Manual

3-10 Detailed Descriptions of ACL Commands
Path Smoothness
At high speeds the move sequence path must be smooth. In other words, the vectors and
arcs must be arranged so that there are no sudden changes of direction. Where the direction
must change substantially, an arc should be used. If this rule is violated (for example, a
square with sharp corners) the stepping motors may slip, with a loss of the position
reference.
If path smoothness is maintained, the maximum torque demanded of the stepping motors
will be related to the specified acceleration value; see the discussion of radial and tangential
acceleration under the AA command.
At low speeds the stepping motors have more torque, so sudden changes of direction may be
allowable. The speed limit depends on how sharp the angles are, how much mass is attached
to the carriage, and how much shaking or jarring of the entire mechanical system is
allowable.
Length Limitations
The maximum length of any arc resulting from a single AA or AR command during a
Continuous Path sequence is 65534 microsteps. The arc length is the distance traveled along
the arc, which is the radius times the sweep angle (in degrees) times pi/180. Thus, the
maximum radius of a single-command 360-degree arc is 10430 microsteps. (Longer arcs
can be produced by dividing them into several AA or AR commands.)
The total length (i.e., the sum of all the vector and arc lengths) of a given Continuous Path
move cannot exceed a certain number of microsteps. This number is proportional to the
smaller of the X and Y microstep factors (see the RE command), and is limited to 507888
microsteps if the sequence contains any arcs.
The following table shows a few representative limit values:
Table 8 - Arc Length Limitations
Smaller RE
Microstep Factor
Longest Sequence
With Arcs
Longest Sequence
Without Arcs
1.0000 65534 microsteps 65534 microsteps
2.0000 131068 131068
4.0000 262136 262136
8.0000 (default) 507888 524272
16.0000 507888 1048544
32.0000 507888 2097088