MAR-APR 2019

Issue link:

Contents of this Issue


Page 27 of 59

ontrol Connected Plant/Factory Fig. 3: Connected industrial enterprise 28 INTECH MARCH/APRIL 2019 WWW.ISA.ORG SYSTEM INTEGRATION Operational devices are associated with immediacy and quick action, while infra- structure devices are often trended over a much longer time base. A closer look at wireless networking technologies reveals why different types are best suited for certain roles. Power struggle One consistent and common-sense bot- tom line when evaluating wireless tech- nologies is the trade-off between power consumption and range (figure 2). Com- mon consumer Wi-Fi is a large power consumer with relatively short range, although it delivers massive bandwidth. Low-power networks like Zigbee are find- ing a place in home automation scenar- ios, but their extremely low range limits them to personal area network applica- tions. Industrial wireless networking such as ISA100 Wireless occupies a balanced region somewhere in the middle. This leaves LPWA residing by itself in the low-power, wide-area position indi- cated by its name. For IIoT implementa- tions, this is the sweet spot for two main reasons. The first is that low-power en- ables IIoT devices to be operated with just batteries, only needing replacement after years of service. No additional local power conduit and wire, or a local power source such as solar cells, are required, making these devices very convenient for hard-to-reach locations. The power con- straint is not about saving power strictly for consumption costs, it is instead about enabling the device to be installed as a truly wireless physical island requiring minimal maintenance. The second reason is that IIoT devices tend to be widely scattered around a site, so long-range communications are nec- essary. This also means it is far easier to add future sensors as funding allows with- out requiring additional components. At the end of the day, power consump- tion, range, and the resulting available bandwidth determine where an industri- al wireless network technology fits best. Conventional industrial wireless net- work efforts were originally focused around supporting the operational type of applications, mostly due to the avail- able underlying technologies at the time. To achieve sufficient performance that results in responsive control (action time less than about 1 second), the design of operational wireless networks is neces- sarily more heavily engineered up front. Sometimes this involves specifying redundancy options. In cases where operational wireless networks are used in conjunction with classically wired systems, a well-engineered system will handle the two similarly, although of course they would be distinguishable. There are ways to leverage opera- tional wireless networking to monitor infrastructure-type signals, but the end user would be overpaying for hardware and design efforts every step of the way. Instead, it makes more sense to select a networking technology targeted for infra- structure applications. Focused on infrastructure Contemporary LPWA networks have be- come available as the core technologies have improved, often based on consumer electronics breakthroughs. Advances in re duced power consumption (such as with handheld devices and consumer Blue- tooth wireless) and maximized wireless network bandwidth have translated into similar benefits for industrial applications. LPWA implementations, such as Lo- RaWAN, have now reached a practical level where they can be used to integrate thousands of sensors at a site. Addition- ally, LPWA is extensible beyond an on- premises solution to connect over the cloud, which effectively makes the trans- mission distance unlimited as long as Internet access is available. It is worth not- ing that 3G/4G/5G mobile network- ing systems are a form of LPWA but are not considered here for industrial networking use due to relatively high service pro- vider costs. This is because they are more aligned as the backbone of com- mercial communi- cation networks at this time, as opposed to being considered workable for general wireless sensor networks. Also, end users would likely be concerned about build- ing their sensor networks on systems that make them beholden to outside network providers. For these reasons, LPWA networks and small field devices are an excellent fit for infrastructure monitoring applications. They can easily be used to retrofit existing equipment with instrumentation to sup- port preventive maintenance efforts, and they can minimize personnel exposure by being installed in areas that formally required operator rounds. The data delivered by IIoT devices in a LoRaWAN system can be used by analyti- cal applications in parallel with operation- al systems, or it can be cross-connected to operations (figure 3). Many times, IIoT data Range long Power consumption high ISA100 Wireless Figure 2. Wireless balancing act: When comparing power consumption against communication range, it is easy to see why LPWA networking occupies the sweet spot for IIoT implementations. Take ac�on Mission cri�cal data OT IIoT IIoT data Measure • Safety and stability • High performance • Autonomous issue resolu�on • Response to change • Value crea�on • Transfer of know-how Monitor & Analyze Decide Connected Enterprise Connected industrial enterprise Connected enterprise control Connected plant/factory Figure 3. Benefits of wireless: Industrial wireless technologies, whether for operations or IIoT infrastructure, should be used where they fit best to sense conditions, initiate controls, and empower decision making.

Articles in this issue

Links on this page

Archives of this issue

view archives of InTech - MAR-APR 2019