
2. STEP SEQUENCE BASICS
B–61863E/15
STEP SEQUENCE FUNCTION
978
(4) Initial Step
[ ]
Sn
(Pm)
While a normal step can be activated by a transition, the initial step
is activated automatically when execution of the program starts, as
shown in Fig. 2.1 (e).
Stopping program (STOP) Executing program (RUN)
S1 (step1) S1 (step1)
P10
S2 (step2)
P20 P20
S3 (step3)
P10
S2 (step2)
S3 (step3)
[ ] [ ]
Fig. 2.1 (e) Activate of initial step
Although the initial step, which is usually executed first, is often
placed at the top of a program, it can also be specified at some point
within a program. It is always activated first. After being deactivated
once, it can be subsequently be activated again. In this case, it acts
in the same way as a normal step.