Re: Sending and receiving addressable contact closures.

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Alan - do take a look at the Viom from Phaedrus - this is controllable
via a single RS232 port or an RS485 version is also available that
allows multiple Vioms to operate on one port.   If you want an Ethernet
version they make the Netiom  and they will be releasing in the next
week or so a xAP version of the Netiom using BSC (Basic Status and
Control) which offers exactly what you seem to need in terms of
addressable I/O control.

Devices have 16 inputs, 16 outputs, 4 analog inputs, counters , high and
low latches and serial I/O   (VIOM has some timers and logical state
handling onboard too)

http://www.phaedrusltd.co.uk

Kevin

Alan Ainslie wrote:

>Some clever guy on our group must know the answer to this.  I have been
>looking in all the wrong places I guess.:-
>
>I need to send instructions to a number of switches to close or open:
>accessed by address.
>
>I also need to read the status of other switches as inputs.
>
>This is all ON/OFF so no proportionality and I do not want to use a PC,
but
>am happy to make up a central controller and then to make up the
devices
>that go onto the control bus.  Ideally control bus would be two wires
plus
>the heavy 12V supply to power relays and things.
>
>Anyone any ideas for chip set to do this robustly and economically. 
Devices
>will be outdoors.  Everything is 12V only.  Numbers?  Less than 50 of
the
>addressable switches and less than 20 of the input contacts closures.
>
>Application?  Well, almost an automated home: in truth this is to
control
>signals and to read status of various devices on a 7 1/4 gauge large
steam
>railway located-----in an automated home.
>
>Any railway nuts out there welcome to a day on the Spinney light
Railway in
>Surrey.  Fully signalled at present using authentic 1930s railway
>technology.  new stuff is for a large extension and I really don't want
to
>be running more miles of cables for the mice to eat.
>
>Alan
>
>
>