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CJ2 CPU Unit Software User's Manual - CIP ETI

CJ2 CPU Unit Software User's Manual - CIP ETI

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5 Understanding Programming5-5 Symbols5-5-1 OverviewSymbols Symbol TablesI/O memory area addresses or constants can be specified using character strings by registering thecharacter strings as symbols. Register the symbols in the symbol tables of the CX-Programmer.Programming with symbols enables programming with names rather than having to be aware of theactual addresses.Symbol tables are saved in a CX-Programmer project file (.CXP) along with other parameters, suchas the user program and I/O tables. Conditions for Using SymbolsWhether using symbols is required or optional depends the programming language as well aswhether the symbol is used inside or outside of a function block, as given in the following table.Program element Programming language Specifying symbolsProgramming outside function blocks Ladder diagram OptionalSTRequiredSFCOptionalProgramming inside function blocks (Inside Ladder diagramRequiredfunction blocks, symbols are called “variables.”)ST55-5 Symbols5-5-5 Network Symbols (<strong>CJ2</strong>H-<strong>CPU</strong>6@-EIPonly)<strong>CJ2</strong> <strong>CPU</strong> <strong>Unit</strong> <strong>Software</strong> User’s <strong>Manual</strong>5-45

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