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Author Topic: Inconsistant clock  (Read 2628 times)

chuck wirtz

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Inconsistant clock
« on: March 29, 2005, 05:57:13 PM »

Initial setup lights work fine a few days
later they are coming on at all different


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  • Roger H.
Re: Inconsistant clock
« Reply #1 on: March 30, 2005, 10:43:42 AM »

Chuck:  There is a well-known hardware
design flaw with the clock inside the CM15a
that makes it possible for the clock to
gain time if there is the right type of
electrical noise on the powerline.  X10
hasnít commented on this.  My suggestion is
to put X10 filters on equipment that can
generate electrical noise (computers, TVs,
motors, etc.).  This is always a good idea
anyway.  It is a tough problem to track
down, but other than using a different
controller, it is about the only thing you
can do.

donald mcmow

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Re: Inconsistant clock
« Reply #2 on: March 31, 2005, 03:58:28 AM »

This problem can also affect other plug-in
clocks that use the A/C powerline to
generate the signal to generate
the "seconds" for counting. It depends upon
the way the signal is filtered. Since the
X10 protocal uses the A/C sin wave to sense
and transmit it's signal, there is less
filtering to combat inadvertant signal
counts. This may result in noise being
counted as a full second rather than being
rejected. Over time these counts add up and
result in the internal CM15A clock being
inaccurate as compared to your computers
clock. Periodic connection of the computer
will result in the 2 clocks being re-synced
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