Rockwell Automation 999 IMC S Class Compact Motion Controller (Cat. No. 4100-999-122) - Manual (Page 114)

5-34 Understanding IMC-S/23x Setups
Publication 999-122 - January 1997
If ABSOLUTE is selected when you execute a homing command, the
controller will request the absolute position of the feedback transducer
to initialize the axis position.
Note: There is a two-second delay (approximately) with absolute
homing to allow the absolute transducer converter to read the
absolute position.
In operation, the absolute homing procedure:
A. Disables feedback
B. Activates the absolute position strobe output to read the current
absolute position of the axis from the absolute transducer
converter
C. Sets the actual position of the axis to the current absolute
position of the feedback device plus the home position
D. Re-enables feedback
Using absolute homing, the home position parameter acts as an offset
to the absolute position read from the absolute transducer converter.
For example, assume that an axis is using a resolver for feedback with
position units of degrees, the current absolute position of the resolver
is 146.0
°
, and the Home Position parameter is 34.0
°
. In this case,
absolute homing sets the current actual position of the axis to 146.0 +
34.0 = 180
°
.
Absolute_MV
Absolute_MV is an absolute homing procedure. You can only use the
Absolute_MV homing procedure when you are using both of the
following:
•
Allen-Bradley Bulletin 1326 dual resolver packages (operating in
master/vernier fashion)
•
REC transducer card (not REC-4096)
The IMC-S/23x uses these two products to determine the transducer’s
absolute position by way of a single home command. During homing,
the two resolver positions are multiplexed into the IMC-S/23x through
a single feedback input. The IMC-S/23x performs calculations to derive
the absolute position. To use Absolute_MV:
1. Select Absolute_MV and press ENTER. The following message
appears:
1326AB-MOD-VD: Package number?
(256/255 or CUSTOM)