10.3 Parameter Settings for Fully-Closed Loop Control
10.3.3 Setting the Number of External Encoder Scale Pitches
10
Fully-Clo
s
ed Loop Contr
ol
10-7
10.3.3
Setting the Number of External Encoder Scale Pitches
Set the number of external encoder scale pitches per Servomotor rotation in Pn20A.
Setting Example
If the external encoder is connected directly to the Servomotor, the setting will be 1,500
(30 mm/0.02 mm = 1,500).
Note: 1. If there is a fraction, round off the digits below the decimal point.
2. If the number of external encoder scale pitches per Servomotor rotation is not an integer, there will be devi-
ation in the position loop gain (Kp), feedforward, and position reference speed monitor. This is not relevant
for the position loop and it therefore does not interfere with the position accuracy.
Related Parameters
10.3.4
Setting the PAO, PBO, and PCO (Encoder Divided Pulse
Output) Signals
Set the position resolution in Pn281 (Encoder Output Resolution).
Enter the number of phase A and phase B edges for the setting.
Setting Example
If a single pulse (multiplied by 4) is output for 1
μ
m, the setting would be 20.
If a single pulse (multiplied by 4) is output for 0.5
μ
m, the setting would be 40.
The encoder divided pulse output would have the following waveform if the setting is 20.
“
↑
” indicates the edge positions. In this example, the set value is 20 and therefore the number
of edges is 20.
Note: The upper limit of the encoder signal output frequency (multiplied by 4) is 6.4 Mpps. Do not set a value that
would cause the output to exceed 6.4 Mpps.
If the output exceeds the upper limit, an A.511 alarm (Encoder Output Pulse Overspeed) will be output.
Specifications
External encoder scale pitch: 20
μ
m
Ball screw lead: 30 mm
Pn20A
Number of External Encoder Scale Pitches
Setting Range
Setting Unit
Default Setting
When Enabled
Classification
4 to 1,048,576
1 scale pitch/revo-
lution
32,768
After restart
Setup
Number of external encoder
pitche
s
per
S
ervomotor rotation
External encoder
(
s
cale pitch: 20
m)
Workpiece po
s
ition
after movement
Workpiece po
s
ition
before movement
Ball
s
crew lead:
3
0 mm
Position
Specifications
External encoder scale pitch: 20
μ
m
Ball screw lead: 30 mm
Speed:1,600 mm/s
Pha
s
e A
Pha
s
e B
S
ine wave pitch
