Allen-Bradley ControlLogix Reference Manual

CIP Axis Attributes
Chapter 4
Rockwell Automation Publication MOTION-RM003I-EN-P - February 2018 199
Commutation Offset
Usage Access Data
Type
Default Min Max Semantics of Values
Required - CE
(PM)
SSV#/
GSV
REAL 0
DB
0
Electrical Degrees
# Indicates the attribute cannot be set while the tracking command (Tracking Command bit in CIP Axis Status is true).
The Commutation Offset attribute specifies the commutation offset of the PM
motor mounted feedback device in units of electrical degrees. This attribute
specifies the offset from a commutation reference position defined by applying
DC current into the A terminal and out of the shorted B and C terminals of the
motor and letting the rotor to move to its magnetic null position relative to the
stator. On an absolute encoder or resolver, the offset is the difference from the
device's zero absolute position and the commutation reference position. On an
incremental encoder or Hall sensor with UVW signals, the offset is the difference
between the position corresponding to a transition of the commutation device's
W (S3) channel (with the U (S1) channel high and the V (S2) channel low) and
the commutation reference position. The commutation offset is only applicable to
the motor mounted Feedback 1 device.
When the optional Commutation Alignment attribute is supported and set to
Controller Offset, the drive will apply the Commutation Offset value from the
controller to determine the electrical angle of the motor. In this case, a valid
Commutation Offset value must be entered by the user, read from the Motor
Database, or determined by the Commutation Test. In the unusual case where the
commutation offset is also stored in the motor, and differs significantly from
Commutation Offset value from the controller, the drive will transition to the
Start Inhibited state
If the Commutation Alignment attribute is not set to Controller Offset or
Database Offset, the Commutation Offset value from the controller is ignored by
the drive and the drive must determine its internal commutation offset value by
other means. Without a valid commutation offset, the drive will be Start
Inhibited.
Commutation Self-Sensing Current
Usage Access Data
Type
Default Min Max Semantics of Values
Optional - CE
(PM)
Set/GSV REAL 100 0 200 % Motor Rated
When a PM motor feedback drive device is an incremental encoder without
UVW tracks for commutation, a Self-Sensing algorithm is run during the Starting
state that determines the Commutation Offset to apply to the position feedback.

Allen-Bradley ControlLogix Specifications

General

Brand	Allen-Bradley
Model	ControlLogix
Category	Industrial Electrical
Language	English