## 6 Case Study
### Establishment of Monitoring Network  
The pressure test system consists of three subsystems: assembling, pressing and packing. Because of the complexity and representativeness of the pressing link, the pressing subsystem is described as representative. Using the method provided in Section 4.1, the EDSPN model of a monitoring network can be generated. 1. Create a table \(X_{\text{PLC}}\) of PLC variates. Next, export all variables directly in PLC_Config software, and then, import all variables in Dview and divide variable groups according to the actual situation. Last, map \(X_{m}\) in the variable group to the place, and the work of mapping is complete. 2. Establish the state-transition relationship of the place. Because the state-transition relationship cannot be generated directly by PLC for the time being, the state-transition relationship is defined manually according to the actual situation. The status is revealed in Table 1. Among them, for example, \(p_{2}\), \(p_{7}\), \(p_{10}\), \(p_{15}\), \(p_{20}\), \(p_{23}\), \(p_{28}\), \(p_{31}\), \(p_{36}\), \(p_{39}\), \(p_{44}\) indicates the one-side sealing test completion state of different stations. There are a total of 11 stations, and the pressure test process of each station is the same, so the transitions in Table 2 are the same. 3. Insert transitions between adjacent states. The meanings of transitions are revealed in Table 2. As different workstations may test different products, the last transition \begin{table}
\begin{tabular}{c c} \hline \hline
**State** & **Meaning** \\ \hline \multicolumn{2}{c}{\(p_{1}\)} & Assembly completion state \\ \(p_{2}\), \(p_{7}\), \(p_{10}\), \(p_{15}\), \(p_{20}\), \(p_{23}\), \(p_{28}\), \(p_{31}\), \(p_{36}\), \(p_{39}\), \(p_{44}\) & One-side sealing completion state \\ \(p_{3}\), \(p_{8}\), \(p_{11}\), \(p_{16}\), \(p_{21}\), \(p_{24}\), \(p_{29}\), \(p_{32}\), \(p_{37}\), \(p_{40}\), \(p_{45}\) & Other-side sealing completion state \\ \(p_{4}\), \(p_{9}\), \(p_{12}\), \(p_{17}\), \(p_{22}\), \(p_{25}\), \(p_{30}\), \(p_{33}\), \(p_{38}\), \(p_{41}\), \(p_{46}\) & Shell-strength completion state \\ \(p_{5}\), \(p_{13}\), \(p_{18}\), \(p_{26}\), \(p_{34}\), \(p_{42}\) & Equipment resources \\ \(p_{6}\), \(p_{14}\), \(p_{19}\), \(p_{27}\), \(p_{35}\), \(p_{43}\) & Manpower resources \\ \(p_{47}\) & Low-pressure test completion state \\ \(p_{48}\) & Qualified state \\ \(p_{49}\) & Unqualified state \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Definition of place. Figure 8: Operation process. time is displayed in the software as a reference. Finally, the resulting Petri net is demonstrated in Figure 9.
4. Map tokens in the initial marking. Code the station, operator and workpiece respectively and make a bar code. Briefly, the station and operator are coded sequentially according to the serial number. The station code consists of three characters. The first character represents the machine, and the second and third characters are serial numbers. For example: M01 represents the machine of Station 1. The operator code is similar to the station and consists of four characters. The first character represents the company code, and the second, third and fourth characters are serial numbers; for example, R001 represents worker [PERSON]. As for workpiece coding, it is more complex, as illustrated in Figure 10. It consists of 13 characters, in which the first 3 characters are serial numbers, the 4 th and 5 th characters are product type codes, the 6 th and 7 th characters are the model code and pressure-level code, respectively, then, the last 6 characters represent the production date. The monitoring network for monitoring the status of the node is thus completed.