hello
I have 3 of the square Tuya human presence sensors. HERE: https://smarthomescene.com/wp-content/uploads/2022/11/tuya-human-presence-sensor-zy-m100-package.jpg
However, 1 is older, purchased 1 year ago and shows as ZY-M100-L, and the other 2 I just purchased now and show as ZY-M100-S. They are all 3 identical otherwise in the outside. I want them all to be mounted on the wall. I don’t have a way of mounting them on the ceiling. Is this a problem? Why the difference in the model? Thanks
Well, the ceiling model is supposed to stay up around the middle of the room to cover the area, while the other model you can put it on a wall or over furniture but in this case you have to pay attention to the angle of the area covered, you can have some gray area not covered.
I am checking now the functioning of the ceiling model, I cannot see any sensors just after discovering it.
Will dig a bit more.
Any luck / update?
I am using the ceiling sensor and it is quite good. During the day it is sensible even when I sit on the sofa, but then after, it is less sensible. Maybe there are parameters to change, I will work on that otherwise I need a pressure sensor to understand when I am still and sit on the sofa 
how quickly does it sense your presence? Usable to turn on the lights also?
Yes, it is fast enough to react to the need to turn on a light, sometimes it takes more but I think it depends on the state of the (Zigbee in my case) network mesh.
Difference between S and L is that S spams zigbee network 2-5 times a second even if nothing changes and kills the whole network)))
Any idea where to buy the ZY-M100-L version?
i’d already bought every single one if I new…
Thanks. I gave up and using the Sonoff version now.
