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815
FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
36 Interrupt Function and Pulse Catch Function
36.8 Pulse width/Pulse period measurement function [M8075 to M8079, D8074 to D8097]
31
FNC275-FNC279
Data
Transfer 3
32
FNC280-FNC289
High Speed
Processing 2
33
FNC290-FNC299
Extension File
Register
34
FNC300-FNC305
FX
3U
-CF-ADP
35
SFC•STL
Programming
36
Interrupt
Function
37
Special Device
38
Error Code
A
Version Up
Information
B
Execution Times
2) Pulse period measurement
The pulse period of the input signal from X000 is measured.
- Timing chart
The pulse period is not measured when the input signal rises for the first time after the PLC mode is changed
from STOP to RUN, or when the input signal rises for the first time after the pulse period measurement mode
(M8080) is set to ON from OFF. (Accordingly, D8078 and D8079 are not updated.)
The pulse period is measured when the input signal rises at the next time. (As a result, D8078 and D8079 are
updated.)
Make the pulse width/pulse period measurement setting flag (M8080) remain OFF for 1 operation cycle or more
when discontinuing the pulse input.
If M8080 does not remain OFF for 1 operation cycle or more, the "a" period shown below is stored as the pulse
period.
X000
OFF
ON
This duration is measured.
FNC 04
EI
FNC 03
IRET
END
Step
0
FNC 06
FEND
I001
interrupt
pointer
X000 Rising edge interrupt
Interrupt return
Interrupts are enabled after EI (FNC 04)
instruction.
The main program is described.
X000 is used for the pulse width/pulse period
measurement function.
When X002 turns ON, the pulse period measurement
mode is actuated.
When the interrupt routine is executed at the
rising edge of the input signal from X000, the
pulse period of input signal from X000 stored in
D8078 and D8079 is transferred to D1 and D0.
*1
M8075
M8000
RUN monitor
FNC 12
DMOV
D8078 D0
User program
Pulse width
measurement
setting flag
M8076
X002
M8080
/Pulse period
M8080
RUN/STOP
RUN
X
000
a
The pulse period is measured.
(D8078 and D8079 are updated.)
The pulse period is measured.
(D8078 and D8079 are updated.)
The pulse period is
not measured.
The pulse period is
not measured.
one operation cycle
ON ON
pulse period