In the course of the progressive automation and linking of industrial machines IO-Link was specified already in 2006 as a standardised digital interface for actuator and sensor levels. This allows for a simple and cost-effective connection to controls and higher-level bus systems and networks.
The international standard IEC 61131-9 laid the foundation for worldwide use in 2012.
IO-Link is not a fieldbus, but a digital point-to-point connection. Just as in conventional analogue connection technology, one cable leads from every sensor or actuator (e.g. valve) to a so-called master (data collector), from which the data is transmitted to other participants (e.g. controls) in the company network. The use of cost-effective, unshielded standard cables and established connection technology (4 or 5-pin M12 plugs) allows for a migration into the digital world with minimal effort.
Unlike with previous analogue systems, the digital IO-Link communication protocol enables for the transfer of information in addition to the process data, such as value status (validity of the process data) and events (error messages) as well as device information (ID, parameters, diagnosis etc.).
The bi-directionality of the data connection is a particular advantage of IO-Link technology. Unlike standard analogue technology or switch connections, where the information only flows in one direction, higher-level controls can communicate bidirectionally with the sensor or actuator thanks to IO-Link.
Settings which e.g. need to be performed manually by means of buttons in conventional pressure switches, can now be carried out from the control via IO-Link, as part of the start-up or even during ongoing operation.
This remote parameterisation considerably accelerates and simplifies the commisioning of systems and helps to minimise error sources and reduce costs. Especially in maintenance, an IO-Link device can be replaced via plug and play, as the configuration parameters are automatically transferred from the control to the new device, which also eliminates a significant error source and reduces machine downtimes to a necessary minimum.
Thanks to these enhancements of flexibility, components with an IO-Link interface are an integral component in the Internet of Things within the framework of Smart Factory solutions in the age of Industry 4.0