## 2 Materials and Methods
### Digitization and Manufacturing Process Representation  
As defined in [23], a system is a collection of interconnected elements that, when combined, produce results unattainable by the elements operating independently. These elements can be complex and large in scale, consisting of sub-elements working together to achieve a common objective. The concept of a system of systems refers to a scenario in which the constituent elements are themselves collaborative systems, each exhibiting the characteristic of operational independence. In particular, each individual system can achieve a functional purpose independently, without relying on its involvement in the broader system of systems. Furthermore, each system maintains managerial autonomy, meaning it is managed and evolves to fulfill its own goals rather than those of the overarching system [24]. As discussed by [25; 26], these attributes distinguish a system of systems from large monolithic systems. Fields such as enterprise architecture and service-oriented architecture address systems with these defining features, enabling the development of such solutions. The architecture of a system is critical to its success in meeting the objectives of its stakeholders [27]. In this case, it is defined as the collection of structures necessary to understand the system, including its components, the relationships between these components, and their properties. In light of this explanation, the general sub-challenge addressed in this research is to create different individual systems for data collection to build the digital representation of the process. Each system can operate independently and solve the acquisition problem within its own area or domain. Moreover, all of these modules are designed with the necessary communication capabilities to interact and carry out their specific tasks toward achieving the final objective: the optimization of the production process as a whole. To carry out this data gathering process, the Production Data Manager tool, PDManager, developed by the Azterlan Research Center is used (for more information, please visit [[https://www.azterlan.es/en/kh/pdmanager](https://www.azterlan.es/en/kh/pdmanager)]([https://www.azterlan.es/en/kh/pdmanager](https://www.azterlan.es/en/kh/pdmanager)), accessed on 20 January 2025). Specifically, PDManager is a real-time production control system designed to guarantee digitization, traceability, and the orderly storage of key parameters in a centralized database for the manufacturing process of cast components. This system is composed of three root elements:  
1. PDStorage: A centralized relational database where all the gathered data are correlated, keeping the production history. In addition to being used for monitoring and recording information in real time, it can be employed for knowledge generation and predictive model creation based on these provided data. This kind of storage system and its capability to centralize data and information is discussed in the literature [28; 29]. PDAgents: Small software artifacts created as services that focus on the specific task of interacting with third-party entities (i.e., other databases, files, or even machinery), extracting the necessary data from the production process itself. [PERSON] et al showed in [PERSON] et al (2018) how these developments can create the needed data flowing ecosystem for IoT management. The creation of this type of micro-service is the axis of a more complex software architecture that can also help in other domains like smart agriculture [PERSON] et al (2018). 3. PDManager modules: The PDManager system has different modules (some of which can be seen in Figure 2) that, first, allow the operator to interact with and monitor the area where they are located and, second, provide a tool to perform manual correlation of data when automatic correlation is not possible. Regarding the process explanation given in Section 1, to address the aforementioned management process, data must be extracted from the entire manufacturing process.