NI SMD-7611 User manual

USER MANUAL
NI SMD-7611/7612
This manual contains information about the configuration and use of the National Instruments
SMD-7611 and SMD-7612. They are referred to inclusively as the NI SMD-7611/7612.
Functionality on these devices are roughly equivalent. The NI SMD-7611 operates from 24 to
48 VDC, and has a running current of up to 4.5 A per phase. The SMD-7612 operates from 24 to
60 VDC, and runs current up to 7.8 A per phase.
Contents
Safety Information .................................................................................................................... 2
Block Diagram.......................................................................................................................... 3
Getting Started .......................................................................................................................... 3
Mounting the Drive .................................................................................................................. 4
Connecting the Power Supply .................................................................................................. 4
Drive CE Requirements............................................................................................................ 5
Choosing a Power Supply.........................................................................................................5
Voltage.............................................................................................................................. 6
Current .............................................................................................................................. 6
Regeneration ..................................................................................................................... 8
System Wiring Recommendations ........................................................................................... 8
Connecting Motors ........................................................................................................... 8
Connecting Input Signals.................................................................................................. 10
FAULT Output ......................................................................................................................... 13
Configuring the Drive............................................................................................................... 14
Step 1: Selecting a Motor and Setting the Current ........................................................... 14
Step 2: Fine Tuning the Motor Current ............................................................................ 16
Step 3: Setting Idle Current .............................................................................................. 17
Step 4: Load Inertia .......................................................................................................... 17
Step 5: Step Size ...............................................................................................................18
Step 6: Step Pulse Type .................................................................................................... 19
Step 7: Step Pulse Noise Filter ......................................................................................... 20
Step 8: Self Test................................................................................................................ 21
Torque Speed Curves................................................................................................................ 21
Motor Heating........................................................................................................................... 28
Drive Heating ........................................................................................................................... 39
Mechanical Outline................................................................................................................... 40
Technical Specifications........................................................................................................... 41
Alarm Codes ............................................................................................................................. 42

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Safety Information
Only qualified personnel are permitted to transport, assemble, commission, and maintain this
equipment. Properly qualified personnel are persons who are familiar with the transport,
assembly, installation, commissioning and operation of motors, and who have the appropriate
qualifications for their jobs. The qualified personnel must know and observe the following
standards and regulations:
• IEC 364 resp. CENELEC HD 384 or DIN VDE 0100
• IEC report 664 or DIN VDE 0110
• National regulations for safety and accident prevention or VBG 4
To minimize the risk of potential safety problems, you should follow all applicable local and
national codes that regulate the installation and operation of your equipment. These codes vary
from area to area and it is your responsibility to determine which codes should be followed, and
to verify that the equipment, installation, and operation are in compliance with the latest revision
of these codes.
Equipment damage or serious injury to personnel can result from the failure to follow all
applicable codes and standards. We do not guarantee the products described in this publication
are suitable for your particular application, nor do we assume any responsibility for your product
design, installation, or operation.
• Read all available documentation before assembly and commissioning. Incorrect handling
of products in this manual can result in injury and damage to persons and machinery.
Strictly adhere to the technical information on the installation requirements.
• It is vital to ensure that all system components are connected to earth ground. Electrical
safety is impossible without a low-resistance earth connection.
• The STR2 contains electrostatically sensitive components that can be damaged by incorrect
handling. Discharge yourself before touching the product. Avoid contact with high
insulating materials (artificial fabrics, plastic film, etc.). Place the product on a conductive
surface.
• During operation keep all covers and cabinet doors shut. Otherwise, there are deadly
hazards that could possibility cause severe damage to health or the product.
• In operation, depending on the degree of enclosure protection, the product can have bare
components that are live or have hot surfaces. Control and power cables can carry a high
voltage even when the motor is not rotating.
• Never pull out or plug in the product while the system is live. There is a danger of electric
arcing and danger to persons and contacts.
• After powering down the product, wait at least ten minutes before touching live sections of
the equipment or undoing connections (e.g., contacts, screwed connections). Capacitors
can store dangerous voltages for long periods of time after power has been switched off. To
be safe, measure the contact points with a meter before touching.
Be alert to the potential for personal injury. Follow the recommended precautions and safe
operating practices. Safety notices in this manual provide important information. Read and be
familiar with these instructions before attempting installation, operation, or maintenance. The

