According to Dr. Guido Beckmann, Chairman of the ETG Technical Committee, TSN enables controllers to address multiple Ethercat segments across Ethernet networks in real time. The Ethercat device protocol remains fully intact, meaning that no changes to the slave devices are required. The Ethercat automation protocol for communication between controllers will also be expanded to include TSN, making it even more deterministic.

The ETG has specified the technology extension in the form of a profile. Specifically, Ethercat uses the TSN streams with any data rates for real-time capable communication above Ethercat segments. Nothing changes in the segment itself. The stream adaptation for connecting the segment to the heterogeneous TSN network takes place either in the last TSN switch or in the first Ethercat slave device. It concerns the identification of the Ethercat data streams in the TSN network as well as the synchronization and proceeds as follows: In TSN, each stream has a unique stream ID in the network, which is defined by the destination MAC address used. The Ethercat master sends an Ethernet frame to the Ethercat segment (addressed by the stream ID). This telegram is then routed directly through the segment without any adjustments and processed there on-the-fly. On the way back, it is automatically sent back to the Ethercat master in the first slave. The stream ID or MAC address now needs to be adapted here. "This allows the TSN switches to clearly recognize the return channel and route the frame back to the Ethercat master on a time-controlled basis," says Beckmann. For consistent synchronization, the IEEE 802.1AS time must also be mapped to the distributed clock time used in the Ethercat network.

The Ethercat master only has to synchronize with the TSN clock and set the destination MAC address accordingly. According to Beckmann, the advantage of TSN is that an Ethernet interface can now be used multifunctionally - i.e. other Ethernet components can also be addressed via the heterogeneous network using the same interface: "However, this requires a small intermediate layer in the Ethernet driver, which is a solvable task with most Ethercat masters."

As a single Ethercat frame is sufficient to communicate with an entire segment and therefore an entire fieldbus network, Ethercat is virtually predestined for combination with TSN networks. "We achieve this without having to move our technology to the left ourselves," emphasizes Beckmann and adds on request: "This means that we do not define a new Ethercat protocol, but merely define an adaptation layer at the transitions between TSN and Ethercat, which only has a low level of complexity and can be integrated into the TSN switches. This means that everything remains the same for the Ethercat segment. In other words: TSN processes the fields in the Ethernet frame that Ethercat does not touch and vice versa. For the Ethercat user, TSN is therefore completely transparent."