Table of Contents
Advertisement
VD 68000000
VS 125664
CR 1000, -90, 3600
VE
BGS
Stepper Motor Operation
When configured for stepper motor operation, several commands are interpreted differently than
from servo mode. The following describes operation with stepper motors.
Specifying Stepper Motor Operation
In order to command stepper motor operation, the appropriate stepper mode jumpers must be
installed. See chapter 2 for this installation.
Stepper motor operation is specified by the command MT. The argument for MT is as follows:
2 specifies a stepper motor with active low step output pulses
-2 specifies a stepper motor with active high step output pulses
2.5 specifies a stepper motor with active low step output pulses and reversed direction
-2.5 specifies a stepper motor with active high step output pulse and reversed direction
Stepper Motor Smoothing
The command, KS, provides stepper motor smoothing. The effect of the smoothing can be
thought of as a simple Resistor-Capacitor (single pole) filter. The filter occurs after the motion
profiler and has the effect of smoothing out the spacing of pulses for a more smooth operation of
the stepper motor. Use of KS is most applicable when operating in full step or half step operation.
KS will cause the step pulses to be delayed in accordance with the time constant specified.
When operating with stepper motors, you will always have some amount of stepper motor
smoothing, KS. Since this filtering effect occurs after the profiler, the profiler may be ready for
additional moves before all of the step pulses have gone through the filter. It is important to
consider this effect since steps may be lost if the controller is commanded to generate an
additional move before the previous move has been completed. See the discussion below,
Monitoring Generated Pulses vs. Commanded Pulses.
The general motion smoothing command, IT, can also be used. The purpose of the command, IT,
is to smooth out the motion profile and decrease 'jerk' due to acceleration.
Monitoring Generated Pulses vs. Commanded Pulses
In general, it is necessary to make sure that the controller has completed generating all step pulses
before making additional moves. If additional motion commands are given while step motor is
already moving, some steps may be missed.* This is most particularly important when moving
back and forth. For example, when operating with servo motors, the trippoint AM (After Motion)
is used to determine when the motion profiler is complete and is prepared to execute a new motion
command. However when operating in stepper mode, the controller may still be generating step
pulses when the motion profiler is complete. This is caused by the stepper motor smoothing filter,
KS. To understand this, consider the steps the controller executes to generate step pulses:
First, the controller generates a motion profile in accordance with the motion commands.
DMC-1600
Maximum Deceleration
VS for 20 Hz
Ten cycles
Chapter 6 Programming Motion • 101
Advertisement
Table of Contents
