In the last few years, the emergence of standards-based solutions for wireless communications has initiated a radical change. Also, Novel-distributed signal processing algorithms, energy-efficient medium access control and fault-tolerant routing protocols, self-organising and self-healing sensor network mechanisms etc., have contributed immensely in growth of the wireless technologies on industrial front.
Sensor networks for monitoring and control are not a new concept. Wired implementations have found widespread use owing to their simplicity and low cost nature. On the other hand, the use of proprietary wireless networks has historically been limited to just a few niche applications. Over the last few years, the emergence of standards-based solutions for wireless communications has dramatically changed the market‘s perception of the technology.
Of the many benefits that a standards-based solution offers, a key advantage is interoperability. The emergence of standards such as IEEE802.15.4 and ZigBee, which are targeted at RF applications requiring low data rate, long battery life, and secure networking, have equally changed the market‘s perception of wireless technologies for sensor networks. The key catalyst for this growth is the availability of integrated chip solutions at market affordable prices.
Getting Started With Wireless Automation: What are the Industrial WLAN Requirements?
Industrial WLAN requirements differ from those originating from within enterprise and home environments. These include:
- Strict delay requirements: For example, enterprise VoIP applications can tolerate delay latency of up to 150 ms and up to 1 per cent data corruption in transit due to adaptive play-out control and error concealment algorithms. In contrast, the delay requirement for industrial Ethernet is 10 ms for field device applications, and below 1 ms for motion control applications. In addition, minimising delay jitter is also important for periodic control communications.
- Deterministic performance guarantee: In industrial networks, runtime performance degradation is not an option for missioncritical applications. This requirement is also enforced during device roaming, which leads to the requirement for real-time handover.
- Support for large and varying number of devices: With industrial applications one WLAN access point is likely to serve a large number (in the order of hundreds) of field devices and sensors. Supporting large and varying number of clients in the context of an industrial WLAN can overload the MAC protocol.
- Network security: Industrial WLANs used in factories must meet industrial safety and security regulations. These requirements include premises protection, and detection of rogue clients and access points.
- Network commissioning: Industrial networks place special emphasis on network commissioning, because runtime network failure is unacceptable. For industrial WLANs, the commissioning requirements include auto-commissioning where a large number of devices are to be used, and the execution of radio planning and assisted site surveys.
Wireless control networks are expected to revolutionise the whole process automation industry, insiders believe. But, despite single big installations the implementation seems to progress only slowly. A new study by ARC casts a spotlight on an exciting technology and explains why standards and legislation can be both driving force and ball and chain. More in Wireless Automation yet Has to Live up to Its True Potential
In general, these industrial WLAN requirements may serve as basis (not limited) for selection of technology, protocol and topology from the available wireless options. Learn more about the market for wireless automation technology on page 2!
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