The Profibus User Organisation (PNO) was quick to understand the significance of TSN as a future real-time Ethernet standard. Similar to the migration from Profibus to Profinet, the PNO aims to integrate the new options in the entire system without changing the user interface to the network. To this end, the PNO is currently working on defining the integration of TSN in the Profinet Data Link Layer, as an alternative to RT/IRT protocols.
Profinet can benefit from the advantages offered by TSN without changing the Profinet core functions during the transmission of process, alarm and diagnostic data. How fruitful this approach is, can be seen in the migration from Profibus to Profinet, where the PNO also succeeded in retaining the application program interface to the network while incorporating the new potentials of Ethernet communication. Besides working on the integration of TSN, the PNO is also busy with the integration of OPC UA functions in the Profinet specification, for suitable applications such as HMI and controller-controller communication. The relevant industry associations for Ethernet/IP (ODVA) and Ethercat (ETG) are also adopting similar approaches for the integration of TSN into their standards.
The promising new features provided by TSN, OPC UA and MQTT can, however, only be exploited if the new protocols have also been implemented in the communication interface of the automation devices. Implementing the complex functions is not a trivial undertaking and requires sound expert knowledge. While it is mostly possible to implement OPC UA and MQTT as a software update – provided there is sufficient memory space – TSN integration requires a complete hardware redesign of the communication interface of the automation device. The main reason for this is that TSN has sophisticated synchronisation and scheduling mechanisms which cannot be implemented without special hardware solutions (protocol chips).
Furthermore, TSN also uses Gigabit Ethernet, compared to current industrial Ethernet protocols, which are primarily based on 100 Mbit technology. For device manufacturers, the changeover to the new communications landscape either involves complex hardware and software development projects or opting for a modular solution based on ready-to-use interchangeable embedded communication modules.