An Example of Linear Interpolation Motion:
#LMOVE
label
DP 0,0
Define position of X and Y 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
AV 4000
Set trippoint to wait until vector distance of 4000 is reached
VS 1000
Change vector speed
AV 5000
Set trippoint to wait until vector distance of 5000 is reached
VS 4000
Change vector speed
EN
Program end
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 counts / s.
Specifying Vector Speed for Each Segment
The instruction VS has an immediate effect and, therefore, must be given at the required time. In some
applications, such as CNC, it is necessary to attach various speeds to different motion segments. This can be done
by two functions: < n and > m
For example: LI x,y,z,w < n >m
The first command, < n, is equivalent to commanding VSn at the start of the given segment and will cause an
acceleration toward the new commanded speeds, subjects to the other constraints.
The second function, > m, requires the vector speed to reach the value m at the end of the segment. Note that the
function > m may start the deceleration within the given segment or during previous segments, as needed to meet
the final speed requirement, under the given values of VA and VD.
Note, however, that the controller works with one > m command at a time. As a consequence, one function may
be masked by another. For example, if the function >100000 is followed by >5000, and the distance for
deceleration is not sufficient, the second condition will not be met. The controller will attempt to lower the speed
to 5000, but will reach that at a different point.
As an example, consider the following program.
#ALT
Label for alternative program
DP 0,0
Define Position of X and Y axis to be 0
LMXY
Define linear mode between X and Y axes.
LI 4000,0 <4000 >1000
Specify first linear segment with a vector speed of 4000 and end speed 1000
LI 1000,1000 < 4000 >1000
Specify second linear segment with a vector speed of 4000 and end speed 1000
LI 0,5000 < 4000 >1000
Specify third linear segment with a vector speed of 4000 and end speed 1000
LE
End linear segments
BGS
Begin motion sequence
EN
Program end
Changing Feed Rate:
The command VR n allows the feed rate, VS, to be scaled between 0 and 10 with a resolution of .0001. This
command takes effect immediately and causes VS to be scaled. VR also applies when the vector speed is specified
with the ‘<’ operator. This is a useful feature for feed rate override. VR does not ratio the accelerations. For
example, VR .5 results in the specification VS 2000 to be divided in half.
Chapter 6 Programming Motion ▫ 80 DMC-40x0 User Manual
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