. Supervisory control and data acquisition ( SCADA) is a architecture that uses computers, networked data communications and for high-level process supervisory management, but uses other peripheral devices such as and discrete to interface to the process plant or machinery. The operator interfaces which enable monitoring and the issuing of process commands, such as controller set point changes, are handled through the SCADA supervisory computer system. However, the real-time control logic or controller calculations are performed by networked modules which connect to the field sensors and actuators. The SCADA concept was developed as a universal means of remote access to a variety of local control modules, which could be from different manufacturers allowing access through standard automation.

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In practice, large SCADA systems have grown to become very similar to in function, but using multiple means of interfacing with the plant. They can control large-scale processes that can include multiple sites, and work over large distances as well as small distance. It is one of the most commonly-used types of, however there are concerns about SCADA systems being vulnerable to cyberwarfare/cyberterrorism attacks. Functional levels of a manufacturing control operation The key attribute of a SCADA system is its ability to perform a supervisory operation over a variety of other proprietary devices.

The accompanying diagram is a general model which shows functional manufacturing levels using computerised control. Referring to the diagram,. Level 0 contains the field devices such as flow and temperature sensors, and final control elements, such as. Level 1 contains the industrialised input/output (I/O) modules, and their associated distributed electronic processors.

Level 2 contains the supervisory computers, which collate information from processor nodes on the system, and provide the operator control screens. Level 3 is the production control level, which does not directly control the process, but is concerned with monitoring production and targets. Level 4 is the production scheduling level. Level 1 contains the (PLCs) or (RTUs). Level 2 contains the SCADA software and computing platform. The SCADA software exists only at this supervisory level as control actions are performed automatically by RTUs or PLCs. SCADA control functions are usually restricted to basic overriding or supervisory level intervention.

For example, a PLC may control the flow of cooling water through part of an industrial process to a set point level, but the SCADA system software will allow operators to change the set points for the flow. The SCADA also enables alarm conditions, such as loss of flow or high temperature, to be displayed and recorded.

A loop is directly controlled by the RTU or PLC, but the SCADA software monitors the overall performance of the loop. Levels 3 and 4 are not strictly process control in the traditional sense, but are where production control and scheduling takes place.

Begins at the RTU or PLC level and includes readings and equipment status reports that are communicated to level 2 SCADA as required. Data is then compiled and formatted in such a way that a control room operator using the HMI can make supervisory decisions to adjust or override normal RTU (PLC) controls. Data may also be fed to a, often built on a commodity, to allow trending and other analytical auditing. 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 according to such as the. Data is accumulated against these unique process control equipment tag references. Examples of use.

Example of SCADA used in office environment to remotely monitor a process Both large and small systems can be built using the SCADA concept. These systems can range from just tens to thousands of, depending on the application. Example processes include industrial, infrastructure, and facility-based processes, as described below:. include, and refining, and may run in continuous, batch, repetitive, or discrete modes. processes may be public or private, and include and distribution, wastewater collection and, and, and. Facility processes, including buildings, airports, and.

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They monitor and control systems (HVAC), and. However, SCADA systems may have security vulnerabilities, so the systems should be evaluated to identify risks and solutions implemented to mitigate those risks. SCADA system components. A SCADA schematic overview showing control levels 0, 1 and 2 A SCADA system usually consists of the following main elements: Supervisory computers This is the core of the SCADA system, gathering data on the process and sending control commands to the field connected devices. It refers to the computer and software responsible for communicating with the field connection controllers, which are RTUs and PLCs, and includes the HMI software running on operator workstations. In smaller SCADA systems, the supervisory computer may be composed of a single PC, in which case the HMI is a part of this computer. In larger SCADA systems, the master station may include several HMIs hosted on client computers, multiple servers for data acquisition, distributed software applications, and disaster recovery sites.

To increase the integrity of the system the multiple servers will often be configured in a or formation providing continuous control and monitoring in the event of a server malfunction or breakdown. Remote terminal units. Further information: Also known as PLCs, these are connected to sensors and actuators in the process, and are networked to the supervisory system in the same way as RTUs. PLCs have more sophisticated embedded control capabilities than RTUs, and are programmed in one or more programming languages.

