Galil DMC-2X00 - Manual (Page 40)

Step 9c. 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 TD. 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-2x00 profiler commands the step motor amplifier. All DMC-2x00 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-2x00 you must follow this procedure:
Step A. Install SM jumpers
Each axis of the DMC-2x00 that will operate a stepper motor must have the corresponding
stepper motor jumper installed. For a discussion of SM jumpers, see section Step 2. Install
Jumpers on the DMC-2x00.
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 A-axis on the ICM-2900). Consult the documentation for
your step motor amplifier.
Step C. Configure DMC-2x00 for motor type using MT command. You can configure the DMC-
2x00 for active high or active low pulses. Use the command MT 2 for active low step motor
pulses and MT -2 for active high step motor pulses. See description of the MT command in
the Command Reference.
Step 10. 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
KI 0 <return> Integrator gain
and set the proportional gain to a low value, such as
KP 1 <return> Proportional gain
KD 100 <return> Derivative gain
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• Chapter 2 Getting Started
DMC-2X00