Banishing the darkness

BASF’s new site in Zhanjiang, China, is keeping Dr Kai Krüning on his toes. The company is investing several billion euros there in what is its biggest capital project to date. The Zhanjiang integrated production complex will be the global chemical company’s third-largest Verbund site, after Ludwigshafen and Antwerp. “Right now we’re starting up one new on-site facility after another,” says Krüning, who is BASF’s project lead for standardization of process control systems. Beforehand there are all the components to be installed – sensors, actuators and suchlike – followed by tests of their functioning and interoperation. As one of the project’s suppliers, Endress+Hauser has contributed sensors by the thousand. But it’s not only the sheer size of the project that makes it so special; there’s also the unprecedented degree of digitalization.

In Zhanjiang, BASF is leading the chemical industry in the adoption of Ethernet-APL (Advanced Physical Layer). A technology developed specifically for process industry requirements, this is a highly robust and reliable type of Ethernet that carries both data and power over a single, shielded twisted-pair cable. This allows intrinsically safe, high-speed digital communication, even in explosion hazardous areas, all the way down to the sensors and actuators at field level. “A lot of users are really excited about Ethernet-APL right now,” says Karl Büttner, the marketing lead for Ethernet-APL at Endress+Hauser.

And just why is this technology raising such high expectations? That’s a question for Gerd Niedermayer, a senior E&I engineering manager who has been with BASF for over 35 years. His office is located in one of the buildings at BASF’s vast Verbund site in Ludwigshafen. “We want to use data from intelligent field instruments for things like asset management, preventive maintenance and process optimization,” he explains. “But with our current process communication infrastructure, access to this data is often poor if not impossible. Ethernet-APL solves the problem.”

In process industries, the field level is often a blind spot on a company’s digital dashboard – a bit like a stretch of rural track midway along the data superhighway. That’s because analogue signals are still the norm for process control, not least in chemical plants. Here, even state-of-the-art field instruments still use trusty 4–20 mA current loop technology to send their measurement signals to the control system. And while many implementations incorporate the HART protocol to modulate digital diagnostic or status messages on top of the analogue measurement signals, the data rates are very low. Fieldbus systems that enable digital communication with field instruments – e.g. PROFIBUS PA – have, of course, been around for nearly 30 years. But they have practical limitations in terms of low bandwidth, complex topologies and the sometimes less-than-smooth interoperability of their various components. All of which makes for highly complicated engineering and field instrument swap-outs.

APL stands for Advanced Physical Layer. In networking, the term ‘physical layer’ relates to everything tangible through which the electrical or optical signals flow. From a technical viewpoint, Ethernet-APL is a pared-back but specially hardened form of Ethernet that functions safely, even in explosion hazardous areas.

With Ethernet-APL, field instruments send data to an APL switch – a device that functions somewhat like a home network router, connecting multiple devices together. From the switch, data continues on its way to the control system or into the cloud – directly, unmediated by gateways. This has the advantage that all the data from field instruments is available in real time and hence usable by applications such as preventive maintenance or detailed process analysis. In other words, Ethernet-APL represents a shift to modern, end-to-end industrial communication. Its impact may be compared to the transition from those acoustic coupler modems of yesteryear to today’s fiber-optic connections. It is the digital foundation for the next generation of process automation.

The new approach based on Ethernet-APL first started emerging around a decade ago. BASF’s Gerd Niedermayer well remembers the time when this new technology was presented at a workshop run by NAMUR, an international association of automation technology users in process industries. “Ethernet-APL instantly struck a chord with me because it offers so many advantages.” Indeed, it is a technology that combines the robustness and intrinsic safety demanded by many process industry applications with the superior bandwidth of Ethernet. It also supports cable lengths of up to one kilometer. “With transmission rates as high as 10 Mbit/s, Ethernet-APL is 10,000 times faster than HART and 300 times faster than classic fieldbuses. This allows large amounts of data to be sent back and forth in real time.”

Gerd Niedermayer always knew that the physical transmission technology was only the start of things. The project would also call for a suitable communication protocol as well as interfaces and standards to integrate instruments into the control system and bring access to the instrument data. BASF compiled all the requirements into a solution outline. “We wanted a high-performance end-to-end communication solution that could transfer data at high speed to both the control system and the asset management system – and do so without significant additional overhead. The new technology also needed to deliver advantages in terms of both upfront capital and lifecycle operating costs,” says Niedermayer. This was the thinking at the global chemical company as it decided to take an active part in shaping and driving Ethernet-APL’s development. “We were seeking a standardized and interoperable solution, so we decided to partner closely with vendors from the very beginning.” Transparency, grit and determination were needed. But it paid off. Working with makers of measurement instruments, field switches and control systems, BASF managed to develop Ethernet-APL to market readiness in the space of just five years. “It was a true pioneering feat,” says Niedermayer.

