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  1. Discover IO-Link
  2. Setup and support
  3. Understanding the IODD

Discover the power of the IODD

The IODD (IO-Link Device Description) is a compact file describing how IO-Link devices communicate information higher level systems or controllers. It provides details about cyclic data structure and available acyclic commands.

The IODD is available as a file to upload into your PLC and as a PDF. It provides full documentation for the location of devices' information and the method of interactiion.

These files are available on the Downloads tab of the sensor datasheet page.

Screenshot of IODD download from the ifm website

Process data and IODD structure

The image below shows the some of the information available in the IODD PDF file. It shows how the data is mapped in the PLC. This example is for a radar level sensor, LW2720.

Screenshot of IODD process data pdf with numbered callouts

Additional device information

The IODD PDF serves as a compendium and one-stop-shop of available information of an IO-link device, both cyclic and acyclic, and provides a full account of the communication structure.

The IODD contains a host of useful information. Let's break down some of it.

  • Device variant is the model number, vendor, speed, and highest level capabilities of the device.
  • Process data is information about the cyclic data. It includes scaling, multiple configurations if applicable, and the array location for the data. 
  • Parameter overview provides information about the acyclic data. It includes data type, reporting format, and index location.
  • Basic settings consist of device aspects that can be changed remotely by a controller or higher level system.
  • System command is an expansion of basic settings accessed through acyclic communication, such as reset commands, memory queries, and setpoint configuration.
  • Identification shows origin and type of device, including serial number. It is used to enable automatic device replacement and error-proofing in maintenance cycles.
  • Parameters provide the full description and structure of individual device parameters.
  • Diagnosis details location and structure of diagnostics information.
  • Events and error types describe event code and error code reference material.
Screenshot of partial parameter overview from IODD file