Wireless win: Industry groups working on standard for linking field devices to control networks
With manufacturers showing more interest in deploying wireless field devices, the need for a more robust, standards-based backbone transport link between remote gateways and central control systems and other platforms rises in importance. A new collaborative partnership between ISA and the Fieldbus Foundation will address the issue.
“We’ve got lots of need for wireless where field devices are remote from the central control facility, making it inconvenient or impossible to run wires or fiber,” says Herman Storey, senior global solutions consultant for a Fortune 10 oil company. “It’s pretty hard to string wire—not to mention expensive—between an offshore platform and an onshore control center, for example. We’ve had to run communications over WiMAX, Wi-Fi, satellite, and cell phone links to make it happen.”
Though there are proprietary solutions available, there are no open standards in backhaul. “An open standard would lead to better stability and life expectancy, and improved change management,” Storey states.
Storey was instrumental in getting ISA and the Fieldbus Foundation to consider working together to develop an open, wireless backhaul protocol standard. The two groups announced in October they’ll collaborate to develop such, and formed the ISA 100.15 Wireless Backhaul Backbone Working Group, co-lead by Dr. Penny Chen, principal systems architect with Yokogawa , representing ISA; and Dave Glanzer, director of technology development for the Fieldbus Foundation.
|An industrial backhaul backbone would link a Fieldbus-enabled network to a centralized control system—and in the case of ISA 100.15, the backhaul link would be wireless.|
The group will focus on defining common network interfaces to enable interoperability between different wireless field networks, including, among others, ISA 100.11a, WirelessHART, ZigBee, RFID, UWB, and 802.11a/b/g/n-based wireless networks on the edge of the enterprise. It also will define prioritization of multiple applications to ensure quality of service—and to address security. The first of these backhauls will employ Fieldbus Foundation’s High Speed Ethernet (HSE) technology. The standard will be embodied within the ISA 100 family of standards; and be jointly owned and co-marketed by both groups.
“We found that the problem doesn’t end in the field,” says Wayne Manges, program manager at the U.S. Department of Energy Oakridge National Laboratory, and chairman of ISA 100. “If the backhaul isn’t secure and reliable, all your effort on the front end is lost.”
End point-to-end point wireless connectivity must address what Manges calls the fab four: throughput, reliance, security, and latency. “If you don’t address all four, you can get into trouble real quick,” he says. ISA 100.11a has garnered much of the attention of late, but “it only focuses on solving the wireless communication problem up to the gateway,” Manges adds.
A backhaul backbone is a major component of hierarchical network communications architecture—one that sits between gateways that link subnetworks arrayed at the edge of the enterprise and centralized core control points. In contrast, Fieldbus is a family of industrial network protocols for real-time distributed control, managing links between PLCs and measurement and control, sensors, actuators, and controllers. An industrial backhaul backbone, then, would link the Fieldbus-enabled network to a centralized control system—and in the case of ISA 100.15, the backhaul link would be wireless.
WirelessHART is supported by Fieldbus; and efforts are under way to have it included in ISA 100.11a.
“We’re presuming that ISA 100.15 will be complementary to what we’re doing,” says Ron Helson, executive director of the HART Foundation.
Manges says the key is to find the appropriate wireless technology and protocols that can provide the quality of service required for industrial backhaul.
But as the consultant Storey points out, “So far, it’s all been done ad hoc. The goal now is to join the expertise of ISA and that of Fieldbus, and get the best of both, where we’ll have interoperability and support and won’t have to do the creation work in-house. That should save us money and may put new capabilities into the field too.”