Among the development partners was Endress+Hauser. The two companies have a longstanding and close relationship. “We have been a BASF preferred instrumentation vendor for decades,” explains Udo Nalbach, a chemical engineer and strategic account manager at Endress+Hauser. “BASF is very open to new developments, engages early and intensively with innovations, and is quick to implement them if they pan out.” Nalbach recalls how BASF and Endress+Hauser put their heads together soon after that seminal NAMUR workshop. “Together, we investigated a range of issues, including the reasons why fieldbus networking has never really taken off. Our findings in these areas informed our work to develop and standardize Ethernet-APL and make it a successful technology.”

As well as pure functionality, the engineers and technicians at the laboratory investigated practical usability. The instruments with Ethernet-APL connectivity had to be easy to use and deliver cost savings. How quick and simple are they to install, wire and integrate? How fast is loop checking and commissioning? How will remote parameterization and fault correction work? How easily can instruments be replaced while a plant is operating? Is the system readily scalable? Can the instruments be used in hybrid environments – for example, in combination with PROFIBUS PA units? And most importantly of all: What about interoperability? Will the instruments integrate smoothly in process industry environments that use equipment from multiple vendors? So many questions, so many high expectations – yet the Ethernet-APL technology showed its strength in a whole battery of load tests.

Endress+Hauser conducted multiple load tests of its own, each employing 240 instruments per control system in accordance with requirements defined by BASF. That’s 240 components from various manufacturers. And they all worked together seamlessly to form a reliable, robust Ethernet-APL-based system. “Today’s world is complex to the point that no one vendor can bring a new technology to fruition on its own,” says Udo Nalbach. “Hence, manufacturers need to collaborate end-to-end, from field instrument through to control system. The key is rigorous standardization.” This is where the PROFINET protocol comes in, governing communication between field instruments and the process control system. Standardized device profiles simplify system integration and allow easy, hassle-free instrument replacement. A driver model uniformly binds devices into asset management systems. And the sensor data is structured in a vendor-neutral format.

BASF is currently installing its first PROFINET-APL field instruments at sites including two new plants in Ludwigshafen. The global chemical company has taken this a step further with most of the plants at its new Verbund site in Zhanjiang, China – the whole complex is APL-ready by design. “When planning many of the plants here, we didn’t yet know when we would have access to a full portfolio of PROFINET-APL instruments,” explains Kai Krüning. So, they chose an APL-ready migration pathway in which everything from control system to field switch uses PROFINET technology. BASF had earlier subjected the network’s ring topology to comprehensive testing in partnership with Endress+Hauser. This infrastructure supports parallel use of both PROFIBUS PA and PROFINET-APL instruments, so BASF had the flexibility to equip its plants with PROFIBUS PA instruments in the first instance. “Looking ahead, whenever we need to swap out an instrument, we can replace it with an APL one,” says Krüning. Two plants in Zhanjiang have in fact already been equipped with Ethernet-APL instruments. “We’ve just brought the first of these online,” explains Krüning.

Kai Krüning made sure all employees involved in plant operation, maintenance and asset management were fully trained in the new technology. And his feedback from the mega-project in China is positive: “Commissioning and loop checking are faster with Ethernet-APL than with PROFIBUS PA. My colleagues there tell me the technology is much easier to use, and that parameterization via the asset management system is simpler.” For Gerd Niedermayer, too, the technology has so far delivered on its promise: “We are making major hardware cost savings, especially in terms of engineering and commissioning.”

Will Ethernet-APL be a game changer in the process industries? Will it be a catalyst for digitalization? “In brownfield projects, there are still a few obstacles to overcome,” says Karl Büttner, “but in greenfield projects, the euphoria is warranted.” His colleague Udo Nalbach concurs: “This technology will achieve a much more widespread uptake than conventional fieldbus technologies. Today, there’s almost no reason to build a 4–20 mA plant.” Kai Krüning, who is helping to shape BASF’s future in Zhanjiang, agrees: “We see Ethernet-APL as the platform for the next steps in the digital transformation process.” And for Gerd Niedermayer, who has been working in the process industry for over three decades, the goal is clear. “We’ve reached the first milestones. The task now is to continue along our path and establish Ethernet-APL as the industry standard.”