Page History

The Open Systems Interconnection model (OSI model) is a conceptual model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection."^[2] In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.^[3]

Image Added

The design of the technology modules with PROFIBUS is oriented toward the OSI layer model (Open Systems Interconnection Reference Model). Here, the communication process between two nodes is distributed over seven "layers", from layer 1 ("physical layer", trans-mission technology) to layer 
7 (“application layer”, interface to the application). PROFIBUS uses layers 1, 2 and 7.

...

The actual application process lies above layer 7 and is not part of the OSI model.

Kilder:

https://en.wikipedia.org/wiki/OSI_model

https://www.linkedin.com/pulse/what-osi-model-moein-ascari/