Reference Manual

PMAC 2 Software Reference

184 PMAC On-Line Command Specification

• The motor position bias register, which contains the difference between motor and axis

zero positions, is set to 0.

• If Ix10 for the motor is greater than 0, specifying an absolute position read, the sensor is

read as specified by Ix10 to set the motor actual position. The actual position value is set

to the sensor value minus the Ix26 “home offset” parameter. Unless the read is

determined to be unsuccessful, the motor “home complete” status bit is set to 1.

• If Ix10 for the motor is set to 0, specifying no absolute position read, the motor actual

position register is set to 0.

• Because the motor is “killed” the actual position value is automatically copied into the

command position register for the motor.

• There are several things to note with regard to this command:

• The motor is left in the “killed” state at the end of execution of this command. To enable

the motor, a $ command should be used if this is a PMAC-commutated motor and a

phase reference must be established; otherwise a J/, A, or <CTRL-A> command should

be used to enable the motor and close the loop.

• If bit 2 of Ix80 is set to 1, PMAC will not attempt an absolute position read at the board

power-on/reset; in this case, the $* command must be used to establish the absolute

sensor. If bit 2 of Ix80 is set to 0 (the default), PMAC will attempt an absolute position

read at the board power-on/reset.

• With Ix10 set to 0, the action of $* is very similar to that of the HOMEZ command. There

are a few significant differences, however:

• $* always kills the motor; HOMEZ leaves the servo in its existing state.

• $* sets the present actual position to be zero; HOMEZ sets the present commanded

position to be zero.

• $* zeros the hardware encoder counter in most cases; HOMEZ does not change the

hardware encoder counter.