Galil DMC-2X00 - Manual (Page 92)

Additional Commands
The commands VS n, VA n, and VD n are used to specify the vector speed, acceleration and
deceleration. The DMC-2x00 computes the vector speed based on the axes specified in the LM mode.
For example, LM ABC designates linear interpolation for the A,B and C axes. The vector speed for
this example would be computed using the equation:
VS
2
=AS
2
+BS
2
+CS
2
, where AS, BS and CS are the speed of the A,B and C axes.
The controller always uses the axis specifications from LM, not LI, to compute the speed.
VT is used to set the S-curve smoothing constant for coordinated moves. The command AV n is the
‘After Vector’ trip point, which halts program execution until the vector distance of n has been
reached.
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 a,b,c,d < 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.
Instruction Interpretation
#ALT Label for alternative program
DP 0,0 Define Position of A and B axis to be 0
LMAB Define linear mode between A and B 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
0.0001. 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 0.5 results in the specification VS 2000 to be
divided in half.
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• Chapter 6 Programming Motion
DMC-2X00