Well, we have two problems (just summarizing
what Roger posted):
1) The expectation that the TM751 should be
able to control its internal "appliance
module" when it receives a wireless command
for itself no matter what as long as it’s
powered.
2) X10 signals being "corrupted" (sorry,
Computer Science guy here) over the UPS side
of the power line when working on batteries.
My very limited knowledge on the hardware
principles involved prevents me of adding any
meaningful explanation for 2) but I came
across a bunch of other posts where this
behaviour has been observed (not explained
tough).
At this point, my real problem is 1). The
power output of the TM751 itself will control
some small loads which I would like to work
even in case of power failures (part of an
alarm system, if you ask). And Roger, I tried
an extension cord (1 meter) and no changes. I
even tried a second TM751, same thing. In the
exact same configuration, connected at the
exact same outlets, UPS side, power from
battery doesn’t work, power from house works.