Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual - Manual (Page 302)

Publication 1784-UM003A-EN-P – June 2003
294 Motion Object Attributes
Active Bi-directional Home with Switch then Marker
This is the most precise active homing sequence available. When this sequence
is performed, the axis moves in the specified Home Direction at the specified
Home Speed until the home limit switch is detected. The axis then decelerates
to a stop and moves in the opposite direction at the specified Home Return
Speed until the home limit switch is cleared. After clearing the home limit
switch, the axis continues in the same direction at the Home Return Speed
until the first encoder marker is detected. The Home Position is assigned to
the axis position at the moment that the marker is detected, and the axis then
decelerates to a stop. If Home Offset is non-zero, then the Home Position will
be offset from the point where the marker is detected by this value. The
controller then moves the axis back to the Home Position at the specified
Home Return Speed using a trapezoidal move profile. If the axis is configured
as a Rotary Axis, the move back to the Home Position takes the shortest path
(i.e., no more than ½ revolution). Axis behavior for this homing sequence is
shown below.
Figure 13.5 Active Home Bi-directional with Limit Switch and Marker
If the controller detects that the state of the home switch at the start of the
homing sequence is active, the controller immediately reverses the homing
direction and begins the return leg of the homing sequence.
Active Uni-directional Home with Switch
This active homing sequence is useful for when an encoder marker is not
available and either uni-directional motion is required or proximity switch is
being used.