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IO-Link FAQ – Frequently Asked Questions on Community, Development, Certification, and Products

Welcome to TEConcept’s IO-Link FAQ. IO-Link is the globally established communication standard for sensors and actuators in automation – yet practical implementation often raises similar questions: How does certification work? What does the IO-Link Community regulate? And what role do IODD or IO-Link Safety play in development? On this page, we’ve gathered and answered the most frequently asked questions about fundamentals, development, certification, and products – concisely and drawn from our over 20 years of experience as an IO-Link Competence & Test Center. If your question isn’t covered in the IO-Link FAQ, feel free to reach out to us directly.

What is IO-Link?

In this section of our IO-Link FAQ, we answer the most important questions about IO-Link technology: What exactly is IO-Link, how does communication work, what advantages does the standard offer, and how does it differ from classic fieldbuses?

IO-Link is the world’s first standardized IO technology standard (IEC 61131-9) for bidirectional digital communication with sensors and actuators in industrial automation. The point-to-point communication is based on the proven 3-wire sensor and actuator connection – without special requirements for cable material. IO-Link is therefore not a fieldbus, but rather the logical evolution of established connection technology.
  • Bidirectional communication: Sensors and actuators send and receive data – diagnostics and parameterization in real time.
  • Remote configuration: Parameters can be adjusted remotely without interrupting machine operation.
  • Simple wiring: Standard 3-wire cable, no shielding required – compatible with M5, M8, and M12 connectors.
  • Fieldbus-independent: IO-Link can be integrated into all common fieldbus systems (PROFINET, EtherNet/IP, EtherCAT, etc.).
  • Miniaturization: Enables intelligent sensors in compact form factors.
  • International standard: Globally valid according to IEC 61131-9.
IO-Link is not a fieldbus, but rather a point-to-point connection at the lowest automation level – between an IO-Link Master and an individual sensor/actuator. The IO-Link Master itself is then integrated into the higher-level control layer via a fieldbus (e.g., PROFINET).
IO-Link supports three transmission speeds: COM1 at 4.8 kBaud, COM2 at 38.4 kBaud, and COM3 at 230.4 kBaud. Most modern devices use COM3 for maximum performance.
IO-Link Safety extends the standard to include functional safety and enables safety-related applications over the same infrastructure. IO-Link Safety Masters communicate with higher-level safety systems such as PROFIsafe, CIPsafety, or FSOE – IO-Link Safety Devices can therefore be deployed in virtually all common systems worldwide.
IO-Link Wireless eliminates the physical cable connection and enables reliable real-time communication between sensors, actuators, and controllers. It is particularly suitable for robotics, mobile applications, and environments where cables are impractical or not possible.

IO-Link distinguishes four data types: Process data (cyclic real-time measured values such as temperature, pressure, position), Parameter data (device configuration such as sensitivity, switching points, characteristic curves), Diagnostic data (device status, wear, errors), and Event data (acyclic warnings and alarms). This comprehensive data availability is a key element for Industry 4.0 and predictive maintenance.

IO-Link Community, Membership & Events

The IO-Link Community is the global alliance of over 500 companies. In this section of our IO-Link FAQ, you’ll learn more about membership, the competence centers, and community events such as the Forum, User Workshop, and Interop.

The IO-Link Community is a global association of over 500 companies that drives the development and dissemination of IO-Link. It promotes interoperability, certification, and integration into industrial networks. Members are manufacturers, developers, and users from the automation technology sector.
  • Use of the official ‘IO-Link’ brand and logo (when complying with the specifications)
  • Full access to all IO-Link specifications
  • Participation in technical working groups and influence on specification development
  • Access to patents of other member companies
  • Joint marketing activities and increased market visibility
  • Network with leading automation companies worldwide

Membership is completed in three steps:

  • Step 1: Membership in PI (PROFIBUS & PROFINET International) – this is a prerequisite for the IO-Link Community. PI charges an annual membership fee. More information: profibus.com/pi-organization/regional-pi-associations
  • Step 2: Written confirmation of the IO-Link Community Rules (rulebook available for download).
  • Step 3: Request starter package at: info@io-link.com

Yes. The IO-Link Community offers a licensing option: Individual products can be licensed and marketed under the IO-Link label without full membership.

Contact for further information:

IO-Link Support Center, Ohiostraße 8, 76149 Karlsruhe – info@io-link.com

IO-Link Competence Centers are officially accredited technical competence centers of the IO-Link Community. They provide support for testing, training, and implementation of IO-Link – for manufacturers, integrators, and users. There are currently 10 IOL-CCs worldwide in countries such as Germany, USA, China, Brazil, Italy, and Czech Republic. TEConcept is an official IO-Link Competence Center.
The Working Groups are specialized expert teams within the IO-Link Community. They develop and maintain specifications, conduct interoperability tests, and promote global acceptance. Companies can contribute as experts (so-called ‘Call for Experts’).

The IO-Link Community offers a variety of events for different levels:

IO-Link Forums Large community events with presentations, trending topics, and an accompanying micro-fair. Ideal for a solid market overview and networking — also suitable for beginners.

