The Observant C3 and Solo Tank Level solution uses the Senix ToughSonic Ultrasonic Sensor. This sensor sends ultrasonic pulses that reflect off the water surface back to the sensor. The time between sending and receiving the signal is used to determine the water level.
The under-range error can occur if:
- Something is blocking the sensor's diaphragm
- The water level is too close to the bottom of the sensor
- The distance being measured is beyond the maximum of the sensor
You can identify the Under-range error on the Monitor Card :
It will also be reported in Manage Equipment :
Resolving the Error
The under-range error is generally caused due to an obstruction on the sensor diaphragm. Often spiders and other insects may have nested on the sensor, or there is a build up of dirt. A site visit is required to clean the sensor face.
Water level too close to sensor
Another common reason for this error is the water level reaching too close to the bottom of the sensor. Since the sensor cannot measure any surface closer than 4", if the water level in the tank reaches within 4", the sensor will report an under-range error. Because of this, the bottom of the sensor should be at least 4" above the highest level that might be measured.
Water level too far from sensor
The 'Under-range' error can also be caused if the distance from the sensor to the water level (or bottom of the tank) is beyond the maximum distance the sensor can measure. The most commonly used version of the Senix ToughSonic has a maximum range of 4m.