Functions, Function Blocks, And Operators - Mitsubishi Electric MELSEC Q Series Programming Manual

Functions, function blocks, and operators

The following table shows differences among functions, function blocks, and operators.
Item
Output variable assignment
Internal variable
Creating instances
Output variable assignment
A function always outputs a single operation result. A function that does not output any operation result or outputs multiple
operation results cannot be created.
A function block can output multiple operation results. It also can be created without any output.
An operator always outputs a single operation result. It cannot be edited.
Ex.
The following table shows the examples.
Function
4 PROGRAM CONFIGURATION
24
4.2 POUs
Function
Cannot be assigned
Not used
Not necessary
Function block
Outputs one
operation result
Function block
Can be assigned
Used
Necessary
Outputs multiple Outputs multiple
operation results
Without any output
Operator
Cannot be assigned
Not used
Not necessary
Operator
Outputs one
operation result