CSDP Plus Servo Drive User Manual

SEt-36 Electronic Gear Ratio Numerator
• Setting range: 1 to 65535 pulse
• Factory Default: 2500
• Changes while the servo is OFF
An encoder generating 2048 pulses per revolution can make a
complete revolution when the controller transmits 2048 pulses to the
drive. If the electronic gear is used, only 1000 pulses can make the
encoder finish a complete revolution.
In order to use an electronic gear, the speed reduction ratio from the
motor shaft to the system is needed.
The speed reduction ratio is the ratio of revolutions of the system to
the motor. If the system make one revolution when the motor makes
five revolutions, the speed reduction ratio is 5. If the system make five
revolutions when the motor revolves once, then the speed reduction
ratio is 0.2.
The numerator and denominator of the electronic gear can be
calculated as below.
Numerator = Number of pulses of the encoder ✕ Speed reduction ratio
Denominator = Number of pulses per one revolution of the motor
In case of a ball screw whose speed reduction ratio is 1 and the
number of pulses of the encoder per one revolution is 5000, if the
controller approves 1000 pulses for the servo drive to make the motor
finish one revolution, the numerator of the electronic gear is 5000 and
the denominator is 1000.
The ball screw finishes one revolution with 1000 pulses and thus a ball
screw with 10 mm pitch can move 10 µm with one pulse command.
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