Like the RSSI monitor, this unit interprets the receiver FER and reports back to your transmitter what the current link quality is.
In addition, every single frame loss is counted and accumulated for review after flying (or during). Any fail-safe events are also counted.
The unit always uses slot 1 on the SBUS2, and presents the following virtual sensors:
Slot 1: Temp125/F1713
Slot 2: RPM sensor (frame loss count)
Slot 3: RPM sensor (fail safe count)
Counts are not stored in non-volatile memory, but can instead be logged by the telemetry logging feature of the tx.