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Function Block Specifications Section 2-1
• For details on system-defined variables, refer to Appendix C External
Variables.
• To reference user-defined variables in the global symbol table, the vari-
ables must be registered in the global symbol table using the same vari-
able name and data type as the external variable.
Variable Properties Variable Name
The variable name is used to identify the variable in the function block. The
name can be up to 30,000 characters long. The same name can be used in
other function blocks.
Note A variable name must be input for variables, even ones with AT settings (spec-
ified address).
Data Type
Any of the following types may be used.
Note (1) The TIMER data type is used to enter variables for timer numbers (0 to
4095) in the operands for TIMER instructions (TIM, TIMH, etc.). When
this variable is used in another instruction, the Timer Completion Flag (1
bit) or the timer present value (16 bits) is specified (depending on the in-
struction operand). The TIMER data type cannot be used in structured
text function blocks.
(2) The COUNTER data type is used to enter variables for counter numbers
(0 to 4095) in the operands for COUNTER instructions (CNT, CNTR,
etc.). When this variable is used in another instruction, the Counter Com-
pletion Flag (1 bit) or the counter present value (16 bits) is specified (de-
pending on the instruction operand). The COUNTER data type cannot be
used in structured text function blocks.
AT Settings (Allocation to Actual Addresses)
With internal variables, it is possible to set the variable to a particular I/O
memory address rather than having it allocated automatically by the system.
To specify a particular address, the user can input the desired I/O memory
address in this property. It is still necessary to use variable name in program-
ming even if a particular address is specified.
Note (1) The AT property can be set for internal variables only.
Data type Content Size Inputs Outputs Internals
BOOL Bit data 1 bit OK OK OK
INT Integer 16 bits OK OK OK
UNIT Unsigned integer 16 bits OK OK OK
DINT Double integer 32 bits OK OK OK
UDINT Unsigned double integer 32 bits OK OK OK
LINT Long (4-word) integer 64 bits OK OK OK
ULINT Unsigned long (4-word) integer 64 bits OK OK OK
WORD 16-bit data 16 bits OK OK OK
DWORD 32-bit data 32 bits OK OK OK
LWORD 64-bit data 64 bits OK OK OK
REAL Real number 32 bits OK OK OK
LREAL Long real number 64 bits OK OK OK
TIMER Timer (See note 1.) Flag: 1 bit
PV: 16 bits
Not supported Not supported OK
COUNTER Counter (See note 2.) Flag: 1 bit
PV: 16 bits
Not supported Not supported OK
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