Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 30

■ Subroutine type function blocks
The program of a subroutine type function block is stored in the FB/FUN file and called by the calling source program when
executed.
Use a subroutine type function block to reduce the program size.
(Program file)
Main program
FB1_a
FB1
FB2_a
FB2
Up to 32 subroutine type function blocks, macro type function blocks, and functions in total can be nested.
3 PROGRAM ORGANIZATION UNITS
28
3.3 Function Blocks (FB)
Execution
flow (FB file)
FB1 program
FB3_a
FB3
(FB file)
FB2 program
(FB file)
FB3 program