Bensuddy

Hello, I am new to the programming of logic controllers. I have a Chinese FX3U 24 inputs and outputs with analog in and outputs. I am trying to teach myself the basics of the programming but I am stuck at the analog part.    what I am looking to do is create a program so that when a 12v battery bank voltage drops and rises it can trigger other outputs. I have a voltage divider which outputs 1/5 of the input.    Thanks for your help in advance.  Ben.