In order to write rules related to Analog Voltage reading the Whenever is a Time Occurrence with an AND Statement to check the voltage level
Whenever Every 30 Seconds
AND Analog Zn (Zn xxx) Is Greater Than Analog Value of x.x Volts
Then ….
—-However—- in order to use the zone to truly monitor an Analog Voltage you would need to remove the onboard 2KΩ Pull Up Resistor. Modification to the board does void the Warranty. I would suggest you use a zone on the M1XIN for this application.
Perhaps instead of using an Analog sensor use leak detectors mounted at different levels within the cistern and create your rules based upon the zone becoming Not Secure?