Actually if sensor output does not exceed 1.1 v , arduino internal refference also can be used. I measured 5v power line and its stable enough even at high wattage.
Continiously, about 10 times a second in both directions. Actually this is not important, everything works fine with any rate since LCD an S12s rememeber last state.
I have MAC wheel with LM35 temperature sensor and S12SN controller with LCD3 display. Unfortunately S12SN does not have any input wire fortemperature sensors. Also I could not find a point at the controller's PCB which reads the temperature. Finally I did it with insertion of temperature data...
I've successfully decoded communication protocol between LCD3 display and S12S controller (both available at bmsbattery.com) in both directions. Please see attached files.