Re: What can I replace this latching relay system with?

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On 1 Aug 2006 08:38:14 -0700, "Steve Wechsler" <swechsler@xxxxxxxxxxx>
wrote in message  <1154446694.321980.322180@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>:

>Wow, you guys are great!
>
>Unfotunately, it's probably going to be a couple of weeks before I can
>do a complete trace of all wiring. Here's what I know so far:
>
>1) Wall switches are installed in frames embedded in plaster rather
>than full electric boxes, and are horizontal (The frames are
>horizontal, but the switches are vertical. This configuration is no
>longer sold by GE). Most plates only have one switch installed, but
>some have two or three.

SOunds fine. Retrofitting a modern AC switch box if necessary would be
straightforward assuming stud construction and not plaster lathe over
brick or stone with negligible void behind the lather. (Chiseling out
brick to create space for new installations can get old, fast.)

>2) Latching relays are installed inside ceiling boxes. Low voltage
>wires do not enter the boxes directly, but instead enter the relays
>through an entry in the side drilled through the box. There is no
>central controller. Unswitched 120V wiring runs to each ceiling box.

It might turn out to be useful that the National Electrical Code has
changed so that low-voltage can enter box with AC. As you know, "your
mission" is to determine is to whether each AC  load is "home-runned" to
the entrance box or not. If they are, you could install the very best
hard-wired system for lighting automation for the cost of what others lay
out for kludged stuff over power lines or RF.


>3) There is three conductor low voltage wiring going from each switch
>to the ceiling box that it controls. Some relays have more than one
>switch controlling them.

Yes, That hasn't changed.

>4) All boxes have a two conductor wire for power from a central
>transformer. The power wire is daisy chained.

By "all" I assume you mean both the wall switch and the ceiling, right?

>5) Some relays have an additional wire running from them to a 9-way
>remote rotary controller.
>
>I guess what I was hoping was that there would be something like an
>RS422 network that I could run on the existing wires. I may need to
>back to those controllers that Marc mentioned (but unfortunately those
>don't even provide for any automation).


Key here to using RS-485 (assuming  that power to the relays in not
home-runned, because were that the case you would have other, better
options) is the topology of the "two conductor wire for power from a
central transformer .. .[which] ... is daisy chained."

If it is truly daisy-chained  (connected serially, one after another, with
no branches, or spurs) RS-485 control of dimmers in the ceiling is a good
possibility.

Even if it isn't the perfect topology to begin with, it might still be
coaxed into working for RS-485 (depending in part on baud rate) with a
combination of judicious rearrangement (removal of spurs and other
non-daisy-chain segments) and use of a electronics to buffer the RS-485
signal and split the line into segments.

Elk makes a ELK-M1DBHR M1 Data Bus Hub For Retrofit

http://www.elkproducts.com/products/m1/M1_Data_Bus_Hubs.htm (bottom half
of page)

that is designed to retrofit non-twisted and star wiring to meet RS-485
twisted pair and daisy chain topology. Might be jist the ticket. You would
install one where the transformer is now. Is the 2-conductor low-voltage
power wire  twisted  (as in "twisted pair")?. Lots of old 3-conductor
phone wire in my other houses has been twisted and would have worked great
for RS-485.

If you can clean up the signals enough to use RS-485 (depending on baud
rate too) there are numerous options including DMX512 (aka DMX-512 = the
world's standard for dimmed lighting in theatres, stage, music venues
etc). Or Leviton/NSI Luma-Net (I use both of these) or one of the several
other struggling _proprietary_ systems that are "out there" that someone
is sure to suggest (from the frying pan to the ... ;-)

Keep us posted .. Marc
Marc_F_Hult
www.ECOntrol.org