Mitsubishi Electric MELSERVO-J4 series, Instruction Manual

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16 FULLY CLOSED LOOP SYSTEM
16.3 Operation and functions
Setting of feedback pulse electronic gear
If an incorrect value is set in the feedback pulse electronic gear ([Pr. PE04], [Pr. PE05], [Pr. PE34], and [Pr.
PE35]), [AL. 37 Parameter error] and an abnormal operation may occur. Also, it may cause [AL. 42.8 Fully
closed loop control error by position deviation] during the positioning operation.
The numerator ([Pr. PE04] and [Pr. PE34]) and denominator ([Pr. PE05] and [Pr. PE35]) of the electronic gear are set to the
servo motor-side encoder pulse. Set the electronic gear so that the number of servo motor encoder pulses per servo motor
revolution is converted to the number of load-side encoder pulses. The relational expression is shown below.
Select the load-side encoder so that the number of load-side encoder pulses per servo motor revolution is within the following
range.
4096 (2
12
)

Number of load-side encoder pulses per servo motor revolution

67108864 (2
26
)
■
When the servo motor is directly coupled with a ball screw and the linear encoder resolution
is 0.05 μ m
Conditions
Servo motor resolution: 4194304 pulses/rev
Servo motor reduction ratio: 1/11
Ball screw lead: 20 mm
Linear encoder resolution: 0.05

m
Calculate the number of linear encoder pulses per ball screw revolution.
[Pr. PE04] × [Pr. PE34]
[Pr. PE05] × [Pr. PE35] Number of motor encoder pulses per servo motor revolution
Number of load-side encoder pulses per servo motor revolution
=
Geared servo motor
Table
Linear encoder
Linear encoder head
[Pr. PE04] × [Pr. PE34]
[Pr. PE05] × [Pr. PE35]
400000
4194304
3125
32768
1
11
=
1
11
= × ×
= 20 mm/0.05 μm = 400000 pulses
= Ball screw lead/linear encoder resolution
Number of linear encoder pulses per ball screw revolution