Industrial communications: the next big thing!

17 October 2022

Suzanne Gill asked what control engineering can expect the next big development to be in industrial communication technologies.

As industrial field devices, such as instruments, analysers and variable speed drives, become increasingly intelligent, users seeking to access information from them to implement advanced control require improved connectivity. 

Every network requires physical layers, communication protocols, and information models to provide a complete solution. For industrial communications, Ethernet and fieldbuses are well-understood. “When an appropriate form of Ethernet is used in conjunction with a protocol like HART-IP and an information model like PA-DIM, users can obtain the required connectivity and fully unlock the capabilities of industrial communications,” said Paul Sereiko, director of marketing at the FieldComm Group. 

Standard Ethernet transport media, both wired and wireless, is usable for some industrial applications, but it is not always ideal for delivering high reliability in challenging applications. “Two-wire Ethernet-APL is an industrialised form of Ethernet media, spanning greater distances and supplying sufficient operating power to simplify installations,” explained Sereiko. “In the future, we will see a combination of newer physical layers, including different variants of Ethernet, combined with traditional installations such as 4-20mA and fieldbus systems. But standards are needed for consistent data delivery from field devices to host systems.”

Although many industrial protocols exist, Sereiko believes that HART-IP is particularly compelling because it extends the HART protocol, a leading bi-directional digital information exchange method for smart process control field devices, with security and asset management capabilities. HART-IP is a simple-to-use, high-level application technology that operates independently of the underlying physical layer. Additionally, it flattens the industrial control network which means that a PLC- or DCS-based control system can use HART-IP to monitor, control, configure, and obtain diagnostics of intelligent field devices. “Additionally, or alternately, host systems, such as an asset management application, can also use HART-IP to integrate with the field devices directly and concurrently,” pointed out Sereiko.

The Process Automation Device Information Model (PA-DIM) is a specification for protocol-agnostic communication of common process automation instrument parameters, including semantic IDs as defined by IEC 61987, using OPC UA information modelling techniques. Originally developed collaboratively by OPC Foundation and FieldComm Group, today six additional organisations are planning to participate in the continued development of this important standard. These include ISA100 WCI, ODVA, NAMUR, Profibus International, VDMA, and ZVEI. “By eliminating vendor and protocol dependencies, and using a structured hierarchy, PA-DIM ensures parameters can be easily reused among multiple software tools and protocols. This also means that like parameters can be compared – regardless of media, protocol, or field device supplier – in a machine-readable form appropriate for analytics and other computing,” explained Sereiko. 

A variety of Ethernet media options, such as Ethernet-APL, combined with an industry-standard communication protocol like HART-IP and the PA-DIM information model, are now providing a solution for establishing bi-directional access between intelligent industrial devices, and among controllers and other host systems. This combination is said to benefit users with straightforward configurations, high bandwidth, and secure communications.

Martin Rostan, executive director at EtherCAT Technology Group believes that cybersecurity will become a big topic in industrial communication technologies and the connectivity required by the Industrial Internet of Things (IIoT) and Industry 4.0 concepts means that control engineers will have to deal with the topic. “When and to what extent will depend primarily on two things – what the network architecture looks like and which network technology is used,” he said.

Looking at the the architecture, a hierarchical model has always worked well. The real-time control network – the machine level field bus to which the I/Os and drives are connected – is separated by the controller from the next level communication system and the factory network. The controller provides and conditions, the process data that the higher-level systems require, and also regulates the access to the lower-level devices, such as I/O nodes.

The controller acts effectively as a cyber-security firewall for the underlying network, and it transforms hardly comprehensible raw data from the I/O level into meaningful information. Transporting data directly from the sensor to the cloud only makes sense in some applications. “For example, the user cannot know without further information whether 85°C motor temperature is okay or too hot,” said Rostan. “Often not even the motor itself knows this, because it depends on the application and the current situation. A controller, however, can tell the operator's cloud service whether the current motor temperature is okay or not. And, for those cases where the provision of raw data is desired – for example, by the motor manufacturer who wants to see for warranty claims whether the motor is being operated within specification – the user should be able to decide whether to allow that. And that is much easier to do in the controller than on each sensor or device.”

For some, however, the hierarchical architecture is now considered outdated – complete access is demanded, with a single network from bottom to top. “This is also the justification for demanding the same network technology below the controller as above,”continued Rostan. “What may look tempting at first glance, however, harbours many problems: in terms of responsibility and liability, independent performance of the control network, address duplication and costs, and especially regarding cyber security. Suddenly, I/O nodes, networked sensors and drives are directly visible and accessible in the factory network and possibly beyond. And here we don't even have to assume deliberate attacks: even an accidental change of parameters on the wrong device would have far-reaching consequences.”

So, in this brave new world, all devices will need cybersecurity protection, which will require certificates on every I/O device, and certificates expire, so they must be updated. “Security requires additional computing power and memory on the devices, and this alone leads to increased costs. And meeting security requirements with this architecture means that control engineers must build up profound cyber-security know-how,” said Rostan.

He went on to point out that the choice of network technology also plays a decisive role. “With switch-based Industrial Ethernet solutions, each device must be cyber-protected, especially if the technologies are fully or partially based on the Internet Protocol. EtherCAT, however, is neither switch-based nor does it rely on the Internet Protocol. The EtherCAT protocol is directly embedded in the Ethernet frame. Since almost all cyber-attacks require the Internet Protocol for routing, with EtherCAT they go nowhere. Furthermore, the EtherCAT chips filter out non-EtherCAT frames by hardware, and by principle EtherCAT devices cannot be persuaded to falsify data not intended for them, even by compromised firmware. In addition, EtherCAT ports that are not used can be switched off in hardware. EtherCAT is therefore already so well protected per se that no further cybersecurity measures are required beyond what is needed anyhow for the controller. Therefore, no knowledge of certificates and cyber security is required to operate this Industrial Ethernet fieldbus.”

