22 LABELS
22.3 Classes
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22
22.3 Classes
The label class indicates from which POU and how a label can be used.
Different classes can be selected depending on the type of POU.
Global label
Class Description Applicable POU
Program
block
Function block Function
VAR_GLOBAL A common label that can be used in both program blocks and
function blocks
VAR_GLOBAL_CONSTANT A common constant that can be used in both program blocks
and function blocks
VAR_GLOBAL_RETAIN A latch type label that can be used in both program blocks and
function blocks
Local label
Class Description Applicable POU
Program
block
Function block Function
VAR A label that can be used within the range of a declared POU.
This label cannot be used in other POUs.
VAR_CONSTANT A constant that can be used within the range of a declared
POU.
This label cannot be used in other POUs.
VAR_RETAIN A latch type label that can be used within the range of a
declared POU. This label cannot be used in other POUs.
VAR_INPUT A label that inputs a value into a function or function block.
This label receives a value, and the received value cannot be
changed in a POU.
VAR_OUTPUT A label that outputs a value from a function or function block
VAR_OUTPUT_RETAIN A latch type label that outputs a value from a function block
VAR_IN_OUT A local label that receives a value and outputs the value from a
POU. The value can be changed in a POU.
VAR_PUBLIC A label that can be accessed as the public variable from other
POUs
VAR_PUBLIC_RETAIN A latch type label that can be accessed as the public variable
from other POUs
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