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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
3) When counter is reset
When a transition to the next step occurs before the reset instruction of the counter is
executed, the present value of the counter and the ON status of the contact, which is
ON, are held if the corresponding step becomes inactive.
To reset the counter, the RST instruction, etc. must be executed at another step.
Step n
Step (n+1)
Transition
condition n
Example:
oC0 K10
rC0
When counter C0 is reset at step (n+1) or later, the
present value is cleared and the contact turns OFF.
(2) The PLS or
P instruction used for the operation output of any step is executed every time
the corresponding step turns from an inactive to an active status.
The program shown on the left is actually executed in a
ladder as shown below. Because the step conditions contact
is ON when the step is active and OFF when the step is
inactive, the PLS or
P instruction will be executed every
time the corresponding step becomes active.
PLS Y0
Step n
Step (n+1)
Example:
PLS Y0
St ep condit ions cont act
When act ive: ON
When inact ive: OFF
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