The items and descriptions are sourced from:
The business layer focuses on standards that represent business objectives and the resulting overall processes regarding the exchanged information at the lower layers. The layer addresses regulatory and market perspectives, business models, business cases and products, business processes and regulations influencing business models.
The function layer includes standards that cumulate common functions derived from applications, systems and components. Remote access and horizontal integration take place within the layer to ensures the integrity of the information and conditions in the process and the integration of the technical level.
The information layer focuses on standards that regulate information flows, information objects and data models being used by components, services and their functions to exchange information. A common semantic base is the key requirement to ensure consistent integration of different data and achieve interoperability between components at this layer.
The communication layer includes standards regarding integration and communication protocols as well as related mechanisms that contribute to interoperability of components. Also includes the provision of services for control of the integration processes
The resources layer addresses standards regarding the distribution of all participating physical Industry 4.0 components. This includes equipment and machinery (typically at field and process level), control systems, applications and network infrastructure.
On the right horizontal axis of RAMI 4.0 are the hierarchy levels from IEC 62264, the international standards series for enterprise IT and control systems. These hierarchy levels represent the different functionalities within factories or facilities. The IEC 62264 standard is based upon ANSI/ISA-95. To represent the Industry 4.0 environment, these functionalities have been expanded to include work pieces, labeled 'Product', and the connection to the Internet of Things and services, labeled 'Connected World'. (From https://www.isa.org).
Industry 4.0 promotes a less hierarchical approach of lexible systems and machines were functions are distributed through the network. The network can cross company boundaries ('Connected World'). Participants interact across hierarchical levels: participants are able to communicate with each other. Products are part of the network. See also https://www.plattform-i40.de/PI40/Redaktion/EN/Downloads/Publikation/rami40-an-introduction.html