Ethernet-APL is a hot topic as of late. The spec was published in 2021. First products will be entering the market over the coming year. The proposition is pretty slick: a robust, two-wire, powered Ethernet physical layer including intrinsic safety for operation in hazardous areas.
Ethernet-APL is undoubtedly an enabler of digitalization in the process control industries. However, it is not a complete solution. It is just a physical layer. Protocols are still needed to format and communicate data and information. And yet: a physical layer and some data do not make a complete solution either!
To meet the stringent requirements of the process control industries, simple data transfer is not enough.
For example, comprehensive diagnostics are needed. They help enable predictive maintenance with ‘stop-light’ levels of severity (NAMUR NE 107). Time-stamping and sequence-of-events are also employed. In the case of a flood of alarms, quickly locating which alarm first created the cascade becomes easy.
Since process control plants run 24/7, uptime is paramount. With media, device, and even controller redundancy, appropriate levels of availability can be installed per system. Also with 24/7 operation comes the need to reconfigure devices mid-process. Stopping the controller to reparameterize a device is not possible. Dynamic reconfiguration handles this by establishing communication relationships in parallel and swapping over seamlessly.
Finally, application profiles and information models help to organize data into human and machine-readable format to speed device replacement and integration with higher level systems.
What do all of these features have in common? Well, PROFINET, of course. And therein lies the difference. PROFINET is more than just some simple data moving across a wire. It’s a suite of features tailor-made for industry whilst maintaining the openness of standard Ethernet. It’s like having your cake and eating it too.