Ethernet is already advancing with new speeds and adoption in new markets. While the slower moving industrial market is still operating at 10- or 100-Mb speeds, the IT world is already benefitting from 1- to 10-Gb speeds. Some industrial networks are already delivering 1-Gb support. But while speed helps to handle more traffic, it does little to improve reliability in a market that requires 100% reliability.
Today, we can engineer Ethernet reliability into an application. That is done first by knowing what products will be using the network and second by coordinating their use of that network. By default, this requires closed, not open networks. Closed networks can’t help with the need to provide continuous improvement, digital transformation, etc.
All of industry has the desire to improve performance, save costs, and eliminate downtime. Access to more information, especially information from previously unavailable sources, like closed control networks, would be a significant boon to digital transformation strategies, but how do we gather that information?
The solution is to make Ethernet technology (not just speed) improvements to enable the better coordination of communications. Today, Ethernet relies on a process of identifying collisions in communications and letting those communications recover through a process of differing wait times. Devices on a network will try again to communicate, after varying moments of wait times. While this is a good process for general-purpose information technology (IT) and operational technology (OT) networks, it is challenging to control traffic message sizes so that a device doesn’t consume an inordinate level of bandwidth at any one time. While it would be great to improve all end devices on a network for conformance, another solution would be to enable a “traffic cop” to “shape” traffic through frame preemption and prioritization. In an effort to remove communications collisions, devices on the network should be able to synchronize the clocks to a very high precision. Devices can then select timeslots for their communications, knowing that these have been negotiated for dedicated use. Precision timestamping is at the nanosecond level of accuracy.
These Ethernet enhancements resulted in a focus on Time Sensitive Networking (TSN) and were started in 2012 by the IEEE 802.1 working group. The first result was delivered in a new specification in the first quarter of 2018. These enhancements meant something very important to the industrial automation world. For the very first time, vendors could deliver converged (combined) IT and OT network solutions. This brought with it several benefits, some immediate and some to be realized over time, through broad adoption.
- Access to all OT devices from an IT network—enabling improvements in analytics, asset management, device management, and configuration and all things digital transformation.
- Improved performance—the combination of scheduling, prioritization, and greater bandwidth are resulting in the ability to handle larger and more complex applications, reliably, especially in the motion control and robotics markets.
- Simplified architectures—resulting in cost savings and improved reliability.
- Easier troubleshooting—users can now leverage IT tools such as SNMP (Simple Network Management Protocol) to interact with and manage OT network devices. Again, bringing a greater understanding of control elements and enhancing their reliability.
Benefits Over Time
- Reduced cost through new product delivery and market competition—initial solutions at the end of 2018 focused on high-performance applications around a limited set of vendors. But over time, more and more device vendors and infrastructure vendors have stepped forward with compatible product offerings and are now offering a robust ecosystem of solutions from which to choose.
Future of Time-Sensitive Networking
Ethernet with TSN doesn’t need to become the entire backbone for enterprise communications. It is more likely that end-users and system integrators will implement “islands of TSN” dedicated to a machine or a production line, leveraging high-performance, deterministic, and reliable communications performance there, while bridging those communications to IT networks to enable wider access to information, achieving their digital transformation.
There is one concern in the market. With more and more vendors leveraging Ethernet with TSN, how can we ensure co-existence or interoperability? That question has recently been addressed with a new, cross-vendor initiative, the “TSN Industrial Automation Conformance Collaboration.” This collaboration between Avnu, CC-Link Partner Association, ODVA, OPC Foundation, and PROFIBUS & PROFINET International is created to deliver a single common conformance test plan for the IEC/IEEE 60802 Profile of TSN for Industrial Automation.
In summary, as the push continues for higher performance, tighter controls, and converged networks, there needs to be an equal focus on maintaining reliability. The adoption of Ethernet with TSN will be the easiest solution for managing that need for reliability through added bandwidth, communications scheduling, and traffic management.