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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
13 High Speed Processing – FNC 50 to FNC 59
13.7 FNC 56 – SPD / Speed Detection
2. 32-bit operation (DSPD)
The input pulse is counted only for [ +1, ] x 1 ms. The measured value is stored in [ +1,
], the present 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 measured value [ +1, ] is in proportion to the number of rotations as shown below:
S
1
S
2
S
2
D
D
D
D
D
D
D
D
FNC 56
DSPD
S
1
D
S
2
Command
input
Command
input
Measured value
ms
S
1
Current value
ms
Remaining time (ms)
The command contact is set to ON.
[ +3, +2] counts "OFF
→
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
→
ON" operation o
f
is started again.
D
S
2
D
[ +5, +4] is used to measure the remaining
time.
D
Counting time
S
1
D
[ +1, ]
D
D
[ +3, +2]
D
[ +1, ]
S
2
S
2
ms
[ +1, ]
S
2
S
2
[ +1, ]
S
2
S
2
D
[ +5, +4]
D
S
2
D
D
D
D
D
S
1
Counting time
D
D
N(rpm)
Input X000
Proximity switch
"n" pulses/rotation
60 [ +1, ]
nt
t: Measurement time duration specified as [ +1, ] (ms)
N =
× 10 (r/min)
3