## 3 Architectural Model
### Solutions for Monitoring a Plastic Injection Molding Production Line
#### 3.1.3 Intervention Tracking System  
Following the call, the operator reaches the production unit for which a request has been made. The intervention tracking system aims to guarantee that no intervention can be carried out without the operator declaring the start of their intervention on the production unit using a login. This condition, in order to be achieved, cannot be left to the common sense of the operator, but it is necessary to provide mechanisms that make it possible. Many presses for plastic injection molding make it possible to block the PLC commands of the machine if the user has not logged in. This option is particularly useful for the purposes of this research because it guarantees that an operator must register in order to adjust the machine parameters or carry out any other operation. Depending on the type of machine, logging in can be completed with a username and password or with a magnetic card associated with the ID of each operator. Furthermore, this type of information would be available via communication protocols (Euromap or OPC) and, in turn, recorded automatically by the system. This constraint does not represent a problem for managing emergency conditions, as the presses are equipped with an emergency button in each corner of the machine. The sheets of the data required from the intervention tracking system are reported in Table 3.  
The duration of the intervention is calculated in the following way:  
\[\text{Duration of the intervention}\ (DI)=DTi_{i}-DTi_{i} \tag{4}\] \begin{table}
\begin{tabular}{c c c} \hline \hline
**Name** & **Variable** & **Description** \\ \hline Date and Time request & \(DTTi_{i}\) & The variable reports when the request is effected. \\ Machine ID & \(M_{i}\) & ID of the machine where intervention is effected \\ Request ID & \(R_{i}\) & An ID is associated with each request. \\ Intervention required & \(I_{i}\) & The types of intervention can be conductor, \\  & & maintenance, or technologist. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Datasheets: intervention request system. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Name** & **Variable** & **Description** \\ \hline Date and Time & \(DTTi_{i}\) & The variable reports when the \\ intervention start & \(DTie_{i}\) & Intervention starts. \\ Date and Time & \(DTie_{i}\) & The variable reports when the intervention ends. \\ intervention end & \(M_{i}\) & Machine’s ID where intervention is effected. \\ Machine ID & \(M_{i}\) & This variable identifies the operator. \\ Operator ID & \(O_{i}\) & This is associated with each intervention \\ Intervention ID & \(I_{i}\) & An ID is associated with each intervention \\  & & tracked by the system. \\ Request ID & \(R_{i}\) & If the intervention is associated with a request. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Datasheets: intervention tracking system. Furthermore, a new variable called Machine Stop During Intervention (\(MSDI_{i}\)), which pertains to the time that the machine is in \"stop\" state during the intervention, can be created. The variable date and time intervention end can be manually inserted by the operator when the intervention ends or can be obtained automatically via the interaction of the data of the intervention tracking system with the data from the telemetry; when the machine resumes production, the intervention can be deemed complete. In the automatic collection way of the variable \"date and time intervention end,\" an approximation is made, but with a view to obtaining the \(MSDI_{i}\) variable and not to precisely calculating the duration of the operator's intervention; this approximation could be accepted because it still allows the desired information to be obtained. By summing the \(MSDI_{i}\) variables observed in a chosen time interval and associated with a specific operator ID, it is possible to construct the Stop Time by Operator (STO) indicator, which expresses the total time (in minutes) that the production unit was in the stop state during the intervention by the operator identified by the specific ID.