Rockwell Automation 999 IMC S Class Compact Motion Controller (Cat. No. 4100-999-122) - Manual (Page 90)

5-10 Understanding IMC-S/23x Setups
Publication 999-122 - January 1997
The Imaginary Axis
The imaginary axis can only generate command position and is
automatically configured for command only operation. The following
message
is displayed when the imaginary axis is selected. Functionally, the
imaginary axis is identical to a physical servo axis, except that it has
no servo loop or physical connections. A conversion constant and
unwind value (if the imaginary axis is configured as rotary) must be
entered for the imaginary axis in the machine setup menu, and values
for its maximum velocity, acceleration, and deceleration in the servo
setup menu.
Rotary Axes
All configured axes may be defined as either linear or rotary axes. To
define an axis as linear (the usual case), answer
NO to the Rotary
Axis? question. To define an axis as rotary, answer YES .
Rotary axes use a feature called electronic unwind to provide infinite
position range by electronically "unwinding" the axis position
whenever the axis moves through a complete physical revolution.
Rotary axes request an unwind value in the machine setup menu.
Position Units
The IMC-S/23x allows user-defined engineering units rather than
feedback counts to be used for measuring and programming all
motion-related values (position, velocity, etc.). These position units can
be different for each axis and should be chosen for maximum ease of
use in your application. For example, linear axes might use position
units of Inches, Meters, or mm while rotary axes might use units of
Revs or Degrees.
The Position Units and Position Unit parameters are the ASCII text
strings used in the machine and servo setup menus to request values
for motion-related parameters. Enter the singular form of the unit as
the Position Unit and the plural form for Position Units. A maximum
of eight characters may be used to specify each string.
For example, to use units of inches for an axis, enter
Select: IMAGINARY
Axis Type is COMMAND
Position Units = Inches
Position Unit = Inch