By Matt Migliore
|WirelessHART-enabled devices are currently being deployed in live application environments. Here Emerson Rosemount wireless transmitters provide access to flow percentage readings from nonintrusive ultrasonic flowmeters in an application monitoring treated water usage at a UK power generator. Photo courtesy of Emerson Process Management (www.emersonprocess.com).|
With all the talk of wireless being bandied about at trade shows and other industry forums, you might think process automation sans wires were a wholly new concept. But such is not the case, as wireless has been in use in the plant and in the field since the late 1980s. So what’s all the fuss about?
Well, the fuss is not specifically about wireless, but rather the standards that are currently being developed with the aim of enabling wireless to go from spot solution to widespread adoption. Along this line, wireless standards bodies are currently working to move beyond the proprietary nature of past iterations of wireless automation. Yet, with several organizations toiling toward this end, a traditional single-source standard seems unlikely.
For fluid handling systems designers, there are two key emerging wireless standards efforts to keep an eye on — WirelessHART and ISA100.
WirelessHART is a currently available specification offered as part of the HART Communication Foundation’s HART 7 protocol. WirelessHART is an expanded capability of the HART Communication Protocol, developed from industry users input through the combined, cooperative efforts of HCF member companies and organizations involved in wireless technology. WirelessHART has been recognized as an international standard by the IEC (International Electrotechnical Commission) IEC/PAS 62591Ed. 1.
ISA100 is a broad-based wireless standardization effort led by individuals from the user, supplier, government, and academic communities. ISA100 is working to produce a suite of wireless standards that would cover everything from monitoring and noncritical control to wireless for critical applications. The first ISA100 standard slated for public release is ISA100.11a, a specification for soft-point control and application monitoring, which is expected to debut before the end of Q1 2009.
Both ISA100 and WirelessHART are designed to meet the wireless performance requirements of industrial application environments.
History of ISA100 & WirelessHART
One of the key milestones in the move toward industrial wireless standardization can be traced back to December 2002 when the Department of Energy’s, Industrial Technologies Program for Energy Efficiency and Renewable Energy (www.eere.energy.gov) published a report titled “Industrial Wireless Technology for the 21st Century.” In this document, the DOE cited a study by the National Academy of Sciences (www.nas.edu), which found that wireless could improve industrial energy efficiency by as much as 10 percent. In order to accomplish this savings, however, the DOE identified a need for a certain level of wireless standardization in order to achieve the uptake required for the projected impact.
Wayne Manges, co-chair of the ISA100 Committee and a program manager for the DOE’s Industrial Technologies Program, cites this realization as key to driving the early phases of the industrial wireless standards movement. After concluding that standardization was a need, Manges says the DOE solicited industrial manufacturers to apply for grants to develop wireless devices, under the condition that any company awarded funding would also assist in the development of a wireless standard.
As part of this program, Manges says the winning proposals from Honeywell, Eaton and GE were awarded $2 million each over three years to create wireless devices and help spearhead the wireless standards movement. The Wireless Industrial Networking Alliance (www.wina.org) was also conceived at this time as a separate, government-subsidized promotional vehicle for the wireless standards effort. WINA has since become a self-sustaining organization, and no longer receives government funding.
ISA (www.isa.org) was introduced to the standardization effort when, after receiving a number of complaints from its member companies regarding the poor performance of proprietary wireless solutions, it reached out to WINA to forge a partnership to further develop wireless standards, resulting in ISA100.
Manges says, “It was clear from very early on that no one wireless standard would be able to meet every wireless need.” So, he says, ISA100 was conceived of as a suite of standards.
The first two standards that were worked on under the ISA100 initiative were ISA100.11, a soft control-based standard, and ISA100.14, a monitoring standard. As work on these two standards progressed, Manges says it became clear that the manufacturers were building devices to support both standards. As such, he says the two standards were merged into what is known today as ISA100.11a.
Because WirelessHART is an evolutionary extension of an established global standard, the technology has taken a more direct path to market. Rather than starting from scratch, the developers of this technology were able to build on an established and field-proven international standard, the HART Protocol. The aim was to provide industry users a simple, reliable and secure wireless communication method for process measurement and control applications. And, further, to protect user investment in the more than 26 million wired HART devices installed worldwide. Following an extensive review and approval process by the foundation’s 225-plus member companies, the HCF Board of Directors authorized the release of the WirelessHART standard on Sept. 7, 2007, and certified products are currently making their way into live applications.
WirelessHART technology features a self-organizing and self-healing mesh architecture, which the HART Communication Foundation (www.hartcomm.org) says is more reliable and simpler to install and maintain than legacy star-connected systems. Because WirelessHART is an extension of the HART Protocol, it supports both new wireless field devices and provides a retrofit for existing wired HART devices.
In a perfect world, end-users and manufacturers could design around a single, one-size-fits-all wireless standard. But, in reality, it would be naïve to think a single standard could meet all of the possible wireless needs of industrial applications. And while some manufacturers, including ABB, Emerson Process Management, Endress+Hauser, and Siemens, have been vocal in support of WirelessHART, and big-name end-users, such as ExxonMobil, are touting the application flexibility of ISA100, it is a foregone conclusion at this point that both standards will play a role in the future of industrial wireless.
