Re: GM 2.8L V6 ALDL - Carbytes

["Shawn R. Lin" <slin01@mail.orion.org>]

Dale Klein wrote:
> 
> >Unfortunately like Carbytes, it changes $58
> >to $56.  Not sure why though.
> 
>          I think I understand the reason that the $56 gets changed to
> $58.  Read the macro help and examples in carbytes v2.0 carefully.
>          The second byte in a 'frame' or packet is some base value, like
> $56 in my case for 94-95 camaro 8051, plus the number of data bytes
> (everything after the first three bytes) in the message your're
> sending.  so if I'm asking for mode 1 message 0, I'd say  '$f4 $57 $01 $00'
> (and also the hex characters '$CS'  ;>)  )   the $00 is the one data byte.
>          that is a 1 data byte message, so $57.  there are other messages
> you might send, like $f4 $56 $08, which is 'shut-up, stop chatter and
> listen', which has only one data byte, so there is a $56.
[snip]

Thanks for the explanation!  You are absolutely correct, Carbytes IS
adding up the checksum right.  It's just smarter than I thought, it's
correcting my invalid string to a valid string.
Go figure, now that I know what I'm SUPPOSED to send to the ECM, I think
now I just need to figure out how to get the timing right.

Shawn



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