Feature: Communications
Wireless protocols for industrial settings By Rolf Horn, Applications Engineer, Digi-Key Electronics
I
ndustry 4.0 has imparted machines with more intelligence and automated facilities with more efficiency and flexibility. Industry 4.0 smart machines and modular automation are defined by secure and adaptable
connectivity, data collection, and continous machinery-condition monitoring and adjustment of production process parameters, among others. Te wireless technologies to support these functions are based on cellular, Wi-Fi, Bluetooth and IEEE 802.15.4 standards and protocols. Wireless communication devices can be
costlier than wired networks, but they oſten prove the most cost-effective option over the long run, since there are no costs nor additional time and effort associated with them as with running cables.
WiFi-based automation standards In 1997, the Institute of Electrical and Electronics Engineers (IEEE) released standard 802.11 defining the wireless implementation of local area networks. To ensure its market adoption, the industry
consortium Wi-Fi Alliance soon followed, led by wireless-device companies invested in establishing testing and certification programs to maintain cross-supplier product interoperability. Today IEEE 802.11 is supplemented by additional Wi-Fi Alliance standardisation, for exceptionally reliable device compatibility. Whilst Wi-Fi is quite useful for
monitoring applications and connecting machines to enterprise-level systems, its speed, latency and connection stability issues have limited its applications to: • Barcode scanners that communicate data to manufacturing execution systems, able to tolerate delays of up to two seconds;
• Motion sensors that do not need real-time control; and
• Long-term machine-condition monitoring. Tere have been efforts to adapt Wi-Fi
to industrial control applications, but with limited success – apart from the Chinese industrial wireless communication standard WIA-PA (Wireless Network for Industrial Automation and Process Automation). Wi-Fi operates at either 2.4 or 5GHz, with
20 November 2022
www.electronicsworld.co.uk
the higher frequencies allowing faster data transfer but at a reduced range, since higher frequencies dissipate quicker when passing through walls and other solid objects. Specialised standards use other frequency bands; for example, IEEE 802.11ah low-data Wi-Fi (HaLow Wi-Fi) operates around 900MHz and is typically used in sensors needing extended ranges and very low power consumption. At the other end, IEEE 802.11ad Wi-Fi (WiGig) operates at around 60GHz to provide very fast data transfer.
IEEE 802.15.4 wireless standards Other wireless options include low-rate wireless personal area networks, or LR- WPANs, as defined by the IEEE 802.15.4 standard. Tese technologies prioritise low cost and low power over speed and range. With the basic specification allowing data transfer rates of 250kbit/s at ranges to 10m, this solution links low-cost devices without additional communications infrastructure. Protocols based on the IEEE 802.15.4 standard such as 6LoWPAN, WirelessHART and ZigBee are fast becoming preferred IIoT protocols:
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