Specifications

CHOOSING YOUR SETTINGS
ADVANCED MICRO CONTROLS INC.
3
22
DIP Switch Settings (continued)
Output Waveform (SB2-4 & SB2-5)
Physical inaccuracies in the motor, such as tolerances in windings and laminations, tend to add a third har-
monic to the dynamic torque curves of a stepper motor. This additional dynamic torque is not evident when
full-stepping the motor. However, this harmonic torque can have a pronounced effect when half-stepping or
microstepping the motor by affecting resolution and smooth motor operation. The Output Waveform feature
allows you to compensate for this unwanted third harmonic torque.
This feature is not used when full-stepping the motor. Because of this, these switches, along
with the switches for the Step Resolution setting and Anti-Resonance Enable, are used to put
the SD17063 in Self Test Mode. See Self Test Mode on page 53, for more information on
using the Self Test.
The output current waveforms for half-stepping and microstepping are digitized and stored in the drives non-
volatile memory. In addition to the pure sine waveform, the drive also stores three other waveforms. These
three waveforms reduce the current waveform’s 3
rd
harmonic by 4%, 6% or 10%. The state of the two Output
Waveform switches determines which current waveform is applied to the motor.
By reducing the third harmonic in the motor’s current waveform, you directly compensate for the additional
third harmonic caused by the motor’s tolerances. This increases resolution and allows smoother motor opera-
tion.
1) Determining the Output Waveform setting is usually done while testing the system. This is
done because motor inaccuracies are usually not determined for individual motors. You
may want to try all of the settings to determine which works best for your application. You
may be able to do this with the SD17063’s Self Test. If you are setting the Current Loop
Gain, you should do this before determining the Output Waveform setting. See Current
Loop Gain (SB1-4 & SB1-5) on page 21 to determine if you need to adjust the current loop
gain.
2) The default Output Waveform setting is Pure Sine. This is because the motor runs most
efficiently when powered with this waveform. Therefore, if you do not see any perfor-
mance gains by using a modified waveform, or you do not need these performance gains,
leave the Output Waveform setting to Pure Sine.
3) Setting the Output Waveform may also improve positional accuracy. However, if you
require very fine positional accuracy, it is strongly recommended that you use some type of
positional feedback from the motor to the indexer.
4) The state of the Output Waveform switches are latched on power up. Therefore, you must
cycle power to the drive or activate the Reset Input to make the drive recognize a change to
this setting.