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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
(4) The method for using a step transition watch dog timer is shown below.
Transition condition a
Step where time
check is performed
Time setting...10 1s=10s
Annunciator (F) No. ...F1
H010A
10 (s)
F1
annunciator
MOVP H010A SD60, oSM90
(a) When SM90 is turned ON in the operation output of the step that performs a time check as
shown below, the step transition watchdog timer starts timing.
(b) If transition condition a is not satisfied within the set time (10s) after SM90 has turned ON,
annunciator F1 turns ON.
(However, the SFC program continues operation.)
(c) When transition condition a is satisfied within the set time and SM90 turns OFF, the step
transition watchdog timer stops timing and is reset.
(5) If the annunciators (F0 to F255) turn ON, the number of detected annunciators that turned ON
and the annunciator numbers are not stored into SD62, SD63 and SD64 - SD79.
(6) The step transition watchdog timers of the same number can be used at different steps if they
do not become active simultaneously.
Example:
S5
S6
t4
t5
t6
Watchdog timer 1
Watchdog timer 2
As there is no chance that steps 5 and 6 will be
concurrently active, the same watch dog timer can be
used at both steps.
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