RTU use expands, must make full use of advantages
Control Engineering China (CEC) noted an expansion of remote terminal unit (RTU) use and asked an expert, Dr. Fang Yuanbai, professorate senior engineer of Kunming Engineering & Research Institute of Non-ferrous Metallurgy, about related trends.
CEC: RTU applications have expanded significantly the past two years from oil and gas fields to other areas. Well-known automation companies accelerated development, and mergers and acquisitions happened. RTU technologies also advanced. Why is RTU popular?
Fang Yuanbai: RTU started to be used by the U.S. oil and gas industry in the 1980s and gradually expanded to electricity, environmental protection, heating networks, water conservancy, and long-distance pipelines. Recently it has further expanded to transportation, metallurgy, petro chemistry, logistics, and agriculture. It continues to gain popularity. We can say that in a specific application, such as data collection in the oil and gas field area, RTU is the main trend. However, in the whole oil and gas industry, RTU is not a main trend in automation equipment systems, where, in my opinion, programmable logic controllers (PLCs) and distributed control systems (DCSs) are more popular. Output, sales volume, and actual application of PLC and DCS manufacturers far exceeds that of RTU manufacturers.
RTU is gaining popularity for the following reasons:
The enterprise increasingly needs information. In the past, some measurements were given up because they are scattered and the cost to collect data is too high. Now data collection is needed.
As enterprises increase in size and mergers occur, groups can span across cities or even some provinces. Central management requires remote data collection.
As RTU costs decrease, enterprises that gave up remote data collection because of high investment costs are now starting to implement RTU systems.
RTU technologies have advanced. Communications, Internet, database, and signal transmission technologies also promote wider RTU use and market expansion. Industrial wireless transmission technologies provide new RTU signal transmission methods.
Some newly emerging industries, such as solar power plants, wind power plants, and smart buildings, are new applications for RTUs. Previously, we heard of digital oil fields, digital petro chemistry, and digital pipelines. Recently I heard about digital mines in the metal mineral industry, and I also heard propaganda about a “digital city,” although we are still far from it, actually.
CEC: The definition of enterprise RTU is a little different. How do you define RTU?
Fang Yuanbai: In my opinion RTU can be defined narrowly and broadly. RTU in a narrow sense is defined as the basic components of a SCADA (supervisory control and data acquisition) system. RTU in a broad sense is defined as the remote input/output (I/O) connections used by control systems, including PLC, DSC, field control systems (FCS), and SCADA.
The earliest SCADA had only data collection capability, and RTU had only two basic functions: data collection and processing, and data transmission. However, with the functions of the system expanded, RTU added PID control, logic control, and mathematical computation (such as gas temperature and pressure compensation). So RTU for SCADA and remote I/O of PLC, DCS, and FCS have some common and different attributes. RTU for SCADA can be connected to a control system comprising PLC, DCS, and FCS. For example, we connected a remote supervisory and control terminal (an RTU product from Schlumberger) to a DCS system in 1990s. Remote I/O and even PLCs, DCSs, and FCSs can be connected to SCADA systems. Beijing Echo Technology Co., which focuses on development of industrial RTU products, rolled out the Echo 5100 distributed control system with field control layers composed of RTUs or PLCs based on a standard DCS structure.
CEC: What’s your view on RTU technology advances?
Fang Yuanbai: SCADA systems aren’t applied as often as PLC, DCS, and FCS are. To boost the application of RTU and SCADA, we must make full use of RTU advantages. For example, RTUs are mainly installed in the field, especially in rural areas. Usually PLC and DCS remote I/O are not used in these areas. To gain market share, RTUs need to withstand high temperatures and humidity, have dielectric strength, and resist interference, so RTUs are superior to PLC and DCS remote I/O.
Wireless was applied to many RTU and SCADA applications earlier than PLC, DCS, and FCS applications, and the scope of SCADA applications is much wider. However, the industrial wireless standards were proposed and set by manufacturers of PLCs, DCSs, and FCSs. This may be because of the lack of influence or lack of vision of RTU manufacturers.
Market volume of automation (including control systems) ranks high globally. However, the big players in this market are still overseas automation companies, such as U.S.-based Emerson Process Management, German-based Siemens, U.S.-based Honeywell, Japan-based Yokogawa, and U.S.-based Foxboro [now part of U.K.-based Invensys]. China Beijing Hollysys and Hangzhou Supcon are growing and can compete with big players overseas, in some areas. However, when it comes to RTUs, few companies (such as Beijing Echo Technology Co.) can compete with overseas players. I hope more China enterprises focus on the development and market promotion of RTU, build high-end national brands, and make a greater contribution to the development of the RTU industry in China.
RTU and SCADA are:
– Growing rapidly in many markets as costs decrease and capabilities increase
– Advancing and important in China and abroad
– Dominated by non-Chinese companies, though several China-based companies are gaining
– This appeared in Control Engineering China and was translated for the Control Engineering North American print and digital edition. Edited by Mark T. Hoske, content manager CFE Media, Control Engineering, Plant Engineering, and Consulting-Specifying Engineer, firstname.lastname@example.org.
http://article.cechina.cn/12/0819/08/20120819084130.htm (See the original article in Chinese)
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