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DMC-1700/1800 Chapter 6 Programming Motion • 87
Independent Axis Positioning
In this mode, motion between the specified axes is independent, and each axis follows its own profile. The user
specifies the desired absolute position (PA) or relative position (PR), slew speed (SP), acceleration ramp (AC), and
deceleration ramp (DC), for each axis. On begin (BG), the DMC-1700/1800 profiler generates the corresponding
trapezoidal or triangular velocity profile and position trajectory. The controller determines a new command position
along the trajectory every sample period until the specified profile is complete. Motion is complete when the last
position command is sent by the DMC-1700/1800 profiler. Note: The actual motor motion may not be complete
when the profile has been completed, however, the next motion command may be specified.
The Begin (BG) command can be issued for all axes either simultaneously or independently. XYZ or W axis
specifiers are required to select the axes for motion. When no axes are specified, this causes motion to begin on all
axes.
The speed (SP) and the acceleration (AC) can be changed at any time during motion, however, the deceleration
(DC) and position (PR or PA) cannot be changed until motion is complete. Remember, motion is complete when
the profiler is finished, not when the actual motor is in position. The Stop command (ST) can be issued at any time
to decelerate the motor to a stop before it reaches its final position.
An incremental position movement (IP) may be specified during motion as long as the additional move is in the
same direction. Here, the user specifies the desired position increment, n. The new target is equal to the old target
plus the increment, n. Upon receiving the IP command, a revised profile will be generated for motion towards the
new end position. The IP command does not require a begin. Note: If the motor is not moving, the IP command is
equivalent to the PR and BG command combination.
Command Summary - Independent Axis
COMMAND DESCRIPTION
PR X,Y,Z,W Specifies relative distance
PA x,y,z,w Specifies absolute position
SP x,y,z,w Specifies slew speed
AC x,y,z,w Specifies acceleration rate
DC x,y,z,w Specifies deceleration rate
BG XYZW Starts motion
ST XYZW Stops motion before end of move
IP x,y,z,w Changes position target
IT x,y,z,w Time constant for independent motion smoothing
AM XYZW Trippoint for profiler complete
MC XYZW Trippoint for “in position”
The lower case specifiers (x,y,z,w) represent position values for each axis.
The DMC-1700/1800 also allows use of single axis specifiers such as PRY=2000
Operand Summary - Independent Axis
OPERAND DESCRIPTION
_ACx Return acceleration rate for the axis specified by ‘x’
_DCx Return deceleration rate for the axis specified by ‘x’
_SPx Returns the speed for the axis specified by ‘x’
_PAx
Returns current destination if ‘x’ axis is moving, otherwise returns the current commanded
position if in a move.