Omron ACCURAX G5 User Manual page 297

External Feedback Pulse Dividing Ratio Setting (Pn324, Pn325)
Set the dividing ratio for the encoder resolution and external scale resolution.
Parameter
number
Pn324
Pn325
Check the number of encoder feedback pulses and the number of external scale 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.
Pn324
=
Pn325 Number of external scale output pulses per motor rotation
If this divider setting is wrong, there will be deviations between the position calculated from
encoder pulses and the position calculated from external scale. 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 scale resolution 0.1 μm
Encoder resolution 20 bits
Servomotor
encoder resolution: 20 bits/rotation
Encoder Output Pulses per Motor Rotation (Pn324)
20 bits = 1,048,576
Pn324
= =
Pn325 Number of external scale output pulses per motor rotation
Accurax G5 AC SERVOMOTOR AND SERVO DRIVE USER'S MANUAL
Parameter name
Set the numerator of the external scale
External Feedback divider setting. Normally, set the number
Pulse Dividing of encoder output pulses per motor
Numerator rotation. If the set value is 0, the encoder
resolution is set automatically.
Set the denominator of the external scale
External Feedback
divider setting. Normally, set the number
Pulse Dividing
of external scale output pulses per motor
Denominator
rotation.
Number of encoder output pulses per motor rotation
External Scale Output Pulse Per Motor Rotation (Pn325)
10 [mm] / 0.1 [μm/pulse] = 100,000 [pulse]
Number of encoder output pulses per motor rotation
5-6 Full Closing Control
Explanation
10 mm
Ball screw
Ball screw pitch 10 mm
1,048,576
100,000
Setting
Unit
range
20
0 to 2 -
20
1 to 2 -
1 Rotation
External scale
resolution: 0.1 μm
5-31
5