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IO-Link FAQ

What is IO-Link?

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 any special requirements for the cable material. IO-Link is therefore not a fieldbus, but the logical further development of established connection technology.
  • Bidirectional communication: Sensors and actuators send and receive data – real-time diagnostics and parameterization.
  • Remote configuration: Parameters can be adjusted remotely without interrupting machine operation.
  • Simple wiring: Standard 3-wire cables, 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 a compact design.
  • International standard: Globally valid according to IEC 61131-9.
IO-Link is not a fieldbus, but 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 level 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 – meaning IO-Link Safety Devices can be used in almost 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 impossible.

IO-Link distinguishes between four data types: process data (cyclical real-time measurement values such as temperature, pressure, and position), parameter data (device configuration such as sensitivity, switching points, and characteristic curves), diagnostic data (device status, wear, and 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

The IO-Link Community is a global association of over 500 companies driving the development and adoption of IO-Link. It promotes interoperability, certification, and integration into industrial networks. Members include manufacturers, developers, and users from the field of automation technology.
  • Use of the official ‘IO-Link’ brand and logo (subject to compliance 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

Joining takes place in three steps:

  • Step 1: Membership in PI (PROFIBUS & PROFINET International) is a prerequisite for joining 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 (rules available as a download).
  • Step 3: Request a starter kit from: 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 a full membership.

Contact for further information:

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

IO-Link Competence Centers are technical competence centers officially accredited by the IO-Link Community. They provide support for testing, training, and the 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 the Czech Republic. TEConcept is an official IO-Link Competence Center.
The Working Groups are specialized teams of experts 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’).

Certification & IODD

Anyone wishing to market an IO-Link product under the IO-Link brand name must successfully pass 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 on – and test internally before formal certification, as the protocol test is the most common reason for failure.
The IODD (IO Device Description) is a standardized XML file that fully 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’s declaration). The IODD is required for commissioning in the IO-Link Master and must be published in the IODDfinder (the central multi-vendor database).
The IODDfinder is the central, cross-vendor database of the IO-Link Community for all available IODD files. Manufacturers provide the IODDs for their devices there so that users and system integrators can easily access them.
The IODD Viewer displays the contents 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 from the IO-Link Community website.
The IODD Checker is a validation tool for IO-Link Device Description files (IODDs). It verifies whether an IODD complies with the applicable specification, including checks for syntax errors, missing mandatory fields, and deviations from the standard. This helps identify potential integration issues with IO-Link Master systems at an early stage. The IODD Checker is available for free download from 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: Ensuring electromagnetic compatibility in the industrial environment
  • 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 sensors). They are continuously expanded by the IO-Link Community and are intended to simplify the cross-vendor interchangeability of devices.

TEConcept – Services & Support

TEConcept supports companies throughout all five phases of the product lifecycle:

  • Idea & Concept Phase: Technology assessment, feasibility workshops, rapid prototyping, and 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 use: Diagnostic tools, lifecycle support, variant development

TEConcept provides fully ported, complete software implementations of the IO-Link specification:

All stacks are delivered with full 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 performs 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 takes over the complete execution of IO-Link conformance tests – including protocol tests, physical layer tests, and EMC tests. In case of failure, analysis and optimization are carried out together.
The IO-Link Pathfinder is a structured workshop that examines the suitability of IO-Link for your specific product requirements and provides a concrete project roadmap. Ideal for companies that are new to IO-Link development or want to add IO-Link to an existing product.
Yes. An IO-Link USB Master connects your PC directly to IO-Link devices. On one side, the Master communicates with the computer via USB; on the other, it communicates with your sensor or actuator via IO-Link. Our tools fully support this interface, allowing you to configure, parameterize, and test IO-Link devices conveniently from a PC—even without a programmable logic controller.
  • Phone: +49 761 21443640
  • Email: info@teconcept.de
  • Website: Contact Form