NI 9501 User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9501
Stepper Drive
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NI 9501 Operating Instructions and Specifications 2 ni.com
This document describes how to use the National Instruments 9501
module and includes specifications and pin assignments for the
NI 9501. Visit ni.com/info and enter rdsoftwareversion to
determine which software youneed for the modules youare using.
For information about installing, configuring, and programming the
system, refer to the system documentation. Visit ni.com/info and
enter cseriesdoc for information about C Series documentation.
Note The safety guidelines and specifications in this
document are specific to the NI 9501. The other
components in the system may not meet the same safety
ratings and specifications. Refer to the documentation for
each component in the system to determine the safety
ratings and specifications for the entire system.
Safety Guidelines
Operate the NI 9501 only as described in these operating
instructions.
Hot Surface This icon denotes that the component may be
hot. Touching this component may result in bodily injury.

© National Instruments Corp. 3 NI 9501 Operating Instructions and Specifications
Safety Guidelines for Hazardous Locations
The NI 9501 is suitable for use in Class I, Division 2, Groups A, B,
C, D, T4 hazardous locations; Class I, Zone 2, AEx nA IIC T4, and
Ex nA IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if youare installing the NI 9501 in a
potentially explosive environment. Not following these guidelines
may result in serious injury or death.
Caution Do not disconnect I/O-side wires or connectors
unless power has been switched off or the area is known
to be nonhazardous.
Caution Do not remove modules unless power has been
switched off or the area is known to be nonhazardous.
Caution Substitution of components may impair
suitability for Class I, Division 2.
Caution For Division 2 and Zone 2 applications, install
the system in an enclosure rated to at least IP 54 as
defined by IEC 60529 and EN 60529.

NI 9501 Operating Instructions and Specifications 4 ni.com
Caution For Division 2 and Zone 2 applications, install a
protection device between the input signal and the Vsup
pin. The device must prevent the Vsup-to-channel voltage
from exceeding 42 V if there is a transient overvoltage
condition.
Special Conditions for Hazardous Locations Use in Europe
This equipment has been evaluated as Ex nA IIC T4 equipment
under DEMKO Certificate No. 07 ATEX 0626664X. Each module
is marked II 3G and is suitable for use in Zone 2 hazardous
locations, in ambient temperatures of –40 °C ≤Ta ≤70 °C. If you
are using the NI 9501 in Gas Group IIC hazardous locations, you
must use the device in an NI chassis that has been evaluated as
Ex nC IIC T4, EEx nC IIC T4, Ex nA IIC T4, or Ex nL IIC T4
equipment.
Electromagnetic Compatibility Guidelines
This product was tested and complies with the regulatory
requirements and limits for electromagnetic compatibility (EMC)
as stated in the product specifications. These requirements and
limits are designed to provide reasonable protection against
harmful interference when the product is operated in its intended
operational electromagnetic environment.

© National Instruments Corp. 5 NI 9501 Operating Instructions and Specifications
This product is intended for use in industrial locations. As such,
there is no guarantee that harmful interference will not occur in
aparticular installation, when the product is connected to a test
object, or if the product is used in residential areas. To minimize
the potential for the product to cause interference to radio and
television reception or to experience unacceptable performance
degradation, install and use this product in strict accordance with
the instructions in the product documentation.
Furthermore, any changes or modifications to the product not
expressly approved by National Instruments could void your
authority to operate it under your local regulatory rules.
Caution To ensure compliance with the applicable
regulatory requirements, product installation requires
either special considerations or user-installed, add-on
devices. See the product installation instructions for
further information.
Caution The inputs/outputs of this product can be
damaged if subjected to Electrostatic Discharge (ESD).
To prevent damage, industry-standard ESD prevention
measures must be employed during installation,
maintenance, and operation.

NI 9501 Operating Instructions and Specifications 6 ni.com
Special Guidelines for Marine Applications
Some products are Lloyd’s Register (LR) Type Approved for
marine (shipboard) applications. To verify Lloyd’s Register
certification for a product, visit ni.com/certification and
search for the LR certificate, or look for the Lloyd’s Register mark
on the product label.
Caution In order to meet the EMC requirements for
marine applications, install the product in a shielded
enclosure with shielded and/or filtered power and
input/output ports. In addition, take precautions when
designing, selecting, and installing measurement probes
and cables to ensure that the desired EMC performance is
attained.