Dr Al Beydoun, president and executive director at ODVA, says that IEC/IEEE 60802-based TSN promises to provide coexistence, higher network utilisation and improved configuration tools when compared to today’s standard, unmodified Ethernet. He said: “The technologies of preemption, scheduling, universal QoS implementations, path reservations, and IEEE 802.1CB fault tolerance are currently being specified and they all rely on moving time synchronisation standards up a layer – from fieldbus specifications to IEEE 802.1. 

“All devices that participate in IEC/IEEE 60802 communication need to have a common implementation and understanding of time and so IEEE Std. 802.1AS-2020 will be the time protocol that drives time synchronisation. IEC/IEEE 60802 TSN devices will need to adhere to the same rules in processing and forwarding communication packets as defined in traffic schedules to participate in real-time (TSN) communication. Finally, all IEC/IEEE 60802 client devices will gain access to and run on an IEC/IEEE 60802 based network using the common language of YANG.”  

IEC/IEEE 60802-enabled TSN can offer a solution that introduces Software Defined Networking to industrial networking in a standardised way, while enabling deterministic converged transport. EtherNet/IP will release a best-of-breed solution when appropriately standardised by IEC and IEEE to take advantage of these benefits. 

A new Common Industrial Profile (CIP) Application Profile is due for release after IEC/IEEE 60802 is published, which will make IEC/IEEE 60802-enabled TSN an option for EtherNet/IP. “End users will be able to natively implement the TSN application profile or leverage a gateway to allow for converged communication over a TSN network,” continued Beydoun. “Either approach will allow for fair network level access with other IEC/IEEE 60802-compliant devices. Existing EtherNet/IP devices can also work on TSN networks, although their Quality of Service (QoS) on the wire may be degraded when compared to a non-TSN network.” 

An example of the benefit of IEC/IEEE 60802 TSN is being able to adapt CIP Motion by aligning the network with the motion control planner using a common notion of time. Once CIP Motion and 60802 are aligned, network transport can be facilitated using scheduling as necessary to meet the needs of the network and coexist fairly with existing traffic. 

Once a converged network exists – regardless of protocol, device manufacturer, or device type – the door is open to more opportunity for savings on wiring, easier network management, cloud-based data analysis, a mixture of IT and OT traffic on the same network, and more comprehensive plant metrics, for example.

Applications such as security cameras, cloud analytics and real time I/O data running over the same wire can become a reality. A more cohesive plant control network that can be better linked to enterprise level IT networks allows for better asset visibility, more opportunities for data analysis and production optimisation, and less worker training and maintenance costs. 

“Individuals active within the ODVA organisation, alongside IEC and IEEE are continuing to work to contribute to the IEC/IEEE 60802 working group that is identifying the TSN components which will ultimately be included in the joint standard,” said Beydoun. Both new and existing users will be able to take advantage of the low overhead nature of EtherNet/IP driven by close adherence to key IEEE Ethernet standards and by employing commercial off the shelf (COTS) technology where possible, along with both UDP and IP technology, depending on the use case. 

The first edition of the IEC/IEEE 60802 TSN specification is expected to come to market in late 2023. EtherNet/IP is anticipated to have an IEC/IEEE 60802 TSN compatible specification available as soon as is practical after the IEC/IEEE 60802 TSN specification is released.

Complementing Ethernet
John Browett, general manager at the CC-Link Partner Association (CLPA), argues that TSN is supporting the next big developments in industrial communications technologies.

TSN technology complements standard industrial Ethernet to offer accurate synchronisation, traffic prioritisation and scheduling. Thanks to these functions, it can handle multiple types of data and their different priorities over a single network infrastructure. As a result, it is possible to share information and generate more holistic business intelligence while reducing cabling requirements, which, in turn, can reduce network complexity, capital expenditure and operational expenses.

“We can confidently state that the adoption of TSN marks the first, crucial step in the creation of unified, comprehensive network architectures that serve all types of automation,” said Browett. “The power of TSN to drive convergence enables engineers to implement many more future-oriented industrial communications technologies, even beyond Ethernet. These provide a pathway to the realisation of the connected industries of the future as well as the creation of smart, flexible and proactive supply chains, where all players can share key insights with their partners and end users.

“For example, the reduction in the number of cables required to create factory or enterprise-wide networks will continue and may even lead to the complete transition towards wireless technologies.”

Expanding the use of wireless technologies in the operational technology (OT) domain, the latest 5G and 802.11 Wi-Fi standards are able to support ultra-reliable low-latency communications (URLLC) to meet the needs of manufacturing facilities. The addition of TSN functions to these can therefore lead to communications with bounded low latency, low jitter and extremely low data loss. “TSN-wireless hybrids may be the key to creating network architectures with unprecedented levels of flexibility while increasing data accessibility and availability to support a wide range of activities, such as enhanced remote monitoring,” continued Browett.

He argues that there is still more to come too. “While 5G adoption is still underway, work to develop the next generation of wireless solutions, i.e. 6G, has already begun. These networks are expected to support even more heterogeneous applications, such as virtual and augmented reality, artificial intelligence infrastructures and the metaverse.” 

All these communications technologies can help companies advance the digital transformation of their businesses and even their entire supply cycles. Given this will also be enabled by TSN, forward-looking businesses that want to keep up with the latest, most promising trends to drive their competitiveness should look at adopting new frameworks that are compatible with the technology.

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