Set Value Specification Method; Cautions On Routines; Details On Timer Operation And Timer Accuracy - Mitsubishi Electric FX3G SERIES Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4.5.3

Set value specification method

1. Specifying a constant (K)
X003
2. Indirectly specifying a data register
X001
X003
4.5.4

Cautions on routines

1) Use timers T192 to T199 in subroutines and interrupt routines. These timers execute counting when a coil
instruction or END instruction is executed.
When such a timer reaches the set value, its output contact turns on when a coil instruction or END instruction is
executed.
Because general type timers execute counting only when a coil instruction is executed (Refer to "4.5.5 Details on
timer operation and timer accuracy" below), they do not execute counting and do not operate normally if they are
used in subroutines or interrupt routines in which a coil instruction is executed only in a certain condition.
2) When a retentive timer for 1 ms pulses (T246 to T249) is used in a subroutine or interrupt routine, note that its
output contact turns on when the first coil instruction is executed after the retentive timer has reached the set
value.
4.5.5

Details on 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.
X010
T 0
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:
T
α : 0.001 sec (timer for 1 ms), 0.01 sec (timer for 10 ms) or 0.1 sec (timer for 100 ms)
+T
0
−α
T : Timer set value (sec)
T : Operation cycle (sec)
0
If the contact is programmed before the timer coil, "+2T
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.
96
Constant
(decimal integer)
10-second timer
T10
K100
FNC 12
K100 D 5
MOV
D5 = K100
10-second
T10
D 5
timer
Counting operation (If the operation cycle is long,
it automatically counts two or more clocks.)
Input processing X010 = OFF→ON
Timer starts counting
T 0
K12
Y010
1st cycle
T10 is a 100 ms (0.1 sec) type timer.
When the constant "100" is specified, T10 works as a 10-
second timer (0.1 sec × 100 = 10 sec).
Turns on when T10 reaches the indirectly specified value of
the defined data register, previously set by a digital switch.
Note that the set value of a latched (battery backed) type
register is not held correctly sometimes when the battery
voltage becomes low.
1.2 sec
time-
out
2nd cycle "n"th cycle
" is obtained in the worst case.
0
4 Devices in Detail
4.5 Timer [T]
Contact is not
activated at this point
T 0
Contact is
activated
Y010
ON
"n+1"th cycle