IO-Link User Workshops Hands-on training in small groups. Ideal for users and developers who want to specifically deploy IO-Link within their company. Basic knowledge is helpful but not required.

IO-Link Interop Interoperability tests where manufacturers test their IO-Link devices and masters against products from other providers. Specifically for manufacturers with market-ready products.

IO-Link knowledge is also shared at events held by the PROFIBUS User Organization (PI) and its regional associations. You can find current dates and reports on our participation in IO-Link events or the SPS trade fair in Nuremberg in our news section.

Certification & IODD

Certification and IODD creation are central topics for anyone looking to bring IO-Link products to market. This section of our IO-Link FAQ answers the most frequently asked questions about test procedures, IODD requirements, and IO-Link conformance testing.

Anyone who wants to market an IO-Link product under the IO-Link brand name must successfully complete the IO-Link conformance test. The test includes Physical Layer tests, protocol tests (data and application layer), and EMC tests. TEConcept tip: Take care of IO-Link membership or licensing early – and test internally before formal certification, as the protocol test is the most common source of errors.
The IODD (IO Device Description) is a standardized XML file that completely describes an IO-Link device: manufacturer, article number, parameters, process data, diagnostic functions, and much more. It is provided as a ZIP package (including language files and manufacturer declaration). The IODD is required for commissioning in the IO-Link Master and must be published in the IODDfinder (the central multi-manufacturer database).
The IODDfinder is the central, cross-manufacturer database of the IO-Link Community for all available IODD files. Manufacturers provide the IODDs of their devices there so that users and system integrators can easily retrieve them.
The IODD Viewer displays the content of IODD files in a structured format – including device information, parameters, and process data – without requiring a complete engineering tool. It is available for free download on the IO-Link Community website.
The IODD Checker is a validation tool for IO-Link Device Description files (IODD). It checks whether IODD files comply with the valid specification – including syntax errors, missing mandatory fields, and standard violations. This allows problems during integration into IO-Link master systems to be identified early. The IODD Checker is available for free download on the IO-Link Community website.
  • Physical Layer Test: Testing of signal levels, bit timing, and current consumption
  • Protocol test (Device/Master): Automated test cases according to IO-Link test specification (data link and application layer)
  • EMC conformance test (Device/Master): Ensuring electromagnetic compatibility in industrial environments
  • IO-Link Safety (optional): Additional tests for safety-related devices
Device Profiles are standardized descriptions of process data, parameters, and functions for specific device categories (e.g., pressure sensors, displacement transducers). They are continuously expanded by the IO-Link Community and are intended to simplify cross-manufacturer interchangeability of devices.

TEConcept – Services & Support

As an accredited IO-Link Test & Competence Center, TEConcept supports companies throughout the entire product lifecycle. In this section of our IO-Link FAQ, you’ll learn how our software stacks, test systems, and workshops support you in your IO-Link development.

TEConcept accompanies companies through all five phases of the product lifecycle:

  • Idea & Concept Phase: Technology evaluation, feasibility workshops, rapid prototyping, system specification
  • Development Phase: Stack integration (Device & Master), electronics & software development, IODD design
  • Validation Phase: Certified protocol, EMC, and Physical Layer tests
  • Market Launch: Documentation, sales training, troubleshooting
  • Field Deployment: Diagnostic tools, lifecycle support, variant development
TEConcept offers fully ported, complete software implementations of the IO-Link specification:

All stacks are delivered with complete source code, documentation, and fully ported to the target hardware. Supported MCUs: STM32, Renesas, NXP, Texas Instruments, Analog Devices, and many more.

Yes. TEConcept is an officially accredited IO-Link Competence Center (IOL-CC) & Test Center and conducts conformance tests for Devices, Masters, and IO-Link Safety Masters. The test systems used (Device Tester, Master Tester) are approved by the IO-Link Community.
Yes. As an official test center, TEConcept handles the complete execution of IO-Link conformance tests – including protocol tests, Physical Layer tests, and EMC tests. In case of failures, analysis and optimization are performed jointly.

Yes. TEConcept offers the IO-Link Safety Master Stack, a ready-to-use software component for implementing safety-related IO-Link Masters, as well as the IO-Link Safety Master Tester, a test system approved by the IO-Link Community for certification preparation. An overview of the entire Safety portfolio is available on the IO-Link Safety page.

The IO-Link Pathfinder is a structured workshop that evaluates the suitability of IO-Link for your specific product requirements and delivers a concrete project roadmap. Ideal for companies entering IO-Link development for the first time or extending an existing product with IO-Link.
Yes – with an IO-Link USB Master, you connect your PC directly to IO-Link devices. The Master communicates via USB with the computer on one side, and via IO-Link with your sensor or actuator on the other. Our tools fully support this interface, allowing you to configure, parameterize, and test IO-Link devices conveniently from your PC – even without a programmable logic controller.
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  • Email: info@teconcept.de
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Our IO-Link FAQ is continuously expanded. As an accredited IO-Link Competence Center, we’re happy to share our knowledge with the community and regularly add new topics from practice to our IO-Link FAQ.

Missing a question in our IO-Link FAQ? Contact us — we’re happy to add frequently asked questions to our guide section.

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