13 - 74
13. POSITIONING MODE
(a) Concept of electronic gear
Adjust the electronic gear (parameters No. PA06 and PA07) to make the driver 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 driver.
T ravel distance
Deviation counter
+
-
Value converted to the number of virtual
pulses (FBP) per revolution
Servo motor
Encoder
M
CDV
CMX
FBP conversion
(Note)
Parameter No. PA06 and PA07
Parameter No. PA05
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.
CDV
CMX
=
PA07
No.
Parameter
PA06
No.
Parameter
The following setting examples are used to explain how to calculate the electronic gear.
POINT
The following specification symbols are required to calculate the electronic
gear
Pb
: Ballscrew lead [mm]
1/n
: Reduction ratio
S
: Travel di
stance per servo motor revolution [μm/rev]
: Angle per revolution [0.001 /rev]
(b) Setting example
1) Ballscrew setting example
CDV
CMX
=
S
10000
=
1000
Pb
n
1/
10000
=
1000
10
1/2
10000
=
1
2
Hence, set 2 to CMX and 1 to CDV.
Machine specifications
Ballscrew lead Pb = 10 [mm]
Reduction ratio: 1/n = Z
1
/Z
2
= 1/2
Z
1
: Number of gear cogs on servo motor side
Z
2
: Number of gear cogs on axis side
Number of virtual pulses per revolution: 10000 [pulse/rev]
Number of virtual pulses per
revolution of servo motor
10000[pulse/rev]
Pb= 10[mm]
Z
1
1/n=Z
1
/Z
2
=1/2
Z
2
1/n