IO-Link is the first technology for communicating with sensors and actuators below the fieldbus level to be adopted as an international standard (IEC 61131-9), and now the technology is being expanded to include wireless communication.

The IO-Link community has completed work on the specifications for IO-Link Wireless and has published an approved version at the 2018 Hanover Trade Show.

IO-Link Wireless defines wireless communication between sensors/actuators and controllers (PLC) in the industrial automation environment. Performance, functionality and capacity are comparable to cable-bound solutions.

IO-Link wireless

IO-Link Wireless offers real-time latency of 5 ms for communication with up to 40 devices (sensors and actuators). Reliability lies above a packet-error rate (PER) of 10-9, while the rates of other comparable wireless standards, such as WLAN, Bluetooth and Zigbee, are around 10-3.

IO-Link Wireless supports roaming functions and the option of using battery-operated or energy-harvesting sensors with minimal energy consumption in a real-time network. A key feature of IO-Link Wireless is its compatibility with industry- and process-automation protocols. Planning, commissioning, operation and maintenance can all be carried out using standard IO-Link tools. This guarantees backward compatibility with cable-bound IO-Link systems.

In parallel with the specification work, the necessary test specifications and test scenarios needed when the first suppliers develop their components for the new system are already being defined in the IO-Link wireless working group. IO-Link also held an IO-Link Wireless developer workshop at Helmut-Schmidt-Universität (HSU) in Hamburg, Germany in June of 2018. This workshop enabled interested device manufacturers to develop IO-Link wireless components.

IO-Link integrated in OPC UA

On the basis of existing use cases, the IO-Link Community developed a method for implementing an integration of IO-Link in OPC UA in 2017.

But in the past nine months, the Community has also developed a corresponding standard for the data and function model to allow IO-Link devices and IO-Link masters to be represented accordingly in OPC UA in the future. The so-called “Companion Standard IEC 61131-9” specification now available for the integration of IO-Link in OPC UA, follows the requirements of the OPC Foundation.

The joint working group of the IO-Link community and the OPC Foundation (C4/PG51) charged with developing this Companion Standard is currently working at full speed to complete this specification so as to be able to distribute a review-ready version to all IO-Link, PROFIBUS & PROFINET International (PI) and OPC Foundation members. In addition, the implementation of reference systems, which are necessary for the test, has begun as has the development of products that can offer this OPC UA interface for IO-Link.

IO-Link protocol

For IO-Link, the point-to-point protocol for sensors/actuators, now with more than 7,000 available different masters and devices, a fiedbus-independent integration via OPC UA is very interesting, as it can be used to further expand the breadth of possible automation solutions: IO-Link masters, which bundle the data from sensors and actuators, can process these data not only as fieldbus nodes, but can also make higher levels available inside and outside of the automation pyramid via OPC UA.

In this way, sensor data can be integrated with little effort and seamlessly in MES and ERP systems, which is often referred to as “sensor-to-cloud” functionality. For many applications, this opening to OPC UA means new flexibility for the use of sensors and actuators.

Employees from more than 20 companies are actively involved in this working group technical experts from the IO-Link field as well as experts from the OPC UA area, who have already successfully contributed to other Companion Standards. The final draft for the Companion Specification (draft for voting) was released in May 2018.

News report by IO-Link