> I am currently working on a network of PIC controlled units for
> minitoring machines in a manufacturing plant.  The units will connect to
> a 485 bus and will be interogated by a PC (master/slave setup).  I am a
> bit unsure about the practical aspects of such a bus in an industrial
> environment since this is my first attempt at it.  I would appreciate any
> comments from people who have done this before:
>
> I was thinking on routing the bus through each slave unit.  You would
> have a female plug going in and a male plug going out.  If the unit needs
> to be removed, then the two parts of the bus can simply be plugged into
> each other.  The alternative is to use T-style taps from the bus, but
> I am not sure how to make the T connections easily and reliably.  Also,
> is DB9 plugs/sockets acceptable in the industrial environment?
>
We use a 485 bus(57600 baud) on our plastic molding machine monitoring
equipment. The
differental operation of 485 helps its noise immunity plus we run it in
sheilded cable.
Remeber the terminator. We use a terminal system that lets the units be
wired in or out of the bus (usually the term board does not have to be
removed for service).