PLCs are often used in place of RTUs as field devices because they are more economical, versatile, flexible and configurable. Communication infrastructure This connects the supervisory computer system to the remote terminal units (RTUs) and PLCs, and may use industry standard or manufacturer proprietary protocols. Both RTUs and PLCs operate autonomously on the near-real time control of the process, using the last command given from the supervisory system. Failure of the communications network does not necessarily stop the plant process controls, and on resumption of communications, the operator can continue with monitoring and control. Some critical systems will have dual redundant data highways, often cabled via diverse routes.

Human-machine interface. More complex SCADA animation showing control of four batch cookers The human-machine interface (HMI) is the operator window of the supervisory system. It presents plant information to the operating personnel graphically in the form of mimic diagrams, which are a schematic representation of the plant being controlled, and alarm and event logging pages. The HMI is linked to the SCADA supervisory computer to provide live data to drive the mimic diagrams, alarm displays and trending graphs. In many installations the HMI is the graphical user interface for the operator, collects all data from external devices, creates reports, performs alarming, sends notifications, etc. Mimic diagrams consist of line graphics and schematic symbols to represent process elements, or may consist of digital photographs of the process equipment overlain with animated symbols.

Supervisory operation of the plant is by means of the HMI, with operators issuing commands using mouse pointers, keyboards and touch screens. For example, a symbol of a pump can show the operator that the pump is running, and a flow meter symbol can show how much fluid it is pumping through the pipe. The operator can switch the pump off from the mimic by a mouse click or screen touch. The HMI will show the flow rate of the fluid in the pipe decrease in real time. The HMI package for a SCADA system typically includes a drawing program that the operators or system maintenance personnel use to change the way these points are represented in the interface.

These representations can be as simple as an on-screen traffic light, which represents the state of an actual traffic light in the field, or as complex as a multi-projector display representing the position of all of the elevators in a skyscraper or all of the trains on a railway. A 'historian', is a software service within the HMI which accumulates time-stamped data, events, and alarms in a database which can be queried or used to populate graphic trends in the HMI. The historian is a client that requests data from a data acquisition server. Alarm handling. Further information: An important part of most SCADA implementations is. The system monitors whether certain alarm conditions are satisfied, to determine when an alarm event has occurred. Once an alarm event has been detected, one or more actions are taken (such as the activation of one or more alarm indicators, and perhaps the generation of email or text messages so that management or remote SCADA operators are informed).

In many cases, a SCADA operator may have to acknowledge the alarm event; this may deactivate some alarm indicators, whereas other indicators remain active until the alarm conditions are cleared. Alarm conditions can be explicit—for example, an alarm point is a digital status point that has either the value NORMAL or ALARM that is calculated by a formula based on the values in other analogue and digital points—or implicit: the SCADA system might automatically monitor whether the value in an analogue point lies outside high and low- limit values associated with that point.

Examples of alarm indicators include a siren, a pop-up box on a screen, or a coloured or flashing area on a screen (that might act in a similar way to the 'fuel tank empty' light in a car); in each case, the role of the alarm indicator is to draw the operator's attention to the part of the system 'in alarm' so that appropriate action can be taken. PLC/RTU programming 'Smart' RTUs, or standard PLCs, are capable of autonomously executing simple logic processes without involving the supervisory computer. They employ standardized control programming languages such as under, (a suite of 5 programming languages including function block, ladder, structured text, sequence function charts and instruction list), is frequently used to create programs which run on these RTUs and PLCs. Unlike a procedural language such as the or, IEC 61131-3 has minimal training requirements by virtue of resembling historic physical control arrays. This allows SCADA system engineers to perform both the design and implementation of a program to be executed on an RTU or PLC. A (PAC) is a compact controller that combines the features and capabilities of a PC-based control system with that of a typical PLC. PACs are deployed in SCADA systems to provide RTU and PLC functions.

