November 2015
20
I
ndustrial
C
ontrol
& C
ommunications
Meeting the integration challenge
in programmable logic controllers
By Suhel Dhanani,
Maxim Integrated
Industry 4.0 is fundamentally
transforming what it takes to win in
the PLC market. Smaller form factors,
higher I/O density, and advanced
capabilities - success today
demands new strategies for
managing competing demands for
more functions in less space.
For equipment OEMs, Industry 4.0 rep-
resents a massive opportunity. The number
of sensors used to track environmental and
process variables continues to increase. This
is accelerating the transition to distribut-
ed-control architecture, where plant opera-
tors reduce bottlenecks and shorten control
loops by moving programmable logic control-
lers (PLCs) closer to the processes that they
control. Ultimately, the promise of improved
operational efficiencies and yields will lead to
the largest overhaul of plant operations since
the invention of the PLC. This poses a consid-
erable challenge for PLC engineers.
To win in this market, system designers will
need to pack more I/Os and more function-
ality into enclosures that keep shrinking. The
problem is that there is relatively little space
to be gained from digital scaling of the micro-
processor. Nowadays in advanced PLC mod-
ules, analog and passive components consume
approximately 85% of board space. Engineers
can no longer afford to ignore the obvious
problem on their boards. Many of the analog
and discrete components that have worked so
well in previous systems are simply too big for
micro PLCs and embedded controllers. The
promise of Industry 4.0 will only be realized
through greater levels of integration, across
the PLC system design. PLCs have been at the
nexus of industrial transformation ever since
the introduction of the Modicon 084 in 1969.
Thanks to the digital revolution, they have
become progressively more powerful over the
years, capable of handling more inputs, larger
words, and more complex instruction sets.
Today, innovations in analog and sensor tech-
nology are helping manufacturers take full
advantage of the massive compute resources
available, both within the factory and in the
cloud. Industry 4.0 represents a vision for
what’s possible when you combine this intelli-
gence with pervasive sensing, distributed con-
trol, and robust, seamless connectivity. And
once again, the PLC finds itself at the center
of a revolution. This is creating new business
opportunities for PLC OEMs, as manufac-
turers increase capital expenditures to take
advantage of these technologies. However, it
also raises a variety of challenges for system
designers.
Thanks to the steady march of Moore’s Law,
we now have massive amounts of processing
power at our disposal. This processing power
enables enterprises to crunch terabytes or
even petabytes of data to enhance decision
making, generate new insights, and optimize
processes. For manufacturers, the biggest
challenge is collecting and acting on this data.
Three technology trends have emerged to
address this problem. Pervasive sensing: the
cost of sensors and their interfaces continues
to decline, enabling manufacturers to track
more variables and types of data. Distributed
control: moving process controllers closer
to the machines that they control eliminates
bottlenecks and improves manufacturing
throughput and flexibility. Seamless connec-
tivity: manufacturers are connecting the fac-
tory floor to the enterprise network to unlock
the potential of big data and analytics. This
brings numerous benefits, but it also raises
many security issues at the system level.
The biggest problem in PLCs is the one that no
one sees. A recent market study revealed that
most engineers still believe that digital tech-
nology offers the best opportunity for space
savings. Yet, digital chips consume just 15% to
20% of the board space in PLC modules. The
real problem is the amount of PCB devoted to
analog and discrete components. These devices
consume as much as 85% of available board
space in PLC modules, but they do not scale
like digital chips. So PLCs now need greater
levels of integration to conserve PCB space
while delivering the required functionality.
Solving this PCB space problem requires a
new approach to analog design. Gone are the
days when system designers could just select
catalog parts with adequate specs and then
perform heroic feats in layout to make them fit
the PLC enclosure. Today the market requires
Figure 1. Maxim Micro PLC
Reference Design shows how
much space can be saved when
engineers take advantage of
the latest advances in analog
integration.
