# A Model for Working Environment Monitoring in Smart Manufacturing
## 5 Results  
The experiment data summary is presented and discussed in this section. The traffic was captured with the network analyzing tool Wireshark and logged data were latter used for traffic analyses. The traffic load in the case of the scenario with four sensor nodes deployed is shown in the Figure 8. Figure 8 shows traffic load in packets per second in communication between the server and four sensor nodes, with no delay between data sending interval. The higher values (blue lines) represent TCP packets, lower values (red line) represent MQTT packets, and the lowest values (dark line close to the 0) represent error packets. A higher traffic load was achieved with the usage of 10 sensor nodes in scenario 4. This traffic load is shown in Figure 9, where the number of MQTT packets sent to the server, the MQTT packets sent from a single sensor node, and the TCP errors per second are presented. The higher values (red line) represent MQTT packets send to the server from sensor nodes, middle values (blue line) represent MQTT packets sent from individual sensor nodes to the server, and the lowest values (dark line close to 0) represent error packets. Figure 7: Deployment and connectivity of the testing platform components. The traffic load for the same scenario is shown in Figure 10. Figure shows the number of MQTT packets sent to the server, MQTT packets sent from single sensor node, and TCP errors per minute. The higher values (red line) represent MQTT packets sent to server, lower values (blue line) represent MQTT packets sent from individual node, and the lowest values (dark line close to the 0) present error packets per minute. Figure 8: Traffic load for scenario 3, with four nodes and no packet sending delay. Figure 10: Traffic load in packets per minute in communication between the server and ten sensor nodes. Figure 9: Traffic load in scenario 4 in packets per second in communication between the server and ten sensor nodes. Table 1 shows the average and maximal number of MQTT packets for all nodes (total MQTT) and for each node separately per second. The 10 sensor nodes are displayed in the table with the last octet of IP address (192.168.0.14, 192.168.0.15, 192.168.0.17, 192.168.0.18, 192.168.0.19, 192.168.0.20, 192.168.0.21, 192.168.0.22, 192.168.0.24, and 192.168.0.26). The flowchart of the communication between the server and the four test devices is presented in the Figure 11. The presented flowchart contains no errors, and the communication between each node and server is made in two packets in pairs. One packet is for sending the MQTT message from the node to server, and represents the MQTT publishing message. The second message is the ACK message from the server, with the confirmation that the packet is correctly received. The testing platform and partially implemented proposed model worked satisfactorily. Errors in communication occurred only during a small percentage of the time. The interval in the communication with the increasing number of errors is shown in the Figure 12. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & **TCP Errors** & **Total MQTT** & **0.14** & **0.15** & **0.17** & **0.18** & **0.19** & **0.20** & **0.21** & **0.22** & **0.24** & **0.26** \\ \hline Average & 0.56 & 174.11 & 17.57 & 17.41 & 17.46 & 17.71 & 17.19 & 17.40 & 17.35 & 17.54 & 17.39 & 17.09 \\ Max & 16 & 206 & 22 & 22 & 21 & 22 & 22 & 21 & 21 & 21 & 21 \\ Std. Dev. & 1.37 & 35.66 & 4.08 & 4.23 & 3.82 & 4.15 & 4.16 & 3.97 & 3.90 & 3.73 & 3.80 & 4.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Server message queuing telemetry transport (MQTT) packet load per second in the 10 nodes scenario.