Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual - Manual (Page 303)

Publication 1784-UM003A-EN-P – June 2003
Motion Object Attributes 295
When this sequence is performed in the Active Homing Mode, the axis moves
in the specified Home Direction at the specified Home Speed until the home
switch is detected. The Home Position is assigned to the axis position at the
moment that the limit switch is detected. If Home Offset is non-zero, then the
Home Position will be offset from the point where the switch is detected by
this value. The controller then continues to move the axis to the Home
Position at the specified Home Speed using a trapezoidal move profile. By
setting a Home Offset greater than the deceleration distance, unidirectional
motion to the Home Position is insured. However, if the Home Offset value is
less than the deceleration distance, then the axis is simply decelerated to a stop.
The axis does NOT reverse direction to move to the Home Position. In this
case, the PC-bit leg of the associated MAH instruction is not set when the
IP-bit leg is cleared.
In the case where this homing sequence is performed on a rotary axis and the
Home Offset value is less than the deceleration distance when the home event
is detected, the control automatically adds one or more revolutions to the
move distance. This guarantees the resulting move to the Home Position is
unidirectional.
Active Uni-directional Home with Marker
This active homing sequence is useful for single turn rotary and linear encoder
applications when uni-directional motion is required.
When this sequence is performed in the Active Homing Mode, the axis moves
in the specified Home Direction at the specified Home Speed until the marker
is detected. The Home Position is assigned to the axis position at the moment
that the marker is detected. If Home Offset is non-zero, then the Home
Position will be offset from the point where the marker was detected by this
value. The controller then continues to move the axis to the Home Position at
the specified Home Speed using a trapezoidal move profile. By setting a Home
Offset greater than the deceleration distance, unidirectional motion to the
Home Position is insured. However, if the Home Offset value is less than the
deceleration distance, then the axis is simply decelerated to a stop. The axis
does NOT reverse direction to move to the Home Position. In this case, the
PC-bit leg of the associated MAH instruction is not set when the IP-bit leg is
cleared.
In the case where this homing sequence is performed on a rotary axis and the
Home Offset value is less than the deceleration distance when the home event
is detected, the control automatically adds one or more revolutions to the
move distance. This guarantees the resulting move to the Home Position is
unidirectional.
Active Uni-directional Home with Switch then Marker
This active homing sequence is useful for multi-turn rotary applications when
uni-directional motion is required.