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.
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.
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 even
easier. 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
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 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.
