IO-Link enables bidirectional communication between controllers, sensors, and actuators – serving as the foundation for rapid parameterization, intelligent diagnostics, and maximum system availability in the IIoT.
IO-Link is a communication interface established in 2006 that makes sensors and actuators intelligently and fully accessible to automation systems. Instead of purely binary signals, IO-Link transmits digital measured values, parameters, and diagnostic data via a simple point-to-point connection using standard 3- or 5-wire cables. This makes the last meter between the device and the controller digitally, transparently, and flexibly usable.
An IO-Link master connects to the connected IO-Link devices—sensors or actuators—and transmits both cyclic process data and acyclic supplementary information such as parameters or device status. Communication takes place independently of the fieldbus protocol used: PROFINET, EtherNet/IP, or other networks remain unaffected. Each connection operates as a point-to-point link over which data is reliably transmitted in the millisecond range. In addition to pure data transmission, devices can be centrally parameterized, values adjusted, and statuses specifically queried.
IO-Link increases process transparency, reduces configuration effort, and significantly simplifies device replacement. Parameter sets can be centrally managed and automatically restored if necessary (data retention mode). At the same time, the devices provide additional information for diagnostics and maintenance, which minimizes downtime and increases system availability. Through the combination of simple wiring, flexible parameterization, and deep device access, IO-Link becomes a central component of modern, networked, and efficient automation solutions.
Until now, integrating IO-Link devices into PROFINET projects usually required additional effort. Users had to manually enter device IDs or classes, and program or configure parameters such as measurement ranges or output signals using separate software tools.
With SIDI (Simple IO-Link Device Integration), TURCK offers a solution that allows IO-Link devices to be integrated directly into PROFINET project planning environments such as the TIA Portal. The IO-Link devices are described as PROFINET submodules in the GSDML (Generic Station Description Markup Language) of the IO-Link master. TURCK provides a SIDI library for this purpose, which by default includes all of its own IO-Link devices as well as devices from our strategic opto-sensing partner, Banner Engineering. Additionally, selected devices from other manufacturers are also integrated.
If a connected device is included in the SIDI GSDML, the PLC programmer can select it directly from the device catalog of their engineering environment. All IO-Link-relevant properties are clearly visible there; parameters such as measurement ranges, output signals, or pulse rates can be conveniently configured in plain text. This enables end-to-end offline engineering with IO-Link devices.
IO-Link devices can operate in two modes: SIO mode (Standard I/O Mode) and IO-Link mode. In SIO mode, a sensor or actuator behaves like a traditional digital switch. It provides only a binary on/off signal or functions as a simple output. No communication takes place; the IO-Link master’s port functions solely as a digital input or output. This mode is suitable for simple applications with a fixed switching threshold and is fully backward-compatible—operation is possible even without IO-Link-enabled infrastructure.
In IO-Link mode, however, the full range of functions of an IO-Link device is available. The IO-Link master initiates digital communication via a wake-up request on the C/Q line. In addition to cyclic process data, acyclic information such as parameters, identification data, or diagnostics can also be transmitted. This mode is ideal for configurable devices, condition monitoring, and intelligent maintenance concepts.
TURCK addresses the previous integration limitations of IO-Link in PROFINET systems with SIDI (Simple IO-Link Device Integration). This effectively gives IO-Link devices the identity of a genuine PROFINET module, allowing them to be parameterized directly in the TIA Portal. No additional tools are required—IO-Link devices in IO-Link mode are thus just as easy to use as classic fieldbus modules.
IO-Link reduces the number of variants by making devices configurable via software rather than hardware. Traditional sensors often require different models for various measurement ranges, switching functions, or filter settings. IO-Link-enabled devices, on the other hand, are based on a universal base model that can be precisely adapted to the specific application via software. A single physical device can thus meet numerous requirements.
