Wireless Networking in the Process Industry

Looking for more information, we contacted study author Tim Shea, who was glad to fill in some details. Despite the global recession, he said, which drove some suppliers out of business, the wireless market grew at a compound annual growth rate (CAGR) of about 9% from 2007 levels. This growth should continue, he went on, with the VDC study predicting a CAGR for most wireless products of 30%+ through 2015, driven both by the improving economy and by pent-up demand. One factor influencing growth, he added, was the desire to save money — by replacing cables and by easier and lower cost installation and maintenance “in remote applications where wired solutions are not practicable or not possible.” Other factors contributing to demand, he added, were the need to support distributed control and diagnostic monitoring applications (especially for low-power, short-range apps like ZigBee) and the inherent scalability of wireless.

So far most wireless applications in the field have been in monitoring, data gathering and open-loop process applications, and the VDC study suggests this will continue. Areas of fastest expected growth were human machine interfaces, process controls and logic controls, in that order, but the fastest growth in percentage terms, said Shea, was expected to be in motion control, although much of that large percentage can be attributed to its present small base.

While industrial use of wireless is mostly for monitoring, Shea expects to it used increasingly in less-critical control applications, where latency of 100 ms or more is not a problem — things like pumps that need checking at intervals of less than one second, for example — but does not expect to see major adoption in the next three to five years.

Industrial wireless is different

We have seen an explosion in wireless applications for personal and commercial applications, like linking together computers, PDAs, printers and Internet access points, Shea went on, and in all of these applications the emphasis is on speed. He cited the IEEE 802.11 networks as an example, where the data rates have increased over time to 54 Mbps; in fact IEEE 802.11n, approved in 2009, can reach data rates of 150 Mbps. Few industrial applications need that kind of speed; data rates may be low indeed, down to a few bits per second or even per minute. In control and sensing applications, he explained, the greatest need is for reliability, accuracy and scalability: “Depending on the application, garbled or dropped data can result in anything from a disruptive glitch to a devastating failure.”

Choice of protocol

Multiple wireless networking protocols are available. The VDC study concluded that those based on IEEE 802.11b, 802.11g, ISA100.11a and WirelessHART would realize the greatest growth, with the latter two finding good growth and future demand in the process industries. Some legacy narrowband 2.4 GHz systems and even a few 800-900 MHz systems will find use where there is a need for greater distances, said Shea, as well as “a perception for greater reliability and greater security.”

User perceptions

When queried about perceived advantages and disadvantages of wireless, 52% of respondents to the VDC study felt that wireless provides solutions where wireline is impossible or impracticable, while 40% mentioned that it is easier/quicker to install. Also, 18% mentioned that wireless allows mobile applications, 18% that it is more suitable for remote locations and 16% that it is more flexible (easier to modify, etc.).

On the side of wired networks, 48% cited wireline as being more reliable than wireless (due to its noise immunity, etc.), while 35% of respondents felt that wireline is more secure than wireless. The same percentage said that they were more familiar with wireline, and found it easier to understand. Twenty-nine percent said that wireline has more bandwidth than wireless and is faster, 12% that it is easier to configure/specify, and 12% that wireless performs poorly in bad weather. Finally, 12% felt that wireless is not suitable for control applications.

User motivations

When asked about their motivations for using wireless, 36% of respondents to the VDC study cited its flexibility and ease of expansion or relocation, while 29% were motivated by its easy/fast installation. Fifteen percent cited lower costs, while 13% were motivated by the desire to gain knowledge and experience with the technology.

Summary

Wireless networking is gaining steadily in popularity in the process industries, driven to a large extent by its ease of use, low installation cost and flexibility. Those supplying that industry would do well to remain abreast of that trend, and to take the necessary steps to make sure their products fit into the new paradigm.