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4 OPERATION CONTROL PROGRAMS
4.4 Labels
4.4 Labels
A label is a variable consisting of a specified character string used in I/O data or internal processing.
Using labels in programming enables creation of programs without being aware of devices.
For this reason, a program using labels can be reused easily even in a system having a different module configuration.
Types
Labels
A label provides the same data within a single project. It can be used in all programs in the project.
The settings of a label include a label name, and data type.
By opening labels, they can be referenced from GOT, and can be used for monitoring and accessing data.
When programming with labels for input and output devices, assign the labels to the devices directly.
The following types of labels are available.
• System label
A system label is a label that provides the same data in all projects compatible with iQ Works. It can be
referenced from the GOT and the CPU modules on other stations, and used for monitoring and accessing
data. For details, refer to the following.
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Data types
The data types of a label are classified according to the bit length, processing method, and value range.
The types are shown below.
Primitive data type
The following table lists the data types included in the primitive data type.
When using double word [unsigned]/bit string [32 bits], double word [signed], double-precision real number
data types, use an even number device.
Data type Description Value range Bit length
Bit BOOL Represents the alternative status, such as ON or OFF. 0 (FALSE), 1 (TRUE) 1 bit
Word [unsigned]/bit string [16 bits] WORD 16-bit array. 0 to 65535 16 bits
Double word [unsigned]/bit string [32 bits] DWORD 32-bit array. 0 to 4294967295 32 bits
Word [signed] INT Positive and negative integer values. -32768 to 32767 16 bits
Double word [signed] DINT Positive and negative double-precision integer values. -2147483648 to 2147483647 32 bits
Double-precision real number LREAL Numerical values of decimal places (double-precision
real number values).
K-1.79E+308 to K-2.23E-308,
K0.0,
K2.23E-308 to K1.79E+308
64 bits
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