Error Limit; Correction - Galil Motion Control DMC-1600 Series User Manual

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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.
When a Galil controller is configured for step motor operation, the step pulse output by the
controller is internally fed back to the auxiliary encoder register. For SPM the feedback encoder
on the stepper will connect to the main encoder port. Enabling the SPM mode on a controller
with YS=1 executes an internal monitoring of the auxiliary and main encoder registers for that
axis or axes. Position error is then tracked in step pulses between these two registers (QS
command).
Where TD is the auxiliary encoder register(step pulses) and TP is the main encoder
register(feedback encoder). Additionally, YA defines the step drive resolution where YA = 1 for
full stepping or YA = 2 for half stepping. The full range of YA is up to YA = 9999 for
microstepping drives.

Error Limit

The value of QS is internally monitored to determine if it exceeds a preset limit of three full motor
steps. Once the value of QS exceeds this limit, the controller then performs the following actions:
1. The motion is maintained or is stopped, depending on the setting of the OE command. If
OE=0 the axis stays in motion, if OE=1 the axis is stopped.
2. YS is set to 2, which causes the automatic subroutine labeled #POSERR to be executed.

Correction

A correction move can be commanded by assigning the value of QS to the YR correction move
command. The correction move is issued only after the axis has been stopped. After an error
correction move has completed and QS is less than three full motor steps, the YS error status bit is
automatically reset back to 1; indicating a cleared error.
Example: SPM Mode Setup
The following code demonstrates what is necessary to set up SPM mode for a full step drive, a
half step drive, and a 1/64
count/rev encoder. Note the necessary difference is with the YA command.
Full-Stepping Drive, X axis:
#SETUP
OE1;
KS16;
MT-2;
YA1;
YB200;
YC4000;
SHX;
104 • Chapter 6 Programming Motion
×
TP
YA
=
QS
TD
YC
th
microstepping drive for an axis with a 1.8
Set the profiler to stop axis upon error
Set step smoothing
Motor type set to stepper
Step resolution of the full-step drive
Motor resolution (full steps per revolution)
Encoder resolution (counts per revolution)
Enable axis
×
YB
o
step motor and 4000
DMC-1600

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