Straight talk: TSN – turbo power for PROFINET and OPC UA

Time-Sensitive Networking – Straight talk: Siemens is leading the way.

Time-Sensitive Networking – Straight talk: Our commitment to digitalization

Digitalization sets a high standard for industrial communication. Siemens is already relying on the rapidly growing open-communication standard Industrial Ethernet – with PROFINET at the field level and OPC UA at the control level. But Siemens is taking it one step further: with the Ethernet-based standard TSN (Time-Sensitive Networking) for reserved bandwidths, Quality of Service (QoS) mechanisms, low transmission latency, and parallel transmission of multiple protocols – including real-time-capable ones – in industrial networks.

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Matthias Gärtner
TSN FAQ 9 I Matthias Gärtner, product manager for the Digital Factory, Factory Automation De Business Unit, Siemens

"PROFINET over TSN" specification is complete

PROFINET specification 2.4 has been completed and can be downloaded by all PI members. This specification includes Time-Sensitive Networking (TSN) capabilities in the PROFINET standard for the first time. The publication was possible alongside the approval of PROFINET specification 2.4 by the PI. Naturally, specification 2.4 also includes all the details on PROFINET which are separate from TSN – as usual, PROFINET will remain fully compatible with all previous versions.

Experience gained from the use of PROFINET in the field as well as from the joint standardization activity from IEC/IEEE 60802 (converged TSN network) will be incorporated step by step. 

Find more information on the PI website.

(More FAQs about TSN will follow. The already published FAQs can be found in the "What is TSN" section further down the page.)

What is TSN?

Straight talk on the path to the future: PROFINET and OPC UA with TSN.

Increasing digitalization of production processes requires more and more openness, robustness, determinism, and flexibility in industrial communication. Only production that communicates and responds extremely agilely can ensure the fast and reliable manufacturing of individual products while also meeting tight delivery schedules.

Straight talk for a giant step toward digitalization

While industrial control systems are dependent on real-time communication, IT systems rely primarily on open access to data. That’s why companies operate these networks separately. In the face of increasing digitalization, this separation must now be replaced by open, end-to-end networking that permits flexible, deterministic production. TSN (Time-Sensitive Networking) creates a standardized basic technology within the framework of IEEE 802.1 for guaranteed Quality of Service (QoS) and increased demands in the Ethernet. TSN comprises a series of individual standards that exclusively pertains to the OSI layer 2 of communication. This means that the user interface remains unchanged even with TSN.


From the automotive industry and machine-building to the food and beverage industry: TSN offers decisive advantages for industrial production, including reserved bandwidths, Quality of Service (QoS) mechanisms, low transmission latency, and parallel transmission of multiple protocols – including real-time ones. Siemens will be relying on TSN to help shape the digital transformation of industrial networks – from the field level and machine-to-machine (M2M) communication to the control and operator levels.

Driving development together

TSN has already gotten off to a promising start. As part of its ongoing development, it’s being tested at Labs Network Industrie 4.0 (LNI4.0). LNI4.0 is connecting testing environments and installations throughout Germany to further the advance of Industrie 4.0, and Siemens is one of the founding members. Along with a number of other industrial enterprises, the company is doing everything it can to test TSN interoperability with multiple vendors, and is conducting research in the test bed to assess the potential of TSN for M2M communication and machine networking all the way to the cloud. The knowledge obtained will be made available to standardization committees as needed for use in future development.

Frequently asked questions about TSN

Will TSN replace PROFINET in the future?

TSN alone will never be able to replace PROFINET because TSN involves basic technology on which communication protocols can be based.


The PI (PROFINET International) is already working on using PROFINET, in addition to RT an IRT, also based on TSN.

TSN standardizes the real-time mechanisms on Layer 2, which, in the current Ethernet-based fieldbus systems such as PROFINET with IRT, have typically been resolved via special hardware. Protocols that run based on TSN will thus be able to run with hardware standardized via the IEEE in the future, even for isochronous applications. In this way, PROFINET with TSN provides the advantages already known from PROFINET with IRT (chronological accuracy, reproducibility, bandwidth reservation, diagnostics), but on the basis of standard hardware.


Of course, the RT and IRT mechanisms will remain a component of the PROFINET specification and will continue to benefit from PROFINET innovations.


By the way: PROFINET based on TSN does not just address the IRT applications (isochronous motion control applications), but also the application area addressed with RT.

What does convergence mean in regards to TSN?

In a "convergent network" data from various applications can be transferred simultaneously across a single line.


This way, real-time data can be transmitted in parallel using OPC UA based on TSN, cloud data based on MQTT, video data and other industrial real-time capable protocols such as PROFINET based on TSN.

What are the benefits of Ethernet with TSN compared with today’s Ethernet?

Basically, Ethernet with TSN supplements the existing Ethernet mechanisms in the areas of Quality of Service (QoS), including bandwidth reservation, as well as synchronization, low latencies, and even seamless redundancy.


