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12 Applied Instructions (High Speed Processing)
294
FXCPU Structured Programming Manual
[Basic & Applied Instruction]
12.7 SPD / Speed Detection
2. 32-bit operation (DSPD) [FX3GC PLCs Ver. 1.40 or later, FX3UC PLCs Ver. 2.20 or later, and
FX
3S/FX3G/FX3U PLCs]
The input pulse specified by is counted only for the period of "time specified by multiplied by 1 ms."
The measured value is stored in [ +1, ], the current value is stored in [ +3, +2], and the
remaining time is stored in [ +5, +4] (ms).
By repeating this operation, the measured value [ +1, ] will store the pulse density (which is
proportional to the rotation speed).
1) Timing chart
2) The value [ +1, ] is in proportion to the number of rotations as shown below.
Command
input
DSPD
EN
s1
s2
ENO
d
Device for
pulse input
Time data
Pulse density data
Command
input
Measured
value
Current value
Remaining time (ms)
The command contact is set to ON.
[ +3, +2] counts "OFF to ON" operation of .
[ +1, ] ms later, the counting result is stored to
[ +1, ].
Accompanied by this operation, [ +3, +2] is reset,
and then counting of the "OFF to ON" operation of
is started again.
[ +5, +4] is used to measure the remaining time.
Counting time Counting time
[ +1, ]
[ +3, +2]
[ +1, ] ms
[ +1, ] ms
[ +5, +4]
d
s1
s2
d
d d
dd
d d
d d
d d
d d
s1
s1
s2
[ +1, ] ms
s2s2s2s2
s2s2
Input X000
t: Measurement time duration specified as
[ +1, ] (ms).
nt
60 [ +1, ]
3
10 (r/min)N =
Proximity switch
"n" pulses/rotation
N (rpm)