Garmin GMI 20 - Manual (Page 19)

GMI 10 Quick Start Manual 1
NMEA 2000 Device Requires Calibration—a NMEA 2000 device
requiring calibration has been detected.
Shallow Water—alarm – the boat has entered water shallower than the
specified depth.
Simulating Operation—the unit is in demo mode.
Surface Temperature—alarm – the water is approaching the specified
temperature.
Unable to claim NMEA 2000 Address—there is a conflict between
NMEA 2000 devices on the NMEA 2000 network.
Water Speed Sensor is not Working—water speed calibration error –
recalibrate the speed sensor.