The applications signal their communication requirements on the network and are guaranteed the requested QoS from the network. The various connections run in streams that enjoy bandwidth protection thanks to resource allocation in the memories of Ethernet switches. Basically, each of these streams can become real time-capable. As a result of these encapsulated streams, TSN also makes it possible to run multiple real time-capable protocols simultaneously in a single network (network convergence). This is fundamentally different from today’s Ethernet-based real-time protocols where the network only allows one real time-capable protocol.

Will TSN require special Ethernet processors or will the current standard Ethernet components also function?

A "TSN-capable" hardware block is needed for TSN; the currently installed Ethernet blocks generally cannot be expanded to TSN via software.


It is foreseeable, however, that the "standard Ethernet block" will be a TSN-capable Ethernet block in the future. That is the main motivating factor for Siemens to put PROFINET on TSN. All of the major block manufacturers have already begun to develop, or have at least announced that they will develop hardware blocks with TSN mechanisms. For device manufacturers, this results in many possibilities for the various hardware designs of their devices.

Will I need OPC UA and PROFINET in the future?

Yes. OPC UA and PROFINET are protocols which are used by the ISO-OSI model in the layers 5 to 7. Both OPC UA and PROFINET will use TSN as basic technology of layer 2. OPC UA has its strengths in vertical communication and networking of machines at control level, while PROFINET meets all requirements in the field. That's why the strategy at Siemens stays the same:

  • Control level and above = OPC UA 
  • Field level = PROFINET

What does OPC UA mean?

OPC Unified Architecture (OPC UA) is the standard for exchanging data for secure, reliable, manufacturer, and platform-independent industrial communication. 


OPC UA is perfectly suited for exchanging data among various operating systems between applications from many diverse automation component manufacturers and has been defined for vertical communication.


OPC UA is available in two versions – client/server and PubSub (publish/subscribe).


  • OPC UA client/server communication is a kind of point-to-point communication in which a client is given access to the data of a server. It is always based on TCP/IP and can therefore never become real-time capable.
  • With the OPC UA PubSub  method, this involves “one-to-many“ communication. One publisher provides data, which can then be received by any number of subscribers in the network. The OPC UA PubSub communication can be fed in via various protocols (e.g. UDP), depending on performance requirements.

Which applications are implemented with OPC UA PubSub based on TSN?

OPC UA originated in vertical communication and is now becoming established in the market for M2M communication as well.  


The need for real-time communication on the controller level should essentially be limited to controller-to-controller communication. For technical reasons, only the OPC UA PubSub method can be combined with TSN. Client/server accesses naturally also run via the Ethernet-based network with TSN mechanisms (a so-called TSN network), but, since they are TCP/IP-based, cannot be mapped in real-time capable and bandwidth-protected streams.

What is the new TSN standard IEC/IEEE 60802?

The upcoming IEC/IEEE 60802 standard is a project of IEC SC65C/MT9 and IEEE 802, so experts from standard Ethernet and the application protocols above work closely together. This standard will define a TSN profile for industrial automation in which certain functions, configuration models with the associated protocols and options can be selected from a wide range of options. This is the only way to achieve a convergent network, i.e. different protocols use the same network.


In future, all components for setting up a TSN network must be standardized according to IEC/IEEE 60802 (TSN-IA). The specification is based on corresponding use cases, a first official version is expected in 2022.

Watch the video on TSN real-time communication on YouTube:

Watch video: PROFINET based on TSN

HM und SPS en Shoutbox
TSN in practice

Straight talk on the path to TSN: PROFINET and OPC UA

TSN unites existing IEEE standards that exclusively affect OSI communication layer 2. TSN isn’t a communication protocol; rather, it’s a basic technology that can be used in the coming years by both PROFINET and OPC UA as a kind of “turbo power.”

A sample model from the discrete industries

When machines communicate via TSN – Siemens demonstrates how it works

How might M2M communication with TSN look like in practice? Going beyond the theoretical, Siemens already has a trade show model that demonstrates this in practice using two robots with synchronized movements. Each of the robots communicates with a SIMATIC controller via PROFINET. Both controllers are synchronized via OPC UA PubSub (publish/subscribe) based on TSN. Thanks to bandwidth reservation, data transmission in the TSN network is precisely predictable, independent of load.


To demonstrate how TSN communication and standard Ethernet communication can be used in the same network, data in the model is also transmitted from the controller to a cloud – like MindSphere – via a communication processor.

Downloads, support, services

Straight talk with more information

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Straight talk: Let us advise you on TSN

The development of industrial networks never stands still. What is Siemens doing with TSN? How will you and the top-two technologies OPC UA and PROFINET benefit from Time-Sensitive Networking? And how can you optimize your network with TSN? Our experts are happy to answer these questions and many more.

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