2-127
2 Instruction Descriptions
NJ-series Instructions Reference Manual (W502)
Timer Instructions
2
AccumulationTimer
The following figure shows a programming example and timing chart for a PT of T#10ms. Variable abc
changes to TRUE when variable A is TRUE for a total of 10 ms (i.e., the total time).
Use the TON instruction (page 2-116) for a timer that resets the timer output and elapsed time when In
changes to FALSE.
• ET and Q are updated only when the instruction is executed. Therefore, Q does not change to TRUE
precisely when the total time of timer operation reaches PT. Q changes the next time the instruction is
executed after the total time of timer operation reaches PT. The change in Q can therefore occur with
a delay of up to one task period.
• Set PT and ET in nanoseconds (ns), but remember the timing accuracy is 100 ns.
• If In and Reset are both TRUE, Reset has priority. That is, ET changes to 0 and Q changes to FALSE.
• The timer starts as soon as operation starts if In is already TRUE.
• If T#0ms or a negative number is set for PT, Q will change to TRUE as soon as the value of In
changes to TRUE.
• You can change the value of PT before the value of ET reaches the value of PT. Operation is as fol-
lows:
Additional Information
Precautions for Correct Use
Timer status Value of Q
Value of PT after it is
changed
Operation
After comple-
tion of timing
TRUE --- The value of Q remains TRUE.
The value of ET also does not change. (It remains at
the value of PT before it was changed.)
Timing in
progress
FALSE
PT ≥ ET When the value of In changes to TRUE, timing is
continued. When the value of ET reaches the value
of PT, the value of Q changes to TRUE and ET is no
longer incremented.
PT < ET When the value of In changes to TRUE, the value of
Q changes to TRUE immediately. Incrementing ET
stops immediately.
AccumulationTimer_instance(A, T#10ms, abc, def, ghi);
LD ST
abc
A
ghi
def
T#10ms
AccumulationTimer
In Q
PT ET
Reset
AccumulationTimer_instance
In=A
Q=def
TRUE
FALSE
ET=ghi
PT=T#10ms
Reset=abc
TRUE
FALSE
TRUE
FALSE
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