100
FX
3G
/FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.5 Timer [T]
4.5.5
Details of timer operation and timer accuracy
A timer (except interrupt execution type) starts counting when a coil is driven, and its output contact turns on
when the first coil instruction is executed after the timer has reached timeout.
As shown in the above operation diagram, the accuracy of operation of the timer contact after the coil is
driven until the contact turns on is shown in the following outline:
If the contact is programmed before the timer coil, "+2T
0
" is obtained in the worst case.
When the timer set value is "0", the output contact turns on when a coil instruction is executed in the next
cycle. An interrupt execution type timer for 1 ms pulses counts clock pulses of 1 ms as an interrupt
processing after a coil instruction has been executed.
4.5.6
Program examples [off-delay timer and flicker timer]
Off-delay timer
Flicker timer (blink)
In addition, the flicker operation can be performed by the ALT (FNC 66) instruction.
Multi-timer by the applied instruction STMR (FNC 65) <FX
3U
/FX
3UC
PLC>
By this instruction, off-delay timers, one-shot timers and flicker timers can be easily created.
→
For details, refer to Section 14.6.
X010
T 0
K12
T 0
Y010
Input processing X010 = OFF
→
ON
Counting operation (If the operation cycle is long,
it automatically counts two or more clocks.)
Contact is not
activated at this point
T 0
Contact is
activated
2nd cycle
"n"th cycle
"n+1"th cycle
Y010
ON
Timer starts counting
1st cycle
1.2 sec
time-
out
α
: 0.001 sec (timer for 1 ms), 0.01 sec (timer for 10 ms) or 0.1 sec (timer for 100 ms)
T : Timer set value (sec)
T
0
: Operation cycle (sec)
T
+T
0
−α
X001
T 5
Y000
T 5
K200
T5
(20 sec)
X001
Y000
Y000
X001
X001
T 2
T 1
T 2
K10
K20
T 1
Y000
Y000
T 2
One
operation
cycle
X001
T1
T2
T1
2
sec
1
sec
2
sec
( )