As Industry 4.0 trends have taken shape over the last number of years, rapid advances in technology are now awaiting adoption by industry. But creating technology merely for technology’s sake serves the few rather than the many. Focusing instead on addressing use-cases has proven effective, but something more is needed for adoption to occur. And that is: ease-of-use. A renewed focus on usability is required for today’s technologies to become tomorrow’s solutions.
Serial Networks
Let’s all take a trip down memory lane to the days of PROFIBUS DP. Which, by the way, isn’t going away and is still a great technology used in many factories today. If we think back to the way we installed these serial networks, there were certainly opportunities for mistakes. You had 9-pin D-Sub connectors, rotary switches for device addressing, segmentation with repeaters, termination resistors, and so on. It wasn’t overly complicated, but it wasn’t idiot-proof either.
The result was that the most common causes of problems on a PROFIBUS network were wiring or installation issues. With industrial Ethernet all of that changed. Now, instead of an RS-485 physical layer, we use the Ethernet physical layer, eliminating all those wiring complications.
This means that, if you need to extend the network, you simply install an Ethernet switch. Rotary switches for addressing and termination resistors are no longer needed. With the step from PROFIBUS DP to PROFINET, we’ve eliminated most causes for problems on an industrial network.
The Ethernet Upgrade
With PROFINET, we’ve made addressing easy because the controller handles it. And with PROFINET we use names—not numbers—to address devices. BOOTP or DHCP are not needed (although they are optional). Instead, you assign the names, and the controller assigns the IP addresses. And it gets better. If you program the network topology into the controller, it can auto-assign device names, making the process even easier.
But what if you need to replace a device? The same underlying technologies—DCP (Discovery and Configuration Protocol) and LLDP (Link Layer Discovery Protocol)—that enable easy naming and addressing also make it possible to swap a failed device for a replacement. Simply remove the failed device and swap in a replacement. That’s it. No computer or configuration tools are required. Just plug and play. PROFINET leverages these IT technologies to make it happen ‘automagically’.
TSN and APL Usability
So how does the future look with TSN (Time-Sensitive Networking) and Ethernet-APL (Advanced Physical Layer)?
First things first. You might be asking: I have been hearing about TSN for years now, where is it? The reason TSN is taking time to reach fruition is because of how fundamental it is. And if fundamental networking aspects are not transparently usable by upper layer protocols, then the whole building collapses. So while the underpinnings of TSN were completed a few years ago, the work being done now is to make it easy to manage. At the end of the day, TSN is just Ethernet. And just as Ethernet is easy to use today, TSN should be just as easy.
As for Ethernet-APL— an intrinsically safe version of Ethernet for explosive and hazardous environments—it is as fundamental as TSN, if not more so. Whereas TSN is an ISO/OSI Layer 2 technology, APL is a Layer 1 technology. But the same principles should apply regarding usability. PROFIBUS PA already exists as an intrinsically safe way to network instruments directly in hazardous areas, so the concept is not new. Ethernet-APL now allows PROFINET to do the same. And just like the step from PROFIBUS DP to PROFINET, usability is greatly enhanced moving from a serial physical layer to Ethernet. It is left to the protocol to implement the naming, addressing, device replacement, and other usability features. In other words: Ethernet-APL takes PROFINET down to the instrument, with PROFINET making it all easy to manage.
Our goal at PI is to make technological advances like TSN and APL easy to use. Otherwise, adoption will lag. These technologies are foundational, but not the complete story. TSN gets us there for robust converged networks, but because it’s just Ethernet, it should have the same high level of usability as non-deterministic Ethernet does today. That’s where efforts are focused now. APL brings PROFINET into hazardous areas, but APL is just the physical layer. The PROFINET protocol is what makes the difference in terms of usability.
Michael Bowne