RS485 is a differential signal, so you want to minimise the noise
difference on the two wires. Twisting them together is the easiest way
of doing this as magnetically induced  interference tends to cancel,
and electric  field interference is turned into a common mode signal.
You don't _have_ to use twisted pairs, but if there is noise -
particularly magneticlly induced noise - then twisted pairs are the
safest bet.

RP

2009/4/27 solarwind <x.solarwind.x@gmail.com>:
> Does an RS-485 cable HAVE to be twisted pair?
>
> -- [ solarwind ] -- http://solar-blogg.blogspot.com/
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