9.2.3 Sine Wave Pitch (Frequency) for an External Encoder
Set Pn20A to the number of external encoder pitches per motor rotation.
(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: If there is a fraction, round off the digits below the decimal point.
(2) Related Parameter
(3) Error
The number of speed pitches per motor rotation causes error in the position loop gain (Kp), feedforward, and
position reference monitor unless the number of encoder pitches is an integer. This has no influence on the
accuracy of positioning, thus does not cause position error.
9.2.4 Number of Encoder Output Pulses (PAO, PBO, and PCO) from the
SERVOPACK
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 1μm, the set value will be 20.
If the output of a single pulse (multiplied by 4) is 0.5μm, the set value will be 40.
The pulse output 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: he upper limit frequency of the encoder signal output (multiplied by 4) is 6.4 Mpps. Do not allow the upper limit fre-
quency to exceed 6.4 Mpps. If exceeds, the alarm A.511 (overspeed of encoder output pulse rate) is 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 lead: 20 μm
Ball screw lead: 30 mm
Pn20A
Number of External Encoder Pitches
Classifica-
tion
Setting Range Setting Unit Factory Setting When Enabled
4 to 1048576 1 pitch/Rev 32768 After restart
Setup
Position
Specifications
External encoder pitch: 20 μm
Ball screw lead: 30 mm
Speed: 1600 mm/s
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