asers, vision systems, RFID and other advanced technologies often start out as solutions looking for problems. In the early stages, researchers and academicians are all agog over the possibilities, but end users, industrial machine builders and system integrators just like you remain skeptical. “Prove to me that it works, and I’ll buy it,” is your time-honored response to pioneering use of new technology.
And so it goes with mesh networks. Our staff still is looking for evidence that they work in a control application. You’ve probably heard stories of the benefits of mesh networks, and that they’re being used in universities, farms, wastewater treatment plants and IT installations. You may even have a mesh network at your company headquarters, linking all the PCs in accounting and human resources.
It’s been shown that wireless mesh networks can save a fortune in wiring and installation costs. Preliminary results from monitoring applications are promising. The problem is finding a working mesh network being used in a real process control, machine control, or discrete automation application.
A Mesh of Monitoring Apps
We contacted most every process control, automation and networking vendor, looking for industrial mesh networks. Our research revealed some industrial monitoring applications are starting to emerge, especially on the wireless side. For example, at Intel’s Ronler Acres semiconductor fab plant in Hillsboro, Ore., vibration engineer Mick Flanigan works with vibration sensors linked by a mesh network. It’s all still in development, Flanigan says, but the results are promising.
“We monitor pumps, compressors, and other plant facilities equipment with vibration sensors,” he reports. “Each machine has 1â€“12 vibration sensors that report via wireless to a central wireless processor, which converts the data and transmits it to a PC that runs asset management software.”
Robert Poor, chief technology officer of Ember has been promoting an installation of Ember’s wireless network in an unnamed water treatment plant. He points out that the wireless network functions well in the presence of concrete walls, pipes and other obstacles.
Mark Pacelle, vice president of marketing at Millennial Net pointed out two installations that use his company’s mesh network equipment. One is an energy management company. “Wiring is an expensive part of implementing an energy management application,” says Pacelle. “With wireless, no re-wiring work is required in a retrofit situation and the cost barrier has been eliminated.”
He also described a natural gas processing company that is using wireless. “Natural gas byproducts such as hydrocarbons, oil and water are stored in tanks in gas fields and trucked off site on a scheduled basis,” he explains. “The company uses wireless sensor networks to monitor gas pressures and fluid levels within the tank farm.”
All these are sensor networks, and are used for monitoring only. It seems no one is controlling anything with a mesh network. Not yet, anyway. There’s evidence that the technology is in beta test, but on balance there were very few if any, willing to talk about it. It’s apparent the jury is still out on this new technology in control apps.
Beta Sites Everywhere
One reason we can’t find mesh networks in process control and automation is that the products are pretty new. Of all the controls vendors we asked, only two replied. Moore Industries announced its Net Concentrator System (NCS) in 2003, and added wireless capability in April 2004. Moore’s NCS is primarily a data acquisition system that can interface with any OPC-compatible DCS, SCADA, or PC-based system. It works with several types of networks.
“The NCS is a smart, rugged I/O system that allows not only control but universal channel mapping across Ethernet, fiber or wireless networks,” says Scott Saunders, director, strategic marketing, at Moore. “The mapping works on a simple â€˜Producer-Consumer’ concept where any NCS node in the network can communicate with any other node on that network. This allows pertinent data to be exchanged between those nodes that only need to send it or see it.”
Saunders could only come up with one example of an actual installation, a retrofit to an existing network at an SNWA (Southern Nevada Water Authority) potable water plant. “SNVA installed the network to gather and share information between remote sites, pumping stations, filter beds, and the control room,” says Saunders. “There already was a fiber and Ethernet network in place, so the NCS fit perfectly into his existing network infrastructure. A few sites were connected to the network via an unlicensed radio system.”
Foxboro announced the Mesh Control Network Architecture for its I/A Series Version 8.0 control systems early in 2004, but did not start shipping until November 2004. “We’ve shipped I/A Series Version 8.0 systems incorporating the new technology for more than 20 different customer projects around the world,” says Roland Gendreau, product marketing manager at Foxboro. “These are in various stages of implementation, from engineering to site acceptance tests. By the time this appears in print, several I/A Series Version 8.0 systems using Mesh Process Control Network technology will have been fully commissioned.”