Mitsubishi Electric MELSERVO-JN Series Instruction Manual page 422

13. POSITIONING MODE
(a) Concept of electronic gear
Adjust the electronic gear (parameters No. PA06 and PA07) to make the servo amplifier setting match
the travel distance of the machine. Also, by changing the electronic gear value, the machine can be
moved at any multiplication ratio to the travel distance set in the servo amplifier.
Travel distance
Note. This process converts the number of the virtual pulses required to rotate the servo motor one turn to the value
set in parameter No. PA05.
CMX Parameter
=
CDV Parameter
The following setting examples are used to explain how to calculate the electronic gear.
(b) Setting example
1) Ballscrew setting example
Machine specifications
Ballscrew lead Pb = 10 [mm]
Reduction ratio: 1/n = Z
Z : Number of gear cogs on servo motor side
1
Z : Number of gear cogs on load side
2
Number of virtual pulses per revolution: 10000 [pulse/rev]
CMX 10000
=
CDV S

Hence, set 2 to CMX and 1 to CDV.
Parameter No. PA05
FBP conversion
(Note)
Value converted to the number of virtual
pulses (FBP) per revolution
No. PA06
No. PA07
POINT
The following specification symbols are required to calculate the electronic
gear
Pb : Ballscrew lead [mm]
1/n : Reduction ratio
S : Travel distance per servo motor revolution [μm/rev]
: Angle per revolution [0.001 /rev]
/Z = 1/2
1 2
10000 10000
= =
1/ n Pb 1000 1/2
  
Parameter No. PA06 and PA07
+
CMX
CDV
-
2
=
10 1000 1

13 - 71
Servo motor
Deviation counter M
Encoder
1/n
1/n=Z /Z =1/2
1 2
Z
2
Z
1
Number of virtual pulses per
revolution of servo motor
10000[pulse/rev]
Pb=10[mm]