Scada

Supervisory Control and Data Acquisition Concept Communication Automationen werden entsprechend dem OSI-Schichtenmodell in mehrere Schichten unterteilt. Dies wird durch die Automatisierungspyramide veranschaulicht. Dabei ist das Level 1 die prozessnahe Schicht. Der Terminus SCADA bezieht sich gewöhnlich auf zentrale/dezentrale Systeme, die die gesamte Installationen überwachen, visualisieren sowie steuern und regeln. Der größte Teil der Regelung wird automatisch durch Fernbedienungsterminals (RTU) oder durch Speicherprogrammierbare Steuerungen (SPS) beziehungsweise Level-1-Automationen durchgeführt. Die Aufgabe der Level-2-Automation ist es, die Funktion der Level-1-Automation zu optimieren, sowie Stellgrößen und Sollwerte auszugeben. Die Level-3-Automation dient hingegen der Planung, Qualitätssicherung und Dokumentation. Die Datenerfassung beginnt gewöhnlich mit...

Security issues the lack of concern about security and authentication in the design, deployment and operation of some existing SCADA networks the belief that SCADA systems have the benefit of security through obscurity through the use of specialized protocols and proprietary interfaces the belief that SCADA networks are secure because they are physically secured the belief that SCADA networks are secure because they are disconnected from the Internet See also DNP3 IEC 60870 Modbus BACnet LonWorks 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  systems, office networks and the Internet has made them m...

SCADA architecture development SCADA systems have evolved through four generations as follows: Early SCADA system computing was done by large minicomputers. 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 Remote Terminal Unit 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 PDP-11 series made by the Digital Equipment Corporation. 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 respons...

SCADA and 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...

Alarm handling An important part of most SCADA implementations is alarm handling. 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 a...

SCADA system components 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 dual-redundant or hot-standby formation providing continuous control and monitoring in the event of a server malfunction or breakdown.A SCADA system usually consists of the following main elements ...

The SCADA concept in control operations 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 control valves. 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. Industrial processes include manufacturing, Process con...

SCADA  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 protocols. In practice, large SCADA systems have grown to become very similar to distributed control systems 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. It is one of the most commonly-used types of industrial control systems, however there are concerns about SCADA systems being vulnerable to cyberwarfare/cyberterrorism attacks. Supervisory control and data acquisition (SCADA) is a control system architecture that uses computers, networked data communications and graphical user interfaces for high-level process supervisory management, but uses other peripheral devices such as programmable lo...