Re: X10 HA vs. security

[Charles Sullivan <cwsulliv@xxxxxxxxxxxx>]

On Mon, 02 Oct 2006 19:02:51 -0700, pithen wrote:

> I just bought myself a new condo last month (oh yeah, first time
> homeowner!) and was toying with the idea of buying an X10 CM11A off
> ebay and using it with Heya to do some simple automation stuff. One
> thing in particular that I'd like to do is rig up some door sensors so
> that I know a) if I forget to close the garage door, and b) to alert my
> girlfriend and I if somebody comes in uninvited while we're sleeping.

What's "Heya"?  Perhaps you mean Heyu (for Linux, Unix, and Mac OS X)?
http://www.heyu.org

X-10 is currently peddling the RCA-branded CM11A on their "On Sale" page
for $10 + $6 S&H  http://www.x10.com/promotions/hc60rx_vt_kit.html
At that price, consider getting two (for $26).  Heyu can run more than
one at the same time, or you'll have a spare.

> I guess I have a few questions here. First, among the droves of info
> about X10, I can't really seem to sort out anything regarding whether or
> not the door sensor (which I believe is considered a security module)
> will send regular X10 signals to the CM11A which can be read by Heya.
> Any info on this?

The DS10A Door/Window sensors send a "security" RF signal which isn't
recognized by X-10 TM751 or RR501 Transceivers, so won't transmit an
X10 signal on the powerline.  One alternative is to use a PF284 or PSC01
"Powerflash" module which plugs into the AC line and which sends an X10
powerline signal on contact closure between its external terminals.

> Second, I've noticed several threads complaining about how old and
> unreliable X10 is. Is it all *that* unreliable? If I were to use newer
> modules which support status polling (I believe they exist, right?)
> could I not just include in my scripts something that would keep trying
> to turn a device on or off until the status polling reflected this
> change? I see there are other alternatives out there, but seeing as I
> just bought my first place my budget is such that, well I probably
> shouldn't even be looking at X10 nevermind something more expensive.

There are two major causes of X10 reliability problems:
The first is the phase issue - having an X10 transmitter on one phase
of the house wiring and a receiving module on the other phase, and with
no good signal path between the phases. A signal coupler (which can
be as simple as a capacitor) usually solves this problem.

The second results from modern appliances like PC, UPS, and TV which
have switching power supplies.  These can either introduce noise on
the powerline which swamps out the X10 signal or have heavy capacitive
filtering which shorts out the X10 signal.  Special X10 plug-in noise
filters are available for offending appliances.

Using 2-way modules as a workaround for marginal problems with either
of the above is not a good solution - better to fix the problem at
its source.

There are other potential problems, but taking care of the above two
(and using Heyu) will provide very good reliability for the vast
majority of users.

Regards,
Charles Sullivan