With the successful launch of Ethernet-APL, the topic of Single Pair Ethernet (SPE) is gaining new momentum. PROFINET is excellently positioned to also play a leading role in SPE.
It was no small piece of work that process automation accomplished with the development and standardization of Ethernet-APL. Since last year there have been a large number of certified Ethernet APL devices available on the market – and Ethernet APL is now really taking off.
Thus, Ethernet-APL is the first SPE technology to be successfully standardized for industrial communication, beyond the limitations of a single protocol. What you need to know is that although PROFINET plays a leading role when it comes to Ethernet APL, Ethernet APL is also supported by other organizations.
Challenge: SPE
The manufacturing industry is facing similar discussions about the connection of devices at the last meter as the process industry did a few years ago. Single-Pair Ethernet (SPE) requires less cabling than traditional 4-wire or 8-wire Ethernet because power and data can be transported over the same cable, using just two wires. This means faster commissioning of devices with an integrated power supply. This would also make new wiring solutions and more compact sensors and actuators possible. The greater flexibility due to the thinner cable would benefit not only robot and crane applications, but also networked buildings or IoT applications. In addition, fewer copper cables are required, which is also in the interest of sustainability as it saves construction and installation costs. The network design is simpler, longer cables are possible and seamless data access is possible across all levels.
“SPE will significantly expand the application possibilities of Ethernet – and thus of PROFINET. With 10BASE-T1L and the Ethernet-APL foundation, PROFINET can address this topic comprehensively.” Volker Goller, Analog Devices
SPE technology also includes various standards that support different data rates and cable lengths and are therefore suitable for different applications. In addition, providers of sensors and actuators usually address several target industries with their components. Due to the technical constraints of the target markets and implementation options, various sub-standards have been developed, which differ primarily in terms of data rate and cable length. There are also different performance classes available for the power supply. The result: In the future, different devices would have to be developed, tested, approved, produced and stored for various applications. Neither manufacturers nor users welcome such a development. A joint approach to developments relating to Ethernet SPE therefore offers enormous advantages. Devices that are first used in the PA environment with Ethernet-APL, could also be used in manufacturing automation or in hybrid industries, such as the packaging industry, with little conversion effort. This would ensure the interoperability of devices and systems from different manufacturers.
Initial Work is Promising
Nevertheless, PI is not resting on its laurels and is now taking SPE further. Ethernet-APL serves as a bit of starting capital. This is because every Ethernet-APL device can also be used in an SPE environment, since APL is a superset of 10Mbit/s SPE. Or the other way around:
APL = SPE + Intrinsic Safety
However, there is a difference when it comes to the power supply between SPE and Ethernet-APL. While Ethernet-APL relies on so-called “engineered power”, i.e. statically switching the power supply on or off via Ethernet-APL, SPE uses IEEE802.3 standard PoDL (“Power over Data-Line”). Simply put: PoDL enables the switch to find out which performance class it belongs to before it is switched on. This means that devices that have not previously been explicitly configured on the switch can be switched on and off without any problems.
The aim is to achieve a unified and automatic use of devices with PoDL and Ethernet-APL devices with “engineered power”. Initial work looks promising and this work was presented at the PI stand at this year’s Hanover Fair.
Think About the Future Today
It is now clear that there are many applications for long-range Ethernet physics. But is 10 MBit/s enough? In fact, 10 Mbit/s is completely sufficient for many applications, even outside the process industry. However, not always! It therefore makes sense to prepare PROFINET for the upcoming 100BASE-T1L standard today. Because at 100 Mbit/s and cable length likely up to 500 meters, SPE becomes attractive for many high-performance applications. Especially since 100BASE-T1L is supposed to have the same industrial robustness as 10BASE-T1L.
SPE will significantly expand the application possibilities of Ethernet – and thus of PROFINET. With 10BASE-T1L and the Ethernet-APL foundation, PROFINET can address this topic comprehensively. In addition, early integration of 100MBit/s SPE will enable PROFINET devices based on the new 100BASE-T1L from day one.
