Step 8C. Connect Step Motors; Step 9. Tune The Servo System - Galil Motion Control DMC-1600 Series User Manual

Step 8c. Connect Step Motors

In Stepper Motor operation, the pulse output signal has a 50% duty cycle. Step motors operate
open loop and do not require encoder feedback. When a stepper is used, the auxiliary encoder for
the corresponding axis is unavailable for an external connection. If an encoder is used for position
feedback, connect the encoder to the main encoder input corresponding to that axis. The
commanded position of the stepper can be interrogated with RP or DE. The encoder position can
be interrogated with TP.
The frequency of the step motor pulses can be smoothed with the filter parameter, KS. The KS
parameter has a range between 0.5 and 8, where 8 implies the largest amount of smoothing. See
Command Reference regarding KS.
The DMC-1600 profiler commands the step motor amplifier. All DMC-1600 motion commands
apply such as PR, PA, VP, CR and JG. The acceleration, deceleration, slew speed and smoothing
are also used. Since step motors run open-loop, the PID filter does not function and the position
error is not generated.
To connect step motors with the DMC-1600 you must follow this procedure:

Step 9. Tune the Servo System

Adjusting the tuning parameters is required when using servo motors (standard or sinusoidal
commutation). The system compensation provides fast and accurate response and the following
presentation suggests a simple and easy way for compensation. More advanced design methods
are available with software design tools from Galil, such as the Servo Design Kit (SDK software )
The filter has three parameters: the damping, KD; the proportional gain, KP; and the integrator,
KI. The parameters should be selected in this order.
To start, set the integrator to zero with the instruction
and set the proportional gain to a low value, such as
For more damping, you can increase KD (maximum is 4095). Increase gradually and stop after
the motor vibrates. A vibration is noticed by audible sound or by interrogation. If you send the
command
DMC-1600
Step A. Install SM jumpers
Each axis of the DMC-1600 that will operate a stepper motor must have the
corresponding stepper motor jumper installed. For a discussion of SM jumpers, see
Step 2.
Step B. Connect step and direction signals from controller to motor amplifier
from the controller to respective signals on your step motor amplifier. (These signals
are labeled PULSX and DIRX for the x-axis on the ICM-1900). Consult the
documentation for your step motor amplifier.
Step C. Configure DMC-1600 for motor type using MT command. You can configure
the DMC-1600 for active high or active low pulses. Use the command MT 2 for
active high step motor pulses and MT -2 for active low step motor pulses. See
description of the MT command in the Command Reference.
KI 0 (CR) Integrator gain
KP 1 (CR) Proportional gain
KD 100 (CR) Derivative gain
TE X (CR) Tell error
Chapter 2 Getting Started • 23