5.15 Electronic Gear Settings
5-41
5
Device-
S
pecific
S
etting
s
5.15
Electronic Gear Settings
The minimum unit of the position data that is used to move a load is called the reference unit.
The reference unit is used to give travel amounts, not in pulses, but rather in distances or other
physical units (such as μm or °) that are easier to understand.
The electronic gear is used to convert the travel distances that are specified in reference units
to pulses, which are required for actual movements.
With the electronic gear, one reference unit is equal to the workpiece travel distance per refer-
ence pulse input to the SERVOPACK. In other words, if you use the SERVOPACK’s electronic
gear, pulses can be read as reference units.
Note: If you set an electronic gear in the Controller Section, normally set the electronic gear ratio in the SERVO-
PACK to 1:1.
The difference between using and not using the electronic gear is shown below.
•
Rotary Servomotors
In this example, the following machine configuration is used to move the workpiece 10 mm.
•
Linear Servomotors
In this example, the following machine configuration is used to move the load 10 mm. We’ll
assume that the resolution of the Serial Converter Unit is 256 and that the linear encoder pitch
is 20
μ
m.
Workpiece
Re
s
olution: 16,777,216 (24 bit
s
)
Ball
s
crew lead: 6 mm
When the Electronic Gear I
s
U
s
ed
When the Electronic Gear I
s
Not U
s
ed
To move a workpiece 10 mm:
Calculate the number of revolutions.
The Servomotor will move 6 mm for
each revolution, so 10/6 revolutions
are required to move 10 mm.
Calculate the required number of refer-
ence pulses.
One revolution is 16,777,216 pulses,
therefore10/6 × 16,777,216 =
27,962,026.66 pulses.
Input 27,962,027 pulses as the refer-
ence.
If you use reference units to move the workpiece
when one reference unit is set to 1
μ
m, the travel
distance is 1
μ
m per pulse.
To move the workpiece 10 mm (10,000
μ
m),
10,000 ÷ 1 = 10,000 pulses, so 10,000 pulses
would be input.
Calculating the number of reference pulses
for each reference is troublesome.
Calculating the number of reference pulses
for each reference is not necessary.
Linear encoder
When the Electronic Gear I
s
U
s
ed
When the Electronic Gear I
s
Not U
s
ed
To move a load 10 mm:
10 × 1000 ÷ 20 × 256 = 128,000
pulses, so 128,000 pulses are input
as the reference.
If we set the reference unit to 1 μm, the
travel distance is 1 μm per pulse. To move
the load 10 mm (10,000 μm), 10,000/1 =
10,000 pulses, so 10,000 pulses would be
input as the reference.
Calculating the number of reference
pulses for each reference is troublesome.
Calculating the number of reference pulses for
each reference is not necessary.
