348
FX
3U
/FX
3UC
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) [Ver.2.00 or later]
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 repetition of this operation, the measured value [
+1,
] will store the pulse density (which is in
proportion 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 "OFF
→
ON" operation of
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