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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.
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 ...
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 [ fr ] (itself based on binary Petri nets [ 1 ] [ 2 ] ).
The graphic symbols used for electrical components in circuit diagrams are covered by national and international standards, in particular: IEC 60617 (also known as BS 3939). There is also IEC 61131-3 – for ladder-logic symbols. JIC JIC (Joint Industrial Council) symbols as approved and adopted by the NMTBA (National Machine Tool Builders ...
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.
Statement List (STL) - The program consists of a sequence of mnemonic codes of the commands executed one after another by the PLC. Ladder Diagram (LAD) - Graphical representation of the automation task with symbols of the circuit diagram; Function Block Diagram (FBD) - Graphical representation of the automation task with symbols to DIN 40700 ...
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.
Example Ladder Logic Diagram. The schematic diagrams for relay logic circuits are often called line diagrams, because the inputs and outputs are essentially drawn in a series of lines. A relay logic circuit is an electrical network consisting of lines, or rungs, in which each line or rung must have continuity to enable the output device. A ...