Acontis shows how Ethercat, OPC UA and normal IP traffic can be transmitted with the TSN stack and the Ethernet drivers it contains.

© Acontis Technologies

If automation devices are to be connected to a TSN network, the entire real-time chain from the application on the device's real-time operating system (RTOS) to the TSN stack, the Ethernet controller driver and the Ethernet hardware must be kept completely deterministic - both when sending and receiving. In addition, normal, non-real-time TCP/IP/Ethernet communication via the TCP/IP stack of the RTOS must be possible in parallel via the same Ethernet controller without disrupting real-time traffic.

"We adapted to the trend towards TSN at an early stage and can now offer the necessary real-time-capable Ethernet drivers in addition to the standard TSN mechanisms in the TSN stack," says Managing Director Stefan Zintgraf, adding: "The drivers supplied with the conventional real-time operating systems are usually not real-time-capable and are not designed to process high-priority time-scheduled messages together with best-effort telegrams accordingly."

A special mechanism in the Ethernet drivers from Acontis Technologies ensures the necessary handling of high-priority time-scheduled and low-priority best-effort telegrams, such as conventional TCP/IP telegrams. Acontis has gained extensive experience in this area through years of market leadership for its embedded Ethercat master stack with a large number of permutations of RTOS, processor and Ethernet controllers.

The protocols already tested and available above the TSN stack are Ethercat and OPC UA Pub/Sub. As before, the conventional OPC UA client/server is processed via the TCP/IP stack of the RTOS and fed to the low-priority best effort processing queue in the Acontis drivers. When Ethercat is used, the corresponding Ethercat telegrams are generated by the Acontis Ethercat master stack and sent via the TSN stack including the real-time Ethernet drivers and the Ethernet controller using the TSN scheduled traffic method. The special feature here is that conventional unmodified Ethercat slaves can be connected directly to a port of a TSN-capable switch anywhere in the TSN network. No special conversion hardware or modification of existing Ethercat slave devices is required. This opens up an ideal migration path for continuing to use the large number of existing Ethercat slave devices in TSN networks directly and at any location.

When using OPC UA above the TSN stack, the OPC UA publisher generates the corresponding UDP/IP telegrams, which are sent to the TSN network by the TSN stack, driver and hardware accordingly. Conversely, the subscriber receives the corresponding received telegrams deterministically in real time via the API of the TSN stack.