29
5. Now start programming the segments
of the first profile. When a program is
finished (and more often if the task is
long) save to FLASH Memory.
6. Repeat from step 4 to program
additional profiles. Be sure to be on
the proper axis and be sure to select
a new program number each time.
For references:
[Axis 1 is also called Axis X]
[Axis 2 is also called Axis Y]
Profile Definition
A motion profile is a description of the
motion of an axis over a complete cycle
of motion. Typically the description
consists of a graph of velocity (Y
coordinate) vs. position (X coordinate)
and a list of notes related to specific
positions or events which might occur
during motion.
Figure 4-1. Typical Motion Profile
The above profile is made up of three
segments; a move to position 20 in. at
30 in./sec. velocity, decelerate to 2
in/sec. The second segment continues
at 2 in/sec to 30 in. The third segment
returns to 0 in. at 30 in/sec.
A profile could be as simple as an
incremental move (one segment).
Segment Definition
One segment can define the following:
Entry Conditions, Motion Parameters,
Exit Conditions, Jump Conditions, Gains
and Variables.
1. Entry Conditions. This has 2 parts:
a) Dwell Time. This is a time in
seconds that the controller should
wait after completion of the
preceding segment. A zero value
usually applies to all but the last
segment of motion in one
direction.
b) Input Event Conditions. One or
more logical equations to be
evaluated at the end of Dwell
Time. This logic can inhibit the
axis until specified conditions are
met.
2. Motion Parameters
a) Absolute or Relative Target
Position
This is the position to be reached
at the end of a segment.
b) Acceleration/Deceleration
These are the values to be used
for velocity changes in the
segment.
c) Move Velocity
This velocity is intended to be
used for the requested change in
position from Entry Position to
Target Position. After Dwell Time
(if any) and Input Event = TRUE
(if any), the axis will attempt to go
from the input velocity (Target
Velocity of previous segment) to
Move Velocity. If Move Velocity
can be reached before it is
necessary to decelerate, motion
is carried out at that velocity until
deceleration starts.
d) Target Velocity
This is the velocity at which the
axis is to be moving at the end
position of the segment. The
position at which deceleration
should start is computed by the
controller. A short move with a
high Move Speed may therefore
never actually reach Move Speed
because of the start of
deceleration (or acceleration) to
reach Target Velocity. Note that
Target Velocity can be 0 or any
velocity less than the Profile
Maximum Velocity. Having a
Target Velocity as part of the
segment allows the controller to
compute when to start
acceleration or deceleration from
the Move Velocity to reach the
desired Target Point Velocity
rather than having the
programmer do this computing,
and it tends to keep the transition
from one segment to another free
of acceleration spikes.
3. Exit Condition
Conditional exiting is accomplished
with the Exit Event equation. This is
a Logic Output Event description,
which can be a series of equations
evaluated from top to bottom, as
entered from the Hand-Held
Terminal. The Output Event is
evaluated when the Position
Reference output has reached the
Target Position. That is: Position
Reference = Target Position. At this
time the slide may not have reached
the Target Position because of
following error. If the next segment
calls for motion in the reverse
direction and neither the Exit Event
or the Jump Event meet the test for
In Position, the axis may reverse
motion without going all the way to
Target Position. (The In Position
signal becomes TRUE when the
feedback position matches the Target
Position within a tolerance––the axis
tolerance is set in the CFG mode and
a lower program value can be set in
the PRG mode. The In Position is
evaluated in every segment and thus
can be triggered ‘on the fly’.
Note that some judgement must be
exercised in setting the In Position
tolerance. If the machine capability
is barely good enough to satisfy the
programmed tolerance, the program
may occasionally stop or slow
considerably while waiting for the
tolerance to be satisfied. When it is
allowable for an axis to run past a
theoretical endpoint, it may be better
to program the Target Position a little
past the theoretical endpoint position
and open the In Position tolerance.
The Exit Event may test multiple
conditions and may use several
equations. Some or all of these
equations may output a logic TRUE
or FALSE signal to an internal flag
(I/O location). The flag may then be
tested by another segment or by the
other axis.
4. Jump Conditions
There are two conditions:
a) Unconditional Jump. This would
most likely be used to
continuously run a profile or group
of segments as long as ’Run’ is
commanded. A jump is
unconditional if a destination is
programmed, but no logic
equation is entered. For example,
SEGMENT # (2 )
↑
QUIT
F1
<DEL
F2
JUMP TO SAVE
F3
SEGMENT # [1 ]
↓
<SEL
F4
