A little over 10 years ago, I bought an open-box RCS TX10-B thermostat control unit to replace a TX10 unit. “Open Box” means it came without any documentation, but it should, in theory, be a drop-in replacement for the TX10 — the “B” designator indicates that it’s capable of reporting status and temperature, unlike the TX10.
Unfortunately, “open box” means it came without any documentation whatsoever. On the plus side, the wiring is similar to the TX10 (with the additional feature of a physical connection for a “setback switch”) but without knowing the X10 protocol it required, I was left without any means to actually get status reports from the unit.
Using the Internet Wayback Machine to go back to 1998, I located a nifty diagram of the system from Smart Home, from whom I originally purchased the unit. Ten years ago, it was in the process of being replaced by the TX15-B, a more modern-looking unit — and the only one mentioned on the web site of the manufacturer.
Some experimentation demonstrated that the TX10-B substantially uses the same procotol as the TX15-B, which is documented here. It doesn’t seem to support the “autosend” feature, nor does it respond to requests for the outdoor temperature, but otherwise, the document appears to be accurate.
The unit uses the venerable TW-523 to communicate, and I was mildly surprised to discover that my TW-523 was capable of receiving, but not sending. Since the TX10 it was connected to wasn’t capable of sending, either, it may have been defective on the day I bought it, and I’d never have known.
(Yes, it took me 10 years to get around to this project, but now all that’s left to do is the software…)