Manual

9-2 Linearity Correction
The values of <x correction> and <y correction> must be limited such that the maximum
correction is in the range -4.000 to +3.9688 full steps in either axis. Recall that the size of a
microstep is specified by the RE ("Resolution") command. You can specify 1.0000 through
32.0000 microsteps per full step. For example, the Automove factory default is 8.0000
microsteps per full step; at this value the <x correction> and <y correction> parameters
can range from -32.0000 to 31.7500 microsteps.
The Automove System internally stores the <x correction> and <y correction> parameters
and the correction grid spacings in such a way that they remain independent of the
resolution. Therefore, you can change the microstep size and the correction information will
still relate in the same way to the physical travel of your mechanical system.
For example, if you have an Automove 403 XY table and the X correction at (12, 0) inches
from the Home switches has been set to +0.003 inches, the same correction will apply
whether you use RE2,2; or RE8,8; . The OR (Output Correction) command (see below)
would return 0.75 while RE2,2; is in effect, and 3 while RE8,8 is in effect, even
though no new CR command had been executed.
If you do not execute a CR command for a particular grid intersection then the correction
values for that grid intersection remain 0, and no correction is performed there. If an
adjacent grid intersection has nonzero values then the System blends smoothly from the
nonzero values to zero over the intervening distance.
Beyond the ends of the grid the Automove System performs no correction. For example,
suppose you have set the X and Y grid spacing to 1000 microsteps via a CR -1, -1, 1000,
1000; as described below. Also assume you have set all of the grid intersections to a
correction of +10 microsteps in X and Y (via CR 0, 0, 10, 10; CR 1, 0, 10, 10; CR 2,
0, 10, 10; ... CR 19, 19, 10, 10; ). A correction of +10 is applied to all coordinates in the
range 0 through 19000 microsteps. If an MA occurs where either X or Y is outside the range
0 through 19000, no correction occurs.
The linearity correction mechanism affects only the AA, AR, MA, MR, OC, OT, and SP
commands. It does not affect the travel limits, the Origin position, the MT command, the
acceleration, the step rate, or mid-move Digital Outputs changes; these are all set directly in
microsteps. See the TL, SO, MT, AC, SR, MD, and MM commands.
Setting The Grid Spacing
A special case of the CR command sets the correction grid spacing. If you specify -1 for <x
index> and <y index> then the <x correction> and <y correction> parameters become the
X and Y grid spacing, respectively, in microsteps. The grid spacing must be in the range
0.0313 through 1023.9688 full steps. For example, at the default resolution of 8.0000
microsteps per full step the grid spacing can range from 0.2500 through 8191.7500
microsteps.