Mitsubishi Electric MELSEC-Q Series User Manual page 181

10 DEVICES
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(c) The timer response accuracy from the point when input (X) reading occurs,
until the point when the output occurs is + (2-scan time + timer time limit
setting).
Precautions when using timers
The following are a few precautions regarding timer use:
(a) A given timer cannot be designated (by OUT T ) more than once in a
single scan.
If it is, the timer's present value will be updated at each OUT T
instruction, resulting in a meaningless measurement.
OUT
T
END
Sequence
program
(b) When a timer (for example. T1) coil is ON, the OUT T1 instruction cannot be
skipped using a CJ instruction, etc.
If the OUT T
updated.
(c) Timers cannot be used in interrupt program.
(d) If the timer set value is "0", the contact goes ON when the OUT T
instruction is executed.
(e) If the setting value changes to a value which is higher than the present
value following a timer "time-out", the "time-out" status will remain in effect,
and timer operation will not occur.
(f) If two timers are used, the ON/OFF ladders should be created as shown
below.
T0
T1
T0
OUT OUT
T T
END
1 Scan
instruction is skipped, the timer's present value will not be
K10
1 second measurement
T1
following T0 ON
K10
1 second measurement
T0
when T1 ON
ON/OFF repeated every
M0
1 second
MELSEC-Q
OUT OUT
T T
Present value is updated.
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