A BRIEF HISTORY

The development of SCADA can be traced back to the early 1900s with the advent of telemetry. Telemetry involves the transmission and collection of data obtained by sensing real-time conditions. The monitoring of remote conditions became possible with the convergence of electricity, telegraph, telephone, and wireless communication technology. Throughout the last century, more industries, such as gas, electric, and water utilities, used telemetry systems to monitor processes at remote sites.

SCADA began in the early sixties as an electronic system operating as Input/Output (I/O) signal transmissions between a master station and a Remote Terminal Unit (RTU) station. The master station would receive the I/O transmissions from the RTU through a telemetry network and then store the data on mainframe computers.

In the early seventies, DCS (Distributed Control Systems) were developed. The ISAS5.1 standard defines a distributed control system as a system that while being functionally integrated consists of subsystems, which may be physically separate and remotely located from one another. Large manufacturers and process facilities utilized DCS primarily because they required large amounts of analog control.

Further development enabled Distributed Control Systems to use Programmable Logic Controllers (PLC), which being more intelligent than RTUs, have the ability to control sites without taking direction from a master.

In the late nineties, the differences between SCADA and DCS blurred. SCADA systems had DCS capabilities. DCS had SCADA capabilities. Systems were customized based on certain control features built in by designers. Now with the Internet being utilized more as a communication tool, control functions that were once old telemetry systems are becoming more advanced, interconnected and accessible. Automated software products are being developed to exploit the inter-connectivity of the Internet and certain portals can connect to a SCADA system and download information or control a process.

Good SCADA systems today not only control processes but are also used for measuring, forecasting, billing, analyzing and planning. Todays SCADA system must meet a whole new level of control automation, interfacing with yesterdays obsolete equipment yet flexible enough to adapt to tomorrows changes.

Whether you need a new system or are upgrading an older one, it is important to know the system components before you decide on who to talk with and what equipment you will need for your particular application.