As flexible manufacturing systems (FMS) become a reality, the need for efficient, reliable, yet inexpensive, distributed communications becomes crucial. Local Area Networks (LANs), such as MAP, are rapidly emerging as the logical choice for integrating the process level of the automated factory. What makes the performance analysis and design of these networks unique, is the nature of the traffic being carried. Data traffic used for control must meet stringent real-time requirements, which are unlike the time variations accepted for the time-sharing use of a LAN. In this paper, we use a subclass of Petri nets to model the dynamic performance of the automated factory LAN. This subclass, which can be best described as timed concurrent finite state machines, gives the FMS designer the ability to model the various asynchronous, concurrent control processes and carry out a dynamic performance evaluation.