Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 292)

292 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 5 Drive Features
Position Homing The Homing function is a standalone function of the drive that moves the motor
to a home position defined by a switch that is connected to a homing input on a
feedback option module, digital input resident on the Main Control Board, or on
an I/O option module if there is no feedback module. This function is typically
run only once after the drive is powered up or if the drive has become lost. If a
universal feedback option module is used, the homing input is part of the general
Registration hardware. To perform the homing sequences that require this
module, the drive has to configure the Registration function on the module itself.
If a Position Absolute move is made, it is necessary to have performed either a
Find Home or a Position Redefine procedure at some time after drive powerup.
Until this is done, Bit 19 “Home Not Set” in [Profile Status] remains set,
preventing the profile from executing.
The Find Home state is entered from the Initialize Step state when the profile is
enabled with the Find Home bit set in the Profile Command parameter. The
drive performs a procedure to establish the home position. The procedure
consists of a move in Speed mode at the specified Find Home Speed. A digital
input is used to sense when the home position limit switch has been traversed. If
there is an encoder, the registration logic is used to latch the motor position when
the limit switch is reached as the home position. The Find Home function
handles three possible cases; Switch and Marker, Switch only, and Marker only.
Homing Input Selection
With Feedback Device
Both the universal feedback option modules and the encoder feedback option
modules provide a dedicated homing input. The homing input on the feedback
module that is selected by P135[Pos Fdbk Sel] is used for homing. If the marker
pulse from an encoder is used in the homing function it is also selected by
P135[Pos Fdbk Sel].
Without Feedback Device
If the drive does not have a feedback module and a selection in P135[Psn Fdbk
Sel] of “simulator feedback” is made the homing input that the drive uses is
selected from any digital inputs residing on an attached I/O module by P734 [DI
OL Home Limit]. There is no marker pulse input associated with “open loop”
homing.