According to the glossary of the VDI/VDE-GMA 7.21 Industrie 4.0 technical committee, a reference model is defined as a model that can be generally applied and can be used to derive specific models.
There are many examples of this in the field of technology. The most well known is the seven-layer ISO/OSI model, which is used as a reference model for network protocols. The advantage of using such models is a shared understanding of the function provided by every layer and the defined interfaces between the layers.
The development of RAMI 4.0 focused on industrial production as the primary area of application. The spectrum ranges from discrete manufacturing to process technology. The focus on industrial production distinguishes the forward-looking Industrie 4.0 project from the broader IoT (Internet of Things) approach of the Industrial Internet Consortium (IIC).
The architecture model requires a three-dimensional representation. The three axes of RAMI 4.0 describe the hierarchical levels of a manufacturing system networked via the Internet, the lifecycle of systems and products, and the IT structure of an Industrie 4.0 component. The hierarchical levels are essentially the same as the layers of the pyramid of automation.
The description of the lifecycle of systems and products with the corresponding value-added chains is based on the draft of IEC 62890, which makes a distinction between type and instance. The type of a product appears in several phases during the development process. It is finalized with the release of a special product version. Based on the type released for series production, the system then manufactures products that are instances of the type. Component discontinuations or improvements may require changes to products. These changes are made to the type and are introduced into the manufacturing process as a new product version once the change has been finalized and released.
The data generated in the process chains is already largely available in digital form. It is then processed in PLM and ERP systems. In order to manufacture individual products, it must be possible to store the data provided by customers to producers for the manufacture of their instances electronically in a suitable, instance-related format in IT systems. This data must be available throughout the entire lifecycle of the instance and linked to the associated type.
The IT structure of an Industrie 4.0 component is visualized on the vertical axis in the form of six layers, one on top of the other. The layers help visualize business processes, functional descriptions, data mappers, the communication behavior including Quality of Service (QoS), and the linking of assets via an integration layer. In addition to the physical aspects such as components, machines, systems or cables, the asset layer also includes data from the development process.
The data generated during production and in some cases customer-specific data for a specific instance is also considered as an asset. Thanks to the clear identification of all Industrie 4.0 components, the classification of all assets provides more scope for asset management. This scenario also makes it easier to perform a threat analysis of the manufacturing system, which is required for IT security reasons.
When it comes to Industrie 4.0, many users wonder where established industrial communication systems fit in and whether their role will change in future.
It should be noted that protocols, as was the case with assets (e.g., field devices) are incorporated via the integration and communication layer (e.g., PROFINET). With the further refinement of Industrie 4.0 components and the associated administration shell, Industrie-4.0-compliant communication and representation of information will begin to be implemented in 2016 and tested in test applications.