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21 DEVICES
21.3 User Device
Timer
This device starts measurement when the timer coil is turned on. When the current value reaches a setting value, time is up
and the contact is turned on. This timer is an up-timing type device and therefore the current value matches a setting value
when the timer time is up.
Types of timers
There are two types of timers: timer (T) which retains the current value in 16-bit units and long timer (LT) which retains it in 32-
bit units. The timer (T) and the long timer (LT) are different devices and the number of device points can be set for each of
them. In addition, there are the retentive timer (ST) and the long retentive timer (LST), both of which retain the current value
even if the coil is turned off.
*1
*1 For the timer (T)/long timer (LT), the current value returns to 0 when the coil is turned off.
■Timer (T)
This device starts measurement when the coil of the timer is turned on. When the timer current value matches a setting value,
time is up and the timer contact is turned on. When the timer coil is turned off, the current value returns to 0 and the timer
contact is turned off.
■Long timer (LT)
This device can count from 0 to 4294967295 to measure the time. If the measuring unit is set to 0.01ms, the measurable time
range of this device is from 0 to about 11.9 hours. The current value of the long timers is updated by adding a difference of the
counter which is used in the system when the OUT LT instruction is executed. Proper time can be measured even when the
coil instruction of the long timer cannot be executed once per scanning because the counters used in the system count
asynchronously with scanning. When the long timer coil is turned on, measurement starts and when the long timer current
value matches a setting value, time is up and the long timer contact is turned on. When the long timer coil is turned off, the
current value returns to 0 and the long timer contact is turned off.
*1 This figure shows the example when the long timer time limit value setting is 0.01ms.
• For the long timer contact to be turned on after the long timer coil is turned on, the next coil must be
executed after the long timer coil turned off and on. The long timer contact is not turned on simultaneously
when the long timer coil is off and on.
• The long timer (LT) can be used in interrupt programs. ( Page 67 Interrupt Program)
Types of timers
Timer Current value = 16 bits Timer (T) Low-speed timer
High-speed timer
Retentive timer (ST) Low-speed retentive timer
High-speed retentive timer
Current value = 32 bits Long timer (LT)
Long retentive timer (LST)
X0
X0
OFF
OFF
OFF
ON
ON
ON
K10
T0
T0
Y10
Coil of T0 (1))
1 second
Contact of
T0 (2))
1)
2)
1ms
X0
X0
OFF
OFF
OFF
ON
ON
ON
K100
LT0
LT0
Y10
Coil of LT0 (1))
Contact of
LT0 (2))
1)
2)
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