6.3 Settings According to Host Controller
6-19
6
2. Check the number of encoder pulses for the SGM
H servomotor.
3. Determine the reference unit used.
A reference unit is the minimum position data unit used to move a load. (Minimum unit
of reference from the host controller.)
• 0.01 mm (0.0004 in), 0.001 mm (0.00004 in), 0.1
°
, 0.01 inch.
A reference unit of one pulse moves the load by one reference unit.
• When the reference unit is 1 µm
If a reference of 50000 units is input, the load moves 50 mm (1.97 in) (50000 x
1
µm).
4. Determine the load travel distance per load shaft revolution in reference units.
• When the ball screw pitch is 5 mm (0.20 in) and the reference unit is 0.001 mm
(0.00004 in)
Servomotor Model and
Encoder Specifications
Encoder Type
Number of Encoder Pulses
Per Revolution (P/R)
A
Incremental encoder
13 bits
2048
B
16 bits
16384
C
17 bits
32768
1
Absolute encoder
16 bits
16384
2
17 bits
32768
Reference unit: 0.001mm
Determine the reference unit according to
equipment specifications and positioning accuracy.
.
To move a table in 0.001mm units
EXAMPLE
Travel distance per load shaft revolution (reference unit) =
Travel distance per load shaft revolution
Reference unit
Ball Screw
Circular Table
Belt and Pulley
EXAMPLE
5
0.001
= 5000 (reference u n it )
Load shaft
P: Pitch
P
1 revo lution =
P
reference u n it
Load shaft
1 revo lution =
360 ˚
reference u n it
D: Pulley
D
π
D
Load shaft
1 r evo lution =
π
D
referenc e uni t