46 • Chapter 6 Programming Motion DMC-1500
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-1500 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. 511 returned
means the buffer is empty and 511 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 segment counter. As the segments are processed, _CS increases,
starting at zero. This function allows the host computer to determine which segment is being
processed.
Specifying Vector Acceleration, Deceleration and Speed:
The commands VS n, VA n, and VD n are used to specify the vector speed, acceleration and
deceleration. The DMC-1500 computes the vector speed based on the axes specified in the LM mode.
For example, LM XYZ designates linear interpolation for the X,Y and Z axes. The vector speed for
this example would be computed using the equation:
VS
2
=XS
2
+YS
2
+ZS
2
, where XS, YS and ZS are the speed of the X,Y and Z axes.
The controller always uses the axis specifications from LM, not LI, to compute the speed.
In cases where the acceleration causes the system to 'jerk', the DMC-1500 provides a vector motion
smoothing function. VT is used to set the S-curve smoothing constant for coordinated moves.
Additional Commands
The DMC-1500 provides commands for additional control of vector motion and program control.
Note: Many of the commands used in Linear Interpolation motion also applies Vector motion
described in the next section.
Trippoints
The command AV n is the ‘After Vector’ trippoint, which halts program execution until the vector
distance of n has been reached.
In this example, the XY system is required to perform a 90
° turn. In order to slow the speed around
the corner, we use the AV 4000 trippoint, which slows the speed to 1000 count/s. Once the motors
reach the corner, the speed is increased back to 4000 cts / s.
Instruction Interpretation
#LMOVE Label
DP ,,0,0 Define position of Z and W axes to be 0
LMXY Define linear mode between X and Y axes.
LI 5000,0 Specify first linear segment
LI 0,5000 Specify second linear segment
LE End linear segments
VS 4000 Specify vector speed
BGS Begin motion sequence
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