Variety is the spice of life, so they say, unless, of course, you are trying to choose an industrial-strength wireless sensor network (WSN) built on technology that leverages any one of a handful of emerging "open" standards.
For the past few years, industry groups such as the ZigBee Alliance, the Internet Engineering Task Force (IETF), and ISA have been working on building communications protocols that leverage the IEEE 802.15.4 industry standard, a low-rate wireless personal area network (WPAN) that defines the physical and data link layers. Where it gets tricky is at the network and transport layers, where ZigBee, IETF, ISA, and others, including proprietary protocols, duke it out.
It's not a war, per se; rather, advocates from each group say, the real battle is in educating the masses. Indeed, there may be room for all three approaches. For example, ZigBee is big in building automation, whereas the ISA SP100.11a working group, which expects to have a standard out next year, would seem to be a natural fit for process-based applications in the plant. Meanwhile, IETF's IPv6-based, low-power wireless personal area network (6LoWPAN), which uses an Internet Protocol (IP), may be more suitable for enterprise environments. In the short term, these vying standards are confusing; in the long term, they could coexist.
"The market will decide if, in some niches, they pick one over the other," says Roland Acra, president and CEO of Arch Rock Corp., which recently announced its Primer Pack/IP, a wireless sensor network that uses IP over 802.15.4-based radios. Arch Rock's new network allows links into Ethernet, WiFi, and 6LoWPAN networks.
Adopting one approach over another, however, may come down to two things: reliability and applications. The first issue is already working itself out.
"Companies are getting to cheaper and lower-power solutions, and that just makes it all the more tempting because it is really the low power that makes [sensor networks] better," says Harry Forbes, an analyst at ARC Advisory Group. A device with lower power consumption has a longer life, which strengthens the reliability story, he adds.
In addition, the chip technology is improving, the cost of components is coming down, and the protocols are settling into place. So where are the applications?
Tendril Networks Inc. announced in April a network operating platform for building and integrating ZigBee-based applications. The platform also includes an application, Tendril Monitor, for managing day-to-day operations on ZigBee networks.
Arch Rock, which in May secured $10 million in a second round of venture funding, plans to build out its Primer Pack/IP product to address industry-specific problems. That means some applications will be bundled in, Acra says.
"What you will see coming from us are some applications, particularly in greenfield places that have little legacy and little entrenched instrumentation," Arch Rock's Acra said in an interview with Managing Automation. In those greenfield deployments, "we'll come to market with something an end user can consume straight from Arch Rock. But in other spaces we'll have enabling technology, like an integrator, to adapt to end users' needs."
Arch Rock claims the IP-based WSN is just as well-suited to the factory as to the front office, but ARC's Forbes thinks companies in the manufacturing space will not warm up to the IP approach quickly.
"They don't need IP to do what they are doing," Forbes says, especially with the emergence of an ISA wireless standard and industrial protocols, including HART, that are going wireless.
Industrial applications are often part of the industrial communications bundle. As a result, large automation vendors, such as Emerson Process Management, Invensys plc, and Honeywell Process Solutions, which are well on their way with wireless sensor networks, are not likely to transition to IP anytime soon, he says.
In fact, according to a recent ARC Research note reviewing a Massachusetts Institute of Technology panel discussion in which representatives from ISA, IETF, and ZigBee all sounded off, Forbes noted that the three groups face distinct challenges.
Forbes outlined those challenges in the report: "ZigBee faces a very broad set of applications, from medical equipment to energy metering, to home awareness. Application profiles can add value within a vertical industry or application, but development of these has lagged while the ZigBee Alliance has been revising their base-level specification. SP100 is still a work in progress that needs to serve existing industrial applications while at the same time remaining open to absorb the rapid progress that wireless technology will make. The companies commercializing the IETF's 6LoWPAN will need to prove that it can perform well enough in real-world applications to meet end-user requirements."
How it will all turn out only time will tell.
This article originally appeared in the July 2007 issue of Managing Automation.