RE: Combining X10 powerline interfaces

["K. C. Li" <li@xxxxxxx>]

On Sat, 29 Jun 2002, Kevin Hawkins wrote:

>     I understood that basically the power line
interfaces were akin to a
> modem in that they detected the presence of a single tone (120Khz) and
could
> also superimpose this tone back on the power line upon request. In
addition
> they reported the zero crossing points to allow you to time the
insertion of
> the X10 carrier correctly.

You got it. The important thing to remember is that there is no
decoding
involved, apart from modulating/demodulating the 120KHz signal and
recognising that it is an X-10 signal. All X-10 transmissions starts
with
the start code of 1110 in binary. The TW523 only recognises standard
pairs
of 11-bit X-10 commands with 3 power line cycle gaps between each pair.

>     Li - any comments on the ON/OFF v just dimming
LED operation of these
> things (see top post in thread) , could this be caused perhaps by
the

The LED on the interface gives a visual indication that X-10 codes are
being received. The LED lights up when AC power is applied and blinks
off
when X-10 codes are received. The interface is also capable of
receiving
the codes that it transmits, therefore the LED will also provide an
indication of codes being transmitted.

On some of the original TW523 and the converted unit, the capacitive
power
supply is struggling to provide adequate current to drive the circuit
and
the red LED at the same time. The dimming of the LED is sometimes a
visual
indication of the problem. Removing the current drain by removing the
LED
would overcome the problem.

> carrier being inserted abnormally late in the cycle rather than just
after
> zero crossing and also there were some interfaces that didn't handle
all the
> fancy X10 formats (extended, enhanced etc) I had an idea this was the
the
> XM10U or is that basically dumb too ? - it may have been the CM11 I
am
> thinking of...

X-10 Europe has confused the market by introducing versions of the
interface that work slightly differently to the original TW523.

The TW523 is capable of passing along one of the two copies of received
X-10 commands (X-10 commands are usually transmitted twice) and it is
capable of sending but not receiving the (old) extended code/data.
Every
other Bright and Dim commands are passed along also but not every one.

The TW7223 (a) is an European version of the same unit. Internally, it
has
been completely redesigned but functionally it is identical to the
TW523.

The TW7223 (b) is similar to (a) except that X-10 has changed the MCU
inside the unit and rewritten the firmware. It is capable of passing
both
copies of every X-10 command received and is capable of sending and
receiving the extended commands. Unfortunately, the unannounced change
caused chaos as almost all the 3rd party home automation controllers
(eg.
HomeVision, Comfort) on the market at the time were expecting the
original
TW523 behaviour of passing one command out of the two sent. Updated
firmware was needed to overcome the problem.

The XM10U might have been functionally similar to the TW7223 (b) for a
while before X-10 changed the firmware to revert the behaviour back to
the
TW523 way. I have lost track of the changes.

Regards,

Kwong Li
li@xxxxxxx
Laser Business Systems Ltd.
http://www.laser.com



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