NI SMD-7611/7612 User Manual |© National Instruments |3
purpose of this section is to alert users to possible safety hazards associated with this equipment
and the precautions that need to be taken to reduce the risk of personal injury and damage to the
equipment. Failure to observe these precautions could result in serious bodily injury, damage to
the equipment, or operational difficulty.
Block Diagram
Figure 1. NI SMD-7611/7612 Block Diagram
Getting Started
You need the following to use your NI SMD-7611/7612 stepper drive:
a 12 to 48 VDC power supply (60 V max for NI SMD-7612). Refer to Choosing a Power
Supply for help in choosing the right power supply
one of the recommended motors
a small flat blade screwdriver for tightening the connectors
a source of step signals, such as a PLC or motion controller
The connectors and other points of interest are illustrated below. These are detailed later in the
manual.
AMPLIFIER
24-48 VDC (SMD-7611)
24-60 VDC (SMD-7612)
from external power supply
Status LEDs
Motor Selection
Current
Idle Current
Steps/Rev
Load Inertia
Self Test
STEP
DIR
OUT1
O
v
e
rcurr
e
nt
Se
nsors
motor
3.3/5/15V
Regulators
Optical
Isolation
Optical
Isolation
Software
Filter
Digital
Filter
Optical
Isolation
EN
D
S
P
V
o
l
tage
Se
nsors
12345678

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Figure 2 shows an overview of the connectors on the NI SMD-7611/7612 stepper drive.
Figure 2. NI SMD-7611/7612 Stepper Drive Connectors
Mounting the Drive
You can mount your drive on the wide or the narrow side of the chassis using #6 screws. If
possible, the drive should be securely fastened to a smooth, flat metal surface that will help
conduct heat away from the chassis. If this is not possible, then forced airflow from a fan may
be required to prevent the drive from overheating. Refer to Drive Heating for more information.
• Never use your drive in a space where there is no air flow or where other devices cause the
surrounding air to be more than 50 °C.
• Never put the drive where it can get wet or where metal or other electrically conductive
particles can get on the circuitry.
• Always provide air flow around the drive. When mounting multiple drives near each other,
maintain at least one half inch of space between drives.
Connecting the Power Supply
If you need information about choosing a power supply, refer to Choosing a Power Supply.
• Connect the power supply “+” terminal to the connector terminal labeled “V+”.
• Connect power supply “-” to the connector terminal labeled “V-”.
• The green ground screw on the corner of the chassis should be connected to earth ground.
• Use 18 or 20 gauge wire.
The NI SMD-7611/7612 drives contain an internal fuse that connects to the power supply +
terminal. This fuse is not user replaceable. If you want to install a user serviceable fuse in your
system, install a fast acting fuse in line with the + power supply lead. Use a 4 amp fuse for the
SMD-7611 and a 7 amp fuse for the SMD-7612.
Caution Do not reverse the wires. Reverse connection will destroy your drive and
void your warranty.
1 Chassis Grounding Screw
2 Motor and Power Supply Connector
3 Drive Configuration DIP Switches
4 Input and Output Signals
5 Motor Selector Switch
6 Drive Status LEDs
12345678
1
2345 6

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Drive CE Requirements
CE requires you to use an EMI line filter, installed as shown in the following figure.
Figure 3. An EMI Line Filter
If you plan to use a regulated power supply you may encounter a problem with regeneration. If
you rapidly decelerate a load from a high speed, much of the kinetic energy of that load is
transferred back to the power supply. This can trip the overvoltage protection of a switching
power supply, causing it to shut down. NI offers the SMD-7700 regeneration clamp to solve this
problem. If in doubt, buy an SMD-7700 for your first installation. If the regen LED on the
SMD-7700 never flashes, you don’t need the clamp.
Choosing a Power Supply
When choosing a power supply, there are many things to consider. If you are manufacturing
equipment that will be sold to others, you probably want a supply with all the safety agency
approvals. If size and weight are an issue, get a switching supply.
And you must decide what size of power supply (in terms of voltage and current) is needed for
your application.
National Instruments offers two power supplies that are excellent matches for the
NI SMD-7611/7612 drive: PS-12 24V, 6.3A) and PS-13 (48V, 6.7A).

