Is there a circuit diagram of the GX 140?
When using the ADC you need the same reference voltage to prevent errors in tank levels stemming from a variable voltage (12...14.6V) when using voltage sensors. Is there a DCDC buck/boostconverter inside or just fuses?
Another Question, the manual says fuses are 20mA, isn't that too close to 4-20mA sensors, there is always a risk, the fuse trips when the tank is full, regarding voltage / resistive sensors, 20mA would require at least 800 Ohm at 12V and 1.6kOhm at 24V to prevent tripping.
An easy extension of the functionality would be a 1kOhm pull-up resistor in Vcc to enable also 180Ohm / 240 Ohm resistive sensors (Voltage reading 0.0 - 2.2V, 15mA) with a software compensation for linearity.
