By Jim Montague, executive editor
Finding out how process control users employ wireless can be even more difficult than understanding these rapidly evolving technologies themselves. To better define today’s multiplying and growing wireless methods, Control recently conducted its first SP100 Wireless Survey of almost 500 readers about where and how they use wireless in their plant-floor applications.
The survey was written by editor in chief Walt Boyes and Paul Sereiko, CEO of Airsprite Technologies, with help from Jose Gutierrez, CTO of Emerson Inc. and Dave Kaufman, Director of Business Development, Honeywell Process systems, all ISA SP100 committee members. The survey was produced in collaboration with the SP100 committee, and for its use. The data acquired in this survey is presented publicly here for the first time.
The responses to the survey came from a wide cross section of Control’s readership. The largest groups represented were system integrators and engineering design firms, at almost 20%, and end users from the chemicals and allied products verticals at 12.3%. While 35.6% of users buy field devices from one to five vendors, 32.2% buy devices from more than 10 vendors.
Wireless Coverage Needed
Not surprisingly for process plants, 35% of users reported their facilities were larger than 20 acres, while 12% to 15% of them worked at sites that were either 10 to 20, five to 10, or one to five acres each. Despite these acreages, almost 23% said their site would require full wireless coverage for it to be effective, while about 20% reported that less than 50% or less than 20% coverage would be sufficient (Figure 1). In addition, 31.2% report they have one coverage area for wireless, while 25.3% say they have five areas to cover.
Familiarity Causes Worries
Many respondents say they already use several wireless technologies—and not all are old-time radios. While it might be expected that just over 60% of the survey’s respondents use two-way radios, it’s surprising to hear that 51.1% report using WiFi, 39.6% use proprietary wireless and 23.8% use radio frequency identification (RFID) systems (Figure 2).
Still, single-digit percentages of respondents presently have less than 100 wired sensing and/or control devices, while double-digit percentages have 500, 1,000 or more. Meanwhile, contrasting percentage levels are true for how many wireless devices they now have in place (Figure 3).
Despite newer networks and many potential links to wireless, the survey’s respondents believe wireless will eventually tie into traditional technological points in their legacy wired systems. For example, while 24.9% believe that wireless will tie into their fieldbuses, and 37.9% think wireless will link to their IP networks, 44.1% expect wireless will connect to their PLCs and PACs and a whopping 49.8% project expectwireless to integrate with their DCSs.
Wireless Now in Use
However, while many respondents expect wireless to tie into their networks, they remain very concerned about reliability and security. In fact, more than two-thirds (66.4%) say data reliability will most affect their use of wireless, and more than half (54.4%) add that security will most influence their decision.
Using the Data
The vast majority of respondents say that wireless will be used for monitoring (84.8%), while less than half (48.6%) expect it to be used for alerting. Just under a quarter (24.6% and 23.2%) believe it will be used for low-speed control (>2 sec cycle time) and open-loop control respectively. Only 13% expect wireless will be used for high-speed control (<2 sec cycle time).
Most potential users (90.7%) logically expect their wireless devices will be powered by batteries. However, healthy percentages (72% and 56.8%) also project their wireless devices will be driven by line power and 4-20 mA current loops, respectively.
Since most respondents say the physical variables in their processes can change within seconds or less, 37% report that they want to know the exact time that a measurement is taken within 1 second, while just over 18% say they can be notified in 10 seconds or 1 minute. What is not clear is whether they want to know when the measurement was taken with a time stamp, or if a quick response time is more important.
Wired vs. Wireless
Meanwhile, close to half of the respondents (42.6%) say encryption absolutely should be required for wireless messages. About two-thirds (64.8% and 64.3%) add that message authentication and device authentication, respectively, should absolutely be required.
Once they have data from their wireless components, the respondents plan to send it to a variety of systems. They expect these to be mostly digital controls (71.1%) and PLCs (54.7%).
Finally, the respondents report their wireless systems must cooperate with many of today’s fieldbus protocols. Not surprisingly, these include Ethernet (76.2%), Modbus (50%), Foundation Fieldbus 38.9%, and Profibus PA (18.3%).
Plenty More Where This Came From
For more information on wireless and the complete results of our wireless survey, go to www.controlglobal.com/wirelessguide.html
To see graphs on the results of the Wireless Survey, go to www.controlglobal.com/wirelessurvey.html
To read Wireless: A Field Guide to Industrial Wireless click here.