One of my customers sent me an ActiveHome file to troubleshoot a dimming problem. It included several macros that set dimmers to specific brightness levels.
One macro controlled four dimmers. Two were being set to 50%, and two to 100%. I was surprised that ActiveHome needed almost 20 seconds of continuous transmission to do this. Now I see why some folks are running into the XTB-IIR command storm shutdown.
For the old style dimmers, ActiveHome begins with a sequence of 11 bright commands, followed by the number of dim commands required to achieve the desired brightness. Even though all the dimmers were on the same housecode, only the two being set to 100% were paired. The two being set to 50% were controlled individually. Each of them received the 11 bright commands, followed by 5 dim commands to set the 50% level. The two being set to 100% received 11 bright commands, followed by a single dim command. I have no idea why ActiveHome is issuing that dim command. Maybe 100% isn't quite full-on?
Obviously, there is a smarter way to do this. I understand the need for the sequence of bright commands to begin dimming at a known level. But all four dimmers could have been set to full-on together. Then the pair being set to 50% could have been dimmed together with 5 dims. The remaining two that were supposed to be at 100% would need no additional commands. This would reduce the transmission time to about 5 seconds – ¼ of that needed by ActiveHome. And obviously, this can be done in a couple of seconds with the newer dimmers that accept extended commands.