. I am not 
sure what info is at each byte location. Can anyone help?

I have diacom PC interface. Is there a way to use that interface to determine 
the required request message and the type and order of data output from the 
ALDL?

Maybe I have asked too many questions, but I can tell I am getting close to 
figuring out how to accomplish this.

Thanks in advance

Jon


In a message dated 9/3/99 9:38:28 PM US Mountain Standard Time, 
btisdale at cybersol.com writes:

<< Jon -
 
 Got into reading the ALDL myself, for tuning purposes, on my 1991 GMC 
Syclone.  First, is to interface the CPU you're using to the data bus from 
the ALDL.  I think your 94 Chev probably uses the 8192 baud as does mine.  
Not sure what your PIC or Stamp is looking for voltage-wise, but my laptop 
needs standard RS232 protocol, like +/- 12v, converted from the ALDL's 0-5v.
 
 After you can read the idle string, (endless F0 55 BB, in my case), then 
sending a request message to the serial port, you can get the data you need.
 
 Let me know what exactly you're looking for & I'll see if I can help.  My 
prog's in QuickBasic and I've apparently still got some timing problems; 
occasional crashes/resets every few seconds to few minutes.  Still under 
development; but FUN!
 
 Barry >>