You say you are surprised that I would use HC 'A' but proced to anticipate the very reason. Yes, when I placed my sensor outside, facing the driveway, I read the fine print about it resetting to A1. So I decided not to fight the system. Forseeing freezing weather could causing a power loss malfunction which would cause a reset to A!, so I chose to use A1.
The driveway is somewhat huge, easily accomodating a dozen cars and in one back area I have an Heathkit outside floodlamp with integral sensor which I bought as a kit in 1982 for $150 when the sensor technology was new. It has worked unfailingly since then with it's only fault being set off by cats, atlthough it is mounted 9' off the ground. I wish I could tie it into the X-10 system. Nearby I have a Sony CC color camera tied into my TV channel 4. This cameras predecessor worked unfailingly for 6 years until the house painter power washed it into netherworld. I was an engineer for HP and am accustomed to high quality reliable electronics which will explain my tantrums in the forum. My expectations are that things work.
But the new driveway sensor has yet to detect it's first car. Mounted at eye level, it detects humans up close like the postman but it ignores cars But it doesn't turn anything on anyway except the appliance relay in the nearby receiver in the garage. That receiver, set to HC 'A', does send an rf signal down the houre wiring which is seen and logged by the CM115A at the other end of the house. But that CM115A doesn't retransmit a HC 'K' rf signal into the house wiring. Without apologies, I keep repeating this as someone isn't getting the message. The fix is easy, and I'm about to break out the SDK and my VB6 and write my own program but I'd rather spend my time learning a new guitar song which is much more fun. Or hows to give me a copy of the source code and let me fix the problem? No charge.
Methinks some neighbors might be using HC 'A' as years ago I found numerous false positives. But for me the driveway sensor is not that critical. My goal has been, upon receiving trigger, to send TV codes for PIP so the tv would image the car which just drove in. Chosing HC 'K' was fine until now, faced with punching a key in 11 times and holding the eleventh, I wish I'd chose HC 'D' Sometime I would like to see a forum poll on the frequency of house codes useage.