© National Instruments Corp. 7 NI 9501 Operating Instructions and Specifications
NI 9501 Hardware Overview
The NI 9501 is a stepper motor drive for use with 2-phase hybrid
stepper motors in either bipolar or unipolar winding configuration.
It uses an advanced PWM algorithm that reduces torque ripple,
lowers emissions, minimizes power loss, and creates smoother
motion during microstepping.
Note National Instruments offers NEMA 17 and
NEMA 23 stepper motors compatible with the NI 9501.
Go to ni.com/motion/stepper for more information
about NI stepper motors.
The NI 9501 supports software-programmable full step, half step,
and microstepping rates up to 256. When full-stepping,
a resonance occurs at low speeds, generally defined as speeds
between 50 and 150 RPM. This low-speed resonance causes
vibration and reduces the motor torque. Using microstepping
during this speed range provides much smoother motion and
higher motor torque, effectively eliminating the low-speed
resonance. At speeds over 150 RPM, the benefits of microstepping
decrease and can eventually have an overall negative impact on
performance by providing lower motor torque compared to

NI 9501 Operating Instructions and Specifications 8 ni.com
full-stepping. Refer to the NI 9501 topic in the LabVIEW Help,
available by selecting Help»LabVIEW Help, for information
about microstepping options.
The NI 9501 also provides for phase current reduction after the
motor stops moving for a certain amount of time using the Enable
Current Reduction property in software. Unlike servo motors, the
stepper motor coil remains fully energized when the motor is not
moving. This allows for strong holding torque, but generates
substantial heat in the motor. Many applications do not require
maximum holding torque when the motor is at rest, which
means that the motor is wasting power. The amount of current
reduction and delay before current reduction becomes active
is software-programmable. Refer to the NI 9501 topic in the
LabVIEW Help, available by selecting Help»LabVIEW Help,
for more information about current reduction.

© National Instruments Corp. 9 NI 9501 Operating Instructions and Specifications
Figure 1. NI 9501 Block Diagram
CPLD*
NI 9501
V
sup
COM
Phase A–
Phase A+
H-Bridge
H-Bridge
Phase
B+
Phase
B–
Step
Dir
Status
FPGA
Signals
+
–
Isolation
* CPLD = Complex Programmable Logic Device

NI 9501 Operating Instructions and Specifications 10 ni.com
Connecting the NI 9501
The NI 9501 has a 10-terminal detachable screw-terminal
connector that provides connections for the stepper motor signals,
a motor DC power supply, COM, and chassis ground. Refer to
Figure 2 for the pin assignments.
Caution To ensure EMC compliance, special
considerations are required for all cable connections.
Refer to the Cable Requirements for EMC Compliance
section.
Note Yo umust use 2-wire ferrules to create a secure
connection when connecting more than one wire to a
single terminal on the NI 9501 screw terminal.
Caution Do not turn on or plug in the motor DC power
supply until the screw-terminal connector is fully
inserted.

© National Instruments Corp. 11 NI 9501 Operating Instructions and Specifications
Figure 2. NI 9501 Connections
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
(ChassisGround)
0
1
2
3
4
5
6
7
8
9

NI 9501 Operating Instructions and Specifications 12 ni.com
Motor Power Signals
The Phase A± and Phase B± signals power the stepper motor.
Figure 3 shows a typical bipolar stepper motor connection.
Figure 3. Typical Bipolar Stepper Motor (2-Phase Type) Connection
Caution The stepper motor terminals on this drive are
energized when the module is enabled. Do not connect
wires to or disconnect wires from the NI 9501 when it
is enabled.
Use a multiconductor cable with an overall shield and conductors
of 20 AWG or larger for the motor power cable.
0
1
2
3
4
5
6
7
8
9
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
Phase A+
Phase A–
Phase B+
Phase B–

© National Instruments Corp. 13 NI 9501 Operating Instructions and Specifications
The NI 9501 contains bipolar chopper drivers. Two-phase stepper
motors come in 4-, 6-, and 8-wire variations. Youmust wire the
stepper motors in a 4-wire configuration as shown in Figure 3.
Caution Never connect unused stepper motor terminals
to pin 9 (Chassis Ground) or to each other.
When using a 6- or 8-wire stepper motor youmust leave unused
lead wires disconnected. Figure 4 shows a 6-wire and an 8-wire
stepper motor.
Figure 4. 6-Wire and 8-Wire Stepper Motors
6-wire 8-wire

