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MELSEC-Q
10 DEVICES
10.2.10 Timers (T)
Timers are of up-timing, with the time measurement beginning when the coil switches
ON, and ending (time out) when the current value exceeds the set value.
The current value matches the set value when a "time-out" occurs.
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.
Timers Timers Low speed timers
High speed timers
Retentive timers Low speed retentive timers
High speed retentive 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.
Low-speed timers
(1) Definition
(a) Low speed timers are valid only while the coil is ON.
(b) 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.
X0
T0
K10
[Ladder example]
When X0 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.)
T0 coil
OFF
OFF
OFF
ON
ON
ON
1s
[Time chart]
X0
T0 contact
(2) Measurement units
(a) The default time measurement units setting for low speed timers is 100 ms.
(b) The time measurement units setting can be designated in 1 ms units within a
1 ms to 1000 ms range.
This setting is designated at the "PLC system" tab screen in the “(PLC)
Parameter" dialog box.
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