Mitsubishi FX2N-10GM, Hardware / Programming Manual

Page: 87 / 274

FX Series Positioning Controllers Parameters 4
4-11
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
HC-MF 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".)
However, because the input command pulse in the open collector type servo amplifier and the
pulse output from the positioning unit is 200 kHz (100 kHz during interpolation operation) max-
imum, operation at 409,600 Hz is impossible.
In such a case, you should change the electronic gear in the servo amplifier.
The electronic gear can be obtained as follows.
f0 = Pt
×
60
N0
CMX
CDV
×
f0 = 8,192
×
60
3,000
×
1
f0 = 409,600 [Hz]
f0: Command pulse frequency [Hz] (open collector type)
CMX: Electronic gear (numerator of command pulse magnification)
CDV: Electronic gear (denominator of command pulse magnification)
N0:
Rotation speed of servo motor [rev/min]
Pt: Resolution of encoder (positioning feedback pulse) [PLS/REV]
(Pt is "8,192" in the HC-MF Series.)
= Pt
×
60
N0
×
f0
1
CMX
CDV
= 8,192
×
60
3,000
×
CMX
CDV
200,000
1
=
125
256
CMX
CDV
f0: Command pulse frequency [Hz]
(open collector type)
CMX: Electronic gear (numerator of command
pulse magnification)
CDV: Electronic gear (denominator of command
pulse magnification)
N0: Rotation speed of servo motor [rev/min]
Pt: Resolution of encoder
(positioning feedback pulse) [PLS/REV]
(Pt is "8,192 PLS/REV" in the HC-MF Series.)