The sensor has an occupancy algorithm based on how many motion events it sees within a certain timeframe. This was set up so that if someone briefly walks through a room, the sensor will tell the thermostat that the room is “occupied” for 10 minutes. If someone is in a room longer, then the timeout will be increased automatically. Sensors communicate directly with the thermostat via Honeywell Home RedLINK technology. After sensing motion, the communication should take less than 3 seconds to assign the room priority, depending on battery and signal strength.