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6 SFC PROGRAM EXECUTION
MELSEC-Q
6.5 Operation Methods for Continuous Transition
If "with continuous transition" is set, whether a continuous transition will be performed or not can
be selected at each step using the continuous transition disable flag (SM324).
(1) Processing performed when continuous transition disable flag is not used
SFC Program With Continuous Transition Without Continuous Transition
(Block n)
S0
S1
S2
S3
aSM400
aSM400
aSM400
When the corresponding block becomes active,
the processings of all steps are executed in the
same scan, and end step processing is
performed to deactivate the block.
•
When the corresponding block becomes
active, steps are executed in a 1-step-per-
scan format.
•
The end step processing is performed in the
third scan to deactivate the block.
(2) Processing performed when continuous transition disable flag is used
SFC Program With Continuous Transition Without Continuous Transition
(Block n)
aSM400 & aSM324
aSM400 & aSM324
aSM400 & aSM324
S0
S1
S2
S3
• When the corresponding block becomes
active, execution proceeds to step 1 since
SM324 is ON.
When execution proceeds to step 1, the
processing of the first scan is ended since
SM324 turns OFF.
•
In the second scan, execution proceeds to
step 2 since SM324 turns ON again.
When execution proceeds to step 2, SM324
turns OFF.
Since the transition condition of step 2 does
not have the contact of SM324, a transition
occurs and the end step processing is
performed to deactivate the block.
•
When the corresponding block becomes
active, steps are executed in a 1-step-per-
scan format independently of whether SM324
is present or absent.
•
The end step processing is performed in the
third scan to deactivate the block.
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