Typical Industrial Architectures
A typical architecture of a larger industrial automation system consists of three layers – a layer of sensors and simple devices (e.g. motor starters or electronic overload relays), a controlling layer with PLCs, operator panels or intelligent motor drives, and a layer of information systems.
Each layer has different requirements for the volume of exchange data, speed and determinism. The former approach would address these various requirements by specialised networks, especially in the case of the two bottom layers.
In addition, each larger technology supplier recommended an integration method, according to the supplier’s own preference. As a result, we can encounter many different data networks and protocols in existing industrial applications. The interoperability and scalability of, thus, designed and implemented systems are, and will be for a long time, a nightmare for all system integrators and owners of these solutions.
The situation was unsustainable even before the emergence of Industry 4.0 and IIoT. How to deal with this issue?
Ideally, we wanted to have similar solution that has already existed for information and office systems for years – Ethernet. Ethernet itself has been considered as a standard (actually, a family of standards, as specified below), which is not suitable for the industrial environment due to its characteristics (non-deterministic by definition, not supporting real-time messaging, quite expensive etc.) for long time.
However, factors such as the introduction of new technologies (in particular, intelligent switches), changes in network topology (from tree to star topologies), a full-duplex communication, a higher transmission rates and overall Ethernet technology price reduction over time have made Ethernet an interesting solution to be also used for the communication at the two bottom layers of an industrial automation system as well.