Mitsubishi Electric MELSEC FX Series - Page 306

7 Applied Instructions
7.6 High Speed Processing
304
FXCPU Structured Programming Manual
(Basic & Applied Instruction)
Function and operation explanation
1. 16-bit operation (SPD)
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 , the current value is stored in +1, and the remaining time is stored
in +2 (ms).
By repeating this operation, the measured value will store the pulse density (which is proportional to the
rotation speed).
1) Timing chart
2) The measured value is in proportion to the number of rotations as shown below.
Command
input
SPD
EN
s1
s2
ENO
d
Device for
pulse input
Time data
Label
*1
*1. This defines the device that stores the
pulse density data.
Command
input
Measured
value
ms ms
+1
Current value
ms
+2
Remaining time (ms)
The command contact is set to ON.
+1 counts "OFF to ON" operation of .
ms later, the counting result is stored to .
Accompanied by this operation, +1 is reset,
and then counting of the "OFF to ON" operation
of is started again.
+2 is used to measure the remaining time.
Counting time Counting time
d
s1
s2 s2
d
d
d
d
d
s2
s2
s1
s1
d
Input X000
N =
nt
60
10 (r/min)
3
t: Measurement time duration
specified as (ms).
Proximity switch
"n" pulses/rotation
N (rpm)