This paper presents the second version of a software to work with Petri Nets. The software permits ro edit, to simulate and to validate Generalized and Stochastic Petri Nets. The program can be used to model any discrete dynamic system, in particular this paper deals with Flexible Manufacturing Systems, FMS. The software uses the Editor and the simulator developed in previous works, modified and extended to Stochastic Petri Nets. The system is implemented in Visual Basic and Visual C++, under Windows for PC.