MDA AUG-SEP 2018 FINAL AUG-SEP 2018 DIGITAL | Page 33

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plan service intervals, avoid or minimise
production downtime and maximise
production turnover. A prerequisite
for this is that safety switches can also
pass on diagnostic information. This
is already happening, one example is
RFID-based safety sensors which allow
high levels of tolerance to door offset.
If the offset limits are reached, the
sensors issue an electronic warning
signal before the machine shuts down,
thus providing information which can
be used for preventive maintenance.
Networking is another important
element of Industry 4.0: machines and
intelligent workpieces will be able to
cooperate. Machines and transport
systems should be able to make
autonomous “decisions” as to whether
a subsequent production stage should
be delayed or if another welding
robot should take over in the event
that one fails, for example. Converting
production systems or machines to
manufacture different product variants
should also be possible on an automated
basis without interrupting production
processes. New safety engineering
solutions need to be developed for
these changing production methods.
Dynamic safety solutions
While production previously involved
integral system, the safety technology
of the future needs to respond to
dynamic production units by providing
solutions which are just as dynamic.
Machine safety functions will therefore
increasingly be implemented using
programmable safety controllers.
The modular safety controllers in the
PSC product range from Schmersal
provide the option of configuring flexible
custom safety systems on a software
basis. There is also safe communication
between different PSC controllers
via Ethernet SDDC (Safety Device to
Device Communication). This simplifies
the design of complex, multi-part
plants with interconnected safety sub-
systems. In these systems, individual
production cells can communicate with
The Schmersal Safety Installation Systems (from left to right): the PDM passive distributor
module, the PFB passive fieldbox and the SRB-E active input extensions.
one another for safety purposes.
Another advantage of the PSC range is
the option of forwarding additional non-
secure diagnostic signals via a standard
bus system to another automation
controller or the IT environment. This
means, for example, signals can be
evaluated which are relevant to the
avoidance of downtimes and increasing
plant availability.
Economical solutions for
small and medium-sized
machines
Of course, the economic viability of
safety solutions also needs to be taken
into consideration, and not all machines
are complex systems. For small and
medium-sized systems where the user
does not wish to use a bus system at the
sensor/actuator level, the Schmersal
Safety Installation Systems with an
SD interface are a simple installation
solution for series connection. This
means
that
non-safety-related
diagnostics signals can be transmitted
to a standard PLC via the conventional
fieldbus system such as Profibus. The
new multi-functional relay modules
in the Protect SRB-E range from
Schmersal offer cost-effective solutions
which can be used in a wide range of
applications. Each module has multiple
functions, so the customer can simply
select the application or function they
require. At the same time, Schmersal
has a comprehensive range of safety
components with built-in AS-i interface.
All the major ranges from Schmersal
are available with AS-i safety hubs. The
benefit of the AS-i safety solutions is
that they enable extensive diagnostics
options despite minimum cabling.
Standardisation:
Safe data via OPC-UA
In the future, machines will be able to
send safety-related data to a cloud on a
predictive basis. The problem lies in the
fact that different protocols have been
used in the past for communication
between two devices in industrial
automation, and these protocols are not
compatible with one another. In order
for controllers to be able to exchange
data with one another and with the
cloud, companies are working on
integrating OPC UA as the standardised
protocol for data exchange in the next
generation of their products.
august-september 2018 | Global MDA Journal | 33