www.DanaherMotion.com
SERVO
STAR
®
S600
Electronic Gearing and
Software User Interface
This Product Note describes how gearing works on the SERVO
STAR
®
S600. It begins with a
general discussion of gearing and continues with details on hardware and software set up. This
document only describes the software setup for gearing using the Software User Interface for the
SERVO
STAR
S600.
How Electronic Gearing Works
Electronic gearing provides a position command to a drive that depends on the motion of another
device. That device is typically an encoder (or its equivalent) connected to a motor. However, it
can also be a hand-driven encoder used to accept input from an operator or an output from a stepper
motor controller. This is different from internal profile generation where position commands are
calculated inside the drive based on motion parameters, such as distance, acceleration, and velocity.
The external encoder signal provides an input to the gearing software. In many applications, the
motor follows the input, step for step where one revolution of the input device should create one
revolution in the electronically-geared motor. This is called one-to-one gearing.
Other times, it is necessary to have a non-unity scale factor. The gear ratio may be a non-integer,
such as 1:3. It is important that the gearing software not introduce round-off errors when the gear
ratio is non-integer because over long periods of time, the round-off error accumulates and causes
the electronically-geared motor to drift with respect to the input. The SERVO
STAR
S600 supports
non-integer gearing ratios while remaining free of round-off errors.
Gearing Applications
There are several ways to use electronic gearing in applications. They vary depending on the source
of the input signal and how the gear ratio is set. However, they all share the structure where the
electronically-geared drive controls the motor to follow the input.
Following a Non-Driven Encoder
Some gearing applications require that a servomotor follow a non-servo-driven encoder. The
encoder may be on an idle roller of a conveyor belt or in a line-driven induction motor. The
encoder is connected to an axis that is not under the direct control of another drive.
