Yaskawa Sigma-5 User Manual: Design and Maintenance - Rotary Motors - MECHATROLINK-II Communications Reference - Manual (Page 291)

8.3 Parameter Settings for Fully-closed Loop Control
8-17
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8.3.2 Sine Wave Pitch (Frequency) for an External Encoder
Set the number of external encoder pitches per motor rotation to Pn20A.
Pn20A is the speed conversion coefficient when the external encoder is used as speed feedback.
(1) Setting Example
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 is some error in the speed
loop. This is not relevant for the position loop however, therefore it does not interfere with the position accuracy.
(2) Related Parameter
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
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.
" ↑" 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:
= 1600000 = 1.6 Mpps
Because 1.6 Mpps is less than 6.4 Mpps, this value can be used.
Specifications
External encoder sine wave pitch: 20
μm
Ball screw lead: 30 mm
Pn20A
Number of External Scale Pitch
Classifica-
tion
Setting Range Setting Unit Factory Setting When Enabled
4 to 1048576 1 pitch/rev 32768 After restart Setup
Position
Specifications
External encoder sine wave pitch: 20
μm
Ball screw lead: 30 mm
Speed: 1600 mm/s
Phase A
Phase B
Sine wave pitch
Rotation
1600 mm/s
0.001 mm