Control Techniques FM-3, Reference Manual

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107
Setting Up Parameters
Gearing View
Figure 61: Gearing View
Gearing is used to fix the motion of the motor to the motion of the master axis signal at a
specified ratio. This is commonly called “electronic line shafting” or “electronic gearing”. To
gear the motor to the master axis, a ratio must be specified as a relationship between follower
distance units and master distance units. The ratio is as follows:
The ratio is defined as the number of follower distance units to move the motor per master
distance unit of travel. The master distance units are configured on the Master Setup screen.
The gear ratio can be positive or negative and is a signed 32-bit parameter. The resolution of
the parameter is determined by the number of decimal places configured for the Master
Velocity Units on the Master Setup screen.
By default, gearing does not use acceleration or deceleration ramps with respect to the master
encoder. This means that once gearing is activated, peak torque is available to try to achieve
the specified gear ratio. Therefore, if the master axis is already in motion when gearing is
activated, the control loop will attempt to accelerate the motor to the programmed ratio within
one update (800µsec < update rate < 1600 µsec). Analogously, when gearing is deactivated,
the motor will use peak torque to bring the motor to a stop without a deceleration ramp.
# of Follower Distance Units
Gear Ratio = -------------------------------------
1 Master Distance Unit