The fourth industrial revolution, known as Industry 4.0, is based on the idea that all components of the manufacturing environment are connected and can extract and share data and, above all, work collaboratively so that the optimization and operation of the system as a whole result from the communication between the different machines and software tools.
In this way, communications previously focused on presenting data to human users became mainly Machine-to-Machine (M2M).
This ability for machines to “talk” to each other allows the implementation of new advanced features but also creates challenges, such as:
- Which data must be shared?
- How often must the data be extracted?
- How must the data be exchanged?
- What is the purpose of exchanging this data?
This communication between machines has as its primary objective their interoperability, but not only the exchange of “loose” data, usually called raw data. The primary aim of exchanging information between machines is for them to work together and create high-level features that add more value than running the devices separately.
For the exchange of information between machines to be successful, it is necessary to work on two levels: the communication protocol and the semantics of the data being exchanged.
Communication protocols define the rules that are used to control the exchange of data between two pieces of software (for example, a machine control software and a Manufacturing Execution System – MES), such as how the connection, communication, and data transfer take place. In a simplified way, a communication protocol can be described as a set of rules that “coordinate” all data exchange.
Data semantics refers to how we contextualize the extracted data and create value from it. For example, when a given value is extracted from a machine (pressure, force, consumption, etc.), it is necessary to add additional values that help to understand which data were extracted, such as the date, unit of measurement, among others.
To put into practice the exchange of data in a factory environment, different communication protocols were created to simplify the integration of these machines. These protocols are intended to standardize the way machines communicate with each other. Suppose the different machine manufacturers make it possible to communicate with them using known and established protocols. In that case, this will enable new technologies to be developed and integrated, communicating with the machines working in the factory.
Standards are created with these protocols to encourage manufacturers to adopt these approaches so that they are respected, following what is specified in these same standards. Hence, this will make them increasingly used and disseminated.
One of the standards widely used in manufacturing environments is the case of OPC-UA (IEC 62541-5:2020). This industrial communication protocol allows communication between external software and factory machines with a simplified client-server architecture. The machines are servers, and the software that wants to consult the values made available by the machines are clients. Although the OPC-UA protocol is currently one of the best known, this approach remains valid for other industrial protocols, such as EtherNet/IP or PROFINET IO.