Example processes include industrial, infrastructure, and facility-based processes, as described below: These systems can range from just tens to thousands of control loops, depending on the application. Data is accumulated against these unique process control equipment tag references.Įxample of SCADA used in office environment to remotely monitor a processīoth large and small systems can be built using the SCADA concept. SCADA systems typically use a tag database, which contains data elements called tags or points, which relate to specific instrumentation or actuators within the process system. Data may also be fed to a historian, often built on a commodity database management system, to allow trending and other analytical auditing. Data is then compiled and formatted in such a way that a control room operator using the HMI ( Human Machine Interface) can make supervisory decisions to adjust or override normal RTU (PLC) controls. Level 2 contains the SCADA to readings and equipment status reports that are communicated to level 2 SCADA as required. Level 1 contains the programmable logic controllers (PLCs) or remote terminal units (RTUs). Level 4 is the production scheduling level.Level 3 is the production control level, which does not directly control the process, but is concerned with monitoring production and targets.Level 2 contains the supervisory computers, which collate information from processor nodes on the system, and provide the operator control screens.Level 1 contains the industrialised input/output (I/O) modules, and their associated distributed electronic processors.Level 0 contains the field devices such as flow and temperature sensors, and final control elements, such as control valves.The accompanying diagram is a general model which shows functional manufacturing levels using computerised control. The key attribute of a SCADA system is its ability to perform a supervisory operation over a variety of other proprietary devices. Control operations įunctional levels of a manufacturing control operation It is one of the most commonly-used types of industrial control systems, in spite of concerns about SCADA systems being vulnerable to cyberwarfare/cyberterrorism attacks. They can control large-scale processes that can include multiple sites, and work over large distances as well as small distance.
In practice, large SCADA systems have grown to become very similar to distributed control systems in function, while using multiple means of interfacing with the plant. The SCADA concept was developed to be a universal means of remote-access to a variety of local control modules, which could be from different manufacturers and allowing access through standard automation protocols. the real-time control logic or controller calculations, are performed by networked modules connected to the field sensors and actuators. The operator interfaces which enable monitoring and the issuing of process commands, like controller set point changes, are handled through the SCADA computer system. 8 Communication infrastructure and methods.
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