# Dynamic Optimization of Data Packet-based Communication for PLC Visual Monitoring
## 4 Conclusions  
This paper proposed a dynamic packet optimization solution for the data packet-based communication of PLC visual monitoring in the context of networked control systems. The key logic is that the sub-networks in the PLC ladder programs of a supervisory computer should be packed into different packets for efficient communication, and the data packet size of the communication should be optimally determined in consideration of the transmission error rate and the human response delay. The optimization problem is formulated as a nonlinear saw-tooth function with human response constraints and is then solved analytically to obtain the optimized data packet size, which minimizes the total transmission time. The proposed solution can meet the technical needs of optimizing the data packet size and providing an effective human-machine interaction in both simulation and experimental studies.  
This practical research can provide useful guidance for the settings of networked control system applications, especially when field equipment, PLCs, or supervisory computers are deployed in geographically-distant locations, and remote monitoring or fault diagnosis should be implemented effectively. In addition, the research can be a valuable reference for industrial wireless communications and remotely controlling drones or other unmanned vehicles, where the data transmission strategy is dependent on the dynamically-changing environment.  
[PERSON], [PERSON] and [PERSON] conceived and designed the research topic; [PERSON] and [PERSON] performed the numerical analysis; and all the authors were involved in research design, writing and revising the manuscript.  
This research was partially funded by the Major State Basic Research Development Program of China under Grant No. 2017 YFA60700602, the Ministry of Industry and Information Technology of China under Project \"Industrial Internet Platform Test Bed For Optimizing the Operation of Motor and Driving Equipment\" and \"Research and Test Verification of Cooperative Manufacturing Standard for Small and Medium-sized Motor Based on Supply Chain\", Shanghai Key Laboratory of Smart Grid Demand Response, Shanghai Natural Science Foundation of China under Grant No. 16 ZRI416500, and the Natural Science Foundation of China under Grant No. 61290323.  
The authors would like to thank the editor and the anonymous reviewers for the comments and suggestions which have substantially improved the quality of the paper.  
The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.  
\begin{table}
\begin{tabular}{l l l l l l l} \hline
**Experimental System Parameters** & **View1** & **View2** & **View3** & **View4** & **View5** & **View6** \\ \hline The tightening upper bound of the sub-network length \(L\) & 151 & 185 & 212 & 212 & 185 & 151 \\ in the current monitoring views (byte) & 23 & 30 & 40 & 58 & 70 & 80 \\ \hline The number of sub-networks \(N\) & 23 & 30 & 40 & 58 & 70 & 80 \\ The optimized packet size: \(P^{*}\) & 13 & 11 & 9 & 9 & 11 & 13 \\ The optimized length of a packet (byte) & 1963 & 2035 & 1908 & 1908 & 2035 & 1963 \\ \hline Expected time for processing a packet (s) & 0.1604 & 0.1662 & 0.1560 & 0.1560 & 0.1662 & 0.1604 \\ \hline Expected time for updating a monitoring views \(E(P^{*})\) (ms) & 290 & 463 & 707 & 1025 & 1079 & 1007 \\ \hline Actual processing time for updating a monitoring view (ms) & 257 & 442 & 651 & 883 & 847 & 821 \\ \hline \end{tabular}
\end{table}
Table 2: Experimental results on optimized data packet-based communication for monitoring views.