Mitsubishi Electric FX3G SERIES Programming Manual page 821

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
2) Pulse period measurement
The pulse period of the input signal from X000 is measured.
Step
0
M8075
Pulse width
/Pulse period
measurement
setting flag
interrupt
M8000
pointer
I001
RUN monitor
- 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 from OFF to ON. (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.
RUN/STOP
M8080
pulse period
X000
The pulse period is
not measured.
36.8 Pulse width/Pulse period measurement function [M8075 to M8079, D8074 to D8097]
X000
This duration is measured.
FNC 04
EI
M8076
X002
M8080
FNC 06
FEND
X000 Rising edge interrupt
FNC 12
D8078
DMOV
User program
FNC 03
IRET
END
ON
The pulse period is measured.
(D8078 and D8079 are updated.)
36 Interrupt Function and Pulse Catch Function
ON
OFF
Interrupts are enabled after the 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
D0
pulse period of input signal from X000 stored in
D8078 and D8079 is transferred to D1 and D0.
Interrupt return
RUN
one operation cycle
ON
a
The pulse period is
not measured.
The pulse period is measured.
(D8078 and D8079 are updated.)
31
32
33
34
35
36
37
38
A
B
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