Ethernet-APL: The Last (Process) Mile

The field of industrial communications has evolved continuously since the days of the fieldbus wars in the 1990s. Over more than 30 years, suppliers and industry consortia have worked together to create new robust communications solutions for industrial applications. Some open whole new realms of possibilities, while others simply fill in gaps.

Ethernet Advanced Physical Layer (APL) is an initiative of the process industries with the goal of paving the last mile of communications to field devices with an IP-based network infrastructure that takes into account the needs of process users. Until recently, that last mile was a country lane with an astonishingly slow speed (1.2 kbits/s for HART protocol, 31 kilobits/s for process fieldbuses). Today, modern Ethernet-based plant and automation networks send data at superhighway speeds right up to the “exit” (e.g., a gateway between Ethernet and process fieldbus), at which point a legacy network steps down the speed to a snail’s pace for the last mile to the field device. High-speed end-to-end connectivity is a key prerequisite for digitalization, and this break in IP connectivity stands as a barrier to realizing the full potential of digitalization.

At the ARC European Industry Forum in May, Andreas Hennecke of Pepperl+Fuchs updated the audience on the status of Ethernet-APL. According to Hennecke, in addition to the speed boost, a goal of the APL development initiative was to reduce the complexity of integrating and operating remotely connected field instruments in areas such as commissioning, configuration, and device replacement. Field trials considered devices from multiple vendors using different protocols and communications technologies. Test scenarios involved media redundancy, simple device exchange, IP/ping storm tests, and netload tests. One test compared the speeds to download configuration data from a Coriolis mass flowmeter. Via HART, the data needed 8 minutes to download while Profibus PA took 3 minutes. Ethernet-APL managed the task in just 10 seconds. Live data from a radar sensor updates almost instantly (<2 seconds).

Now that the specification and testing are finished, automation suppliers are rolling out devices that support Ethernet-APL. Initial products were available starting in H1 2023, and a slew of new product launches are scheduled for the remainder of this year.

According to Hennecke, the development of APL was a huge team effort with contributions from a variety of industry organizations, including FieldComm Group, ODVA, OPC Foundation, Profibus, and Profinet International, as well as suppliers, such as ABB, Emerson, Endress+Hauser, Krohne, Pepperl+Fuch, Phoenix Contact, Rockwell Automation, Samson, Siemens, Stahl, Vega, and Yokogawa.

So, how quickly will process users adopt Ethernet-APL? While the technology offers clear advantages, it requires users first to implement new communications architectures and to specify the use of products with new communications interfaces - necessities that will keep growth slow at first until convincing business cases emerge. Industry users have been accustomed to current performance levels of process communications for decades and are not necessarily calling for a “faster horse”. While the speed boost is nice to have, users still must figure out what to do with all these data. Here, we can expect to see rapid improvements in both device management (faster deployment, better management of updates and device health) and asset management (comprehensive management of plant assets). In the big picture, Ethernet-APL is quite literally the missing link on the path to digitalization in the process industries.