Like the first legless mammals that flopped ashore from a primordial bog to eventually walk, talk, fly airplanes and eat hamburgers, SCADA too has come a long way since its origins. And much like our swimming forebears, the early iterations of SCADA were hardly recognizable as the SCADA we know today.
The acronym SCADA (Supervisory Control And Data Acquisition) originated in the 1960’s with the advent of mainframe computers, but the concept is actually much older – dating back to the 1930’s, when telephone companies began using magnetic stepping switches for switching telephone circuits. Electric utilities quickly adopted the technology, and the notion of remote supervisory control was born.
The earliest efforts to remotely monitor electrical systems were not as automated as today’s. For security, a human operator was involved in the process. Communication between the master station and the remote terminal would be checked and verified by a human operator before changes were made. This select/check/operate scheme is still used today in some cases.
Ok – technically, we’re still not talking about actual SCADA, but it’s getting closer.
Around 1950 companies began using a telephone type pulse counting system to relay information from one terminal to another. Information was conveyed by both the length of pulses as well as their frequency. This quickly proved to be a very reliable system, and was adopted by electric utilities, gas companies, oil pipelines – even airport control towers.
It was around this time that manufacturers began competing over this technology. Major players included Westinghouse, Visicode and General Electric. This competition led to more rapid advancement as we approached the 1960’s and the development of solid state supervisory control technology.
Manufacturers adopted the new solid state technology almost immediately.
Solid State SCADA
Westinghouse introduced REDAC; GE had GETAC, and Control Corporation introduced a system called Supertrol. These first solid state systems were really just solid state versions of the systems already in place.
The term SCADA came into use around 1965, when computer based master stations became common. By this time, computers were capable of real-time functions, which now included scanning and monitoring data, alarming for changes, and displaying the data on digital displays.
By the end of the decade, CRT displays allowed for more advanced HMIs (Human Machine Interfaces) and periodic data logging was introduced. Better computer technology led to more complex monitoring and more advanced displays, and the introduction of network technology paved the way for today’s world of industrial automation and process control.