I’m looking for a sensor (some kind of optical barrier) which detects if someone walks through a door.
I’d like to switch on and off the lights in the less frequently used rooms based on this sensor. I have installed motion sensors, currently, but after leaving the room the light stays switched on for a couple of minutes. I find that suboptimal.
OH’s main advantage is that you can use any device from any technology, and this being an OH forum - not general Home Automation -, here’s different advice:
If that Homematic sensor does what you want then get and use it via homegear.
Better even, find a software solution:
use timers or the expire binding to switch off lights and set your motion detectors to a short re-trigger period such as some seconds. That should solve your problem without additional HW.
looking at this Homematic sensor it seems that all it is are two motion sensors, and depening on the sequence in which they are activated it is known if a person enters or leaves the room. If you already have zigbee motion sensors, why not install two in a doorway with a similar distance to each other and try to recreate the functionality with a rule.
Comment; I like break-beam sensors, they are reliable and give you different capabilities to PIR type motion sensors. Used together, there can be synergy.
Example, a room sensor detects motion. If there is no following break-beam at the door, you can apply the wasp-in-a-box method and assume a person is still present but motionless. This approach is imperfect but a step up from motion alone.
You can get break-beam pairs cheap off Aliexpress and so on. These are mostly intended for wired burglar alarms, shop door bells, door automation, etc.
So they are inconvenient to use with Zigbee tech - no onboard battery, only contact output - but you could use with a Zigbee contact unit.
In real life, you can more simply modify a Zigbee etc. PIR to behave a bit like a break-beam by carefully choosing a location and field of view, and experimenting with masking. you can play with tape on the outside, and when something like you want, mask inside the case,
