347
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
11
FN
C30-
FN
C39
R
o
ta
tion and
Sh
ift
12
FNC
4
0
-FNC49
D
a
ta
Op
e
ra
tio
n
13
FNC5
0
-FNC5
9
H
igh Speed
Pr
ocessi
ng
14
FM
C6
0
-F
NC6
9
H
and
y
In
st
ru
cti
o
n
15
FNC7
0
-FNC7
9
Ex
te
rn
a
l F
X
I
/O
D
evi
ce
16
FNC8
0
-FNC8
9
Ext
e
rnal
FX
D
evi
ce
17
F
N
C1
00
-F
NC
10
9
Da
ta
Tr
ansf
e
r 2
18
FN
C
110-FN
C
13
9
Fl
oat
ing P
o
in
t
19
FN
C
140-FN
C
149
Da
ta
O
per
at
io
n
2
20
FN
C
15
0-F
N
C
159
P
o
si
tioni
ng
C
ont
ro
l
Explanation of function and operation
1. 16-bit operation (SPD)
The input pulse
is counted only for
×
1 ms. The measured value is stored in
, the present
value is stored in
+1, and the remaining time is stored in
+2 (ms).
By repetition of this operation, the measured value
will store the pulse density (which is in proportion to
the rotation speed).
1) Timing chart
2) The measured value
is in proportion to the number of rotations as shown below:
S
1
S
2
D
D
D
D
FNC 56
SPD
S
1
D
S
2
Command
input
Measured
value
The command contact is set to ON.
Command
input
S
1
D
+ 1 counts "OFF
→
ON" operation of .
ms later, the counting result is stored to .
Accompanied by this operation, +1 is reset, and
then counting of "OFF
→
ON" operation of is
started again.
S
1
D
S
2
D
D
S
1
+ 2 is used to measure the remaining time.
D
Remaining time (ms)
D
+2
Counting time
ms
S
2
Counting time
ms
S
2
Current value
D
+1
ms
S
2
D
N(rpm)
Input X000
Proximity switch
"n" pulses/rotation
N = 60
nt
×
10 (r/min)
3
t: Measurement time duration specified as (ms)
S
2
D