Label Classes - Mitsubishi Electric MELSEC Q Series Structured Programming Manual

4.3.3

Label classes

The label class indicates from which POU and how a label can be used. Different classes can be
selected according to the type of POU.
The following table shows label classes.
Class
VAR_GLOBAL
VAR_GLOBAL_
CONSTANT
VAR
VAR_CONSTANT
VAR_RETAIN
VAR_INPUT
VAR_OUTPUT
VAR_IN_OUT
*1: Not supported by FXCPU.
4.3 Labels
4-16
4.3.3 Label classes
Common label that can be used in programs and function
blocks
Common constant that can be used in programs and function
blocks
Label that can be used within the range of declared POUs
This label cannot be used in other POUs.
Constant that can be used within the range of declared POUs
This constant cannot be used in other POUs.
Latch type label that can be used within the range of declared
*1
POUs
This label cannot be used in other POUs.
Label that receives a value
This label cannot be changed in a POU.
Label that outputs a value from a function block
Local label that receives a value and outputs the value from a
POU
This label can be changed in a POU.
• Input variables, output variables, and input/output variables
VAR_INPUT is an input variable for functions and function blocks, and
VAR_OUTPUT is an output variable for function blocks.
VAR_IN_OUT can be used for both input and output variables.
VAR_INPUT
VAR_IN_OUT
Table 4.3.3-1 Label classes
Description
Applicable POU
Function
Program Function
VAR_OUTPUT
block