Right (re: differential rewiring).  I definitely don't want to mess with=20
the vehicle's CAN bus for several reasons -- keeping this a quick=20
hardware-only change for some added reliability, and tying to existing=20
CAN system will also require some rewiring.  Part of the issue is that=20
the person who has the vehicle does not want to do any other wiring. =20
When I send him the next revision of the board, he should just be able=20
to plug it in and go.

Haven't heard of 1488/1489 in decades -- wouldn't the MAX232/3232 etc be=20
considered updated, more compact versions of the same functionality.

Cheers,
-Neil.



On 12/2/2014 11:10 AM, alan.b.pearce@stfc.ac.uk wrote:
>> I'd suggest a balanced driver/receiver pair for each signal, RS485 drive=
r chips
>> are cheap and readily available.
> That was my initial thought, but he said he couldn't rewire the vehicle f=
or differential wiring.
>
> So my suggestion would be the old standby 1488/1489 RS232 transceiver pai=
r as being rugged bipolar devices that are designed to survive noisy enviro=
nments. Modern ones seem to be able to handle faster than the old RS232 ser=
ial speeds so I suspect would work to the 100kHz rate suggested.
>
> However the other thought is could the data be pick-backed on a CAN syste=
m already existing in the vehicle? Would involve a bit of research into how=
 much data needs to be transmitted, and breaking it up into 8 byte chunks f=
or longer messages, and how your message priorities mix and match with the =
standard vehicle message priorities.

--=20
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