Omron R88D-KTA5L User Manual page 368

5-6 Fully-closed Control
External Feedback Pulse Dividing Ratio Setting (Pn324, Pn325)
Set the dividing ratio for the encoder resolution and external encoder resolution.
Parameter
number
Pn324
Pn325
Check the number of encoder feedback pulses and the number of external encoder output
pulses per motor rotation, and set External Feedback Pulse Dividing Numerator (Pn324) and
External Feedback Pulse Dividing Denominator (Pn325) so that the following formula works
out.
5
Pn324
Pn325
If this divider setting is wrong, there will be deviations between the position calculated from
encoder pulses and the position calculated from external encoder. If the movement distance
is long, these deviations accumulate and cause an internal/external feedback pulse error
counter overflow level error.
 Setting Examples
 Ball screw pitch: 10 mm
 External encoder resolution: 0.1 μm
 Encoder resolution: 20 bits
encoder resolution: 20 bits/rotation
Encoder Output Pulses per Motor Rotation (Pn324)
Pn324
Pn325
5-33
Parameter name
External Feedback
Pulse Dividing
Numerator
External Feedback
Pulse Dividing
Denominator
Number of encoder output pulses per motor rotation
=
Number of external encoder output pulses per motor rotation
Servomotor
20 bits = 1,048,576
Number of encoder output pulses per motor rotation
=
Number of external encoder output pulses per motor rotation
OMNUC G5-SERIES AC SERVOMOTOR AND SERVO DRIVE USER'S MANUAL
Explanation
Set the numerator of the external
encoder divider setting. Normally, set the
number of encoder output pulses per
motor rotation. If the set value is 0, the
encoder resolution is set automatically.
Set the denominator of the external
encoder divider setting. Normally, set the
number of external encoder output
pulses per motor rotation.
10 mm
Ball screw
Ball screw pitch 10 mm
External Encoder Output Pulse Per Motor Rotation (Pn325)
10 [mm] / 0.1 [ μ m/pulse] = 100,000 [pulses]
Setting
Unit
range
20
0 to 2 -
20
1 to 2 -
1 Rotation
External encoder
resolution: 0.1 μ m
1,048,576
=
100,000