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Position control
4.5.8 Setting of the electronic gear (Pr.420, Pr.421)
The position resolution (travel per pulse [mm]) is determined by the travel per motor revolution s [mm] and the number
of pulses per motor rotation, and is represented by the following expression.
The position resolution (travel per pulse [mm]) can be changed with the electronic gear setting.
<<Setting example>> When setting travel per pulse to 0.01mm in a machine with s = 10mm.
Set the ratio of the machine side gear and the motor side gear.
Parameter
number
Name Initial value
Setting
range
Description
420
Command pulse
multiplication numerator
(electronic gear numerator)
1 1 to 32767
Set the electric gear. The gear ratio range
is from 1/900 to 900.
Pr.420 is a numerator and Pr.421 is a
denominator.
421
Command pulse
multiplication denominator
(electronic gear
denominator)
1 1 to 32767
The above parameters can be set when Pr.160 Extended function display selection = "0". (Refer to page 182)
With the operation panel of the drive unit, up to "9999" can be set as a setting value. With a parameter unit or FR configurator, up to the highest value in
the setting range can be set.
:travel per pulse [mm]
s :travel per motor rotation [mm]
Pf :number of pulses per motor rotation (= 5120) [pulse/rev]
=
s
=
s
Pf 5120
:travel per command [mm]
s :travel per motor rotation [mm]
Pf :number of pulses per motor rotation (= 5120) [pulse/rev]
=
s
Pr.420
Pf Pr.421
: 0.01[mm], s: 10[mm], Pf: 5120[pulse/rev]
0.01 =
10
Pr.420
Pr.420 = 128, Pr.421 = 25
5120 Pr.421
NOTE
The electronic gear setting of 1/900 or lower is limited at 1/900, and 900 or higher at 900.