Function Blocks; Operators - Mitsubishi Electric MELSEC Q Series Structured Programming Manual

4.2.4

Function blocks

Functions, function blocks, and operators are used to edit function blocks.
Function blocks can be used by calling them from programs or function blocks. Note that they
cannot be called from functions.
Function block
Function blocks can retain the input status since they can store values in internal and output
variables. Since they use retained values for the next processing, they do not always output the
same results even with the same input values.
Function blocks can be described in the ST or structured ladder/FBD language.
● Instantiation
Function blocks need to be instantiated to be used in programs.
For details of instantiation, refer to the following section.
Section 4.2.8 Functions and function blocks
Instances are variables representing devices assigned to labels of function
blocks.
Devices are automatically assigned when instances are created with local labels.
4.2.5

Operators

Operators can be used by calling them from programs, functions, or function blocks.
Operators cannot be edited.
Operators always output same processing results for the same input values.
Function
Function block
Operator
4.2.4 Function blocks
4.2 POUs
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