Sensor technology of tomorrow for consistent communication Single Pair Ethernet: Lean communication through to the field level of automation.

Single Pair Ethernet (SPE) has what it takes to make connections more sustainable and smarter through to the field level. It is for good reason that sensor manufacturer JUMO relies on SPE as the future-oriented communication medium for its measurement technology. The connection technology required for this comes from Phoenix Contact – and is the result of close collaboration at the project level.

“With Single Pair Ethernet, we are able to make better use of our intelligent sensors”, says Manfred Walter, product manager at JUMO. “I get real added value by being able to transmit more sensor data with SPE”. Having more data is the key to extracting useful information from it. This is simply not possible if a 4 to 20 mA sensor only transmits a bare current value – for example, as an equivalent for a temperature.

The product manager is really enthusiastic about the fact that the SPE connection finally allows sensor information to be distributed seamlessly in a system. Here, Manfred Walter has in mind the boundaries between levels within the automation pyramid, which are difficult to overcome. “At JUMO, we see consistency across all levels as a major strength”. In addition, cables can be saved because data and power are routed via the two wires of the Power over Data Line (PoDL). Essentially, SPE offers the opportunity for consistent communication from the ERP level right down to the sensor and actuator technology at the field level. “And it all works without any media discontinuity”, emphasizes Walter, as the sensor communicates consistently at all levels on the basis of Ethernet protocols.

Using SPE to combat media discontinuity in industrial communication – will this benefit lead to a rethink in the choice of connection technology at the sensor level? In Manfred Walter’s experience, customer expectations in machine building and systems manufacturing continue to be clearly price-driven. The budgets for measurement chains are very limited when planning systems. “It’s a matter of how much a measurement chain can cost and how high the additional price is for the SPE connection”. The conclusive arguments for a consistent Ethernet architecture are difficult to present, especially in standardized tendering procedures. The positive effects on the OEE are an important factor for investment decisions and can therefore best be argued directly.

The transmission technology with SPE represents an important step on the way to convergent networks. While the Time Sensitive Network (TSN), for example, is primarily designed for time-critical tasks in the disciplines of functional safety or motion control, 5G is used for applications that require cellular communication. The same applies to WLAN 6 and 7 in the field of license-free, wireless transmission technology.

Single Pair Ethernet, on the other hand, is ideal for communication through to the field level. The common denominator for all technologies is the convergent Ethernet network – the standardized world for industrial communication. If the stakeholders in automation, electrical engineering, systems manufacturing, and machine building manage to agree on this path in the medium term, then the fieldbus wars with their industry-specific developments will finally be a thing of the past.

The chances of this are favorable. It is all underpinned by the general transmission performance of standard communication from the consumer market. SPE achieves as a medium for the spatially limited machine level a transmission rate of 10 Mbps on a cable length of up to 1,000 m. In comparison, I/O-Link, for example, delivers just 230.4 kbps with a maximum cable length of 20 m. Even though I/O-Link undoubtedly simplifies the connection of sensors considerably, Manfred Walter believes that this data transmission rate will no longer be sufficient for future tasks within coupled sectors.

Speaking of the future, Phoenix Contact and JUMO both see a clear trend toward convergent Ethernet networks, especially among the younger generation of specialists. “To be blunt, due to their upbringing and history, digital natives are less tolerant of the use of so many different systems in industrial automation”, says Martin Müller. The aim must be to ask more questions about what a sensor can do and what it is capable of doing beyond its own measuring range for efficient and resource-saving system operation. "We see an enormous future here", Manfred Walter also emphasizes.