Question about a program in logo

Hi to all 

I want to make a program for automatic feed silos eg 4 silo 

My problem is that if i use four inductive sensors one for each silo as input (request material) (eg I1 for silo 1 , I2 for silo 2, I3 for silo 3 and I4 for silo 4)

I would like when asking 1or 2 or 3 or 4 silos simultaneously the program goes cyclically ie when the time runs out filling of silos 1 to start filling the silos 2 after to go silo 3 after to silo 4 and over again until they filled one by one silos 

Can somebody give me an example program about the problem that you i mentioned ?

I have make a little programm.

I have not the time to make the comments to all the blocks, but i hope you can use this programm.

The programm has 4 timers, one for every silo. When a silo is FULL, the timer of that silo wil by overruled.