Mitsubishi Electric FR-A7AL Instruction Manual page 61

(1) Calculation of the gear ratio (Pr. 420, Pr. 421)
The position resolution (travel per pulse Δ [mm]) is determined by the travel per motor revolution
Δs [mm] and the feedback pulses Pf [pulse/rev] of the encoder, and is represented by the following
expression.
Δ
Δs
Δs
×
Δ
Pf
Pf
Using the parameters, the travel per command pulse can be set separately to set the travel per
command pulse without a fraction.
Δs
×
=
Δ
Pf
In addition, the relationship between the motor speed and internal command pulse frequency is as
follows:
Pr. 420
× = Pf ×
fo
Pr. 421
CAUTION
Set the electronic gear in the range of 1/50 to 20.
Note that setting a too small value will decrease the speed command and setting a too large value will increase the
speed ripples.
: travel per pulse
: travel per motor rotation
: number of feedback pulses
(number of pulses after multiplying the number of encoder pulses by four)
Pr. 420
Pr. 421
No fo: internal command pulse frequency [pps]
60
No: motor speed [r/min]
POSITION CONTROL FUNCTION
[mm]
[mm]
[pulse/rev]
6
55