Ethernet encoders: More than just position determination

The best enhancements are always based
on precise measurement. This is the only
way that lasting and reliable changes can be
made to processes and to ensure that quality products and processes are
available in the long term. Precise measurements accompanied by an equally
precise analysis are an essential feature of Industry 4.0. The latest
generation of Ethernet encoders from SICK opens
up new opportunities for obtaining different measurements and tracking
movements. For example, these new
opportunities can be used for effective
status monitoring.

Smart automation solutions do
much more than simply connect individual components. In the case of mechatronic
systems, the whole is more than the sum
of its parts. However, the crucial factor for Industry 4.0 is the performance
of cyber-physical systems. What is the result for
encoders? The Ethernet communication options of SICK devices and the TCP/IP
connections form a node in the network to open up new opportunities. These go
far beyond the original automation functions of the encoders.

More precise counting for more accurate results

For an encoder, it is useful to
know how often a motor has turned, instead of only being given information
about the period when a voltage is applied.
Obtaining actual figures about the number of times a machine component has
changed its position during the production process is also valuable. In both
cases, the encoder first has to perform its original function of precisely
identifying the position of components and passing this information to the
controller or a servo converter within a closed control loop. The cycle
frequency of the components provides important information about their service
life in the long term. This data is much more useful than simply checking the
date of manufacture and installation of machines
when evaluating the condition of the production facilities.

The power-up times only offer
limited information about the service life, the ageing
of operating materials and the wear levels, particularly as machines are rarely if ever, disconnected from the power
supply and go into standby mode. This new
approach becomes useful when a machine’s components have different service lives, allowing individual parts to be replaced during regular or preventive
maintenance.

The motion timer function of
SICK’s Ethernet encoders makes it possible to record the encoder’s operating
hours accurately. While the operating time meter only provides information
about the number of the hours when the encoder is live, the motion timer
records the periods when the encoder is moving. It also counts the number of
times the encoder is powered up. This
means that maintenance can be carried
just when it is needed, which helps to prevent downtimes. No additional systems
are required to achieve this.

The Ethernet-based encoders can also
improve the working time of production facilities with temperature monitoring. The
use of temperature sensors to measure the process temperatures or to protect
components such as motors from shutting down because of the heat, allows conclusions
to be drawn out about the temperature
profiles of the entire process and when
combined with other parameters, can be used for application-specific condition
monitoring.

More options without accessing the controller

The appeal of this solution lies
in the fact that one single encoder can supply the traditional process data.
For instance data such as position and speed can be communicated via industrial
Ethernet protocols and, at the same time, can make use of additional functions
and configurations via TCP/IP. For this reason, SICK fits its Ethernet encoders
with a dual port switch, separating the machine function from the overlying
status monitoring. This process opens up the possibility of performing these
higher level tasks independently, regardless of any restrictions imposed by a
machine controller.

In practice, intelligent SICK
encoders can be configured to meet the requirements of individual applications and
specific conditions. By setting the limits and thresholds individually and
directly in the encoder via the software system in the PLC or via a web server
and a browser-compatible end device, the correct measuring range can be specified for every application with a high
level of standardisation. When the
specified position, speed and temperature thresholds are reached, the encoder automatically sends a signal via the
Ethernet connection to indicate that an investigation must be carried out. This
function operates independently of the machine controller.

Communication via the
well-established industrial Ethernet protocols – Ethernet I/P, EtherCAT and
PROFINET – allows the process data to be converted to the most suitable mathematical
and physical units and evaluated accordingly. As the data is imported into control or MES systems in the
right format, no further calculations are needed to produce the required
figures.

Customised encoders – another aspect of Industry 4.0

The adaptability of SICK’s
encoders also extends to their connectivity, particularly with plug options, mechanical supports and cable lengths. At SICK, customising
is based on a sophisticated variant
management system with flexible production options. This closes the loop to Industry 4.0, which is an industrial
revolution built on individualised
large-scale production.

Written by Heiko Krebs, Head of Product Management Encoders, SICK
Stegmann GmbH, Donaueschingen.

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