Manufacturing companies benefit from this in particular: design, purchasing, and maintenance departments reduce effort through fewer part numbers, simplified inventory management, and standardized, interchangeable sensor technology. Additionally, IO-Link enables the storage of parameter sets on the master. When a device is replaced, the settings are automatically transferred to the new device (data retention mode according to V1.1), making preconfigured variants unnecessary.
TURCK further enhances this effect with SIDI. Since IO-Link devices can be parameterized directly within the engineering system, the appeal of multifunctional sensors increases even further. Variant diversity is thus consistently replaced by flexibility—a decisive advantage, particularly for modular machine and plant concepts.
There are essentially three ways to configure IO-Link devices: via the controller, via the IO-Link master, or via configuration software on a PC within the automation network. At TURCK, the TAS (TURCK Automation Suite) is used for this purpose. Which option makes the most sense depends on the infrastructure in use. In traditional projects, parameterization is often performed using tools such as TAS, PACTware, or other IODD interpreters. There, parameters can be clearly visualized, adjusted, saved, or exported as a file.
Even more convenient is direct parameterization via the IO-Link master itself—for example, via an integrated web server or an IODD configurator. TURCK masters from the TBEN, FEN20, or TBPN series natively support this approach and also enable automatic downloading of the IODD from the Internet.
For use in PROFINET projects, SIDI (Simple IO-Link Device Integration) offers the simplest solution. Here, all relevant parameters can be set directly in plain text within the TIA Portal or comparable engineering tools—without additional software and without manual index or subindex entries. This makes parameterization of IO-Link devices just as convenient as with classic fieldbus modules.
IO-Link is not a fieldbus, but a point-to-point communication layer below the fieldbus and Industrial Ethernet layers. While PROFINET, EtherNet/IP, or AS-Interface organize networks with many participants, IO-Link always connects exactly one IO-Link master to a single device—via an unshielded standard cable.
The technologies also differ significantly in terms of installation. Fieldbuses require defined topologies, addressing schemes, and often shielded cables. IO-Link is deliberately kept simple: three wires are sufficient, five if needed (Class B). Each IO-Link connection operates independently of the fieldbus technology used by the IO-Link master. This allows a PROFINET system to connect IO-Link devices in parallel without altering their communication principle.
With SIDI (Simple IO-Link Device Integration), TURCK closes a key gap in PROFINET environments. Since IO-Link devices, by design, do not have their own GSDML, their integration previously required additional effort. SIDI functionally elevates IO-Link devices to the level of native PROFINET modules—including parameterization and diagnostics directly within the engineering system.
The IODD (IO-Link Device Description) is the standardized device description for an IO-Link device. It contains all the information required by an engineering system or software to uniquely identify a device, configure its parameters, and read diagnostic data. This includes, among other things, communication profiles, parameters with index and subindex structures, the structure of process data, as well as identification and diagnostic information.
Without the IODD, an IO-Link configuration tool cannot fully interpret a device. Therefore, it is loaded and evaluated during parameterization in tools such as TAS, PACTware, or other IODD interpreters. In PROFINET systems, SIDI handles this step particularly elegantly: The IODD information is integrated into the GSDML of the IO-Link master. As a result, all parameters are directly visible and configurable in the TIA Portal—without separate IODD processing. In short: The IODD is the digital data sheet of an IO-Link device.
TURCK offers one of the most comprehensive IO-Link portfolios on the market, featuring sensors, actuators, hubs, and masters—providing maximum choice, consistent standards, and high system compatibility.
TURCK is consistently advancing IO-Link technology: from sensors and actuators to IO-Link masters and integration into control systems, IT systems, and IIoT applications. This results in seamless, future-proof automation solutions.
With SIDI (Simple IO-Link Device Integration), TURCK IO-Link devices can be configured directly in the TIA Portal. All parameters are available in plain text—without the need for additional software, manual index entries, or external tools.
In our know-how section you will find all TURCK whitepapers as well as the recordings of our webinars. Instead of giving a long lecture on general technical basics, we quickly get to the core of the fascinating questions surrounding automation.
