Chapter 4 Labels; Label Types - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

4
LABELS
A label is a variable consisting of a specified string used in I/O data or internal processing.
Using labels in programming enables creation of programs without being aware of devices and buffer memory sizes.
For this reason, a program using labels can be reused easily even in a system having a different module configuration.
When labels are used, there are some precautions on programming and functions used. For details, refer to the following.
Page 49 Precautions
4.1

Label Types

There are two types of labels described in this manual.
• Global labels
• Local labels
Global labels
A global label is a label that provides the same data within a single project. It can be used in all programs in the project.
A global label can be used in program blocks and function blocks.
The settings of a global label include a label name, class, and data type.
By opening global labels, they can be referenced from GOT and other stations, and can be used for monitoring and accessing
data.
■ Device assignment
Devices can be assigned to global labels.
Item
Label to which no device is assigned
Label to which a device is assigned
Local labels
A local label is a label that can be used only in the declared POU. Local labels outside the declared POU cannot be used.
The settings of a local label include a label name, class, and data type.
There are other types of labels available in addition to the global labels and local labels.
[System labels]
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 and Motion controllers on other stations, and used for
monitoring and accessing data.
For details, refer to the following.
 iQ Works Beginner's Manual
[Module labels]
A module label is a label defined uniquely by each module. A module label is automatically generated by the
engineering tool from the module used, and can be used as a global label.
For details, refer to the following.
 Function Block Reference for the module used
4 LABELS
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4.1 Label Types
Description
• Programming without being aware of devices is possible.
• Defined labels are allocated to the label area or latch label area in the device/label memory.
• If a device is to be programmed as a label against a device that is being used for input or output, the device can be
assigned directly.
• Defined labels are allocated to the device area in the device/label memory.