8.3.2 Sine Wave Pitch (Frequency) for an External Encoder
Set the number of external encoder pitches per motor rotation to Pn20A.
(1) Setting Example
Specifications
External encoder sine wave pitch: 20 μm
Ball screw lead: 30 mm
If the external encoder is connected directly to the motor, the set value will be 1500 (30 mm/0.02 mm = 1500).
Note 1. If there is a fraction, round off the digits below the decimal point.
2. If the number of external encoder pitches per motor rotation is not an integer, there will be deviation in the posi-
tion loop gain (Kp), feedforward, and position reference speed monitor. There is no effect on the positioning
accuracy.
(2) Related Parameter
Number of External Scale Pitch
Pn20A
Setting Range
4 to 1048576
8.3.3 Setting Encoder Output Pulses (PAO, PBO, and PCO)
Set the position resolution to Pn281. Set the number of phase A and phase B edges.
(1) Setting Example
Specifications
External encoder sine wave pitch: 20 μm
Ball screw lead: 30 mm
Speed: 1600 mm/s
If the output of a single pulse (multiplied by 4) is 1 μm, the set value will be 20.
If the output of a single pulse (multiplied by 4) is 0.5 μm, the set value will be 40.
The encoder output pulse will have the following waveform if the set value is 20.
Phase A
Phase B
"↑" shows the edge position. In this example, the set value is 20 therefore the number of ↑ 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, the overspeed of encoder output pulse
rate alarm (A.511) will be output.
Example:
The frequency is as follows if the set value is 20 and the speed is 1600 mm/s:
1600 mm/s
0.001 mm
Because 1.6 Mpps is less than 6.4 Mpps, this value can be used.
Setting Unit
1 pitch/rev
Sine wave pitch
= 1600000 = 1.6 Mpps
8.3 Parameter Settings for Fully-closed Loop Control
Position
Factory Setting
When Enabled
32768
After restart
Classifica-
tion
Setup
8
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