IEC 61131-7:2000 pdf free download – Programmable controllers
1 Scope and object
This part of lEC 61131 defines a language for the programming of Fuzzy Control applicationsused by programmable controllers.
The object of this part of lEC 61131 is to offer the manufacturers and the users a well-definedcommon understanding of the basic means to integrate fuzzy control applications in theProgrammable Controller languages according to lEC 61131-3，as well as the possibility toexchange portable fuzzy control programs among different programming systems.
To achieve this, annex A gives a short introduction to the theory of fuzzy control and fuzzy logicas far as it is necessary for the understanding of this part of IEC 61131. lt may be helpful forreaders of this part of lEC 61131 who are not familiar with fuzzy control theory to read annex Afirst.
2Normative references
The following normative documents contain provisions which，through reference in this text,constitute provisions of this part of lEC 61131.For dated references,subsequent amendmentsto，or revisions of，any of these publications do not apply.However，parties to agreementsbased on this part of IEC 61131 are encouraged to investigate the possibility of applying themost recent editions of the normative documents indicated below.For undated references, thelatest edition of the normative document referred to applies. Members of lEC and IS0 maintainregisters of currently valid lnternational Standards.
IEC 60050-351:1998，International Electrotechnical Vocabulary (IEV) – Part 351: Automaticcontrol
IEC 61131-3:1993,Programmable controllers – Part 3: Programming languages
ln this example，Valve_Control_1 is a user defined Function Block Instance of the FunctionBlock Type Fuzzy_FB. The Function Block Type Fuzzy_FB may be programmed in FuzzyControl Language FCL according to clause 5.The Function Block Fuzzy_FB is used here in aprogram or a Function Block which is represented in the graphical language FBD (FunctionBlock Diagram) of lEC 61131-3.
5 Fuzzy Control Language FCL
5.1 Exchange of fuzzy control programs
The definition of the Fuzzy Control Language FCL is based on the definitions of theprogramming languages in lEC 61131-3.The interaction of the fuzzy control algorithm with itsprogram environment causes it to be “hidden” from the program.The fuzzy control algorithm istherefore externally represented as a Function Block according to IEC 61131-3.The necessaryelements for describing the internal linguistic parts of the fuzzy control Function Block likemembership functions，rules，operators and methods have to be defined according to thisclause.
The language elements of FCL standardize a common representation for data exchangeamong fuzzy control configuration tools of different manufacturers shown in figure 2.Using thiscommon representation，every manufacturer of programmable controllers may keep hishardware,software editors and compilers. The manufacturer has only to implement the datainterface into his specific editor. The customer would be able to exchange fuzzy controlprojects between different manufacturers.
After the keyword FUZZIFY, the name of a variable which is used for the fuzzification shall benamed. This is the name of a previously defined variable in the VAR_INPUT section.Thislinguistic variable shall be described by one or more linguistic terms. The linguistic termsintroduced by the keyword TERM described by membership functions in order to fuzzify thevariable. A membership function is a piece-wise linear function. lt is defined by a table ofpoints.