Mitsubishi Electric MELSEC FX3U Programming Manual page 389

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Explanation of function and operation
1. 16-bit operation (SPD)
The input pulse
value is stored in
By repeating this operation, the measured value
the rotation speed).
Command
input
FNC 56
SPD
1) Timing chart
Command
input
S
1
D
Current value
S
ms
2
2) The measured value
N(rpm)
is counted only for
S S
1
+1, and the remaining time is stored in
D
S S D
1 2
+1
D
Measured
value
S S
2 ms 2 ms
Counting time Counting time
D +2
Remaining time (ms)
is in proportion to the number of rotations as shown below:
D
Input X000
Proximity switch
"n" pulses/rotation
13 High Speed Processing – FNC 50 to FNC 59
× 1 ms. The measured value is stored in
2
+2 (ms).
D
will store the pulse density (which is proportional to
D
The command contact is set to ON.
+ 1 counts "OFF → ON" operation of
D
ms later, the counting result is stored to
S
2
Accompanied by this operation,
then counting of the "OFF → ON" operation of
started again.
D + 2 is used to measure the remaining time.
D
60
× 10 (r/min) 3
N =
nt
t: Measurement time duration specified as
13.7 FNC 56 – SPD / Speed Detection
, the present
D
.
S
1
D
D +1 is reset, and
S
1
S
2
11
12
13
14
.
is
15
16
17
18
(ms)
19
20
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