Rievtech PR-12 Series, Руководство пользователя и программиста

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of addresses.
#INPUT1
# symbols in a local variable before
INPUT1
Global symbol name
??.? or ????
A question mark indicates an undefined address (which must be
defined before the program is compiled).
Global scope and local scope
The symbol value in the symbol table has a global scope, and the symbol value in the
local variable table has a local scope.
Global symbol
Global symbols can be used in the X Ladder program editor.
In the X Ladder program, you can use the global variable table to assign the global
symbol.
local variable
Local variables can be used in the X Ladder program editor.
Local variables are assigned in the local variable table of the respective POU, and the
scope is limited to the POU of the local variable. Each POU has a separate local
variable table.
Attention: if you use the same address name in the local and global variables table,
local variables are preferred.
Local variables use temporary L memory, and do not require the PLC program
memory space. The subroutines that use only the local variable parameters (or don't
use the parameters) are mobile subroutines, They can be used in more than one
program.If you want to use a parameter in a plurality of POU ,It is best to define it as
a global symbol in the global variable table, and do not define it as a local variable, or
you must assign each POU 's local variable table separately.Because local variables
use temporary memory, every time POU is called, be sure to initialize local variables
in POU.Global symbol table supports global symbol constant. Local variable table
does not support symbolic constants.