Mitsubishi Electric MELSEC-F Series User Manual page 64

FX -1PG User's Manual
3U
How to use an electronic gear
Some servo motors require pulse trains at 200 kHz or more (in calculation) in order to satisfy the rated
rotation speed. For example, the command pulse frequency required to operate the MR-JN Series servo
amplifier and HF-KN Series servo motor manufactured by Mitsubishi at the rated rotation speed of 3,000 rev/
min can be obtained as follows.
(Suppose that the electronic gear ratio is the initial value "1/1", the number of command input pulses per
revolution is the initial value "10,000".)
f0 = FBP × 100 ×
3,000
f0 = 10,000 ×
f0 = 500,000 [Hz]
However, because the input command pulse in the open collector type servo amplifier and the pulse output
from the FX -1PG is 200 kHz maximum, operation at 500,000 Hz is impossible.
3U
In such a case, you should change the electronic gear in the servo amplifier.
The electronic gear can be obtained as follows.
CMX
= FBP × 100 ×
CDV
CMX
= 10,000 ×
CDV
CMX
5
=
CDV 2
The table below shows the setting of major electronic gears and pulse rates obtained by the above
calculation.
Rated rotation
speed of servo
motor
3,000 r/min
58
N0 CDV
f0
×
60 CMX
CMX
×1
60
CDV
N0
FBP×100 : Number of command input pulses per
N0 1
f0
×
60 f0
CMX
3,000 1
×
60 200,000
CDV
N0
FBP×100 : Number of command input pulses per
Servo amplifier
Maximum input pulse
frequency
10,000 PLS/REV
200 kHz
50,000 PLS/REV
(open collector)
131,072 PLS/REV
: Command pulse frequency [Hz]
(open collector type)
: Electronic gear (numerator of command
pulse magnification)
: Electronic gear (denominator of command
pulse magnification)
: Rotation speed of servo motor [rev/min]
revolution [PLS/REV]
: Command pulse frequency [Hz]
(open collector type)
: Electronic gear (numerator of command
pulse magnification)
: Electronic gear (denominator of command
pulse magnification)
: Rotation speed of servo motor [rev/min]
revolution [PLS/REV]
Number of command
input pulses per
revolution
5/2
25/2
4,096/125
7.3 Positioning Parameters
Command pulse frequency (200 kHz)
Electronic gear
4,000 PLS/REV
7 Buffer Memory
Pulse rate