Why Use IO-Link? Universal | Smart | Easy

  • Post category:PI NEWS
  • Reading time:7 mins read

A Tipping Point

When I first encountered the topic of IO-Link 18 years ago, uniform communication at the sensor-actuator level was at a tipping point. It was basically clear to everyone that you can only win with a uniform standard. Every manufacturer already had corresponding proprietary communication interfaces for internal production processes, but access for the customer was difficult. So what was the reason that almost caused it to fail? Backward compatibility with the classic switching signal had to be strictly adhered to and shifting between switching mode and communicating mode was not solved. After hard discussions the knot was broken, and the further definition was completed successfully. At this point, however, the most important characteristic of the IO-Link community has already become apparent: despite all differences and different approaches, the challenges were mastered, and the final product can be admired today.

Wide Compatibility

In addition to compatibility with the switching 3-wire world, IO-Link is characterized by the fact that it does not require a system decision at any time, since the well-thought out IO-Link master element enables mapping to all known bus systems as well as to IoT standards. This fact results in a win-win situation. The IO-Link device manufacturers only need to incorporate one communication standard in one device type and the user benefits from the wide range of products without restrictions due to bus systems or simple support of different bus systems.

Standardized Device Description

IO-Link has succeeded in creating a harmonized parameterization via the IODD (Input-Output-Device-Description) file. Uniform standard parameters are used under the same names across all manufacturers, so that the user can find his way around very quickly without having to read a lot of documentation.  As a side effect some fundamental parameters popped up that are a basic prerequisite for today’s digital world, in particular standardized identification and diagnostic parameters as a basis for future use in digital twins.
But that’s not all, in IO-Link systems the tool-free exchange of IO-Link devices is already realized. So there is no need to search and install parameterization software.  A simple mechanical exchange with automatic update to the current parameter set puts the system back to operation.

In the case of sensors, many manufacturers have profiled the process data of measuring systems, and profiles for actuators, signal lamps and power supplies are under construction, so that the integration of IO-Link components will be further simplified for users. In addition, the IODD already makes it easier for users to set up IO-Link devices using their respective familiar system tools. Furthermore, the IO-Link community adds the convenience of centrally stored IODDs on the IODDfinder and many system tools already support an integrated import of missing IODDs. This eliminates the annoying search for the appropriate IODD on the respective manufacturer pages for more than 25,000 devices from more than 150 manufacturers today.

Quality First

The success of IO-Link is closely linked to the quality integrated from the get-go. By creating the test specification in parallel and consistently implementing it in test tools, the manufacturers of IO-Link components are enabled to check for conformity in a traceable manner. Based on these tests, the manufacturer creates a self-declaration in the form of a Manufacturer Declaration (MD). Through the mandatory publication, for example on the IODDfinder, we achieve maximum transparency for the user.

The access for manufacturers as well as consultants or independent conformity test houses into the IO-Link technology is conveniently arranged by the IO-Link community through accredited IO-Link competence centers and test laboratories in the USA, Europe and Asia. These facilities undergo regular audits by the IO-Link community to meet the high-quality standards.

But IO-Link is more than just each individual component. The greatest benefit for the user is provided by the standardization across the whole system chain. From the end device to the customer application and independent of the component manufacturers. To support the already established integration specifications for various fieldbus systems and IoT standards, the IO-Link master interface has been further harmonized with the help of the standardized master interface (SMI) and provides a solid basis for further integrations.

Extending IO-Link

Besides the original IO-Link definition, useful extensions relevant for automation have been created according to proven principles. Considering the already created tools and IODD definitions, the system has been enriched by IO-Link Wireless and IO-Link Safety. Both extensions carry on the basic idea of IO-Link, i.e. point-to-point communication, mapping in all bus systems or FSCPs (Functional Safety Communication Protocols) and this uniformly across manufacturers.

An Eye Towards the Future

Because it is not enough to rest on our laurels, we have set up a Task Force Future within the IO-Link community. In this way, we want to specifically address future topics for IO-Link, evaluate them and develop concepts to guide the community integration into the IO-Link standard without overburdening users, but still carry the system into the digital future. In particular, the usage of the proven data model in other communication technologies is being considered. One example is the cooperation with the mioty alliance, which, by using the IODD methodology, does not have to develop integration in systems from scratch, but applies existing tools to a new area of communication.

The IO-Link user is always in the focus of the IO-Link community. This is reflected in the regular IO-Link forums, where IO-Link experts explain the IO-Link standard in all its facets and thus provide future users with a broad basis for making decisions about IO-Link.

Transparency for All

Another aspect of the success of IO-Link technology is the transparency of the IO-Link community. By publishing all specifications, anyone who is interested can read them and give us feedback about issues, misunderstandings and ideas for improvement. The relevant definition groups capture the suggestions, evaluate and incorporate them in order to improve the specifications and improve the system further. This openness repeatedly enforces the descent from the “ivory tower” and opens up the technology to previously unrecognized application opportunities.

This again creates an open working culture in the IO-Link community, ranging from IO-Link experts and tool specialists to IoT experts and PLC programmers. It also reveals the demanding challenges we are dealing with, processing the IO-Link data not only for use in the control of a plant, but increasingly in maintenance, condition monitoring tasks as well as robot collaboration up to quality analyses. At this point, the IO-Link community is also very committed and easy to work with. Everyone in the community is allowed to contribute to the corresponding working groups and thus a broad expert knowledge is guaranteed.


Today, IO-Link is an accepted communication standard that provides data from the field to the controller (PLC) via Profinet, but also meets the IoT requirements and supports systems such as omlox and MTP (Module Type Package). Diagnostic data, backwards compatibility, simple device exchange, unique device identification and standardized parameters have become so self-evident that it is no longer seen as a significant milestone in automation and IoT. Almost needless to mention anymore that the system also supports safe applications and handles wireless data transmission.

Therefore, I can state for myself, that we come a long way from an almost failed standard 18 years ago, to an accepted communication standard for simple devices as it has emerged today. IO-Link standardizes far more than just the communication and thus offers users many possibilities to implement their applications without having to dive deep into the system. And to top it off, the whole thing is worldwide!

Joachim Uffelmann,
Head, Steering Committee,
IO-Link Community