I have the Pi external to the CM15A which is plugged into the XTB-IIR ...
It is not a good idea to plug the CM15A directly into the Boost input because the CM15A does not have AGC to ignore powerline noise. I recommend plugging it into a nearby AC outlet, and use the XTB-IIR strictly as a repeater.
The XTB-IIR Boost input is isolated from the powerline by a low-pass filter so it can differentiate between signals coming in there from those coming in over the powerline. A return signal bandpass amplifier passes X10 signals from the powerline back to the Boost input so devices can monitor X10 powerline traffic. Powerline noise near the X10 bandpass can also be amplified and look like X10 signals. The CM15A is a "polite" transmitter, and will delay or inhibit transmissions when it believes there is already X10 traffic on the powerline.
Note that 1.20 and later firmware versions include a mode option to reduce the return signal amplifier gain. That will reduce the amplified noise, but it also reduces the ability of the XTB-IIR to repeat weak incoming X10 signals.
Jeff
Jeff,
I went away for the holidays and never got back to see this thread until this evening...
This may explain some of the intermittent issues I have, which I have been attributing to my unique house wiring. I have two main panels connected in parallel at my incoming power meter, both of which have distant sub panels connected to them. One of the panels has the XTB-IIR connected to it on a dedicated 240V circuit breaker, along with a V572A connected to the XTB. This is where I currently have my CM15A plugged into the Boost outlet and have the PiX10Hub plugged into the USB input of the CM15A. I am relying on the power meter connection to bridge into the other main electric panel and its associated circuits. The wiring in our old and many times improved house is spaghetti. Just a few weeks ago, I found a wire at the roof of my attic that was running the length of the house and unterminated at the far end. It was hot and connected to the line inside one of my living room outlets!!!
Functionally, I think the optimum would be to have the CM15A only provide X10 commands to the XTB. That way, all the AC and RF commands would originate from the XTB. I believe I disabled the CM15A RF transmissions by wiping all the macros and disabling transceived codes through AHP prior to hooking up the PiX10Hub, but I did not make any HW mods to be sure.
So...my question is whether you think I will be better off with the configuration I have now, with the increased powerline noise, or have the CM15A plugged into a wall outlet and have the XTB resend its signals. I will experiment, but since I have no adequate test equipment, it will be difficult to unequivocally determine any improvement.