Given this, the ISA100 Committee and the HART Communication Foundation entered into an agreement in September of 2007 to collaborate and investigate opportunities to incorporate WirelessHART technology into ISA100. Under terms of the agreement, the HART Communication Foundation and the ISA100 Committee granted each other copyright licenses as part of an effort to identify ways in which the two groups might be able to work together. A joint technical subcommittee, ISA100.12, was also established to assess WirelessHART technology and recommend how it might be incorporated into the ISA100 family of standards. At the time of this writing, ISA100.12 is working on a WirelessHART and ISA100.11a comparison document to increase public understanding of the similarities and differences between the two groups.
In the form that is currently working its way through subcommittee evaluation, ISA100.11a provides tunneling capability for WirelessHART. However, Manges says the end-users involved in the ISA100 effort, while they indicated acceptance of that approach, have asked for more robust interoperability. And this is one of the points being addressed as stakeholders work to get the necessary approvals to move the ISA100.11a spec to full committee and public availability.
“One of the alternatives being discussed is a dual-stack,” says Manges. He says that while this may be a good option in some instances, he wonders whether it’s a good idea to require that every device that offers ISA100 also offer WirelessHART. “The question is how do we best meet the needs of the end-user community,” says Manges. At the same time, Manges says the committee must also keep in mind the business cases presented by the device suppliers.
WirelessHART, on the other hand, was able to more easily overcome some of the complexities currently facing the ISA100 development effort by leveraging its existing installed base of HART users and suppliers. Since the HART Protocol already has a solid reputation in the end-user and supplier communities, the HCF was able to bring wireless to market much more quickly than ISA100.
“HART Communication and WirelessHART provide the mechanism and a standard users can use to move forward with new technology without leaving the old behind,” says Ed Ladd, Jr., director of technology programs for the HART Communication Foundation. “In our industry, technology jumps in the past have required throwing out the old for the new. Well, HART Communication, whether wired or wireless, will not allow that to happen, so users have the capability of moving forward with wireless without disconnecting the wired using the same tools, training and people.”
ISA100.11a vs. WirelessHART
As noted earlier, ISA100 was conceived as a suite of standards with the aim of meeting the unique needs of a range of industrial wireless application scenarios. The first standard to be offered under the ISA100 designation will be ISA100.11a, which will provide capabilities for wireless monitoring and soft-point control. One of the key differences between ISA100.11a and WirelessHART will be in how it defines devices in a network. While WirelessHART essentially treats each device as a router, ISA100.11a allows for “dumb” nonrouting devices within the network.
As such, WirelessHART offers a quick-and-easy approach for deploying wireless in an industrial application scenario. ISA100.11a, on the other hand, will provide more flexibility to the end-user in terms of how devices are defined in the network.
Given this, it is conceivable that WirelessHART and ISA100 could ultimately have a more symbiotic relationship than a competitive one, with WirelessHART providing a fast track for end-users to effectively deploy standards-based wireless systems and ISA100.11a providing the application flexibility for more complex applications.
Regarding convergence of WirelessHART and ISA100, Ladd says one way the two standards could work together is in communication from the gateway to the backbone of the network. “At the backbone level, WirelessHART does not dictate what technology should be used,” says Ladd. “So it is perfectly logical that WirelessHART gateways could talk on an ISA100 backbone.”
Manges says one of the complicated obstacles facing the ISA100.12 Working Group as it examines WirelessHART interoperability is ISA100’s status as a standard under review by the American National Standards Institute (ANSI, www.ansi.org). ANSI requires all elements of the standards it reviews to be open to the public, which could be problematic in the case of WirelessHART since it is HCF intellectual property. As such, Manges says the level of inherent support ISA100.11a offers for WirelessHART may be somewhat limited. Nevertheless, he says the ISA100 Committee has been tasked by the end-users community to provide WirelessHART interoperability, and it is working to that end.
The Future of Industrial Wireless
In October at its Global Users Exchange in Washington, D.C., Emerson Process Management showcased real-world applications of WirelessHART technology. Just a year earlier, at the same event, Emerson was demonstrating beta versions of WirelessHART devices that had not yet been released on the open market. Commenting at this year’s Users Exchange on how far things had come in just a year, Steve Sonnenberg, president of Emerson Process Management, said, “[Wireless] is a technology that will be, and is being, used widely within the process industry.” And, regardless of which standards are being used, it seems the inertia behind the wireless standardization effort will ultimately prove this out.
In fact, Manges says industrial wireless may be the first evolution of plant automation that is entirely top-down driven, as he says management in many cases is leading the drumbeat to rid the plant floor of wires. At NASA (www.nasa.gov), for example, Manges says there is a move afoot to require a business case to add wires on the Space Shuttle.
Ladd is equally optimistic about the future of industrial wireless, but he says end-users must give special consideration to the types of applications in which they employ wireless. “In my opinion, the biggest obstacles [for industrial wireless] are potentially the users themselves and fear of the technology. Wireless is here, it works and works well, but users need to be aware of the risks and the rewards,” says Ladd. “Engineered properly, wireless technology will provide a huge technology leap, but don’t get overly enthusiastic. Most importantly, pick the right applications.”
Ultimately, Manges sees wireless as the defacto communications method for industrial applications. “Do you still have a wired phone at home?” he asks. “Anybody who thinks wireless is just about getting rid of the wire, doesn’t understand,” says Manges. “It changes the way we think about our jobs. Our goal is to make wireless the obvious choice.” –
Matt Migliore is the editor in chief of Flow Control magazine. He can be reached at firstname.lastname@example.org.