Mitsubishi MELSEC QS Series, User Manual

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9
DEVICE EXPLANATION
9
- 18 9.2 Internal User Devices
9.2.8 Timer (T)
9.2.8 Timer (T)
(1) Definition
A timer (T) is a device that starts counting when its coil turns ON, and times-out and
turns ON its contact when the current value reaches or exceeds the set value.
The timer is of an up-counting type.
The current value matches the set value when a "time-out" occurs.
(2) Timer types
There are two types of timers: a low/high speed that allows the current value to return
to "0" when a timer coil switches OFF, and a retentive timer that retains the current
value even when a timer coil switches OFF.
(3) How to use timers
With a timer setting (instruction format), a device is assigned for a low speed timer or
high speed timer. The OUT T0 instruction is used to assign a device for a low -speed
timer. The OUTH T0 instruction is used to assign a device for a high speed timer.
With a timer setting (instruction format), a device is assigned for a low speed retentive
timer or high speed retentive timer. The OUT T0 instruction is used to assign a device
for a low speed retentive timer. The OUTH T0 instruction is used to assign a device
for a high speed retentive timer.
(4) Low-speed timers
(a) Definition
Low-speed timers perform counting in 1 to 1000ms units.
The timer is valid only while its coil is ON.
The time measurement begins when the timer's coil switches ON, and the contact
switches ON when a "time-out" occurs. When the timer's coil switches OFF, the
current value becomes "0", and the contact switches OFF.
Diagram 9.17 Timer types
Diagram 9.18 Ladder example and timing chart of low-speed timer
Timers Timers
Retentive
timers
Low speed timers
Low speed retentive timers
High speed timers
High speed retentive timers
X100
T0
K10
OFF
OFF
OFF
ON
ON
ON
X100
T0 contact
[Time chart]
T0 coil
[Ladder example]
When X100 switches ON, the T0 coil switches ON, and
the contact switches ON 1 second later. (The low-speed
timer measures time in 100 ms units.)
1s