Specifications

7. Application Instructions
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7-11
 When interrupting a special auxiliary relay M1050 to M1053, the same
interrupting request will not be activated.
 Interrupting cursor (I001 to I201) must be used after the FEND
command.
 Program Example
Any interrupt signal
occuring between DI
and EI instructions, is
disabled until the
processing between
the DI and EI
instructions is
completed after which
the interrupt program
is run.
Interrupt
subroutine A
Interrupt
subroutine B
EI
Y1
X0
I 101
FEND
IRET
I 201
DI
IRET
END
06 FEND
Terminates the main routine program
 It has the same function as END command during PLC operation.
 CALL must follow right after FEND command. Interrupt commands
also have to follow after FEND command.
 If using several FEND commands, please place the subroutine and
interrupt service programs after the last FEND command.
07 WDT
Resets the watchdog timer
 Resets the watchdog timer.
 Used when the period of time from step 0 to END (FEND) in the
sequence program exceeds the set value of the watchdog timer.
 Set the value of the watchdog timer so “ t1” is from step 0 to WDT
instruction and “ t2” is from the WDT to END (FEND) instruction. (See
the diagram below)
t1 t2
Ste
p
0 END
(
FEND
)
WD
T
 The WDT instruction can be used two or more times during one scan.
However, care should be exercised because, during an error, the
outputs cannot be turned off immediately.
 If the PLC scan time is more than 200ms, the ERROR LED will flash.
The user will have to turn the PLC OFF and then back ON to clear the
fault.
 If the program scan time is over 200ms, users can divide the program
into 2 parts. Insert the Watchdog Timer in between, so both programs’
scanning time will be less than 200ms.
 The WDT time can be changed by the setting value of D1000 (default
is 200ms).
 When the ERROR LED of PLC is steady, M1008 and D1008 can be
watched.