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A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity that requires high reliability, ease of programming, and process fault diagnosis.
IEC 61131-3 is the third part (of 10) of the international standard IEC 61131 for programmable logic controllers. It was first published in December 1993 [1] by the IEC; the current (third) edition was published in February 2013. [2] Part 3 of IEC 61131 deals with basic software architecture and programming languages of the control program ...
Function Block Diagram is one of five languages for logic or control configuration [2] supported by standard IEC 61131-3 for a control system such as a programmable logic controller (PLC) or a Distributed Control System (DCS). The other supported languages are ladder logic, sequential function chart, structured text, and instruction list.
Sequential function chart (SFC) is a visual programming language used for programmable logic controllers (PLCs). It is one of the five languages defined by IEC 61131-3 standard. The SFC standard is defined as Preparation of function charts for control systems, and was based on GRAFCET (itself based on binary Petri nets [1] [2]).
Standard IEC 61131 is divided into several parts: [3]. Part 1: General information. It is the introductory chapter; it contains definitions of terms that are used in the subsequent parts of the standard and outlines the main functional properties and characteristics of PLCs.
A simplified PAL device. The programmable elements (shown as a fuse) connect both the true and complemented inputs to the AND gates. These AND gates, also known as product terms, are ORed together to form a sum-of-products logic array. A programmable logic device (PLD) is an electronic component used to build reconfigurable digital circuits.
Programmable logic controller (PLC)A Programmable Logic Controller, PLC or Programmable Controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. The abbreviation "PLC" and the term "Programmable Logic Controller" are ...
Ladder logic is widely used to program PLCs, where sequential control of a process or manufacturing operation is required. Ladder logic is useful for simple but critical control systems or for reworking old hardwired relay circuits. As programmable logic controllers became more sophisticated it has also been used in very complex automation systems.