© ifm prover IO-Link Handout
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1. Preface
IO-Link is a standardised worldwide I/O technology (IEC 61131-9) for the communication with
sensors and also actuators. The IO-Link association of companies has the aim of developing
and marketing IO-Link as a technology.
To benefit more from the performance of modern sensors and actuators, i.e. being able to
operate machines and systems more productively, consistent communication down to the
lowest field level is required. Leading automation manufacturers have created a standard with
IO-Link that now solves the problem of the "last mile".
In all industrial areas machines and systems are continuously optimised to improve their
productivity throughout the whole life cycle. Besides a reduction of the total cost of ownership
(TCO) the increase in output and uptime contributes to an increase in competitiveness. Due to
the more flexible adaptation to different requirements and ambient temperatures and faster
retrofitting in spite of comprehensive configuration data the machines are becoming more and
more complex. The more functionality they provide, the more information has to be exchanged
across all company levels. Against this background the demand for communication with
sensors and actuators is also increasing since they constitute a direct process interface.
It is not possible to exchange any other data than the actual process value via the standard
interfaces used so far on the sensor/actuator level. Sensor and actuators provide more and
more complex functions with integrated intelligence. Simple switching status or measured
value interfaces restrict communication and lead to information congestion. To have an overall
picture of the machine for optimisation purposes, networking at all levels must be transparent.
It must be possible to map each component with the required depth of information in the
complete system pool. In detail this means for sensors and actuators that not only process
data has to be exchanged but also parameter and diagnostic data.
In existing sensor/actuator installations a specialised and therefore expensive module had to
be used for each signal type. The heterogeneous wiring with screened cables is costly and
even thenl analogue signals were usually transferred with poor quality. Networking of
mechatronic units that are used more and more frequently in mechanical engineering proved
to be quite complex due to the manifold interfaces. During each machine retrofit, all relevant
parameters had to be set manually or via a separate tool directly on each sensor or actuator
which led to inconsistent data storage and long downtimes. Besides the complex saving and
documentation mechanisms the fear of manipulation remained because the parameters were
often directly stored in the sensor or actuator without any additional backup.
Since there was no continuous communication with the superposed levels, the diagnostic data
of the sensors and actuators was not available in the engineering tool. Due to their exposed
position in the process more errors occur with these components than for example with I/O
devices, drives or controllers. If, however, diagnostic information is missing, troubleshooting
and error elimination is often difficult and time consuming. Moreover no preventive
maintenance can be made with the aim to increase machine uptime.