Re: What is X-10?

[gordonb.22cqv@xxxxxxxxxxx (Gordon Burditt)]

>By what I gather, it appears to be an all in one package or system which
>offers surveillance, and remote control for electronic devices. If so, I
>would like such a system.

X-10 is a protocol for controlling devices (e.g. lights, coffee pots,
TV sets, etc.) over power lines in a house.  It is far from an all-in-one
system.  I bought a number of controllers and modules to control stuff
from Radio Shack in the 1980's.  Some of the newer features I may not
be aware of.

Some modules replaced light switches.  Some modules plugged into
outlets and you then plugged the lamp or appliance into it.  Appliance
modules didn't have dimmers and generally had more power capacity.
I believe there were some modules that replaced outlets.

There are a variety of controllers.  Some are intended to sit on a
chair or table.  Some do timed control of the devices on a schedule.
Some are interfaced to a computer.  Some later devices like thermostats
or motion-detectors could be programmed to send commands to modules
under certain conditions.

Each module has a setting for a "house code" and "unit code".  There
are 16 of each.  In theory, a house (or apartment) used 16 or less
of these and a nearby house used a different house code to avoid
(non-malicious) interference.  Of course, there's nothing to prevent
a given house from using more than one code.  Two devices that are
supposed to be controlled together may have the same house/unit
codes.  Some of the manual controllers are a bit awkward to change
between house codes frequently.  (It's possible, but not very
convenient).

You can have an X-10 system with one module and one controller.

The protocol allowed you to select a device, then send it a command,
which included: ON, OFF, DIM, BRIGHT, ALL LIGHTS ON, and ALL OFF.
The modules intended for lamps, such as ones that replaced light
switches or lamp modules that plugged into outlets, had dimmer
capability.  You sent repeated DIM or BRIGHT commands to adjust the
level.  A module knows whether it's supposed to be controlling a
"light" or an "appliance" (dimming an appliance is not a good idea).
ALL OFF is to turn everything off when you go to sleep.  ALL LIGHT
ON is to turn all the lights (not appliances) on when you hear a
burglar.

There is no acknowledgement in the protocol (at least when I was
using it, long ago).  You don't know you are commanding a module
with the wrong code.  If interference jams the signal (certain
printers with switching power supplies and my electric razor did
that.  Also, some people had trouble if the controller and module
were on different phases of the power line), you don't know it
didn't work.  You can also turn on devices manually (turn the
appliance or lamp switch off then on).  Nothing is notified of this,
so you may run into the situation of the computer or timed schedule
not knowing the correct state of the device, because of manual
operation or operation of a manual controller.