thrylosthyra7:
My English are poor,but i ll try my best to understand that book..so rachemmel,do you suggest to use one arduino per xbee module?sounds easy to install(easier than i thought) but more expensive..do you think that the alternatives proposed to the other guy's post could work??
Yes, one Arduino per one Xbee. But you can monitor multiple objects with one Arduino.... Side-by-side windows, adjacent door... When you have to run wiring too far, then it is time for another RF node which requires an Arduino to support it. Remember... An Arduino could be a $3 part if you are not afraid to solder (or, learn to solder.)
Example: http://www.hackster.io/rayburne/hoperf-springs-eternal