SCADA is an acronym that stands for Supervisory Control and Data Acquisition. SCADA refers to a system that collects data from various sensors at a factory, plant or in other remote locations and then sends this data to a central computer which then manages and controls the data SCADA syst ems are used not only in industrial processes: e.g. Steel making, power generation (conventional and nuclear) and distribution, chemistry, but also in some experimental facilities such as nuclear fusion.
The size of such plants range from a few 1000 to several 10 thousands input/output (I/O) channels. However, SCADA syst ems evolve rapidly and are now penetrating the market of plants with a number of I/O channels of several 100 K: we know of two cases of near to 1 M I/O channels currently under development. There are man y parts of a working SCADA system.
A SC ADA system usually includes signal hardware (input and output), controllers, networks, user interface (HMI), communications equipment and software. All together, the term SCADA refers to the entire central system.
The central system usually monitors data from various sensors that are either in close proximity or off site (sometimes miles away). An industrial measurement and control system consisting of a central host or master (usually called a master station, master terminal unit or MTU); one or more field data gathering and control units or remotes (usually called remote stations, remote terminal units, or RTU's); and a collection of standard and/or custom software used to monitor and control remotely located field data elements.
SCADA components Application Servers • Application servers provide the computing platform for the SCADA System, included servers are: - Real-time database - Historical database - Energy Management applications • State Estimation • Optimal/Dispatcher Powerflow • Voltage Stability Assessment • Etc. DNP – Distributed Network Protocol Describes standards for SCADA protocol facilities such as data requests, polling, controls, and report by exception (RBE). Master-slave and Peer-to-Peer communication architectures are supported by DNP 3.0.
Contemporary SCADA systems exhibit predominantly open-loop control characteristics and utilise predominantly long distance communications, although some elements of closed-loop control and/or short distance communications may also be present. Systems similar to SCADA system s are routinely seen in factories, treatment plants etc. These are often referred to as Distributed Control Systems (DCS). They have similar functions to SCADA syst ems, but the f ield data gathering or control units are usually located within a more confined area.
Communications may be via a local area network (LAN), and will normally be reliable and high speed. A DCS system usually employs significant amounts of closed loop control. SCADA systems on the other hand generally cover larger geographic areas, and rely on a variety of communications systems that are normally less reliable than a LAN. Closed loop control in this situation is less desirable.
SCADA comes under the branch of Instrumentation Engineering. The term SCADA stands for Supervisory Control And Data Acquisiti on. Scada systems are used for controlling and monitoring chemical or transport processes and can be used in a factory environment such as electic power generation, water supply systems, gas and oil pipelines or any other distributed processes. A typical SCADA syst em comprises of i/o signal hardware, controllers, software,netw orks and communication.
SCADA system is normally used to monitor and control a remote site or a. Distribution that is spread out f or a long distance. A n RTU (Remote T erminal Unit) or a PLC (Programmable Logic Controller) is usually used to control a site a utomatically.
The SCADA system also provides a host control functions for the supervisor to control and define settings. For example, in a SCADA syst em a PLC can be used to control the flow of cooling water as part of an industrial process. At the same time the supervisor can use the Host control function to set the temperature for the flow of water. It can also have alarms and can record the flow of water temperature and report back to the SCADA system. The RTUs and PLCs are responsible for data collection such as meter readings, equipment status etc and communicate back to the SCADA system.
Thi s data can be stored in a database for later analysis or monitored by a supervisor to take appropriate actions if required. SCADA syst ems typically implement a distributed database, commonly referred to as a tag database, which contains data elements called tags or points. A point represents a single input or output value monitored or controlled by the system.
Points can be either 'hard' or 'soft'. A hard point is representative of an actual input or output connected to the system, while a soft point represents the result of logic and math operations applied to other hard and soft points. Most implementations conceptually remove this distinction by making every property a 'soft' point (expression) that can equal a single 'hard' point in the simplest case. Point values are normally stored as value-timestamp combinations; the value and the timestamp when the value was recorded or calculated. A series of value-timestamp combinations is the history of that point. It's also common to store additional metadata with tags such as: path to field device and PLC register, design time comments, and even alarming information.
SCADA comes under the branch of Instrumentation Engineering. The term SCADA stands for Supervisory Control And Data Acquisiti on. Scada systems are used for controlling and monitoring chemical or transport processes and can be used in a factory environment such as electic power generation, water supply systems, gas and oil pipelines or any other distributed processes.
A typical SCADA syst em comprises of i/o signal hardware, controllers, software,netw orks and communication. SCADA system is normally used to monitor and control a remote site or a distribution that is spread out f or a long distance. A n RTU (Remote T erminal Unit) or a PLC (Programmable Logic Controller) is usually used to control a site a utomatically. The SCADA system also provides a host control functions for the supervisor to control and define settings.
For example, in a SCADA syst em a PLC can be used to control the flow of cooling water as part of an industrial process. At the same time the supervisor can use the Host control function to set the temperature for the flow of water.
It can also have alarms and can record the flow of water temperature and report back to the SCADA system. The RTUs and PLCs are responsible for data collection such as meter readings, equipment status etc and communicate back to the SCADA system. Thi s data can be stored in a database for later analysis or monitored by a supervisor to take appropriate actions if required.
SCADA syst ems typically implement a distributed database, commonly referred to as a tag database, which contains data elements called tags or points. A point represents a single input. Output value monitored or controlled by the system. Points can be either 'hard' or 'soft'. A hard point is representative of an actual input or output connected to the system, while a soft point represents the result of logic and math operations applied to other hard and soft points.
Most implementations conceptually remove this distinction by making every property a 'soft' point (expression) that can equal a single 'hard' point in the simplest case. Point values are normally stored as value-timestamp combinations; the value and the timestamp when the value was recorded or calculated. A series of value-timestamp combinations is the history of that point. It's also common to store additional metadata with tags such as: path to field device and PLC register, design time comments, and even alarming information.