" In the age of data, connectivity is of prime importance. Even the industrial world has set foot into the Industrial Internet of Things. Data can be easily acquired if it is done using standard and open interfaces. This forms the crux of a successful IIOT Implementation.
Industrial Internet of Things: Today and Tomorrow
The
office IT network is built on Ethernet and
has access to the internet, cloud etc. To access the field
information from the board the field level communication also needs
to be based on Ethernet. This enables smooth transition of data
without the use of gateways. But using standard Ethernet in the field
is not advisable as it is prone to the Carrier
Sense Multiple Access with collision detection mechanisms
(CSMA/CD). In the automation world the machines and processes demand
a real time deterministic communication. “Combining the needs of
the industry and demands of the machines and processes we come to a
conclusion that the automation network should be open source with
standard interfaces and having a deterministic system performance”
quotes Bhagath Karunakaran, “Ethernet
POWERLINK satisfies
all these requirements. It is completely open source and truly
hardware and software independent. It couples benefits of standard
Ethernet interfaces complying with the IEEE 802.3 as in internet of
things and the determinism and availability needs of the
industrial IOT.”
Ethernet
POWERLINK provides determinism down to 100µs. Looking at the
software platforms, its implementation can be over
Windows, Linux, VXWorks,
QNX, and any other operating system or without an operating system.
It is also hardware independent with implementation possibilities
right from micro-controller, micro-processor, ARM, FPGA, PCI cards,
and PCs. The complete source code is available open source, free of
cost and is certified and managed by the Ethernet POWERLINK
Standardization Group which is a consortium of over 3200 members and
users. It equips the user to have a complete choice of topology for
his machine and process viz. line, star, tree and ring or a
combination of all.Simple steps to start implementation
There
could be different needs of different players who are involved in
building the machine, process or IIoT project. If one is an OEM or a
system integrator looking to buy off the shelf components then you
could talk with companies such as B&R, Cognex, Baumer, ABB etc.
for their POWERLINK components. If one is an OEM looking to add
custom built embedded components to an off-the-shelf design or a
sensor manufacturer such as encoders, temperature sensors, and
controllers then one can use openPOWERLINK resources available on
sourceforge and build his own hardware or one can choose a module
available off-the-shelf and integrate it in his device on that
platform.
The
openPOWERLINK stack along with the documentation can be found
athttp://openPOWERLINK.sourceforge.net. It
includes the master and slave stack source code, reference designs on
multiple silicon and operating system platforms, FPGA IP cores for
high performance MAC and for daisy chaining HUBs, and configuration
tools.
If
you are a start-up or a university student then there is a readily
available openPOWERLINK implementation on Raspberry Pi2. It involves
a managing node and 2 controlled nodes working on Linux and
communicating data on POWERLINK. The complete procedure for
installing Linux, building the openPOWERLINK libraries and
downloading them in the kits is provided on the website
http://www.ethernet-powerlink.org/en/raspberrypi2/. This is the
easiest method to bring up a POWERLINK network and to work with all
the features offered by the technology.
Ease of working with POWERLINK
Barry
Wehmiller International
implemented this technology on the critical UV curing
controllers needed for the printing industry. Barry Wehmiller
International is a global consulting company providing engineering
and automation solutions for manufacturing organizations around the
world. They have developed controllers for critical UV curing
applications for one of their customers in the printing industry.
These controllers are equipped with multiple control interface like
analogue HMI, web HMI, TCP messaging and Ethernet POWERLINK. “We
used openPOWERLINK stack version v2.0.0 and achieved a completely
real time deterministic response without any performance issues. The
protocol was very easy to implement and took us just 2 days of
training from Kalycito to establish POWERLINK communication.” says
Srinivasan Subramani ”We conducted 72 hours long test and found a
completely error free, deterministic response from POWERLINK. The
oscilloscope test results and wireshark traces confirmed the
robustness of POWERLINK. Our engineers were impressed with the
robustness and reliability of POWERLINK protocol”. The
specifications and technical documentation are well drafted and on
top of it are available freely online on the EPSG website. The source
forge forums provide a perfect arena for availing quality and timely
support while implementation.
Barry
Wehmiller International used the v2.0.0 stack of openPOWERLINK
available on the website ‘openpowerlink.sorceforge.net’. The
first step tried out during implementation was to install the
openPOWERLINK demo which is also available on the same website on two
laptops and establish POWERLINK communication between them. They were
unknown to this technology before downloading the stack and working
with the demo. When the demo was installed on laptops, they were able
to see the exchange of data on POWERLINK. A wireshark trace run on
one of the laptop confirmed the data exchange over POWERLINK.
Srinivasan says “We were surprised see the demo on two Windows
based laptops communicating as a managing node and controlled node in
no time and without any prior experience with the technology. This
gave our engineers a confidence boost to work with POWERLINK.”
The
system consists of a UV controller communicating to the B&R PLC
acting as a main printer controller over POWERLINK. This UV
controller is also equipped with a web server implementation over the
same Ethernet POWERLINK network. Thus the OEM can access the UV
controller from anywhere around the world. The UV curing system was
able to achieve a a low response time inclusive of the web server
implementation and a very high asynchronous bandwidth.
Needs of an IIoT implementation: High availability, high speed and high security
Bhagath
was instrumental in specifying redundancy in POWERLINK back in 2005
and POWERLINK since then is equipped with a multi-master, media and
ring redundancy. This feature minimizes the downtime, has an
extremely fast changeover and is easy to use. “POWERLINK is thus
the only industrial Ethernet protocol to provide master source code
and specifications free of cost. We have now raised the bar by making
redundancy available open source “mentions Bhagath Karunakaran.
POWERLINK
thus address the need of availability on the machine and plant level.
Security also needs to be addressed as it is also an important issue
in the IIoT space. POWERLINK owes much of its unparalleled level of
security to the fact that it is open-source software. The stack’s
source code and any modifications to it are subject to frequent
review by the community. This not only prevents security issues –
they are discovered and eliminated long before they can do any harm –
but also provides effective protection against hidden backdoor
attacks. POWERLINK combines timeslot and polling procedures to
achieve isochronous data transfer. How the master node addresses the
controlled nodes can be configured by software developers using
suitable engineering tools, though this is not transparent to other
entities in the network. “The fact that there is no way whatsoever
for users to access these network configuration details during system
runtime eliminates the need for specific protection against
fraudulent manipulations in the system itself” says Ninad Deshpande
“High speed regardless of network size, total and complete
openness, high tolerance to electrical interference, line and master
node redundancy and inherent security that stops attackers in their
tracks – POWERLINK fulfills all of these criteria.”
Automation meets the IT
POWERLINK
enables the user to gather data from the field in a deterministic
method. On a shop floor there could be requirements for the
controllers from different machines to exchange data or a central PC
working as SCADA would require the data for sending it to the ERP and
MES. The machine builders could use OPC UA which is another open
source protocol based on standard Ethernet for transferring the data.
Being based on standard Ethernet, POWERLINK effectively mergers well
with OPC UA and facilitates seamless data transfer from the shop
floor to the MES/SAP. With the features such as openness, usage of
standard interfaces, compliance with IEEE 802.3, determinism, high
availability, and security provided by Ethernet POWERLINK at the
field level coupled with its cooperation with OPC UA to transfer data
from the field level to the process, ERP, MES layers, has brought
IIoT implementation into reality.
