COVER STORY FEATURE


Note that connecting a secure WSN to a insecure gateway is another point of vulnerability, and end-to-end security must be considered in system design. Industrial IOT is not installed by wireless experts. For the most part, established industries are adding Industrial IoT products and services to their legacy products, and their customers are deploying in environments with a mix of old and new equipment. The intelligence embodied in industrial WSN must confer an ease of use to Industrial IoT products that make transitions seamless to the existing field personnel. Networks should rapidly self-form so that the installer can leave the site with a stable running network, avoid service interruptions by repairing themselves when connections are weak or lost, self-report and diagnose when service interruptions do occur, and avoid costly onsite visits by requiring little or no maintenance once deployed. For many applications, their success relies in part on being deployable in areas that are difficult or dangerous to reach, so the IoT devices must operate on batteries, typically for more than five years. Also, systems should be available for


global deployment, since the widespread adoption of Industrial IoT by end users is often companywide, and requires multisite standardisation. Fortunately, international industry radio standards that comprehend and fulfill this requirement are in place, including IEEE 802.15.4e TSCH. For Industrial IoT applications, the


precise placement of a sensor or control point is critical. Wireless technology offers the promise of no-wires communication, but if you need to power a wireless node by plugging it in, or recharge it every few hours or even months, the cost and impracticality of deployment become prohibitive. For example, adding sensors to rotating equipment to monitor conditions while the equipment is in service is not possible with wires, but the knowledge gained from in-service monitoring can allow customers to predictively maintain this critical equipment, thereby avoiding unwanted and expensive downtime.


To ensure flexible and cost-effective


deployments, every node in an industrial WSN should be capable of running on batteries for at least five years, as this offers users the ultimate flexibility in coverage for Industrial IoT applications. As an example of an industrial TSCH based WSN, Linear Technology’s SmartMesh products typically operate at well under 50µA, making it very feasible to operate for many years on 2 AA batteries. In environments where there is a good source of harvested energy, it is possible to run nodes perpetually on energy harvesting (see Figure 1).


helpful in diagnosing precise cause and effect in industrial applications where information from multiple sensors must be reconciled. Industrial networks are required to run


Figure 2


Industrial monitoring and control networks are business critical. They underpin the systems that affect the basic cost of producing goods, and the timeliness of data is essential. In the past decade, deterministic TSCH-based WSN systems have been field proven in a wide range of monitoring and control applications. These time-slotted systems, such as WirelessHART, provide time- stamped, time-bounded data transmission. In these networks, nodes that require


more opportunities to send data are automatically provisioned with more time slots, and low latency transmission through the network can be achieved through the provision of multiple time slots on successive paths in the network. This coordination of data transmission also dramatically improves the ability to deploy dense networks with frequent transmissions. Without a time schedule, non-TSCH wireless networks will collapse from the uncoordinated flood of radio traffic. Additionally, every packet in a TSCH


network contains an accurate time stamp indicating the time it was sent, and network-wide time is also available at each node to coordinate control signals across a network of WSN nodes if required. The availability of time-stamped data enables data to be properly sequenced by the application even if it is received out of order, which can be


Figure 2:


Network Management Software provides critical visibility to the health of the wireless network such as in this SNAP-ON software utility from Emerson Process Management


Figure 3


Software analytics, such as the Brains.App software from


IntelliSense.io, use the data from industrial wireless sensor networks to streamline plant operations, optimise yield and improve safety


continuously for many years, yet no matter how robust a network is, problems can still occur. The quality of a network that works well at installation may be affected by a variety of environmental factors during its operating life. Early and appropriate alerts to such issues are an important aspect of any industrial network, and the ability to quickly diagnose and remedy issues is key for quality of service. In the best industrial implementations, intelligent networks will remediate such issues by automatically rerouting data on alternate paths, while continuously upgrading the network topology to maximise connectivity (see Figure 2).


SMART NETWORKS There is considerable focus on putting more and more intelligence into things, but this is not the only place where ‘smarts’ belong in an industrial IOT application. Industrial IoT networks should employ intelligent end nodes and network and security management features that mirror the best that enterprise IT and OT has to offer. Networks should be highly configurable to adapt to specific application needs. Given the low power requirements to achieve long battery life, self-knowledge of network power availability and intelligent routing to maximise network wide power consumption should be employed. Additionally, the network should automatically adapt to changes in the RF environment that might favour a dynamic change in topology. Linear Technology’s SmartMesh Network Manager not only provides network security, management and routing optimisation, but it also allows users to reprogram nodes over the air if required, providing an upgrade path for future features as customer needs evolve. The Internet of Things is very much an


industrial phenomenon, with clear business drivers and compelling ROI. In these business critical applications, industrial wireless sensor networks must meet a high bar for smarts, security and reliable wire-free operation over many years. These stringent requirements can be met with existing and emerging wireless mesh networks standards, which will be key Industrial IoT building blocks to help industrial customers transform their businesses and services in the Industrial IoT era (see Figure 3).


Figure 3 / ELECTRONICS


Linear Technology (UK) Ltd. www.linear.com 01628 477 066


ELECTRONICS | JULY/AUGUST 2016 13


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