Linear Interpolation Mode; Specifying Linear Segments - Galil Motion Control DMC-14 5 Series Manual

BG X
AS X
BG Y
EN

Linear Interpolation Mode

The DMC-14XX provides a linear interpolation mode for 2 axes. In linear interpolation mode, motion
between the axes is coordinated to maintain the prescribed vector speed, acceleration, and deceleration
along the specified path. The motion path is described in terms of incremental distances for each axis.
An unlimited number of incremental segments may be given in a continuous move sequence, making
the linear interpolation mode ideal for following a piece-wise linear path. There is no limit to the total
move length.
The LM command selects the Linear Interpolation mode and axes for interpolation. For example, LM
XY selects the X and Y axes for linear interpolation.
When using the linear interpolation mode, the LM command only needs to be specified once unless the
axes for linear interpolation change.

Specifying Linear Segments

The command LI x,y specifies the incremental move distance for each axis. This means motion is
prescribed with respect to the current axis position. Up to 255 incremental move segments may be
given prior to the Begin Sequence (BGS or BGT) command. Once motion has begun, additional LI
segments may be sent to the controller.
The clear sequence (CS) command can be used to remove LI segments stored in the buffer prior to the
start of the motion. To stop the motion, use the instructions STS, STT, or AB. The command, ST,
causes a decelerated stop. The command, AB, causes an instantaneous stop and aborts the program,
and the command AB1 aborts the motion only.
The Linear End (LE) command must be used to specify the end of a linear move sequence. This
command tells the controller to decelerate to a stop following the last LI command. If an LE command
is not given, an Abort AB1 must be used to abort the motion sequence.
It is the responsibility of the user to keep enough LI segments in the DMC-14XX sequence buffer to
ensure continuous motion. If the controller receives no additional LI segments and no LE command,
the controller will stop motion instantly at the last vector. There will be no controlled deceleration.
LM? or _LM returns the available spaces for LI segments that can be sent to the buffer. 255 returned
means the buffer is empty and 255 LI segments can be sent. A zero means the buffer is full and no
additional segments can be sent. As long as the buffer is not full, additional LI segments can be sent at
PC bus speeds.
The instruction _CS returns the number of the segment being processed. As the segments are
processed, _CS increases, starting at zero. This function allows the host computer to determine which
segment is being completed.
Additional Commands
The commands VS n, VA n, and VD n are used to specify the vector speed, acceleration, and
deceleration. The DMC-14XX computes the vector speed based on the axes specified in the LM
mode. For example, LM XY designates linear interpolation for the X and Y axes. The vector speed
for this example would be computed using the equation:
2 2
VS =XS +YS
The controller computes the vector speed with the axis specifications from LM.
60 Chapter 6 Programming Motion
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Begin X motion
Wait until X is at speed
Begin Y motion
2
, where XS and YS are the speed of the X and Y axes.
DMC-14x5/6