In many electrical substation SCADA applications, 'distributed RTUs' use information processors or station computers to communicate with, PACs, and other devices for I/O, and communicate with the SCADA master in lieu of a traditional RTU. PLC commercial integration Since about 1998, virtually all major PLC manufacturers have offered integrated HMI/SCADA systems, many of them using open and non-proprietary communications protocols. Numerous specialized third-party HMI/SCADA packages, offering built-in compatibility with most major PLCs, have also entered the market, allowing mechanical engineers, electrical engineers and technicians to configure HMIs themselves, without the need for a custom-made program written by a software programmer. The Remote Terminal Unit (RTU) connects to physical equipment. Typically, an RTU converts the electrical signals from the equipment to digital values such as the open/closed status from a switch or a valve, or measurements such as pressure, flow, voltage or current. By converting and sending these electrical signals out to equipment the RTU can control equipment, such as opening or closing a switch or a valve, or setting the speed of a pump. Communication infrastructure and methods SCADA systems have traditionally used combinations of radio and direct wired connections, although is also frequently used for large systems such as railways and power stations.

The remote management or monitoring function of a SCADA system is often referred to as. Some users want SCADA data to travel over their pre-established corporate networks or to share the network with other applications. The legacy of the early low-bandwidth protocols remains, though. SCADA protocols are designed to be very compact. Many are designed to send information only when the master station polls the RTU. Typical legacy SCADA protocols include RTU, and Conitel. These communication protocols, with the exception of Modbus (Modbus has been made open by Schneider Electric), are all SCADA-vendor specific but are widely adopted and used.

Standard protocols are, and. These communication protocols are standardized and recognized by all major SCADA vendors. Many of these protocols now contain extensions to operate over. Although the use of conventional networking specifications, such as, blurs the line between traditional and industrial networking, they each fulfill fundamentally differing requirements. Can be used in conjunction with SCADA simulators to perform various 'what-if' analyses. With increasing security demands (such as (NERC) and (CIP) in the US), there is increasing use of satellite-based communication.

This has the key advantages that the infrastructure can be self-contained (not using circuits from the public telephone system), can have built-in encryption, and can be engineered to the availability and reliability required by the SCADA system operator. Earlier experiences using consumer-grade were poor. Modern carrier-class systems provide the quality of service required for SCADA. RTUs and other automatic controller devices were developed before the advent of industry wide standards for interoperability. The result is that developers and their management created a multitude of control protocols. Among the larger vendors, there was also the incentive to create their own protocol to 'lock in' their customer base. A is compiled here.

(OPC) can connect different hardware and software, allowing communication even between devices originally not intended to be part of an industrial network. SCADA architecture development. The 's Training Manual 5-601 covers 'SCADA Systems for Facilities' SCADA systems have evolved through four generations as follows: First generation: 'monolithic' Early SCADA system computing was done by large.

Common network services did not exist at the time SCADA was developed. Thus SCADA systems were independent systems with no connectivity to other systems. The communication protocols used were strictly proprietary at that time. The first-generation SCADA system redundancy was achieved using a back-up mainframe system connected to all the sites and was used in the event of failure of the primary mainframe system. Some first generation SCADA systems were developed as 'turn key' operations that ran on minicomputers such as the series made by the. Second generation: 'distributed' SCADA information and command processing was distributed across multiple stations which were connected through a LAN. Information was shared in near real time.

Each station was responsible for a particular task, which reduced the cost as compared to First Generation SCADA. The network protocols used were still not standardized. Since these protocols were proprietary, very few people beyond the developers knew enough to determine how secure a SCADA installation was.

Security of the SCADA installation was usually overlooked. Third generation: 'networked' Similar to a distributed architecture, any complex SCADA can be reduced to simplest components and connected through communication protocols.

In the case of a networked design, the system may be spread across more than one LAN network called a and separated geographically. Several distributed architecture SCADAs running in parallel, with a single supervisor and historian, could be considered a network architecture. This allows for a more cost effective solution in very large scale systems.

Fourth generation: 'Internet of things' With the commercial availability of, SCADA systems have increasingly adopted technology to significantly improve interoperability, reduce infrastructure costs and increase ease of maintenance and integration. As a result, SCADA systems can now report state in near real-time and use the horizontal scale available in cloud environments to implement more complex control algorithms than are practically feasible to implement on traditional. Further, the use of open network protocols such as inherent in the Internet of things technology, provides a more readily comprehensible and manageable security boundary than the heterogeneous mix of proprietary network protocols typical of many decentralized SCADA implementations. This decentralization of data also requires a different approach to SCADA than traditional PLC based programs. When a SCADA system is used locally, the preferred methodology involves binding the graphics on the user interface to the data stored in specific PLC memory addresses. However, when the data comes from a disparate mix of sensors, controllers and databases (which may be local or at varied connected locations), the typical 1 to 1 mapping becomes problematic.

