Question to those who did a deployment with more than 1-2 sensors, lets say a room or an apartment with many sensors...
(In case that forum is still active...)
What technology did you use to communicate?
People tend to go wireless since that doesn't requires less changes to the home infrastructure, but I don't like the wireless option.
In my recent host renovations I've added lots of tubes for wired-network to different places in the walls (switches, places for potential sensors and such), so now I'm in search for the right technology to use before I start thinking how to build the devices.
For now I'm up to 2 directions:
RS-485 and KNX
KNX is a great technology, developed specifically for smart homes, uses only 2 wires for power AND for communications, allows star and tree connections of the nodes, so that's basically a heaven option. The bad part is that the components are not that availalbe on the market, and their price is not low. Another bad point for that option is that the device needs a large capacitor to store some energy for communication while the same lines will not be stable during the transmissions.
RS-485 is a cheap and easy to get option. It requires separate power lines and 2 lines for communication. Since I have separate infrastructure for that, I think that will not be a prbolem. Another benefit for RS485 is a possibility to get much higer speeds (probably 100's of KBits compared to 9600 for KNX). The bad part for 485 is that the devices should be connected in a line, junctions should have active repeaters. Since most of the trunks that I would connect in a star or tree topology are getting to a central place in the house, I could probably mux all those lines on the master device, that means a bit more complex master hardware, but since the trunks will be shorter, I could get higher transfer speeds from all the connected devices.
For now I'm more inclined toward the RS-485, but still open for other options.