Specifications

4-16

4.3 Labels

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.

Table 4.3.3-1 Label classes

*1: Not supported by FXCPU.

• 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.

Class Description

Applicable POU

Program Function

Function

block

VAR_GLOBAL

Common label that can be used in programs and function

blocks

VAR_GLOBAL_

CONSTANT

Common constant that can be used in programs and function

blocks

VAR

Label that can be used within the range of declared POUs

This label cannot be used in other POUs.

VAR_CONSTANT

Constant that can be used within the range of declared POUs

This constant cannot be used in other POUs.

VAR_RETAIN

Latch type label that can be used within the range of declared

POUs

This label cannot be used in other POUs.

VAR_INPUT

Label that receives a value

This label cannot be changed in a POU.

VAR_OUTPUT Label that outputs a value from a function block

VAR_IN_OUT

Local label that receives a value and outputs the value from a

POU

This label can be changed in a POU.

VAR_INPUT

VAR_OUTPUT

VAR_IN_OUT