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IEC 61131 is an International Electrotechnical Commission ( standard for industrial controllers that has seven parts. IEC 61131-3 defines programming languages. Since 1906, the IEC has been a nonprofit, nongovernmental international standards organization that prepares and publishes international standards for all electrical, electronic, and related technologies collectively known as “electrotechnology.” Eighty two countries are IEC members, and another 82 participate in the affiliate country program. The IEC is headquartered in Geneva, Switzerland, with regional centers in Asia-Pacific (Singapore), Latin America (São Paulo, Brazil), and North America (Boston). eon gas card top up PLCopen

The PLCopen ( organization was founded in 1992 as a not-for-profit industry association of member companies committed to developing open industrial automation software standards to increase functionality while reducing engineering, training, operations, and maintenance costs. PLCopen has a vendor certification program, and certified products are listed on the organization website. PLCopen is headquartered in The Netherlands, with regional representatives in North America (, Japan (, and China ( The website describes certifications of IEC 61131-3 compliant programming systems.

The IEC 61131-3 development platform for building applications is an integrated design environment (IDE) for creating, simulating, and debugging applications. Using IDE applications, people build control and automation logic, define alarms, and create human-machine interface screens in one software platform. arkansas gas prices IEC 61131-3 programs developed in an IDE are downloaded into target processors where they control processes in real time. When applications are downloaded to a target controller, the IDE engineering tools include online debugging, break points, watch windows, and forcing variable functions. Multitasking oriented

IEC 61131-3 defines a task-oriented environment that has the flexibility to meet the control requirements for any application. At the highest level, all the software required to solve a particular control problem can be formulated as a “configuration.” A configuration is specific to a particular type of control system, including the arrangement of the hardware (processing resources, memory addresses for I/O channels, and system capabilities). Within a configuration, users define one or more resources. One can look at a resource as a processing facility that can execute IEC programs. ortega y gasset revolt of the masses Within a resource, one or more tasks can be defined. Tasks control the execution of a set of programs or function blocks. These can be executed either periodically or upon the occurrence of a specified trigger, such as the change of a variable. Programs are built from a number of different software elements written in any of the IEC-defined languages. Typically, a program consists of a network of functions and function blocks, which can exchange data. Function and function blocks are the basic building blocks, containing a data structure and an algorithm. Data types

IEC 61131-3 defines strong data typing to prevent programming errors (e.g., dividing a date by an integer). Common data types are Boolean, integer, real and byte and word, date, array, time of day, and string. Based on these, users can define specific data types for an application, known as derived data types. Variables are only assigned to explicit hardware addresses (e.g., input and outputs) in configurations, resources, or programs, so there is a high level of hardware independence that supports the reusability of the software. electricity transformer health risks The scopes of the variables are normally limited to the organizational unit in which they are declared (e.g., local). This means that their names can be reused in other parts without any conflict, eliminating another source of error. electricity bill calculator If the variables have global scope, they have to be declared as global. Parameters can be assigned an initial value at start up and cold restart to ensure proper operation. Programming languages

Function Block Diagram (FB) has been very common in the process industry and is now used in all applications. It expresses the behavior of functions, function blocks, and programs as a set of interconnected graphical blocks, like in electronic circuit diagrams. It looks at a system in terms of the flow of signals between processing elements. Function blocks contain algorithms and may contain data if required. The inputs and outputs of function blocks have defined data types to prevent errors in programming.

Structured Text (ST) is a very powerful high-level language with its roots in Ada, Pascal, and “C.” It contains all the essential elements of a modern programming language, including selection branches (IF-THEN-ELSE and CASE OF) and iteration loops (FOR, WHILE, and REPEAT). All standard IEC 61131-3 functions can be used in Structured Text programming, and users can create their own function blocks for applications and projects. Sequential Function Chart

Sequential Function Chart (SFC) describes graphically the sequential behavior of control programs and helps to decompose a control problem into manageable parts, while maintaining an overview of the execution flow. SFC consists of steps, linked with action blocks and transitions. gas works park events Each step represents a particular state of the systems being controlled. electricity 101 A transition is associated with a condition, which, when true, causes the step before the transition to be deactivated, and the next step to be activated. Steps are linked to action blocks performing a certain control action. Each element can be programmed in any of the IEC languages, including SFC itself. One can use alternative sequences and even parallel sequences, such as those commonly required in batch applications. For instance, one sequence is used for the primary process, and the second for monitoring the overall operating constraints. Because of its general structure, SFC also provides a communication tool, combining people of different backgrounds, departments, or countries. SFC can be used to define both serial and parallel processes. Application examples include startup sequences, shutdown sequences, batch process control, and machine cycle operations.

The PLCopen XML standard provides an open, nonproprietary, software interface for the interchange of industrial and process control programs between controls, product life-cycle management, machine and process simulation, computer-aided design, documentation software, and other systems. The PLCopen XML schemas, documentation, and an introduction are available free at The files include an explanation of the PLCopen XMLSchema, a document on XML formats for IEC 61131-3, and XML schema files. The PLCopen standard has gained acceptance by the AutomationML organization ( OPC UA

The function blocks are also defined for direct machine-to-machine communications between multiple vendor controllers to coordinate automation. These are important functions for achieving the goals of Industry 4.0, the Industrial Internet of Things, and smart factory applications to improve manufacturing efficiency and productivity. gas meter car These function blocks simplify the integration of production, process control, packaging, and other machines into efficient new system architectures.