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4-14 Input / Output
MN1928
4.5 Other I/O
4.5.1 Stepper control outputs
The stepper control outputs are available across a range of pins, as shown in section 4.2.1.
There are four or six sets of stepper motor control
outputs (model dependent), operating in the range
0 Hz to 500 kHz. Each of the step (pulse) and direction
signals from the NextMove ES is driven by one channel
of a ULN2003 open collector Darlington output device.
The ULN2003 has a maximum power dissipation of
900 mW at 25
°
C. The total combined output
requirements of STEP0 - STEP2 and DIR0 - DIR2 must
not exceed this limit. The maximum current limit for an
individual output is 400 mA if only one output is in use,
reducing to 50 mA if all outputs are in use. These limits
are for a 100% duty cycle.
On models NES002-501 and NES002-502, STEP3
and DIR3 are sourced from the same ULN2003 device
used for the DOUT8 - DOUT11 digital outputs (see
section 4.4.2.2), so the current demands of these
digital outputs must also be considered.
On model NES002-503, STEP3 and DIR3 are sourced
from the same ULN2003 device used for the additional
STEP4 - STEP5 and DIR4 - DIR5 stepper axes outputs. In this case the ULN2003 device is
providing three sets of STEP and DIR outputs, so the specifications are identical to those for
STEP0 - STEP2 and DIR0 - DIR2, detailed above.
It is recommended to use separate shielded cables for the step outputs. The shield should be
connected at one end only.
The ULN2003 drivers are static sensitive devices. Take appropriate ESD
precautions when handling the NextMove ES.
NextMove ES
STEP0
DGND
a3
a14
ULN2003
Step
Output
74AHCT244
GND
Figure 13 - Stepper output - STEP0 output shown
NES002-501 / NES002-502
U
L
N
2003
d
evice
1
STEP0
DIR0
STEP1
DIR1
STEP2
DIR2
STEP3
DIR3
DOUT8
DOUT9
DOUT10
DOUT11
U
L
N
2003
d
evice
2
NES002-503
U
L
N
2003
d
evice
1
STEP0
DIR0
STEP1
DIR2
STEP2
DIR2
STEP3
DIR3
STEP4
DIR4
STEP5
DIR5
U
L
N
2003
d
evice
2
CAUTION
Servo Systems Co. • 115 Main Road • P.O. Box 97 • Montville, NJ,
07045-0097 • (973) 335-1007 • Toll Free: (800) 922-1103
Fax: (973) 335-1661 • www.servosystems.com
