Galil DMC-2X00 - Manual (Page 118)

MT Motor Type (2,-2,2.5 or -2.5 for stepper motors)
RP Report Commanded Position
TD Report number of step pulses generated by controller
TP Tell Position of Encoder
Operand Summary - Stepper Motor Operation
operand Description
_DEa Contains the value of the step count register for the ‘a’ axis
_DPa Contains the value of the main encoder for the ‘a’ axis
_ITa Contains the value of the Independent Time constant for the 'a' axis
_KSa Contains the value of the Stepper Motor Smoothing Constant for the 'a' axis
_MTa Contains the motor type value for the 'a' axis
_RPa Contains the commanded position generated by the profiler for the ‘a’ axis
_TDa Contains the value of the step count register for the ‘a’ axis
_TPa Contains the value of the main encoder for the ‘a’ axis
Stepper Position Maintenance Mode (SPM)
The Galil controller can be set into the Stepper Position Maintenance (SPM) mode to handle the event
of stepper motor position error. The mode looks at position feedback from the main encoder and
compares it to the commanded step pulses. The position information is used to determine if there is
any significant difference between the commanded and the actual motor positions. If such error is
detected, it is updated into a command value for operator use. In addition, the SPM mode can be used
as a method to correct for friction at the end of a microstepping move. This capability provides closed-
loop control at the application program level. SPM mode can be used with Galil and non-Galil step
drives.
SPM mode is configured, executed, and managed with seven commands. This mode also utilizes the
#POSERR automatic subroutine allowing for automatic user-defined handling of an error event.
Internal Controller Commands (user can query):
QS Error Magnitude (pulses)
User Configurable Commands (user can query & change):
OE Profiler Off-On Error
YA Step Drive Resolution (pulses / full motor step)
YB Step Motor Resolution (full motor steps / revolution)
YC Encoder Resolution (counts / revolution)
YR Error Correction (pulses)
YS Stepper Position Maintenance enable, status
A pulse is defined by the resolution of the step drive being used. Therefore, one pulse could be a full
step, a half step or a microstep.
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• Chapter 6 Programming Motion
DMC-2X00