Reference model for data communication

The basic reference model for data communication (ISO 7498) organizes communication in seven layers arranged on top of one another. A set of communication tasks is assigned to each individual layer, wherein the level of abstraction increases from layer to layer. The data are passed from one layer to the next, i.e. communication proceeds in a vertical direction. On the sender side, communication runs from top to bottom, while on the receiver side it runs from bottom to top.

Orientation to this model results in a hierarchical and thereby more transparent communication flow, which on the one hand guarantees completion of the communication tasks assigned to the layers (in the form of services) and on the other hand by provides communication protocols that define the execution of communication tasks. In total, up to seven communication protocols may need to be defined to describe or implement serial communication within a serial bus system.