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Programming the Structure of the Sequencer
S7-GRAPH for S7-300/400 Programming Sequential Control Systems
C79000-G7076-C526-01
6-3
6.2
Structures of a Sequencer
The simplest structure of a sequencer is a linear sequence of steps and transitions
without branches.
A linear sequencer starts with a step and finishes with a transition that can be
followed either by a jump to any step or by a branch stop.
The linear sequence can be extended by the following:
•
Branches (alternative branch, simultaneous branch),
•
Jumps to any steps,
•
Further sequencers operating either dependent on the first sequencer or
completely independently.
•
Permanent instructions located before or after the sequencer.
Examples of Structures of a Sequencer
T2
T1
T4
T3
T6
T2
T1
T3
T5
T6
T2
T1
T4
T3
S1
S1
S1
S2
S2
S2
S3
S4
S3
S5
S3
S4
S5
S6
S1
S7
T4
T11
S4
S6
T4
T9
T8
T11
T10
S7
S8
S9
S10
S1
T4
T7
T5
(1) S7 Graph FB with a linear sequencer
(2) S7 Graph FB with a sequencer with an alternative and simultaneous branch
(3) S7 Graph FB with two sequencers
T4
(1)
(2)
(3)
S1