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Voltage
The motor can provide more torque at higher speeds if a higher power supply voltage is used.
Refer to the Torque Speed Curves section for guidance.
If you choose an unregulated power supply, make sure the no load voltage of the supply does not
exceed the drive’s maximum input voltage specification.
Current
The maximum supply current you could ever need is two times the motor current. However, you
will generally need a lot less than that, depending on the motor type, voltage, speed and load
conditions. That’s because the NI SMD-7611/7612 uses a switching amplifier, converting a high
voltage and low current into lower voltage and higher current. The more the power supply
voltage exceeds the motor voltage, the less current you’ll need from the power supply. A motor
running from a 48 volt supply can be expected to draw only half the supply current that it would
with a 24 volt supply.
We recommend the following selection procedure:
1. If you plan to use only a few drives, get a power supply with at least twice per phase current
rating of the step motor. Example: for a motor that’s rated for 2 A/phase use a 4 A power
supply.
2. If you are designing for mass production and must minimize cost, get one power supply
with more than twice the rated current of the motor. Install the motor in the application and
monitor the current coming out of the power supply and into the drive at various motor
loads. This will tell you how much current you really need so you can design in a lower cost
power supply.
Tables 1 and 2 list the maximum current required for each motor at several common power
supply voltages. Please consider this information when choosing a power supply.
Table 1. NI SMD-7611 Power Supply Current
Switch Motor
Drive Current (A),
peak of sine
Max Power Supply
Current (A)
24 VDC 48 VDC
0Reserved for
custom motors
1
2 ST17-4 2.4 parallel 1.6 1.7
3 ST17-1 1.6 parallel 1.1 1.1
4 ST17-2 2.0 parallel 1.1 1.1
5 ST17-3 2.0 parallel 1.1 1.1
6 ST23-1 3.4 parallel 1.9 2.0

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7 ST23-4 4.5 parallel 3.2 3.3
8 ST23-6 4.5 parallel 3.2 3.4
9 ST24-1 3.36 2.6 2.3
A ST24-2 4.5 5.2 3.2
B ST24-3 4.5 4.3 3.4
C ST34-2 4.5 series 2.6 2.5
D ST34-5 4.5 series 2.4 2.7
E ST34-1 3.816 series 2.1 2.1
Table 2. NI SMD-7612 Power Supply Current
Switch Motor
Drive Current (A),
peak of sine
Max Power Supply Current (A)
24 VDC 48 VDC 60 VDC
0
Reserved for
custom motors
1
2
3ST23-8 64.4 4.0 4.0
4ST23-1 3.4 1.9 2.0 N/A
5ST23-4 53.2 3.3 N/A
6ST23-6 53.2 3.4 N/A
7ST24-1 3.36 2.6 2.3 2.0
8ST24-2 4.8 5.2 3.2 2.7
9ST24-3 4.8 4.3 3.4 2.9
AST34-2 85.1 5.0 5.0
BST34-5 85.2 4.6 4.4
CST34-8 85.2 5.4 5.3
Table 1. NI SMD-7611 Power Supply Current (Continued)
Switch Motor
Drive Current (A),
peak of sine
Max Power Supply
Current (A)
24 VDC 48 VDC

