Fuji Electric SPH Series - 2-6 SFC Elements

2-48
Section 2 Programming Languages
2-6 SFC Elements
An SFC is a program that species the operation of a plant or machine in owchart form. Since it allows the ow of processes
to be programmed in a natural manner, it facilitates the programmer to develop programs efciently and to grasp the ow of a
program as the ow of processes.
For example, the process of painting automobiles can be depicted as shown below in an SFC form.
Start
Hold body
Move
Stop at predefined position
Paint
End of painting
Move and dry body
Start
STEP 1
STEP 2
STEP 3
[Transition condition 1]
[Process 1]
[Transition condition 2]
[Process 2]
[Transition condition 3]
[Process 3]
(STEP1)
(ACT01)
When represented
in SFC form
(STEP2)
(ACT02)
(STEP3)
(ACT03)
(T1)
(T2)
(T2)
N ACT01
N ACT02
N ACT03
T1
T2
T3
The elements of an SFC have the following meanings:
Start
STEP 1
N ACT01
T1
Transition
(condition for moving
to the next step)
Initial step
(beginning of processing)
Actions
(describes the process)
Action qualifier
(an alphabetic character indicating
the control at which the action is to be taken)
Step flag (connects the step to an action)
Step
(segmented elements of a process)
Each action or transition must be assigned to a BOOL variable or programmed using the IL, ST, LD, or FB language.
Notes:
Up to 24 characters are allowed for SFC
step, action, and transition names.