TSN (Time-Sensitive Networking)

Main Article: Industrial Automation (Global Market)

2022: Why TSN Networks Won't Replace Industrial Ethernet in Manufacturing

Given the constant development of TSN networks, thanks to the numerous offers of new products and the ability of TSN to bring determinism to standard Ethernet, the question arises in 2022 - when industrial Ethernet protocols such as Profinet, CC-Link IE, EtherNet/IP and EtherCAT will be replaced by TSN networks. When considering this issue from the point of view of building TSNs and industrial Ethernet networks, an explanation appears as to why such a replacement will not occur.

General TSN profile as per IEC/IEEE 60802

TSN technology refers network to functions only at layer 2 (transmission channel data) for Open Systems Interaction (OSI) Models communication. Therefore, it is only responsible for transferring data from one place to another in a deterministic way, despite what kind of data it is. What needs to be done with data is usually processed at higher levels that meet application requirements. They are managed by industrial Ethernet technologies - said Thomas Burke, global strategic adviser to CLPA (CC-Link Partner Association)

When the question arises about why the joint coexistence of TSN and Ethernet technologies is required, the protocols of which are also deterministic, experts note the need to ensure better convergence of networks.

Typically, most industrial Ethernet protocols do not allow you to combine different types of traffic in the same network. TSN adds this missing capability by allowing multiple types of traffic to share the same network in deterministic processing, "Burke recounted.

In 2022, OEMs and end users need to explore the use of TSN-enabled industrial Ethernet protocols to ensure that these protocols can address the I/O, motion control, and security aspects of the intended application. For example, the TSN CC-Link IE protocol uses layers 3 through 7 of the OSI reference model to extend the capabilities of the layer 2 TSN. This enables deterministic integration of I/O, traffic control, and security with standard TCP/IP traffic.

2020: TSN is a standard that will bind many protocols of industrial automation networks

Working on the Release of Standard Specifications

In the second half of 2020, the TSN specification is nearing completion. At the same time, interest in the prospect of rapprochement between IT and OT is growing. Industrial protocol associations are working hard to refine their protocols to ensure compatibility with the TSN standard within workgroups. Time-sensitive networks (TSNs), as a standard, are expected to have the biggest impact on industrial networks since Ethernet was introduced to manufacturing more than two decades ago.

The goal is to provide a harmonized protocol-independent TSN that avoids different "varieties" depending on the protocol used says Michael Bone, chief executive of Profibus and Profinet in North America

TSN is a set of switching standards developed by the Institute of Electrical and Electronics Engineers under the IEEE 802 Network Standards Group.

TSN promises to make standard Ethernet capable of working in real time and completely deterministic. If the TSN concept is successful, it will mean eliminating network delays and uncertainties in time sensitive applications by timing synchronization and prioritizing data streams through scheduling and coordinating the best communication links noted Ken Austin, Senior Ethernet Product Marketing Officer at Phoenix Contact

Major industrial protocol associations have indicated their support for TSN, and some have published the first concepts of how their protocols will work with it. Associations also collaborate with automation vendors to implement TSN.

At the end of 2020, the industrial automation industry is in the middle of a two-step process: writing IEEE basic standards and developing a profile for industrial automation.

TSN is not one thing. This is a set of IEEE standards that is best regarded as a toolkit stated Michael Bone

Since the IEEE 802 standards cover the entire industry, each industry needs to determine which of these tools it needs and use them to define a general profile for itself. To develop such profiles for industrial automation, IEEE and the International Electrotechnical Commission (IEC) have joined forces and are working on a joint profile called IEC/IEEE 60802 TSN Profile for industrial automation (TSN-IA profile).

Bone and others, however, expect TSN-based networks to start appearing in this area in a few years. They give the following reasons.

First, fill in the TSN-IA profile and refine the last remaining IEEE standards says Michael Bone

The basic TSN technology required for bridges was completed with the release of IEEE 802.1AS this (2020) year. Assuming that it will be implemented at a sufficient pace, the key basic standard for application interaction will be IEEE 802.1Qdj, Configuration Enhancements for TSN, which is scheduled for release in 2023 or 2024 reported by Paul Brooks, Technology Business Development Manager at Rockwell Automation

The IEC/IEEE 60802 Joint Working Group discussing the TSN-IA profile is due to complete its work in 2021. At least these were the expectations before the outbreak of COVID-19.

The second reason TSN implementation will take several years is that once the standard and profile are complete, chipmakers will need time to manufacture TSN-enabled chips.

Automation devices will use standard TSN-based communication chips instead of today's special real-time Ethernet equipment shared by Thomas Brundle, owner of communications products at Bosch Rexroth

The third reason is related to subsequent development cycles.

Manufacturers of automation devices will have to use these chips in their devices says Michael Bone

Finally, the fourth reason is that end users must decide that they can install these devices in their factories.

Since you need a whole device market to do this, it will be a long time before people start seeing TSN in the real world adds Michael Bone

Harmonisation of standards

In order for implementation not to take a large amount of time, industrial protocol associations are already busy preparing their standards to support TSN.

Specification for Profinet's work via TSN has been written, prepared, approved and published since mid-2019 reported by Michael Bone

However, the work of his organization has not been completed. It develops testing procedures that ensure that the devices meet the specification. Bone attributes the rapid release of specifications for Profinet's work with TSN to the fact that many of the mechanisms used by TSN have been part of Profinet for many years. For this reason, he expects TSN's long-term impact on Profinet itself to be minimal.