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Regeneration
When a motor rapidly decelerates from high speed under load, the kinetic energy may be
reconverted into electrical energy and transferred back to the power supply. When using
regulated power supplies, this can trip the overvoltage protection and lead to a shutdown, or
cause damage to the system. Unregulated power supplies do not typically have overvoltage
protection, and may store regenerated energy in capacitors.
System Wiring Recommendations
Maintain at least 2 in. separation between the power supply cable and input lines or encoder
feedback. All power supply cables should be properly shielded, and the shield grounded at the
power supply. Signal cables should be shielded, and grounded as close as possible to the signal
source.
Connecting Motors
This section explains how to connect motors to the NI SMD-7611/7612. Refer to your motor
documentation for any special considerations that may affect your configuration.
Caution Never connect or disconnect the motor while the system is powered on.
Note Ensure any shield or grounding strap on the motor is connected to the chassis
ground screw located near the motor/power connector.
Figure 4. Motor/Power Connector
DST34-1 7.56 4.8 4.2 4.0
EST34-4 7.56 4.4 4.2 4.2
FST34-7 6.72 3.5 3.2 3.3
Table 2. NI SMD-7612 Power Supply Current (Continued)
Switch Motor
Drive Current (A),
peak of sine
Max Power Supply Current (A)
24 VDC 48 VDC 60 VDC

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Figure 5. Grounding Screw on the Chassis
Four Lead Motors
Four lead motors can only be configured according to the following diagram.
Note Motor wire colors are correct for NI stepper motors compatible with the
NI SMD-7611/7612. These wire colors may not match a third-party stepper motor.
Figure 6. Four Lead Motor Connection
Eight Lead Motors
Eight lead motors can be connected in series or parallel. A series connected motor needs less
current than one that is connected in parallel but it will not be able to run as fast. Refer to the
wiring diagrams below to connect an eight lead motor.
Figure 7. Eight Lead Motor Connected in Series

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Figure 8. Eight Lead Motor Connected in Parallel
Connecting Input Signals
The NI SMD-7611/7612 has three input channels:
• STEP: A high-speed digital input for step pulse commends. 5-24 V logic.
• DIR: A high-speed digital input for the direction signal. 5-24 V logic.
• EN: A digital input for removing power from the motor. 5-24 V logic.
Note Activating then deactivating EN clears alarms and faults, and re-enables the
motor in the case of drive faults.
Note STEP and DIR inputs can be converted to STEP CW and STEP CCW by
configuring the internal jumper. Refer to Step 6: Step Pulse Type for more
information.
Figure 9. Input Connector Pin Diagram

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Figure 10. Input Connector Circuit Diagram
Connection Examples
The following section demonstrates example signal connections. Refer to System Wiring
Recommendations for cable instructions.
STEP and DIR
Figure 11. Connecting to Indexer with Sourcing Outputs
Figure 12. Connecting to Indexer with Sinking Outputs

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Figure 13. Connecting to Indexer with Differential Outputs
Enable Input
Connecting the Enable input as shown in Figure 14 causes the drive to disable when the relay is
closed and enable when the relay is open.
Figure 14. Connecting Enable to a Switch or Relay
Connecting the Enable signal as shown in Figure 15 causes the drive to disable when the output
closes.
Figure 15. Connecting a Second Drive to EN
Connecting the Enable signal as shown in Figure 16 causes the drive to disable when the
proximity sensor activates.
Figure 16. Connecting an NPN Type Proximity Sensor to an Input

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Connecting the Enable signal as shown in Figure 17 causes the drive to disable when the
proximity sensor activates.
Figure 17. Connecting a PNP Type Proximity Sensor to an Input
FAULT Output
The NI SMD-7611/7612 has a digital FAULT output. This output closes to signal a fault
condition.
This output can be used to drive LEDs, relays, or the inputs of other electronic devices like PLCs.
The “+” (collector) and “-” (emitter) terminals of the output transistor are available at the
connector. This allows you to configure the output for current sourcing or sinking. Refer to the
following diagrams to configure the FAULT output.
Caution Do not connect the output to more than 30 VDC. The current through the
output terminal must not exceed 80 mA.
Figure 18. FAULT Output Circuit Diagram
Figure 19. FAULT Output Configured for Sinking

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Figure 20. FAULT Output Configured for Sourcing
Figure 21. FAULT Output Driving a Relay
Configuring the Drive
This section contains a series of steps to configure the NI SMD-7611/7612.
Step 1: Selecting a Motor and Setting the Current
The NI SMD-7611/7612 is optimized for use with NI motors. To select a motor, move the rotary
switch to the setting that corresponds to the motor of your choice. You can do this while power
is on, but it is safer to select the motor before applying power to the drive so that you do not risk
applying too much current to the motor.

