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5 Understanding Programming
CJ2 CPU Unit Software User’s Manual
5-5 Symbols
5
5-5-1 Overview
5-5 Symbols
z Symbol Tables
I/O memory area addresses or constants can be specified using character strings by registering the
character 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 the
actual addresses.
Symbol tables are saved in a CX-Programmer project file (.CXP) along with other parameters, such
as the user program and I/O tables.
z Conditions for Using Symbols
Whether using symbols is required or optional depends the programming language as well as
whether the symbol is used inside or outside of a function block, as given in the following table.
5-5-1 Overview
Symbols
Program element Programming language Specifying symbols
Programming outside function blocks Ladder diagram Optional
ST Required
SFC Optional
Programming inside function blocks (Inside
function blocks, symbols are called “vari-
ables.”)
Ladder diagram Required
ST
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