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(7) Precautions for using timers
(a) Use of the same timer
Do not use the OUT T or OUT ST instruction that describes the same timer more than once within one
scan. If used, the current timer value will be updated by each OUT T or OUT ST instruction execution,
resulting in incorrect time measurement.
(b) When the timer is not executed in every scan
Current values are not updated for every scan, resulting in incorrect time measurement. While a coil of a timer
is on, do not make the OUT T or OUT ST instruction jumped to any other part with another instruction such
as CJ.
For subroutine programs where a timer is provided and a coil is on, use the timer once in each scan.
(c) Programs that cannot use timers
Timers cannot be used in interrupt programs and fixed scan execution programs.
(d) When the set value is 0:
The contact turns on when the OUT T or OUT ST instruction is executed.
(e) When the set value is 1:
When the timer limit setting value is greater than the scan time value, the count value of the timer becomes 1 at
execution of the END instruction in a scan where the count value reaches to the timer limit setting value. When
the coil of the timer turns on in the scan next to the one where the count value becomes 1, the current timer
value becomes 1. In this case, the timer times up in the step and the contact turns on. If the contact of the timer
(setting value = 1) turns on in a short time, change the timer with small timer limit setting value and set a
greater value to the contact.
(f) When the set value is changed after time-out
Even if the set value is changed to a larger value, the timer remains timed-out and does not start the operation.
Scan time
END
010 1
1
0
0
OFF
ON
ON
ON
OFF
OFF
X0
Coil of T0
Contact of T0
END END END END END END
X0 K1
T0
Timer limit setting value
Count with END
instruction
Current value
of timer
Measurement
of timer
Program
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