# Design of Remote Upgrade System for Data Processing Unit in Marine Engine Room Simulator
## 5 Testing and Applications
### Remote Upgrade Stability Testing  
The main work of DPU is the collection and output of analog and digital quantity [38]. In order to judge the working capability of DPU after a firmware upgrade. In this work, we test DPU analog output and digital output under fixed load conditions and discuss the test results. \(T_{c}\) is the time interval value between the previous frame of data sent from the client side and the next frame of data. \(T_{s}\) is the time interval value between the previous frame of data sent from the server side and the next frame of data. The quality of the output data is determined by two main performance indicators:  
1. By comparing two adjacent data transmission time interval values \(T_{s}\) with the corresponding two adjacent response data reception time interval values \(T_{s}^{\prime}\), that is, two transceiver interval values. It is permissible to indicate the changing state of performance of the data processing element under specific load test conditions.
2. By analyzing the pattern of variation in the time difference between the packets sent and the response packets received, that is, the pattern of variation in the value of the single send/receive process. These can indicate the current data processing rate of the DPU under fixed load test conditions.  
In single channel mode, the average period \(T_{c}^{\prime}\) of the current output performed by the AO port is 60.28 ms. We use test software to send data at a fixed load, and statistics the interval between sending and receiving data by DPU. According to Figure 9a, the actual average of the two nearest data sending intervals \(T_{s}\) is 60.10 ms, while the average of the two nearest data receiving intervals \(T_{s}^{\prime}\) is 60.14 ms. These two values are roughly equivalent and are closer to the output period of the port. According to Figure 9b, the response interval between each set of data sent by the software and the response data received by the software from the data interaction unit is about 33.06 ms, and the data transmission process is relatively stable.  
In single channel mode, the DPU's DO port outputs high and low levels and the average period \(T_{c}^{\prime}\) is 63 ms. The high voltage is 24 v, whereas the low voltage is 0 v. We also use test software to send data at a fixed load, and statistics the interval between sending and receiving data by DPU. According to Figure 10a, the software's average near data send  
\begin{table}
\begin{tabular}{l c c} \hline \hline
**Upgrade Faults** & **Faults Description** & **Handling Mechanism** \\ \hline Human operation faults & Upgrade buggy firmware & Backup upgrade \\ \hline \multirow{3}{*}{Data communication faults} & Code verification error & Code retransmission \\  & Network disconnection & Communication reestablished \\ \cline{1-1}  & Web server error & Re-upgrade \\ \hline \hline \end{tabular}
\end{table}
Table 3: Analysis and treatment of upgrade faults.  
Figure 9: The interval values are the time for the test software to send and receive data under fixed load. Judging the capability of the DPU’s analog output by its two interval values. (**a**) Statistics of AO sending and receiving interval values. (**b**) Statistics of AO sending and response data intervals.  
interval \(T_{s}\) is 62.04 ms and its average near data receive interval \(T_{s}^{\prime}\) is 62.12 ms. These two values are roughly equivalent and close to the output period of the port. According to Figure 10b, the response interval for each set of data sent by the software and the response data received by the software from the DPU was approximately 42.08 ms, with less variance during the data transmission process.  
The analysis shows that the firmware upgraded for the DPU has stable performance and can complete the AO and DO functions accurately.