A solution to this is, a concept derived from object oriented programming. In a data model, a virtual representation of each device is constructed in the SCADA software. These virtual representations (“models”) can contain not just the address mapping of the device represented, but also any other pertinent information (web based info, database entries, media files, etc.) that may be used by other facets of the SCADA/IoT implementation.

As the increased complexity of the Internet of things renders traditional SCADA increasingly “house-bound,” and as communication protocols evolve to favor platform-independent, service-oriented architecture (such as ), it is likely that more SCADA software developers will implement some form of data modeling. Security issues SCADA systems that tie together decentralized facilities such as power, oil, gas pipelines, water distribution and wastewater collection systems were designed to be open, robust, and easily operated and repaired, but not necessarily secure. The move from proprietary technologies to more standardized and open solutions together with the increased number of connections between SCADA systems, office networks and the has made them more vulnerable to types of that are relatively common in. For example, released a vulnerability advisory warning that unauthenticated users could download sensitive configuration information including from an system utilizing a standard leveraging access to the. Security researcher Jerry Brown submitted a similar advisory regarding a vulnerability in a InBatchClient. Both vendors made updates available prior to public vulnerability release. Mitigation recommendations were standard practices and requiring access for secure connectivity.

Consequently, the security of some SCADA-based systems has come into question as they are seen as potentially vulnerable to. Boys, Walt (18 August 2009).

Automation TV: Control Global - Control Design. Rosa Tang, berkeley.edu. Archived from (PDF) on 13 August 2012. Retrieved 1 August 2012. Boyer, Stuart A. SCADA Supervisory Control and Data Acquisition.

USA: ISA - International Society of Automation. Jeff Hieb (2008). University of Louisville. Aquino-Santos, Raul (30 November 2010).

IEEE Communications Surveys and Tutorials. Bergan, Christian (August 2011). Electric Light & Powers. Utility Automation & Engineering T&D.

Tulsa, OK: PennWell. Retrieved 2 May 2012. Satellite is a cost-effective and secure solution that can provide backup communications and easily support core smart grid applications like SCADA, telemetry, AMI backhaul and distribution automation. OFFICE OF THE MANAGER NATIONAL COMMUNICATIONS SYSTEMctober 2004. NATIONAL COMMUNICATIONS SYSTEM.

Archived from on 11 August 2015. 'SCADA as a service approach for interoperability of micro-grid platforms'.

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Sustainable Energy, Grids and Network. Retrieved May 22, 2017.

'SCADA as a service approach for interoperability of micro-grid platforms', Sustainable Energy, Grids and Network, 2016,:. 21 October 2013 at the. Retrieved September 16, 2013. Exforsys Inc. 11 January 2007. Proceedings of the IEEE ISGT 2016 Conference.

6 September 2016. Boyes, Walt (2011). Instrumentation Reference Book, 4th Edition. USA: Butterworth-Heinemann. Retrieved 21 Jan 2013.

Retrieved 26 Mar 2013. Maynor and R. Graham (2006).

Robert Lemos (26 July 2006). Retrieved 9 May 2007. Rockwell Automation.

Retrieved 26 Mar 2013. Slay, J.; Miller, M. (November 2007). 'Chpt 6: Lessons Learned from the Maroochy Water Breach'. Springer Boston.

Retrieved 2 May 2012. Retrieved 2 May 2012. Archived from on 7 January 2009. (November 2006). 'Substation Communications: Enabler of Automation / An Assessment of Communications Technologies'. UTC – United Telecom Council: 3–21.

Mills, Elinor (21 July 2010). Retrieved 21 July 2010. 21 July 2010. Retrieved 22 July 2010. Malware (trojan) which affects the visualization system WinCC SCADA. Archived from on 25 May 2012. Retrieved 16 September 2010.

National Geographic Channel. Retrieved 14 October 2016. External links Wikimedia Commons has media related to.