12Contents1Introduction........................................................................................................91.1SubjectoftheBook.........................................................................................101.2TheIEC61131standard..................................................................................121.2.1Goalsandbenefitsofthestandard................................................................12Manufacturers(PLChardwareandsoftware).........................................................................13Customers...............................................................................................................................131.2.2Historyandcomponents...............................................................................141.3TheOrganisationPLCopen..............................................................................161.3.1Aims..............................................................................................................161.3.2Committeesandfieldsofactivity..................................................................171.3.3Results..........................................................................................................18Certification...........................................................................................................................18Exchangeformatforuserprograms........................................................................................192BuildingBlocksofIEC61131-3.......................................................................212.1IntroductiontotheNewStandard....................................................................212.1.1Structureofthebuildingblocks....................................................................22Declarationofvariables..........................................................................................................22CodepartofaPOU...............................................