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Table 3. SMD-7611 Motor Specification Table
Model
Number Wiring
Drive Current (A),
peak of sine
Holding
Torque
(oz-in.)
Rotor
Intertia
(g-cm2)Switch
Reserved for custom motors
0
1
ST17-4 Parallel 2.4 113 123 2
ST17-1 Parallel 1.6 31.4 35 3
ST17-2 Parallel 2.0 51 54 4
ST17-3 Parallel 2.0 62.8 68 5
ST23-1 Parallel 3.4 76.6 120 6
ST23-4 Parallel 4.5 159.3 300 7
ST23-6 Parallel 4.5 237.6 480 8
ST24-1 4 leads 3.36 123 280 9
ST24-2 4 leads 4.5 166 450 A
ST24-3 4 leads 4.5 332 900 B
ST34-2 Series 4.5 585 1400 C
ST34-5 Series 4.5 1113 2680 D
ST34-1 Series 3.816 series 396 1100 E
Table 4. SMD-7612 Motor Specification Table
Model
Number Wiring
Drive Current
(A), peak of
sine
Holding
Torque (oz-in.)
Rotor
Intertia
(g-cm2)Switch
Reserved for custom motors
0
1
2
ST23-8 Parallel 635.4 750 3
ST23-1 Parallel 3.4 76.6 120 4
ST23-4 Parallel 5 177 300 5

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Step 2: Fine Tuning the Motor Current
The maximum current for the motor is set when the rotary switch is configured to select a motor.
You may want to reduce the current to save power or lower motor temperature. This is important
if the motor is not mounted to a surface that will help it dissipate heat or if the ambient
temperature is expected to be high.
Step motors produce torque in direct proportion to current, but the amount of heat generated is
roughly proportional to the square of the current. If you operate the motor at 90% of rated
current, you’ll get 90% of the rated torque, but the motor will produce approximately 81% as
much heat. At 70% current, the torque is reduced to 70% and the heating to about 50%.
Switches 1 and 2 on the front of the SMD-7611/7612 drive are used to set the percent of rated
current that will be applied to the motor. Refer to the table below to configure the switches.
ST23-6 Parallel 5 264 480 6
ST24-1 4 leads 3.36 123 280 7
ST24-2 4 leads 4.8 177 450 8
ST24-3 4 leads 4.8 354 900 9
ST34-2 Parallel 8 507 1400 A
ST34-5 Parallel 8 965 2680 B
ST34-8 Parallel 8 1439 4000 C
ST34-1 Parallel 7.56 396 1100 D
ST34-4 Parallel 7.56 series 849 1850 E
Table 5. Configuring Current on Switch 1 and 2
100% 90% 80% 70%
Table 4. SMD-7612 Motor Specification Table (Continued)
Model
Number Wiring
Drive Current
(A), peak of
sine
Holding
Torque (oz-in.)
Rotor
Intertia
(g-cm2)Switch
12
12
12
12

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Step 3: Setting Idle Current
Motor heating and power consumption can also be reduced by lowering the motor current when
it is not moving. The SMD-7611/7612 will automatically lower the motor current when it is idle
to either 50% or 90% of the running current. The 50% idle current setting will lower the holding
torque to 50%, which is enough to prevent the load from moving in most applications. This
reduces motor heating by 75%. In some applications, such as those supporting a vertical load, it
is necessary to provide a high holding torque. In such cases, the idle current can be set to 90%
as shown below.
To set the idle current to 50%, place Switch 4 in the down position. To set the idle current to 90%,
place switch 4 in the up position.
Step 4: Load Inertia
The SMD-7611/7612 includes anti-resonance and electronic damping features which greatly
improve motor performance. To perform optimally, the drive must understand the
electromechanical characteristics of the motor and load. Most of this is done automatically when
you select the motor using the rotary switch. To further enhance performance, you must set
switch 3 to indicate the approximate inertia ratio of the load and motor. The ranges are 0 to 4X
and 5 to 10X. The motors table shown in Step 1 of this section includes the rotor inertia of each
motor. Please divide the load inertia by the rotor inertia to determine the ratio.
Set switch 3 in the down position to configure a ratio of 5-10X. Set switch 3 in the up position
to configure a ratio of 0-4X.
Table 6. Configuring Idle Current on Switch 4
50% 90%
Table 7. Configuring Load Inertia on Switch 3
5 - 10X 0 - 4X
4
4
33

