Overview of Subroutines
Subroutines are programmed as separate entities, either in:
Ladder language (LD),
Functional block language (FBD),
Instruction List (IL),
Structured Text (ST).
The calls to subroutines are carried out in the sections or from another subroutine.
A subroutine cannot call itself (non-recursive).
Subroutines are also linked to a task. The same subroutine cannot be called from several different tasks.
Example
The following diagram shows a task structured into sections and subroutines.
Characteristics of a Subroutine
The following table describes the characteristics of a subroutine.
Characteristic |
Description |
|---|---|
Name |
32 characters maximum (accents are possible, but spaces are not allowed). |
Language |
LD, FBD, IL, or ST. |
Task |
MAST, FAST or Auxiliary |
Comment |
1024 characters maximum |