We are interested in chaos phenomena in manufacturing systems. To study these systems, a common approach is to model them as discrete event systems and with discrete variables. So, we are dealing with what a chaotic behaviour becomes if a production system is modelled in such a way. We observe then that the sole property, due the chaotic characteristics, that remains when we model a chaotic system with discrete variables is the sensitivity to initial conditions. It means that such a system can still be unpredictable because little changes can make it evolve totally differently.