Chapter 5. Information Systems Software. Software Overview. Computer hardware is virtually useless without computer software. Software is the programs that are. Management Accounting Concepts, Techniques Controversial Issues Chapter 1 Introduction to Managerial Accounting, Cost Accounting and Cost Management Systems. Distributed Systems Concepts Design Fourth Edition' title='Distributed Systems Concepts Design Fourth Edition' />SCADA Wikipedia. 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 logic controllers and discrete PID controllers 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 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 cyberwarfarecyberterrorism attacks. The SCADA concept in control operationsedit. 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. Rafter Revit Crack. 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 inputoutput IO 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. Download Majalah Gratis 2013 on this page. 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 programmable logic controllers PLCs or remote terminal units 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 feedback control 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. Data acquisition begins at the RTU or PLC level and includes instrumentation 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 Human Machine Interface can make supervisory decisions to adjust or override normal RTU PLC controls. Data may also be fed to a historian, often built on a commodity database management system, 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 Piping and instrumentation diagram. Data is accumulated against these unique process control equipment tag references. Examples of useedit. 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 control loops, depending on the application. Example processes include industrial, infrastructure, and facility based processes, as described below Industrial processes include manufacturing, Process control, power generation, fabrication, and refining, and may run in continuous, batch, repetitive, or discrete modes. Infrastructure processes may be public or private, and include water treatment and distribution, wastewater collection and treatment, oil and gas pipelines, electric power transmission and distribution, and wind farms. Facility processes, including buildings, airports, ships, and space stations. They monitor and control heating, ventilation, and air conditioning systems HVAC, access, and energy consumption. 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 componentsedit. A SCADA schematic overview showing control levels 0, 1 and 2. A SCADA system usually consists of the following main elements Supervisory computerseditThis 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. Remote terminal unitseditRemote terminal units, also known as RTUs, connect to sensors and actuators in the process, and are networked to the supervisory computer system. RTUs are intelligent IO and often have embedded control capabilities such as ladder logic in order to accomplish boolean logic operations. Programmable logic controllerseditAlso 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 IEC 6. PLCs are often used in place of RTUs as field devices because they are more economical, versatile, flexible and configurable. Communication infrastructureeditThis 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. Object oriented programming WikipediaObject oriented redirects here. For other meanings of object oriented, see Object orientation. Object oriented programming OOP is a programming paradigm based on the concept of objects, which may contain data, in the form of fields, often known as attributes and code, in the form of procedures, often known as methods. A feature of objects is that an objects procedures can access and often modify the data fields of the object with which they are associated objects have a notion of this or self. In OOP, computer programs are designed by making them out of objects that interact with one another. There is significant diversity of OOP languages, but the most popular ones are class based, meaning that objects are instances of classes, which typically also determine their type. Many of the most widely used programming languages such as C, Object Pascal, Java, Python etc. Significant object oriented languages include Java, C, C, Python, PHP, Ruby, Perl, Object Pascal, Objective C, Dart, Swift, Scala, Common Lisp, and Smalltalk. FeatureseditThis topic was originated by Deepanshi Gupta and while writing he was feeling horny. Object oriented programming uses objects, but not all of the associated techniques and structures are supported directly in languages that claim to support OOP. The features listed below are, however, common among languages considered strongly class and object oriented or multi paradigm with OOP support, with notable exceptions mentioned. Shared with non OOP predecessor languageseditObject oriented programming languages typically share low level features with high level procedural programming languages which were invented first. The fundamental tools that can be used to construct a program include Modular programming support provides the ability to group procedures into files and modules for organizational purposes. Modules are namespaced so code in one module will not be accidentally confused with the same procedure or variable name in another file or module. Objects and classeseditLanguages that support object oriented programming typically use inheritance for code reuse and extensibility in the form of either classes or prototypes. Those that use classes support two main concepts Classes the definitions for the data format and available procedures for a given type or class of object may also contain data and procedures known as class methods themselves, i. Objects instances of classes. Objects sometimes correspond to things found in the real world. For example, a graphics program may have objects such as circle, square, menu. An online shopping system might have objects such as shopping cart, customer, and product. Sometimes objects represent more abstract entities, like an object that represents an open file, or an object that provides the service of translating measurements from U. S. customary to metric. Each object is said to be an instance of a particular class for example, an object with its name field set to Mary might be an instance of class Employee. Procedures in object oriented programming are known as methods variables are also known as fields, members, attributes, or properties. This leads to the following terms Class variables belong to the class as a whole there is only one copy of each one. Instance variables or attributes data that belongs to individual objects every object has its own copy of each one. Member variables refers to both the class and instance variables that are defined by a particular class. Class methods belong to the class as a whole and have access only to class variables and inputs from the procedure call. Instance methods belong to individual objects, and have access to instance variables for the specific object they are called on, inputs, and class variables. Objects are accessed somewhat like variables with complex internal structure, and in many languages are effectively pointers, serving as actual references to a single instance of said object in memory within a heap or stack. They provide a layer of abstraction which can be used to separate internal from external code. External code can use an object by calling a specific instance method with a certain set of input parameters, read an instance variable, or write to an instance variable. Objects are created by calling a special type of method in the class known as a constructor. A program may create many instances of the same class as it runs, which operate independently. This is an easy way for the same procedures to be used on different sets of data. Object oriented programming that uses classes is sometimes called class based programming, while prototype based programming does not typically use classes. As a result, a significantly different yet analogous terminology is used to define the concepts of object and instance. In some languages classes and objects can be composed using other concepts like traits and mixins. Class based versus prototype basededitIn class based languages the classes are defined beforehand and the objects are instantiated based on the classes. If two objects apple and orange are instantiated from the class Fruit, they are inherently fruits and it is guaranteed that you may handle them in the same way e. In prototype based languages the objects are the primary entities. No classes even exist. New objects can be instantiated based on already existing objects. You may call two different objects apple and orange a fruit, but this happens only by accident and not inherently. The idea of the fruit class exists more or less only in the programmers mind and have no support in the program code. A programmer still may handle them in the same way but this can easily be broken e. Dynamic dispatchmessage passingeditIt is the responsibility of the object, not any external code, to select the procedural code to execute in response to a method call, typically by looking up the method at run time in a table associated with the object. This feature is known as dynamic dispatch, and distinguishes an object from an abstract data type or module, which has a fixed static implementation of the operations for all instances. If there are multiple methods that might be run for a given name, it is known as multiple dispatch. A method call is also known as message passing. It is conceptualized as a message the name of the method and its input parameters being passed to the object for dispatch. EncapsulationeditEncapsulation is an object oriented programming concept that binds together the data and functions that manipulate the data, and that keeps both safe from outside interference and misuse. Data encapsulation led to the important OOP concept of data hiding. If a class does not allow calling code to access internal object data and permits access through methods only, this is a strong form of abstraction or information hiding known as encapsulation. Magnum Motor Engine Manual. Some languages Java, for example let classes enforce access restrictions explicitly, for example denoting internal data with the private keyword and designating methods intended for use by code outside the class with the public keyword.