The most important developments within industrial network communication further explained

During the Industrial Ethernet event on Thursday, March 24, there will be numerous developments in the industrial network communication is discussed. Looking ahead, we spoke with a number of speakers during the event about Ethernet-APL, TSN and MQTT.

By: Dimitri Reijerman

A leading development within Industrial Ethernet is Ethernet Advanced Physical Layer, or Ethernet-APL. During the Industrial Ethernet event on March 24, Alexander Gilles from Pepperl + Fuchs and Jaap Westeneng from Endress + Hauser in more detail about this new standard, but FHI already spoke to the gentlemen.

According to Westeneng, one of the advantages of Ethernet-APL is the longer cable lengths: “Compared to standard and/or Industrial Ethernet, Ethernet-APL certainly offers the advantage of longer cable lengths. Ethernet, as we know it today, is limited to a maximum cable length of 100 meters and with Ethernet-APL a trunk cable length (trunk) of 1000 meters are used and branch cable lengths (spur) of 200 meters is allowed. Especially for industrial applications, the standard Ethernet cable length is often insufficient and Ethernet-APL offers a comparable range to bus technology for process automation, such as PROFIBUS PA.”

But there are more advantages, Westeneng continues: “You could summarize Ethernet-APL as the 2-wire data highway for endless possibilities; smart, fast and digital. Ethernet-APL is characterized in particular by communication and power supply via two-wire cable (Type A), it is polarity-insensitive and can easily be connected to standard screw or spring terminals. Ethernet-APL is suitable for use in potentially explosive atmospheres based on the 2-WISE standard (IEC TS 60079-47, 2021-03). Furthermore, Ethernet-APL supports all standardized industrial Ethernet protocols, such as. PROFINET, Modbus TCP, EtherNet/IP and HART-IP.”

It is perhaps striking that APL supports speeds of up to 10Mbit/s. “Looking at today's Ethernet speeds of up to 10 Gbit/s, Ethernet-APL with 10 Mbit/s does not seem fast indeed,” says Westeneng. “However, the speed does not only depend on the absolute transmission speed, but also on the amount of data that needs to be sent and the distance to be bridged. Speed is relative – especially if we compare it with the de facto communication standard for the (process) industry: HART communication. HART offers a speed of 1.2 kbit/s (half duplex) and compared to Ethernet-APL which offers 10 Mbit/s (full duplex), Ethernet-APL is 8000 times faster and also 300 times faster than existing bus communication technologies. For industrial applications, Ethernet-APL offers long distances of up to 1000 m and that would not have been possible with higher transmission speeds.”

APL also has a number of physical protections: “APL is a new physical layer and is standardized in IEEE 802.3cg with 10Mbit/s (10BASE-T1L) full duplex communication and based on IEC TS 60079-42 (2WISE) suitable for two-wire intrinsic safe applications and is polarity insensitive, so installation errors will not lead to unexpected problems. In addition, various so-called 'port profiles' have been defined for APL for different nutritional concepts. To ensure interoperability, 'conformance tests' are carried out and installation and engineering guidelines are available to users.”

According to Westeneng, APL is now steadily advancing in the industry, especially now that more and more products are becoming available, says Westeneng: “The first Ethernet-APL products are already available – for example the APL Field Switch from Pepperl+Fuchs is already available and Endress+Hauser will introduce the first Ethernet-APL instrument with PROFINET in mid-2022; magnetic and vortex flow, radar level, pressure and temperature. In addition, APL instrument software configuration tools will also be available based on FDI (Field Device Integration) and connectivity will be provided with cloud-based ecosystems.”

Towards the future, Westeneng expects that Ethernet-APL will play an increasingly important role: “For the (near) future, instruments and devices will increasingly be able to make their source data available via different channels based on standardized services ( e.g. REST API, MQTT, OPC UA). The NAMUR Open Architecture (NOA) offers the so-called '2nd Channel' concept with which data can be accessed in an open and secure manner to cloud-based ecosystems. Ethernet-APL provides the necessary foundation for these developments.”

“Another important development for Ethernet-APL is that it becomes suitable for safety applications (SIL). This development will be determined in particular by the choice of communication technology. PROFINET offers ProfiSafe based on standardized profiles. It is expected that ProfiSafe will also become available for Ethernet-APL instruments and devices.”

TSN

TSN, or Time-Sensitive Networking, is also an important development within the further digitalization of the process industry. This specification, which also contains the necessary substandards, is being developed by the IEEE 802.1 working group.

Nico Hanemaayer from ATS explains why TSN is so important for the (process) industry: “TSN was created because there is no hard real-time functionality in the normal Ethernet protocol. Ethernet is suitable for soft real-time applications. This means that there is a spread – jitter – may be due to the arrival of the messages. In addition, we often talk about cycle times of around 10ms and higher. TSN is intended for hard real-time, which means that motion control and closed loop systems are also within the reach of Ethernet. The desired structure as required by Industry 4.0 will also be made possible by TSN. Controllers can be virtual and do not necessarily have to be positioned close to the devices to be controlled. Physically they can be located elsewhere in the company, in a local cloud.”

However, it will take some time before TSN will be widely applied in the process industry. According to Hanemaayer, this is because it is a fairly young set of standards: “. The reason for this is that there are not many devices that have integrated TSN. Cisco and B&R have equipment that supports it. I think we have to wait until it is engineered into many products. Then it will take off.”

Looking further into the future, Hanemaayer thinks that interesting integrations are still possible around TSN. “TSN will make it possible for OPC Unified Architecture (OPC UA) to be applied at field level. This will improve uniformity. Ultimately, everything will start talking OPC UA and we will increasingly get rid of the tangle of different protocols. However, this is still a thing of the future for the time being.”

During his lecture on March 24 during the Industrial Ethernet, Hanemaayer wants to emphasize the potential of TSN. In his view, the standard is uniform - because it will replace various existing protocols - and cheap if sufficient economies of scale have been created. He also points out the scalability of the technology and the easier delivery of training, because there is only one standard.

MQTT

With the rise of the Industrial Internet of Things, the MQTT protocol, intended to exchange messages between devices, also plays an important role. Diederick Nab from WAGO NL will provide a seminar in which he will provide insight into the role MQTT plays in the industry.

“MQTT is the most widely used IoT communication protocol,” says Nab. “This means, among other things, that it is used as a communication protocol in both the IT and OT domains. What makes MQTT so strong is that the message has little overhead and uses the Pub/Sub model. This ensures a very efficient way of communicating.”

Nab also mentions the many advantages of using MQTT. It is easy to implement because it is a simple protocol. Thanks to different levels of Quality Of Service, data security is also created. Furthermore, the efficient MQTT requires only low bandwidth and is independent of device and interface. Finally, the protocol is state-preserving, meaning the connection remains active, unlike some other protocols. Finally, as mentioned, MQTT is applicable in both the IT and OT domains.

Communication via MQTT can also be easily secured, says Nab: “You can secure the protocol at three different levels. At network level using, for example, a VPN and firewalls, at transport level using TLS/SSL and at application level using username and password. A combination of these options is always the strongest.”

Nab does not dare to say whether the MQTT protocol will be further expanded in the future, “but given the growth in IIOT, the protocol will become increasingly important.” On behalf of WAGO, he will want to inform the visitors of his seminar what the (practical) possibilities of MQTT are and when it offers possibilities compared to other protocols.

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