Reference Manual

PMAC 2 Software Reference

270 PMAC On-Line Command Specification

O{constant}

Function

Open loop output

Scope

Motor specific

Syntax

O{constant}

where:

• {constant} is a floating-point value representing the magnitude of the output as a

percentage of Ix69 for the motor, with a range of +/-100

Remarks

This command causes PMAC to put the motor in open-loop mode and force an output of the

specified magnitude, expressed as a percentage of the maximum output parameter for the

motor (Ix69). This command is commonly used for set-up and diagnostic purposes (for

instance, a positive O command must cause position to count in the positive direction, or

closed-loop control cannot be established), but it can also be used in actual applications.

If the motor is not PMAC-commutated, this command will create a DC output voltage on the

single DAC for the motor. If the motor is commutated by PMAC, the commutation

algorithm is still active, and the specified magnitude of output is apportioned between the

two DAC outputs for the motor according to the instantaneous commutation phase angle.

If the value specified is outside the range +/-100, the output will saturate at +/-100% of Ix69.

Closed-loop control for the motor can be re-established with the J command. It is a good

idea to stop the motor first with an O0 command if it has been moving in open-loop mode.

To do a variable O-command, define an M-variable to the filter result register (X:$003A,

etc.), command an O0 to the motor to put it in open-loop mode, then assign a variable value

to the M-variable. This technique will even work on PMAC-commutated motors.

PMAC will reject this command if the motor is in a coordinate system that is currently

running a motion program (reporting ERR001 if I6 is 1 or 3).

Example

O50 .................... ; Open-loop output 50% of Ix69 for addressed motor

#2O33.333...... ; Open-loop output 1/3 of Ix69 for Motor 2

O0 ...................... ; Open-loop output of zero magnitude

J/ ; Re-establish closed-loop control