VT is used to set the smoothing constant for coordinated moves. The command AV n is the ‘After
Vector’ trippoint, which halts program execution until the vector distance of n has been reached.
An Example of Linear Interpolation Motion:
Instruction
Interpretation
#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 cts / 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 with two functions: < n and > m
For example:
LI x,y < 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 speed, subject 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.
As an example, consider the following program.
Instruction
Interpretation
#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
DMC-14x5/6
Chapter 6 Programming Motion
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