IO-Link Wireless – industrial wireless networking with deterministic cycle time

The IO-Link wireless radio technology, which can be used worldwide, provides a cost-effective, highly reliable and deterministic communication standard. The radio technology uses up to 80 channels in the license-free 2.4 GHz ISM band.

SSDM

In the Sensor and Software Defined Manufacturing SSDM project, the movement accuracy of a robot is to be improved by sensor technology. To achieve this, multi-axis inertial measurement units (IMU) at multiple locations on the robot arm must be wirelessly connected to a controller. The communication requirements to transmit the continuous stream of sensor data are low latency in the range of 10 ms and highest reliability, which pose a challenge to any wireless system. Many existing wireless technologies cannot be used for such time-critical use cases with real-time requirements because they do not meet the highly reliable, low-latency communication requirements.

The project investigated the suitability of IO-Link Wireless for the intended use case. Measurements were made of packet error rates at the bit transmission (physical layer) or medium access (medium access control layer) level. An IO-Link Wireless protocol stack was implemented as a prototype on a dual-core System-on-Chip and successfully tested on the robot.

Our technological solution is focused on high data throughput with IO-Link Wireless and high reliability. In addition to the error protection protocol with packet repetition (ARQ) provided in the standard, an alternative error protection based on network-based coding (Network Coding) was implemented. This allows the usable data rate to be almost doubled or the reliability to be further increased.