Isn’t Profinet a
Siemens product?
No, Profinet isn’t ‘just Siemens,’ as many
questioners ask. Yes, Siemens is a strong supporter
and adopter of the Profinet technology. As are
many other automation device vendors. Profinet
is an open standard defined in the IEC and the
technology is not owned by any single company.
Development on the Profinet standard—along
with all other technologies under the Profibus
and Profinet International (PI) umbrella—is performed
by working groups staffed by volunteers
from many different companies.
Is Profinet a
closed network?
Profinet is not a closed network. Profibus, as a
serial fieldbus for example, was a closed network.
By closing the network, Profibus was able to ensure
determinism. Despite being an Ethernet-based
protocol, the choice was made early-on to keep
a Profinet network open. With the widespread
adoption of Ethernet and now Industry 4.0, today
we are able to appreciate what a wise decision that
has become. Profinet utilizes standard unmodified
Ethernet, meaning any Ethernet-based protocol
can utilize the infrastructure. Inherent Profinet
mechanisms ensure the determinism required for
industrial automation.
Does Profinet require
special hardware?
Since Profinet is based on standard unmodified
Ethernet, no special cables or switches
are required. However, using the same cables
and switches built for office environments on
a factory floor is a recipe for trouble. Profinet
cabling is merely Ethernet cabling that is
shielded and ruggedized against tough conditions.
We recommend end users install managed,
purpose-built switches in their networks.
These offer ruggedized hardware and advanced
features helpful to running and maintaining an
industrial Ethernet network.
Isn’t Profinet
very complicated?
If you have ever set up a Profibus network,
then setting up a Profinet network is basically
the same. If anything, it is likely easier than
Profibus since you do not have to worry about
network segmentation, signal repeaters, or termination
resistors. Profinet is just Ethernet.
With Profinet there are no dipswitches to set,
you simply assign a name to the device you are
installing. The controller assigns the IP address.
Configuration and parameterization of devices
proceeds as it always has.
Is it true that Profinet
traffic is not routable?
It is true that most Profinet traffic is not
routable. This is by design. Profinet utilizes
UDP/IP and TCP/IP where it makes sense.
And skips them where it doesn’t. Automation
traffic is often little pieces of data. It is bits and
bytes exchanged quickly and deterministically
between controllers and devices. The use cases
for routing these little pieces of data across the
Internet are uncommon, if non-existant. There
are other protocols better suited at moving
information as such, for example OPC UA.
Conversely, protocols with large packet sizes,
and reliance on UDP/IP or TCP/IP, are not
optimized for moving automation traffic deterministically
on the factory floor. For installations
that do require some basic routing in their
Profinet networks, devices exist to seamlessly
couple different subnets together.
Is Profinet secure?
That fact that most Profinet traffic is not
routable is an inherent security measure. For
a nefarious actor to manipulate Profinet traffic,
they would need to do so from inside your
network. If a hacker is already in your network,
then you likely have bigger problems to worry
about. Profinet Security Classes are in place to
deal with aspects of authenticity, integrity, and
confidentiality. End users can choose the level
of security appropriate for their installation. In
general, network security should be approached
holistically with a defense-in-depth strategy.
Is Profinet ‘old’
technology?
Profinet is based on Ethernet, which was
invented in the 1970s and has come a long way
since then. It certainly seems like wireless is
taking over as the primary way to move data
in the consumer world, particularly with the
upcoming versions of 5G cellular. While most
Profinet installations utilize Ethernet, many
also seamlessly employ Wi-Fi, Bluetooth, and,
eventually, 5G. Ethernet works very well for its
purpose and has improved along the way. This
appears to be true for the future as well. Today,
industrial Ethernet bandwidth can scale from
10 Mbps to 100 Mbps to 1 Gbps and beyond.
Soon, Time-Sensitive Networking (TSN) stands
to make Ethernet robust for even the most
heavily loaded networks.