The OPC Foundation is also seeking harmonization with TSN, which it is doing through the OPC Field Level Communications (FLC) initiative launched on November 5, 2018. The organization sees TSN as an opportunity to implement its OPC UA (Open Platform Communications with Unified Architecture) at the field level between controllers and devices such as sensors and actuators. TSN will allow OPC UA not only to offer an open, standardized and compatible product for most industrial communications, but also to provide semantic compatibility "from sensors to to cloud."

A key aspect of the FLC initiative is the concept of Universal Quality of Service (QoS).

OPC UA does not define its own transport protocols. Instead, OPC UA is an industrial structure that can be easily adapted to existing transport levels depending on different requirements and use cases. This framework already includes mechanisms for a secure, reliable, manufacturer-independent and information-sharing platform states Peter Lutz, director of the FLC initiative

He also notes that the universal concept of QoS modeling allows information and services to be transferred through various basic transport protocols and physical environments. Lutz says his organization has identified early uses and applications based on the QoS model for controller-controller (C2C) and controller-device (C2D) interactions to automate manufacturing and processes.

C2C and C2D require inter-production semantics for motion control, functional security and remote I/O reported by Peter Lutz

At the same time, real-time communication capabilities with guaranteed bandwidth and low delays are also required. The OPC Foundation has already developed many of the necessary specifications. The first release of the functional safety specification is under review, and the first specification for communication between control devices was announced at an SPS event in Nuremberg, Germany, in 2019. In May 2020, the OPC Foundation established a working group on drive technologies to define a profile for them that provides standardized communication between controllers and drives.

The next step will be to extend the OPC FLC standard for communication between controllers and devices such as I/O and servo motors. The modular architecture of our new controller ctrlX Core allows you to use OPC FLC with TSN and EtherCAT simultaneously without mutual influence says Thomas Brundle

By participating in OPC FLC workgroups from the outset, Bosch Rexroth is preparing a software update that will allow its new automation management platform to adopt a new communication standard.

Preparing for high speed

TSN will not replace protocols that have proven themselves well in applications requiring highly synchronized and deterministic motion control.

TSN is an advanced approach to Ethernet. TSN provides limited determinism in IEEE 802 heterogeneous networks, but still has significant latency says Bob Trask, North American representative of EtherCAT Technology Group

Therefore, high-speed traffic control equipment and other applications will still need an industrial protocol such as EtherCAT, which can guarantee real-time data transmission. EtherCAT will be able to continue to provide these guarantees, since it can be enabled on TSN-based networks and vice versa, without any changes to the devices.

We are working with Beckhoff Automation to develop a TSN device that base the TSN tunnel between the transmitter and the receiver to stream EtherCAT messages reported by Bob Trask

The EtherCAT bridge concept is based on forwarding and processing common personnel on the fly to optimize communication.

It (protocol) can pack a frame with information from a plurality of nodes, going to a group of slave devices adds Bob Trask

Therefore, the integration of EtherCAT into the TSN does not require a port for each slave, and fewer ports can be dispensed with, reducing both complexity and latency. Adding a TSN infrastructure between the master and slave segments also creates a logical separation. The result is greater flexibility for master devices, guaranteed maximum latency, and predictable personnel loss rates.

CC-Link Partner Association (CLPA) also incorporated TSN into its protocol, releasing CC-Link IE TSN in November 2018 as a technology for deterministic high-speed management.

The presence of built-in support for CC-Link IE TSN in devices will allow you to ensure the safety, movement and management of machines and devices that were not previously connected says Tom Burke, Global Strategic Advisor to CLPA and Global Director of Industry Standards at Mitsubishi Electric Automation

Burke says the CC-Link IE TSN is already being rolled out in Asia and that CLPA is also working with its partners to roll it out in Europe and North America. It is planned that CC-Link IE TSN will become the flagship CLPA protocol.

Since we have a huge base of installed devices from all of our partners that support our current protocols, CC-Link IE field and CC-Link IE control, we have a migration plan that allows our providers to add support for CC-Link IE TSN to their existing devices. We are working with our suppliers on appropriate bridges and gateways to make this a reality adds Tom Burke

Wait and See

As of the second half of 2020, not all protocol associations have released their adaptations.

ODVA chose a measured approach, waiting for TSN standards to be finalized before adapting EtherNet/IP for TSN states Dr. Al Beidun President of ODVA

He and his colleagues want to avoid false launches and any associated adverse effects on many participants and users of the EtherNet/IP ecosystem. However, this strategy does not mean that ODVA was dormant. In contrast, she has been busy working through strategic member groups to adapt her EtherNet/IP for TSN. Part of the teams mandate is to develop adaptations that will allow EtherNet/IP to maintain the TSN standard without any proprietary modifications.

All current technologies, including DLR (device-level ring), CIP (Common Industrial Protocol) Motion and CIP Sync, will be able to use the methods that IEC/IEEE 60802 defines through the introduction of new equipment, and some through firmware updates reports Dr. Al Beidun

Member groups are working to minimize additional technology and ensure that existing EtherNet/IP installations can leverage their past investments.

One of these strategic members, Rockwell Automation, supports this work on several levels. For example, at the 2020 ODVA industry conference, a representative made a presentation on adapting CIP Motion to TSN. The automation vendor also supports the standard through prototyping during the pre-development phase of the product.

{{quote 'author = shared by Paul Brooks, Business Development Manager at Rockwell Automation' K fortunately, since EtherNet/IP was developed using the standard unmodified Ethernet and software package// TCP , UDP we IP believe that the main impact of TSN will be on the product hardware. Protocol impact will be relatively small#^[1] }}

See also

• TSN OPC Unified Architecture (OPC UA) Standard
• Honeywell Matrikon OPC Unified Architecture (OPC UA) - Honeywell

Notes