In this second article about TSN, Joakim Wiberg provides some use cases showing the benefits of TSN and an update on the ongoing standardization work.
Time-Sensitive Networking (TSN) is a large set of standards to provide deterministic communication on standard Ethernet. The three pillars under TSN are:
Scheduling and traffic shaping. The means to allow different types of traffic with different priorities to co-exist on the same network. Each traffic type can have different latency and bandwidth requirements.
Selection of communication paths, path reservations, and fault tolerance. Functionality to reservation of communication paths to ensure fault tolerance and bandwidth reservation.
Time synchronization. As the name suggests, “time” is a central aspect of TSN. Devices participating in the TSN communication must share a common understanding of time.
TSN brings two main benefits:
TSN standardizes the use of deterministic data exchange in Ethernet networks. (Currently only possible with proprietary solutions).
TSN enables industrial Ethernet and IT protocols to co-exist on the same cable allowing IT and OT systems to work together.
We can provide a use case example for each main benefit.
Determinism
Companies are currently using proprietary communication protocols to guarantee deterministic data exchange at the production level. But the proprietary solutions are often developed for specific applications or manufacturers. Consequently, their scalability is limited, and they are not compatible with each other. TSN will solve both the scalability and interoperability issues as it will standardize deterministic data exchange through the time synchronization and time-aware shaping functions. TSN will also reduce latency and jitter in industrial networks enabling companies to use the industrial Ethernet for tasks with higher demands. A good example is motion control applications which need low jitter to control the movement of an actuator or the opening and closing of a valve.
One Cable
We can use an example from an automotive assembly plant to show how the convergence of industrial Ethernet and IT protocols can benefit device manufacturers and plant managers. Automotive assembly plants have many IT and OT networks and devices providing data and information to higher-level systems. As TSN can converge IT and OT networks and devices, users can manage everything with one system management tool. The convergence of the industrial and IT protocols improves the accuracy and reliability of data. In an automotive assembly plant, accurate and reliable data is critical.
The TSN standards are part of the IEEE 802.1 working group, but at this level, the standards are generic and developed to solve multiple use cases. So, each industry is writing a separate profile to allow them to narrow the focus, simplifying interoperability and deployment.
List of TSN profiles:
IEC/IEEE 60802 TSN Profile for Industrial Automation
IEEE 802.1DG TSN Profile for Automotive In-Vehicle Ethernet Communications
IEEE 802.1DF TSN Profile for Service Provider Networks
IEEE 802.1DP TSN for Aerospace Onboard Ethernet Communications
Each profile will ensure the dedicated TSN mechanisms are defined to fulfill their performance expectations and kept consistent within their area.
The IEC/IEEE 60802 TSN Profile for Industrial Automation will provide a jointly developed IEC and IEEE standard. It will define the TSN features, options, parameters, protocols, and other networking considerations required to address industrial automation applications. The profile will also create a standard set of instructions explaining how to build and configure a TSN network in industrial automation.
The profiles and related conformance test plans are essential to ensure a unique and interoperable TSN for the industry.
TSN operates in layer 2 in the open system interconnection (OSI) communication model. The existing industrial protocols will still be needed to address the higher-level application functions such as data exchange, connection management, safety, or motion control. A common TSN profile must guarantee device manufacturers a unique TSN implementation effort, regardless of the industrial communication protocols used. It must also guarantee users a unique and interoperable network allowing the coexistence or combination of these higher-level application functions.
For this purpose, the CC-Link partner association, ODVA, OPC Foundation, PROFINET International, and AVNU organizations have formed a group called TSN Industrial Automation Conformance Collaboration (TIACC). TIACC will create a unique conformance test plan to verify the IEC/IEEE P60802 profile, ensuring that devices from different vendors supporting different automation protocols can reliably coexist at the TSN level on shared networks. All the participating organizations will use the test plan as a baseline test and make it available to the broader industrial automation community.
TSN also enables OT and IT convergence on wireless Ethernet infrastructure. 5G is a robust wireless network providing deterministic and low latency exchanges. Leading 5G companies such as Ericsson, Huawei, and Nokia are closely following the standardization process as TSN will enable continuity of industrial automation over this new wireless technology.
It’s hard to provide exact dates. Work started on the IEC/IEEE 60802 TSN profiles for industrial automation in 2017. Drafts are now available, mature, and under review, but the profiles won’t be finalized until at least the first half of 2024.
TIACC was formed in 2022 and has started to work on the IEC drafts. The first results will be seen soon after the release of the IEC/IEEE 60802 profile.
HMS is following the progress of the IEC/IEEE 60802 standardization activities and TIACC. HMS is committed to providing solutions supporting the specifications in the TSN profiles to guarantee our customers good interoperability. For example, HMS participated recently in a PROFINET over TSN interoperability demo with several other manufacturers.
Joakim Wiberg, head of Technology, Anybus. He is also the CTO of ODVA and a frequent lecturer on security and industrial communication.
If you want to learn more about TSN, visit our TSN web page. Also, don't forget to download our TSN whitepaper and read our first article about PROFINET over TSN:
TSN article - What's happening?