Re: Lighting switch state communication

["Jeff Volp" <JeffVolp@xxxxxxx>]

"Marc_F_Hult" <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:uhu4t21i3suv69ku2l1ccu4is9sn3b9li3@xxxxxxxxxx
>
> This collision problem is much more severe with X-10 than INSTEON because
> of
> X-10's much slower data transmission rate.

I've been working on a "polite" mode for the XTB-II where it will sense a
collision immediately, abort the transmission, and re-transmit when the line
is clear.

While some report significant collision problems, I wondered why we don't
see that problem here.  Pushing the numbers, it appears that collisions
should not be much of a problem unless the installation includes X10 motion
detectors in high activity areas.

As most of you know, it takes almost a second for a typical X10
transmission.  Our installation runs about 200 transmissions a day.  All but
a few come directly from the Ocelot.  So, a collision would only show up if
one of the manual transmissions managed to occur during an Ocelot
transmission.

Our motion detectors are either hard-wired directly to the lights, or to the
Ocelot.  So their random nature is not a factor.  In our case the powerline
is carrying X10 traffic less than 0.2 percent of the time (using the
number - gap - function model).  That, and the fact that the RR501 is
supposed to avoid collisions, is probably why we don't have the problem
here.

Adding wireless motion detectors in high activity locations interfacing to
the line through a dumb TM751 paints a different story.  Those motion
detectors can add hundreds of more X10 transmissions to the mix.  Many
people opt for the less expensive TM751, which does not include collision
avoidance.  So the chance of a collision might approach 1% or more.

The bottom line is that collisions can be largely avoided by using a RR501
in place of the TM751, and having most X10 commands be issued by one primary
controller.

Jeff