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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 ...
A remote terminal unit (RTU) is a microprocessor-controlled electronic device that interfaces objects in the physical world to a distributed control system or SCADA (supervisory control and data acquisition) system by transmitting telemetry data to a master system, and by using messages from the master supervisory system to control connected objects. [1]
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.
The Remote Terminal Unit is initially interrogated with what DNP3 terms an "Integrity Poll" (a combined Read of Class 1, 2, 3 and 0 data). This causes the Remote Terminal Unit to send all buffered events and also all static point data to the Master station. Following this, the Master polls for the event data by reading Class 1, Class 2 or Class 3.
RTUs [1] connect to sensors and actuators in the process, and are networked to the supervisory computer system. RTUs have embedded control capabilities and often conform to the IEC 61131-3 standard for programming and support automation via ladder logic, a function block diagram or a variety of other languages.
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]). It can be used to program processes that can be split into steps. Basic Batch SFC, with important elements labeled
Instruction list (IL) is one of the 5 languages supported by the initial versions of IEC 61131-3 standard, and subsequently deprecated in the third edition. [1] It is designed for programmable logic controllers (PLCs). It is a low level language and resembles assembly. All of the languages share IEC61131 Common Elements. The variables and ...
Unlike the RTUs, IEDs are integrated with the devices they control and offer a standardized set of measuring and control points that is easier to configure and require less wiring. Most IEDs have a communication port and built-in support for standard communication protocols ( DNP3 , IEC104 or IEC61850), so they can communicate directly with the ...