PART 1: CX-Programmer
CHAPTER 4 – Reference OMRON
CX-Programmer _Page 64
• CIO
• WR
• HR
• DM
• EM
Note: Automatic address allocation is not possible for structure symbols.
In the symbol table, specify an address in one of the above areas as the first address of the data
structure.
• Symbol Tables in Which Structure Symbols Can Be Registered
Structure symbols can be registered in the following symbol tables.
• Global symbol table
• Local symbol tables for ladder programs
• Internal variables and input-output variables in symbol (variable) tables for function
blocks written in ladder diagrams
Note: Structure symbols cannot be registered for the following items.
• Local symbol tables for ST programs
• Local symbol tables for SFC programs
• Input variables, output variables, and external variables in symbol (variable) tables for
function blocks written in ladder diagrams
• Symbol tables for function blocks written in the ST language
• Size of Structure Symbols
The maximum size of one structure symbol is as follows:
• Internal variables: 32,000 words
• Input-output variables: 2,048 words
• Maximum Number of Structure Symbols
The number of structure symbols that is created for one PLC must satisfy the following formula:
Number of structure symbols + Number of members in those structure symbols ≤ 4,000
Example: A data structure with three members must be counted as 4 elements in determining if the
maximum number of data structures has been exceeded.
• Nesting Levels for Data Structures within Data Structures
A data structure can be used as the member of another data structure.
Data structures can be nested to up to eight levels.
• Subscripts of Data Structure Arrays
Either constants or symbols*1 can be used as subscripts of data structure arrays.
Addresses and formulas cannot be used.
*1: Symbols can be used only for the first data structure array.
• Subscripts of Array Data Structures
The subscripts must be constants.
Symbols, addresses, and formulas cannot be used.
Precautions for Data Structure Symbols
• Character Restrictions for Structure Symbol Names, Structure Data Type Names, and
Member Names
• Character Strings That Would Be Confused with Area Specifications
A, AC, AR, C, CF, CNT, D, DIFF, DM, DR, E, EM, E0_, E1_, E2_, E3_, E4_, E5_,
E6_, E7_, E8_, E9_, EA_, EB_, EC_, ED_, EE_, EF_, E10_, E11_, E12_, E13_, E14_,
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