I am making a Nether wart farm with Redstone++'s capability to dispense seeds, saplings, nether warts and actually plant them. The farm works and automatically harvests and plants the nether wart. All I need to do now is restock the dispensers when they are empty with 32 nether warts from the chest containing all the harvest. This is where I am stuck as I do not know how to achieve this - all I know is that it has something to do with comparators - a component which I do not fully understand.
I am using Minecraft 1.12.2 in Java Edition and Forge 126.96.36.19931 using the Roguelike Adventures and Dungeons modpack.
Below are images of my contraption (note that I am also using the Uppers mod for the upside down hoppers):