The many faces of SCADA

Thought You Knew What A SCADA System Was? Think Again

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By Paul Miller

Today’s state-of-the-art SCADA is not your granddad’s supervisory control and data acquisition system. It’s not even the one you may have cut your teeth on as a new process engineer back in the day. The monolithic master station running proprietary supervisory applications is long gone. So is communication via inflexible, single-purpose, analog remote terminal units (RTUs) over often-tenuous, low-bandwidth radio or telephone system-based links. 

Over time, commercial-grade personal computers (PCs) or servers running more open and interoperable, standards-based HMI and supervisory applications replaced that proprietary master station. Broadband wireless networks or Internet protocol (IP) technology lifted directly from the commercial world have replaced the telephone and old-fashioned radio links. Those dumb, analog RTUs have evolved into today’s much smarter and more functional digital RTUs. And, increasingly, industrial programmable logic controllers (PLCs) or programmable automation controllers (PACs) are taking the place of dedicated RTUs in many SCADA applications. We also now have a new class of intelligent electronic devices (IEDs) that communicate with either the RTUs or directly with the SCADA via standard protocols.

“SCADA used to be a proprietary station that reached out to RTUs with a limited number of points and some minor control algorithms going back and forth,” says Jack Peterson, senior project manager, energy supply and management, at Southern California Edison, Rosemead, Calif. “Today, SCADA is more closely aligned to a DCS or specialized hybrid control system that uses open architecture platforms and today’s high-speed networking technology. These are combined with secure protocols and secure stations following new guidelines, such as those issued by NERC (North American Electric Reliability Corporation) and FERC (Federal Energy Regulatory Commission) in the electric industry. Now SCADAs are sitting on top of PCs or laptops doing everything they used to do – only faster, smarter and more connected.”


This evolution offers many advantages to end users.

“Over the last 25 years, SCADA has evolved by orders of magnitude, pushing more intelligence from the central control room into the field and embracing standard protocols over proprietary protocols,” says Mike Chmilewski, vice president/general manager of the controls business at Invensys Process Systems. “This provides new degrees of freedom for field device selection and for integrating real-time operational data with advanced applications and business systems to enable real-time business control.”

“While SCADA was previously used as a monitoring and control system for RTUs, it now has a broader concept,” says Prasad Pai, Proficy HMI/SCADA iFIX Product Manager at GE Fanuc Intelligent Solutions. “PLCs have taken over much of the control, and SCADA’s scope has expanded into new applications. Because of the flexibility of SCADA, everything that happens in a facility can now be in a single application. What we used to think of as DCS has now become a PLC. It all used to be in one box – both hardware and software. Now a PLC is controlling the plant, and the software, the SCADA, is PC-based. What we used to think of as DCS has shrunk in size, but not in functionality.”

Eduardo Ballina, GEO-SCADA business manager at Wonderware says, “The software originally used for supervisory control has greatly increased in capability over the years. Functionality, such as optimization simulation, and asset management, can now more easily be incorporated into the same solution, bringing these systems from supervisory control into the management space.”

Phil Aponte, HMI/SCADA product marketing manager at Siemens Energy and Automation, says, “SCADA is evolving from a centralized architecture to a more distributed architecture, and the trend is to push production data up the chain to the business. In brownfield facilities, where DCSs, PLCs or other automation platforms from different vendors are already in place, SCADA is also often the path of least resistance for migration purposes.”

As SCADA moved closed, proprietary, application-specific industrial technology to more open and interoperable commercial information technology (IT), cybersecurity became a concern. Post-9-11 visions of terrorists or disgruntled employees hacking into a SCADA system to disrupt the nation’s electricity grid, shut down a critical pipeline, threaten a municipality’s water supply, blow up a tank farm or something spawned today’s thriving cybersecurity industry. With support from the U.S. Department of Defense, Department of Energy, Department of Homeland Security and other governmental agencies, new cybersecurity technology has been developed and is being implemented in industrial facilities. Important new cybersecurity standards are also emerging.

Cybersecurity has developed into a healthy specialty within the already healthy IT consulting industry.


And, of course, somewhere along the line, the very meaning of SCADA changed. Originally, SCADA technology was used almost exclusively to monitor and provide supervisory control and management functions remotely for industrial or municipal operations that extend well beyond the physical confines of a single plant or industrial complex. Traditional SCADA applications included remote monitoring and supervisory control for electric transmission and distribution networks, oil and gas pipelines, and municipal water and wastewater systems. Today, a “SCADA” can be any HMI, supervisory or other application running in a personal computer (typically in conjunction with a separate control platform).

As a result, SCADA technology is being implemented in some new and interesting applications. According to George Quesada, a product manager at ABB, “SCADA has grown by leaps and bounds in the oil and gas industry. This is particularly true in the upstream sector, where drilling activity has been exponential in the last four years, making it a necessity to be able to monitor and control wells, upstream compressor stations, water injection, and well tests.”

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