LAC-1 single axis controller manual

SMAC
LAC-1 Technical Reference Manual
Command: QMn -- Enter Torque Mode --
Argument:
Default:
0 for voltage mode, 1 for current mode
Position mode
This command places the servo axis in the Torque Mode of operation. For mode 0 (or
QM0), the output PWM duty cycle (or analog output for appropriate models) can be manually
controlled by the user program. Once QM0 has been entered, the Set Torque (SQ) command can
be used to set or change the servo output (see the SQ command). Bear in mind, that if the output
was being limited by an SQ command before entering torque mode (while in PM or VM), it will
remain limited while in QM and cannot be changed until the unit is in PM or VM.
For mode 1 (or QM1), the LAC-1 will use one of its A/D channels to monitor servo output
current and attempt to maintain that output current at a steady level as commanded by the user
program (see the SQ and SC commands). In that the A/D converter has 10-bit resolution, this will
result in a value from 0 to 1023 which represents the instantaneous output current with 0 being
approximately 0 Amps and 1023 being approximately 5 Amps with intermediate values being
somewhat linear.
In the case of a motor (for example), when an output command of 512 is set (or about 2.5
amps), the PWM output begins to ramp up until the desired output current is reached. If the motor is
not loaded enough to require 2.5 amps then the PWM will ramp up to 100% putting the maximum
supply voltage to the motor. If at this point the motor is suddenly loaded, the PWM will ramp down
to a level sufficient to supply 2.5 amps to the motor.
Mode QM1 will not function with the D/A module option.
Related Commands: EG, PM, VM
Command: SEn -- Set Maximum Following Error --
Argument: 0