IO-Link technology for industrial applications


IO-Link technology was introduced more than ten years ago and the number of IO-Link devices has increased and more devices are deployed. Technology continues to evolve with new specifications and standards, including IO-Link Safety and IO-Link Wireless. The IO-Link community and workgroups have continually added enhancements to IO-Link as it has evolved.

This ARC overview covers various aspects of IO-Link, including an overview of IO-Link technology, IO-Link devices, IO-Link security, and IO-Link wireless. It also examines user challenges and requirements, key technology features and benefits, and provides recommendations for technology vendors and users.

Current situation

In today’s data-driven environment, end users want smarter machines and more functionality than traditional sensors provide. The shortage of qualified personnel is one of the main reasons. With the exodus of experienced workers, much of the operational, procedural and maintenance knowledge needed to operate the machines disappears. Smart sensors offer a route to digitally capturing information, which can enable applications such as predictive maintenance (rather than reactive or preventive maintenance). But implementing smart sensors is not enough. The information provided by these sensors must reach the right people, at the right time and in the right context to be effective.

IO-Link technology for industrial applications

IO-Link has been around for over a decade and around 27 million IO-Link nodes have been deployed worldwide. IO-Link is a short-distance, two-way, digital, point-to-point, wired and/or wireless industrial communication network standard described in IEC 61131-9. This standard specifies single-drop digital communication interface (SDCI) technology for sensors, actuators, and mechatronics. It extends the traditional switching input and output interfaces as defined in IEC 61131-2 to a point-to-point communication link using coded switching. Point-to-point communication is based on well-established 3-wire sensor and actuator connections. The technology enables the cyclic exchange of digital input and output process data as well as the acyclic exchange of parameters and diagnostic data between a master and associated devices. A master can be coupled via a gateway to a higher level system such as a fieldbus connected to a programmable logic controller.

The IO-Link technology standard is managed by PROFIBUS & PROFINET International (PI), which claims approximately 400 member companies of the IO-Link community. Most members are suppliers of factory and process automation products such as sensors, instrumentation, PLC, DCS, IPC and HMI.

According to the IO-Link community, despite delivery bottlenecks and other uncertainties due to the current pandemic, manufacturers of IO-Link products using IP technology reported positive revenue figures for 2021. last year, 6.3 million IO-Link devices were installed, bringing the total number of installed devices to more than twenty-seven million.

Main features of IO-Link:

  • Fieldbus-independent and can be integrated into all fieldbus systems.
  • Builds on standards such as M12, M8 or M5 connectors and three-wire cables.
  • Enables extensive sensor and actuator diagnostics and parameterization through bi-directional communication.
  • Available with communication speeds of 4.8, 38.4 and 230.4 kBaud.
  • Enables the miniaturization of sensors and actuators.
  • Automated and offers remote device maintenance via two-way communication.

IO-Link security

As the number of installed IO-Link devices grew to twenty-seven million, the technology was enhanced with more capabilities. With the release of the specification in 2017, IO-Link Safety is a key update, filling a gap for implementing safety on IO-Link.

The introduction of IO-Link Safety has made the technology even more attractive for industrial applications. New safety IO devices have been introduced which communicate safety signals directly via IO-Link. These devices extend the benefits of IO-Link to functional safety systems by facilitating high-density safety I/O hubs, simplifying wiring, and transparently implementing more complex safety sensors. IO-Link Safety is an extension of IO-Link which uses an additional safety communication layer above master and device, thus Functional Safety (FS)-Master and an FS-Device were developed and approved by TÜV-SÜD.

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Keywords: Actuators, Factory Automation, Industrial Communication, Industrial Applications, IO-Link Security, Wireless IO-Link, Smart Sensors, ARC Advisory Group.

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