PACE 60-year Anniversary Series: Control Systems
supported by Invensys
The history of automatic feedback control systems dates back more than 2,000 years. One of the earliest on record is a water clock that kept time by regulating a vessel’s water level and flow, attributed to a Greek inventor called Ktesibios in Egypt around 270 B.C.
Automatic control has evolved a lot over the years, and today’s industrial plants rely on an array of control systems, including distributed control systems (DCS), manufacturing execution systems (MES), supervisory control and data acquisition (SCADA) systems, and programmable logic controllers (PLC).
Though has its own unique history, each system shares the workload of gathering data and controlling disparate machines in the plant, allowing them to work in a cohesive fashion.
When the first DCS units appeared on the industrial market in the mid-1970s, they were mainly focussed on control and providing an operator interface. Today, DCS technology has evolved to integrate plantwide assets and operations information.
According to Rockwell Automation manager for process solutions South Pacific region, Andrew Sia, the first DCS products were adopted in Australia in the oil and gas sector. When Sia entered the industry in the mid-1990s, companies were still relying on pneumatic-based control systems and field devices.
“These systems were gradually superseded by new electronic versions. Further development resulted in modern control systems which utilise digital Fieldbus networks (Hart, FF, etc) to gather much more data from field devices than a single temperature or provide a setpoint. More recently the availability of Ethernet field instrument devices has allowed for a more common network throughout the system architecture,” he told PACE.
In Sia’s opinion, one of the biggest milestones in DCS technology since he began working in the industry has been the ability to build a control system with a required network structure that feeds information into a single platform. Connecting this to the overall enterprise provides access to much greater and more complex information.
“Termed the ‘information age’ this has its own challenges, leading users to ask ‘what do we do with all of this information?’” said Sia.
According to Sia, integrated software is now essential to interpret this information in real-time, and manage operations effectively. A platform that includes reporting, interactive dashboards, OEE, asset tracking and business system connectivity, enables truly plant-wide decisions that can produce a positive impact to plant operations and ultimately the manufacturing bottom line.
“Over the last five to 10 years in particular there have been a lot of developments in the technology. We are really only now observing a strong take-up in the local Australian market as the industry was already very well-established,” he said.
Yokogawa introduced the company’s CENTUM in 1975, making it one of the world’s first distributed control systems. (Image courtesy of Yokogawa.)
Sia claims companies utilising the power of software in modern DCS process solutions, coupled with the ability to network through industrial Ethernet and digital buses to the field allowing plant visibility, enable them to make business and operational decisions to significantly improve efficiency and yield in today's highly-competitive economic environment.
When Schneider Electric – industry solutions marketing manager, Alison Koh started her career 16 years ago, it was common for SCADA solution providers to have an electrical workshop where engineers soldered and wired together electrical components and developed DOS-based software to acquire the data for presentation on a black and green monitor.
“Of course, SCADA goes back further than my career, to the 1960s, its adoption driven by the ever-increasing complexity of hardwiring master stations and the move to computers became a realistic proposition in terms of physical space and cost,” she told PACE.
“Uptake continued through into the 1980s as computers improved in performance, size and cost, and escalated dramatically in the 1990s. Today, in Australia, SCADA is viewed as a necessity for a globally-competitive, growth-oriented industrial company.”
Koh was an employee of Citect – one of the first SCADA companies in Australia – before it was acquired by Schneider Electric back in 2006.
“Historically, Citect differentiated from product vendors, having grown out of a system integration company, CI Technologies, and providing tailored systems for manufacturers – the first being Argyle Diamonds, now owned by a major resources conglomerate, back in 1973,” she explained.
“My first experience was using Citect v3.10 for Workgroups in 1997. This, I was told, was a huge step from the previous DOS versions! When we look at what is commonplace today in the SCADA (and also Control/PAC) layer, the evolution is incredible in terms of functionality, data accessibility and granularity.
“This first experience was to integrate a weigh scale data into the Citect system – completely non-standard (by today’s terms) and thus requiring a dedicated communications driver (though we didn’t call it that back then!). Where have PCI slots gone? There was certainly no wireless solutions for plant back in those days.”
March 7, 1902. The first Allen-Bradley Motor Starter – 40HP, 110V, Direct Current – was released in 1902. (Image courtesy of Rockwell Automation.)
Koh has experienced a number of improvements in SCADA technology during her career, including in the areas of redundancy, graphics and the adoption of cloud-based services.
“There have been huge advancements in every area of SCADA Systems. We saw the solidification and enhancement of redundancy, the onset of service-oriented and flexible architectures, mobile solutions, and solid growth in visualisation and graphics. With increasing CPU and storage performance, data acquisition and data storage (trends, alarms and historians) have grown tenfold, allowing access to the remotest data,” she recalls.
“In this decade, the growth of object-oriented configuration, remote centralisation across enterprise and forays into the Cloud (typically owned assets rather than external arrangements) have been notable advancements. Another major development was the SCADA Community, the advance of internationally-accepted standards, and increasing evolved techniques that leverage the technology for more efficient operations, for example, ASM (abnormal situation management).”
Omron Electronics engineering manager, Harry Mulder, has been working in the industry for 24 years; 23 of these have been with Omron. He first came across industrial control systems after finishing his apprenticeship.
“It was in 1989 that I worked for a medium-to-large integration company that installed both building management and water treatment systems, all with their own purpose-built hardware. This was before the days PCs really took hold, so our (propriety) SCADA system also ran on our own computer hardware,” Mulder told PACE.
Mulder explains that Omron’s first control systems involved the automation of simple, stand-alone machines.
“They were mostly just PLCs that replaced old relay logic systems. The main reason for the switch to a microprocessor-based control was that systems with relay logic were proving rather cumbersome and difficult to maintain, even for machines with modest functionality,” he said.
Mulder claims the biggest changes in PLCs over the years have been in the software they use, rather than the components themselves.
“Hardware-wise, control systems have become cheaper, faster, and more capable/powerful; all at an ever-increasing rate of change. This is much like what computer hardware has done. However, due to the importance placed on the reliability of a control system, they have always been several iterations behind computer hardware,” he explained.
“But the really big changes have been in software, both programming software and also the software used within the control system itself. The single biggest advance has been the implementation of standards, which have resolved so many of the inter-operability problems that used to plague the older, propriety control systems.”
According to Mulder, modern control systems are more powerful and incorporate more functionality than their predecessors, however their basic make-up hasn’t changed much.
“PLCs still have ladder diagram (much of it unchanged), but they also incorporate motion control and safety. Networking is the other big change, not only can we now connect to the internet (for truly global connections), but at the other end of the spectrum, our field networks work so much faster and can connect to almost any device,” he said.