Changes

SnapAmp Info

939 bytes added, 18:20, 21 July 2016
/* Axis Drift with Zero Current Commanded - PWMC Commands */
==Peak Current Settings==
<span style="font-family: Arial;">When SnapAmp Powers up the Peak Current settings will not be set and consequently the boards will be in Current Fault mode with the Fault LED on.  Some C Code is required to set the Peak Current Limits and bring the board out of fault mode.  See: Approximate Peak Current Thresholds [http://www.dynomotion.com/Help/SchematicsSnap/UsingSnapAmp.htm here].</span>
 
 
 
==<span id="Drive_Enables_-_Axis_Drift_with_Servo_Disabled_-_Power_up_Issues" class="mw-headline">Drive Enables - Axis Drift with Zero Current Commanded - PWMC Commands<br /></span>==
<span class="mw-headline">The SnapAmp PWMC command goes into PWM switching mode attempting to regulate zero current by measuring the current (an analog signal) and adjusting the voltage (PWM).  This is a problem with any analog signal/drive.  Analog signals are imperfect and will always have bias, nonlinearities, noise, etc.   The SnapAmp Current measurement/control range is +/-35 Amps (a 70 Amp full range).  With such a large range extreme precision is required to control exact zero current.  ie even a 0.1% error = 0.07Amps.  SnapAmp wasn't designed for that high of accuracy as it isn't needed to control a motor well.  Once the servo is enabled the servo will command whatever current is required to hold the motor in position.</span>
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