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Step 5: Step Size
The SMD-7611/7612 requires a source of step pulses to command motion. This may be a PLC,
an indexer, a motion controller or another type of device. The only requirement is that the device
be able to produce step pulses whose frequency is in proportion to the desired motor speed, and
be able to smoothly ramp the step speed up and down to produce smooth motor acceleration and
deceleration.
Smaller step sizes result in smoother motion and more precise speed, but also require a higher
step pulse frequency to achieve maximum speed. The smallest step size of the SMD-7611/7612
is 1/20,000th of a motor turn. To command a motor speed of 50 revolutions per second
(3000 rpm) the step pulses frequency must be 50 × 20,000 = 1 MHz. Six different settings are
provided in the SMD-7611/7612 drive, as shown in Table 8. Choose the one that best matches
the capability of your system.
At lower step resolutions such as 200 steps/rev (full step) and 400 steps/rev (half step), motors
run a little rough and produce more audible noise than when they are microstepped
(2000 steps/rev and beyond). The SMD-7611/7612 drives include a feature called microstep
emulation, or step smoothing, that can provide smooth motion when using full or half steps. By
selecting 200 smooth or 400 smooth, this feature is automatically employed to provide the
smoothest possible motion when using full or half stepping.
Because a command filter is used as part of the step smoothing process, there will be a slight
delay in the motion. If this delay is unsuitable for your application, please choose the non-filtered
setting 200 or 400. The following figure shows an example of the delay that can occur from using
the step smoothing filter.
Table 8. Configuring Step Size on Switches 5, 6, and 7
Step/rev 20000 12800 5000 2000
Switch
position
Step/rev 400 Smooth 400 200 Smooth 200
Switch
position
567
567
567
567
567
567
567 567

NI SMD-7611/7612 User Manual |© National Instruments |19
Figure 22. Delay Due to Filtering
Step 6: Step Pulse Type
Most indexers and motion controllers provide motion commands in the Step and Direction
format. The Step signal pulses once for each motor step and the direction signal commands
direction. Some PLCs may use a different type of command signal: one signal pulses once for
each desired step in the clockwise direction (STEP CW), while a second signal pulses for
counterclockwise motion (STEP CCW). The SMD-7611/7612 drives can accept this type of
signal if you remove the drive cover and move jumper S3 from the default position on pins 1 and
2 to the 1-3 position. In STEP CW/STEP CCW mode, the CW signal should be connected to the
STEP input and the CCW signal to the DIR input.
Figure 23 shows the jumper positions.
Figure 23. Step Pulse Type Jumper Positions

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Step 7: Step Pulse Noise Filter
Electrical noise can affect the STEP signal in a negative way, causing the drive to think that one
step pulse is two or more pulses. This results in extra motion and inaccurate motor and load
positioning. To combat this problem, the drives include a digital noise filter on the STEP and
DIR inputs. There are two settings for this filter: 150 kHz and 2 MHz. 150 kHz, the factory
default, works well for most applications. If you are operating the SMD-7611/7612 at a high
number of steps/rev and at high motor speeds, you may be commanding the drive at step rates
above 150 kHz. In such cases, you should use the 2 MHz setting. The step noise filter is
controlled by a jumper.
To set the filter frequency to 150 kHz, set the jumper as shown in Figure 24. To set the filter
frequency to 2 MHz, set the jumper as shown in Figure 24.
Your maximum pulse rate will be the highest motor speed multiplied by the steps/rev. For
example, 40 revs/second at 20,000 steps/rev is 40 × 20,000 = 800 kHz. Consider this when
deciding if you must increase the filter frequency.
Figure 24. Step Pulse Noise Filter Jumper Positions