
10.STEP SEQUENCE FUNCTION B-63983EN/02
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(5) Divergence and Convergence of Selective Sequence
To describe a complicated sequence, selective sequences
can be used.
A selective sequence offers multiple choices, from among which
the condition becomes true first activates the corresponding step,
as shown in Fig. 10.2.1(f). The divergent paths join to generate
the main sequence.
Fig. 10.2.1(f) Selective sequence
S1
(Divergence of selective sequence)
P23
P21 P22
S21 S22 S23
(Convergence of selective sequence)
When transition P21 evaluates true
¯
When transition P22 evaluates true.
S1
(true)
S21 S22 S23
S2
(true)
S21 S22 S23
¯
S1 (step1)