FLiRS

(Frequently Listening Receiver Slave)

FLiRS is a specialized technology within the Z-Wave protocol that solves a fundamental challenge for battery-operated devices: how to receive a command instantly without rapidly draining the battery. While standard battery sensors (like temperature sensors) sleep most of the time and wake up only at long intervals, devices like smart door locks, security sirens, or battery-powered thermostats need to react immediately.

A FLiRS-enabled device does not stay fully awake. Instead, it "wakes up" for a fraction of a millisecond 1 to 4 times a second just to "listen" for a special wake-up signal (called a Wake-Up Beam) from the smart home hub. If it detects this signal, it instantly wakes up fully and executes the command (e.g., unlocks the door). If there is no signal, the device immediately returns to deep sleep.

Thanks to this clever power management, the device's reaction time is practically instantaneous (usually within 1 to 2 seconds), yet the battery can still last for months or even years.