NI 9501 Operating Instructions and Specifications 14 ni.com
A 4-wire motor is the same as a 6-wire motor except that the center
taps (CT) are not brought out. To use a 6-wire motor in a 4-wire
configuration youcan isolate the center taps for a series (full coil)
configuration. Series configurations produce the most torque per
amp but have the disadvantage of poorer high-speed performance.
Figure 5. 6-Wire Series Stepper Motor Connection
(Higher Torque, Lower Speed)
0
1
2
3
4
5
6
7
8
9
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
Phase A+
Phase A–
Phase B+
Phase B–
NC*
NC*
*NC = Not Connected

© National Instruments Corp. 15 NI 9501 Operating Instructions and Specifications
Yo ucan obtain improved high-speed performance with a 6-wire
motor by using a half-coil configuration shown in Figure 6. This
configuration sacrifices low-speed torque for better high-speed
performance. With this configuration, it is typically not possible to
produce the rated torque of the motor without the risk of the motor
overheating because only half of the windings are used.
Figure 6. 6-Wire Half-Coil Stepper Motor Connection
(Higher Speed, Lower Torque)
0
1
2
3
4
5
6
7
8
9
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
Phase A+
Phase A–
Phase B+
Phase B–
NC*
NC*
*NC = Not Connected

NI 9501 Operating Instructions and Specifications 16 ni.com
For maximum flexibility, youcan connect 8-wire stepper motors
in series, parallel, or half-coil configurations. Connecting the
windings in a series configuration, as shown in Figure 7, produces
the most torque per amp but has the disadvantage of higher
inductance and poorer high-speed performance.
Figure 7. 8-Wire Series Stepper Motor Connection
(Higher Torque, Lower Speed)
Phase B–
0
1
2
3
4
5
6
7
8
9
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
Phase A+
Phase A–
Phase B+

© National Instruments Corp. 17 NI 9501 Operating Instructions and Specifications
Notice that an 8-wire motor wired in a series configuration is
virtually identical to a 6-wire motor and typically has the same
high torque but low-speed characteristics.
Alternatively, youcan connect 8-wire stepper motors in a parallel
configuration as shown in Figure 8. This configuration produces
better high-speed performance but requires more current to
produce rated torque.
Figure 8. 8-Wire Parallel Stepper Motor Connection
(Higher Speed, Lower Torque)
0
1
2
3
4
5
6
7
8
9
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
Phase B–
Phase A+
Phase A–
Phase B+

NI 9501 Operating Instructions and Specifications 18 ni.com
Finally, youcan connect 8-wire stepper motors in a half-coil
configuration as shown in Figure 9. The half-coil configuration
sacrifices low-speed torque for better high-speed performance.
With this configuration, it is typically not possible to produce the
rated torque of the motor without the risk of the motor overheating
because only half of the windings are used.
Figure 9. 8-Wire Half-Coil Stepper Motor Connection
0
1
2
3
4
5
6
7
8
9
Phase A+
Phase A–
Phase B+
Phase B–
Reserved
Reserved
Reserved
COM
Vsup
Phase B–
Phase A+
Phase A–
Phase B+
NCNC
NC
NC
*NC = Not Connected

© National Instruments Corp. 19 NI 9501 Operating Instructions and Specifications
Wiring for High Vibration Applications
If an application is subject to high vibration, National Instruments
recommends that youuse ferrules to terminate wires to the
detachable screw-terminal connector.
Refer to Figure 10 for an illustration of using ferrules.
Figure 10. 10-Terminal Detachable Screw-Terminal Connector with Ferrule
Ferrule

NI 9501 Operating Instructions and Specifications 20 ni.com
LED Indicators
The NI 9501 has four LEDs to display status information.
Enabled
The Enabled LED (green) illuminates when the drive is enabled
and the output power stage is active, and is flashing when the drive
is disabled and the output power stage is inactive. Refer to the
NI 9501 topic in the LabVIEW Help, available by selecting
Help»LabVIEW Help, for information about enabling the drive.
1Enabled (green)
2Vsup (Motor Power) (green)
3User (yellow)
4Fault (red)
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