Last month, PI North America and the PROFI Interface Center hosted a highly anticipated webinar on PROFINET and TSN. Now, the webinar recording and slides are available online for everyone to download. Many attendees viewed the webinar live and participated in a Q&A session. Some of those questions are answered below. If you are not familiar with the new terms mentioned below (TSN domains, NME, etc.), please watch the full webinar.
Q&A BLOCK: PROFINET OVER TSN
Q: Does TSN standardization blur the differences and advantages of PROFINET when compared with competing protocols, which now can offer determinism as well?
A: At that point, these protocols need to compete based on the quality of their data, feature functionality (diagnostics, I/O, ease of use, etc.), and how well they adopt the new TSN standard. PROFIBUS and PROFINET International (PI) has already adopted TSN in the latest PROFINET standard and is in a strong position globally.
Q: What speed and determinism should we expect in TSN domains?
A: We expect to have cycle times down to 31.25 us with 1 us of jitter, depending on the network configuration. But, it is worth noting that PROFINET IRT already offers such performance.
Q: Is there a problem with having non-TSN equipment in the network?
A: To maintain a TSN domain, all devices in the domain must support TSN. Non-TSN devices can be part of the network, but cannot be part of a TSN domain.
Q: We do not need any specialized hardware for PROFINET Real-Time; it works with standard Ethernet devices. For PROFINET over TSN communication, is it possible to include devices with standard ethernet interfaces?
A: Yes, since TSN will be added to Ethernet, it will be included in standard COTS chipsets.
Q: Will TSN domains in PROFINET work with 3rd party switches?
A: Yes, TSN is the new Ethernet standard. Any switch that supports the new standard can be part of a TSN domain, regardless of its manufacturer.
Q: What is the expected Bill of Materials increase per device to integrate TSN in existing PROFINET devices?
A: The costs shouldn’t increase (at least not substantially). The Ethernet chip will now be a TSN-Ethernet chip.
Q: How does TSN enhance existing Time Synchronization like of clocks with IEEE 1588?
A: They are very similar; however, with 802.1AS-2019, there are other features. TSN networks will generate an error if synchronization falls out of expected bounds, unlike 1588 hardware sync. Also, TSN timing packets have priority scheduling.
NETWORK MANAGEMENT ENGINE
Q: How can users configure the Network Management Engine(NME)?
A: The NME is configured from the engineering station, using the GSD files of the devices in the TSN domain. Users do not have to calculate priority tags, streams, time synchronization values, etc. The user will determine the topology and performance requirements. Then, the NME will take care of all the calculations.
Q: What PROFINET capable management tools will support the NME?
A: Engineering tools from various manufacturers will be adding support for it.