Re: XTB-II TW523 Emulation

["Jeff Volp" <JeffVolp@xxxxxxx>]

The XTB-II has been working fine with my Ocelot for the last couple of days.
I can trigger macros from various Leviton 16400s or via RF through a RR501.
So the standard communication mode is working fine.  The LM14A supposedly
includes a mode where it returns its brightness setting as an extended
message, but I haven't tested that mode since the Ocelot has no support for
it.

The one thing I am concerned about is collision detection.  Documentation
for the TW523 says: "Any signals applied to the O.E.M. product are
error-checked, valid X10 codes."  Since all bit patterns are defined, the
only possible errors are a bad start pattern, or a mismatch in the bit
halves.  The XTB-II rejects any message with either of those errors.  During
transmission, X10 says: " The ability to read X-10 codes from its own output
also allows the O.E.M. to incorporate data collision detection.  If the code
received differs from the code transmitted, the code can be assumed to have
been corrupted by noise (or another transmission) on the powerline."  The
fact that the XTB-II does not return any message when there is an error
meets that condition.

If anyone can see a problem with this approach, please let me know.  I could
eliminate error checking during transmission, but that does not meet the
condition that the TW523 is supposed to return only valid X10 codes.  The
TW523 receiver works the same for both transmit and receive.  If it can
return a corrupted message during transmission, it must also return a
corrupted message during normal receive.

Jeff