ElmoMC SimplIQ Digital Servo Drives-Bell Command Reference - Manual (Page 225)

The parameter CA[17] defines how Hall sensors are used for commutation:
Command Description
CA[17] 0: Use only Hall sensors. The electrical angle resolution will be 60
electrical degrees.
1: Hall sensors are used together with a high resolution sensor. On
the first Hall sensor transition, the exact electrical angle is locked
and commutation continues by position sensor increments. The
Hall sensors continue to monitor commutation correctness. The
parameter PA[1] defines the tolerance for this monitoring.
2: Halls are the sole commutation source. On high speeds, use time-
based interpolation for smoothing the electrical angle estimate.
8: Every Hall sensor transition, the exact electrical angle is locked
and commutation continues by position sensor increments until
the next Hall sensors transition.
This mode is useful when there is a play, slippage, or flexibility
between the high resolution sensor and the motor.
4.2.2 Aiding Commutation with High Resolution
Position Sensors
SimplIQ can use any main position sensor to aid commutation. These sensors normally
have good resolution, but must be homed (referenced absolutely) with respect to the
rotor electrical angle.
For commutation calculation, we must know how many bits the shaft sensor counts per
single electrical cycle. If this number is not an integer, the calculated commutation angle
may accumulate numerical errors and cause the motor to lose torque. This is not a serious
issue with linear motors that travel limited distance.
The parameters for high resolution commutation are:
Command Description
CA[16]
Sensor direction.
0: Use normal
2: Invert direction
Note that the sensor direction is also used for control feedback, so set
CA[16] according to your application needs and match CA[25] so that
driving positive current will rotate the motor in the positive direction.
SimplIQ for Steppers Application Note Commutation and Pole Identification
MAN-STECR (Ver. 1.1)
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