Companies hate being surprised with malfunctions or unnecessary investments in premature or unneeded maintenance or equipment. Faster networking and better devices can put an end to these surprises—and boost the factory floor-to-boardroom information flow for a successful enterprise asset management program.
But are these two mechanisms the most important ones? Perhaps more important is delivering the right information to the right people at the right time, and then making speedy decisions and responding. Either alone or combined with fast networks and smart devices, there also may be other equally valid contributors. These include better standards and integration; use of the Internet to ensure better connectivity; more focused, but less frequent, data collection; and adjustment of data-transfer speeds from field devices to collection points. Maybe the type of network and its ability to have always-open pathways for data transmission is the focus.
Today’s technology provides sufficient speed in the data-collection loop, says automation consultant Henry Marks, of Houston-based Marks & Associates. He believes it is preferable to use Foundation Fieldbus (FF)-certified devices “because it (the Foundation’s H1 bus) is bi-directional and the devices are interoperable—and you have a large number of parameters that are continuously monitored.”
However, faster networking is needed from the data cluster to the enterprise, he believes. In the past few years, high-speed Ethernet (HSE) with the Foundation’s protocol has been accepted in plants and in management systems, as well as in process systems, he states. “This is the reason the Fieldbus Foundation decided to use that protocol. It is being used in industry, but is limited.” That’s because manufacturers have protected their proprietary programmable logic controller (PLC) systems—and that has prevented users from capitalizing on advantages of HSE, Marks says. “As a result, very few manufacturers favor using distributed control at the field device level. They still want to do it in their mainframe host, though.”
HSE would be central to a project for a new plant or an upgrade, Marks indicates. The first thing he would do is “lay down a control system network through the facility, and that would be FF-HSE. The control network permits communications among the various linking devices throughout the plant, the user—such as a human-machine interface—and plant common systems, such as asset management.” But, Marks adds, “we don’t see FF-HSE replacing H1 at the device level. Whenever we need information from a device, H1 is more than adequate in terms of speed. However, you cannot communicate from cluster to cluster with H1.The integration of it and HSE communications is vital, because you only use the speed you need.”
But better standards and integration “are far more important than faster networking for managing assets,” says Houghton Leroy, a senior analyst at ARC Advisory Group in Dedham, Mass. Integration standards are the key, he says. “But a lot of control system devices do not have the inherent Internet protocols to manage their performance over an open-standard protocol. We’re talking about Web-based architectures, eXtensible markup language, transfer control protocol/Internet protocol . . . If there’s a network that can distribute the information in a timely manner, it makes rapid decision making and response possible. That’s a connectivity-and-integration issue, not speed-of-network issue.”
Focused data acquisition
Better management may come from focused, but less frequent, data gathering. “Users don’t need to collect most measurements all that often to determine that there’s an impending asset issue,” Leroy says. Agreeing is Randy Miller, senior principal research engineer and manager of loop management services for Honeywell Hi-Spec Solutions, in Thousand Oaks, Calif. “When we look at a typical plant, it will have 1,000 PID (proportional-integral-derivative) loops. We don’t have the bandwidth in the control network to collect data continuously, given the state of the art of networks. We’re forced to go to batch-wise collections, or we can compromise in collecting continuously, but at a slower frequency. The consequence of that compromise is that it lessens the resolution of the data we can collect.” Unless a user monitors a particular loop for a particular operation, he recommends 5,000 samples at one-second frequency for a flow loop. “We would cycle through all flow loops, maybe collecting 20 loops simultaneously,” Miller says, regarding use of a Honeywell product called LoopScout.
Also not to be ignored is the Internet. David Bell, vice president of application engineering for Lisle, Ill.-based SmartSignal Inc., says a client—Panhandle Eastern Pipe Line Co.—uses Equipment Conditioning Monitoring software to track performance of natural-gas compressor stations in its 6,500-mile system. “Incoming data come over the company’s supervisory control and data acquisition network. Analytical results are posted over the Web, so they are available for the maintenance personnel wherever they may be. As far as we’re concerned, the outbound data should be transmitted over high-speed networks such as DSL (digital subscriber line) to give better review.”
To facilitate the sensors-to-boardroom flow of information, on-demand data transmission at the fieldbus level must be the priority. Nick Zucchero, manager of major technology programs in the research-and-development group of Invensys Foxboro, in Foxboro, Mass., says users do not want the control network to introduce any delays in transferring critical information from the device. “Devices connected to the fieldbus world—FF H1, FF HSE, Profibus PA or DP—are becoming more and more intelligent and complex. The microprocessors in there are allowing these devices to carry much more information about the health and operational integrity of the device.”
Reliability is crucial, he says. “A network at the control level, with a high degree of redundancy, is very important.” “The control system has to accommodate the installed base and the installed base has a multiplicity of buses, each with its own performance capabilities and control models,” Zucchero says. “Therefore, you want the control network to be able to take that data and get it to the asset management package on time.
Invensys Foxboro incorporates fast Ethernet as the backbone of its industrial control network systems. The distinction is that devices are connected to a fieldbus system. “We have components on our system called fieldbus modules—the I/O (input/output)—that connect to the mesh network. Fast Ethernet gives us the performance.” Zucchero predicts the focus on networking will be to make the fieldbus more high-performance, “and that will require new types of devices.”
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