Mitsubishi Electric MELSEC-Q Series User Manual page 125

7 FUNCTION
7 - 29
(c) The scan time value is not reset even if the watchdog timer is reset in the
sequence program.
The scan time value is measured to the END instruction.
Internal processing time
END 0
WDT reset
(QCPU internal processing)
REMARK
Scan time is the time elapsed from the time the Basic model QCPU starts
processing a sequence program at Step 0 until the it restarts processing another
sequence program with the same filename at Step 0.
The scan time is not the same at every scan, and differs, depending on
• Whether the commands used are executed or not executed.
• Whether to execute or not an interrupt program.
Use the constant scan function to execute a program at the same scan time every
scan.
Refer to section 7.2 for details of the constant scan function.
Sequence program
Scan time
Watchdog timer measured time
Fig. 7.9 Watchdog Timer Reset
MELSEC-Q
Internal processing time
END 0
Next scan time
WDT reset (QCPU internal processing)
7 - 29