Installation guide

266 Stepper Drive
10.1 – Stepper Features
The MX2000 provides some additional stepper drive
controls features.
•
Allows a starting speed for the stepper to be
programmed.
•
Reducing motor heating at standstill.
•
Ability to increase motor current during motion.
•
Configurable as an open loop or closed loop
stepper drive.
•
Position Verification and Correction capability
on a closed loop stepper.
The starting speed of the stepper can be controlled
using the LOWSPD command. A good starting
point is 1.5 revolution/second. This is important if
low speed mechanical resonance is encountered
during acceleration or deceleration of the load.
A stepping motor can get hot when no motion is
taking place, the selected drive current is flowing in
the windings at standstill causing heating. This
heating can be reduced by enabling the REDUCE
current feature of the stepper, this reduces the drive
current to 50% when the motor is standing still. An-
other method of reducing heating of the motor is
turning off the current to the windings at standstill.
Some caution should be taken under certain condi-
tions when doing this since the motor has no holding
torque. The WNDGS command is used to control
this.
A stepping motor may require some additional
torque during acceleration or deceleration of the
load. A 50% increase in current can be realized dur-
ing motion with the use of the BOOST command.
This should be used with caution since it produces
additional motor heating during motion. A consid-
eration to duty cycle should be taken into account
when using this feature.
A stepper motor without an encoder must be config-
ured as an open loop stepper in the System Configu-
ration. The default configuration settings for the
open loop stepper can be selected in the
Open Loop
Stepper
folder in the user program configuration.
Some of these setting can be modified during pro-
gram execution. The Low speed setting can be modi-
fied by the LOWSPD command. Motor standstill
current can be modified by the REDUCE or
WNDGS command. The Motor Boost current setting
can be altered by the BOOST command. The Steps
per motor revolution and Motor current delay are
only selectable in the Open Loop Stepper folder.
A stepper motor with an encoder can be used for
position verification and or position correction. This
feature can be selected in the user program configu-
ration System folder by assigning this motor axis as
a closed loop stepper. The default configuration for a
closed loop stepper can be selected in the
Closed
Loop Stepper
folder in the user program configura-
tion. Some of these setting can be modified during
program execution. The Low speed setting can be
modified by the LOWSPD command. Motor stand-
still current can be modified by the REDUCE or
WNDGS command. The Motor Boost current setting
can be altered by the BOOST command. Error Ac-
tion can be changed using the ENCMODE com-
mand. Following error can be modified using the
FOLERR command and the Position Error can be
modified using the STOPERR command. The Steps
per motor revolution, Motor current delay, Correc-
tion attempts and Time between attempts are only
selectable in the Closed Loop Stepper folder. The
Encoder folder is used to configure the stepping
motor encoder, the Encoder direction and Line count
items are used to configure the stepper motor en-
coder.
10.2 - Open Loop Stepper Folder
This folder sets the
steps per motor revolution
,
Low speed
,
Motor standstill current
,
Motor boost
current
and
Motor current delay
for an open loop
stepper drive.
Steps per motor revolution
specifies the stepping
motor drive setting for each axis.
Low speed
specifies the starting speed of each axis
in units/second.
Motor standstill current
specifies the state of the
motor current at standstill for each axis. The choices
are normal (100%), reduced (50%) and off (0%).
Motor boost current
enables or disables the boost
current feature of the stepper drive during motion.
The choices are normal (100%) and boost (150%).
Motor current delay
specifies the time delay be-
tween current modes in seconds. This allows time
for the drive to respond to the change in current level
as a result of the BOOST or REDUCE command
(see Program Command section).
normal 100%
Axis 1
Motor
standstill
current
Open Loop
Stepper
normal 100%
Motor Boost
current
Motor current
delay (sec)
0.05
Steps per
motor
revolution
2000
Low speed
(units/sec)
1.5
Axis 2
2000
1.5
normal 100%
normal 100%
0.05