Rockwell Automation GMLC Reference Manual - Manual (Page 251)

Publication GMLC-5.2 - November 1999
214 Motion Blocks
Because the command position does not incorporate any associated
following error or external position disturbances, it is a more accurate and
stable reference for gearing. When gearing to the command position of
the master, you must command the master axis to move in order to cause
motion on the slave axis. See the Installation and Setup manual for your
motion controller for more information on command position.
Same Direction Gearing
When you select Same from the Direction menu, the slave axis moves in
its positive direction at the specified gear ratio when the master axis
moves in its positive direction and vice-versa. If a new gear ratio is not
specified (i.e., if you do not select Set Ratio), the last gear ratio specified
for the slave axis is used. In most cases, this means that the current gear
ratio is retained.
Opposite Direction Gearing
When you select Opposite from the Direction menu, the slave axis moves
in its negative direction at the specified gear ratio when the master axis
moves in its positive direction and vice-versa. If a new gear ratio is not
specified (i.e., if you do not select Set Ratio), the last gear ratio specified
for the slave axis is used. In most cases, this means that the current gear
ratio is retained.
Changing the Gear Ratio (Unchanged Direction Gearing)
Selecting Unchanged from the Direction menu, lets you change the gear
ratio while preserving (and not changing) the current gearing direction
(same or opposite). This is useful when the current direction is not known
or not important.
Reversing the Gearing Direction
When you select Reverse from the Direction menu, the current direction
of the electronic gearing changes from same to opposite or from opposite
to same. This is very useful for winding applications where the gear ratio
must be reversed at each end of the wind. If you do not specify a new gear
ratio (i.e., if you do not select Set Ratio), the motion controller uses the
last gear ratio specified for the slave axis.