The Tank Level Gauge - RTS operates based on the conductance of the measured liquids. The electrodes are placed at each quarter length of the probe. The LED indicator (ultra-bright LED) signals the level of the liquid. The red LED indicates that the liquid level has reached less than 25%.
As an additional option, an external device (such as a buzzer or siren) can be controlled by a relay output pin on the indicator unit. The indicator is able to communicate with the other displays (Remote Indicators) via the 1-wire datalink.