Wireless, in an industrial context, is a pretty broad term. Over the last 10 to 20 years, it’s taken many forms, with some less successful proprietary protocols fading away due to a lack of commercial viability. Users have voted with their pocketbooks and have concentrated on wireless Ethernet for all sorts of applications, with WirelessHART as the primary protocol for device-level networks. So, who is using wireless, and why?
Shane Hale digs into the question in Control Engineering’s November 2018 cover story, Wireless for Operations: Proprietary Versus Standards; Adopters Versus Laggards. He points out two major driving factors:
There are many reasons why facilities adopt wireless networks, but they often boil down to two categories. The first category is reactive; wireless is used to bolster saturated wired infrastructure or in locations hard to access with cable. The second category is proactive; wireless is a critical means to quickly increase the reach of instrumentation and communication capabilities without the costs, long installation time, and possible downtime required for wired instruments.
That’s clear enough and both arguments can apply to wireless Ethernet and WirelessHART, even though they are different in their approaches.
When most people think of wireless, their first thought is the wireless Ethernet (Wi-Fi) networks that connect computers, phones, tablets and other devices to office, home and even industrial networks. While Wi-Fi is very versatile and good for a wide variety of applications, its high-power requirements and high-protocol overheads make it impractical for measurement devices where battery life needs to be measured in years. Still, the ubiquity of Wi-Fi-enabled devices and the high bandwidth it offers make it suitable for wireless plant networks used for other purposes.
But what about wireless device-level networks? Going back 10 to 15 years, there was a lot of activity with various companies trying to develop practical approaches. Some did indeed fade away as better platforms began to separate from the pack. One of the first to develop a strong position in the market was WirelessHART:
The first WirelessHART field devices were released in 2007. To overcome the interference issues inherent in industrial applications, WirelessHART uses a mesh network where each device acts as a repeater for the network, providing multiple paths for signals to reach the access point or gateway. Since it was designed specifically for industrial applications by the FieldComm Group, certified devices from any manufacturer can interact with each other. Additionally, bandwidth use and security considerations are optimized for measurement and control applications. As wireless instruments are frequently battery-powered, the protocol was designed to minimize power usage. Depending on how frequently a given device provides measurement updates to the host, battery life can be up to 10 years.
So that’s what got wireless adoption going, but what about today?
The first generation of wireless instrumentation was all about process variables, but users quickly realized the additional data provided could enable asset condition monitoring and other applications. For example, adding a WirelessHART-enabled acoustic sensor can determine if a steam trap is wasting energy, or if a pressure-relief valve is leaking. While saving the cost of wiring is still a major benefit, the greatest value of wireless instrumentation and networks is the ability to facilitate pervasive sensing systems. With the costs of end devices and networks declining, the ability for plant operators to gather data and support decision-making has increased with many different applications.
You can find more information like this and meet with other people looking at the same kinds of situations in the Emerson Exchange365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the WirelessHART and IIoT Groups and other specialty areas for suggestions and answers.
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