**6.1 PN model generation**

In this phase, we construct the PN model of ISO system based on system requirements and specifications. As several researchers have proposed methods [19], based on that we generated a PN model. Based on functional requirements, the activity involves the PN generation to identify the places and transitions of the case study: ISO system. The identified places and transitions as illustrated in **Table 1**.

Thereafter, we use the TimeNet4.5 [20] tool for SPN creation. Then we assign the transition delay to the transition based on the system requirement. To get


#### **Table 1.**

*ISO places and transitions based on function specification.*

throughput values of transition stationary analysis was performed in the TimeNet tool as shown in **Table 2**.

The PN model was generated using TimeNet tools shown in **Figure 4**.
