OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9478
16-Channel, 0–50 V, Sinking Digital Output Module
with Programmable Current Limits
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Safety Guidelines
Operate the NI 9478 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.
Safety Guidelines for Hazardous Locations
The NI 9478 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 you are installing the NI 9478 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.
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Caution Substitution of components may impair
suitability for Class I, Division 2.
Caution For Zone 2 applications, install the system
in an enclosure rated to at least IP 54 as defined by
IEC 60529 and EN 60529.
Caution For Zone 2 applications, install a protection
device across the external power supply and the COM
pin. The device must prevent the external power supply
voltage from exceeding 70 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. If you are using the NI 9478 in Gas Group IIC hazardous
locations or in ambient temperatures of –40 °C ≤ Ta ≤ 70 °C, you
must use the device in an NI chassis that has been evaluated as
EEx nC IIC T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.
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Special Conditions for Marine Applications
Some modules are Lloyd’s Register (LR) Type Approved for
marine applications. To verify Lloyd’s Register certification,
visit ni.com/certification and search for the LR certificate,
or look for the Lloyd’s Register mark on the module.
Caution To meet radio frequency emission requirements
for marine applications, use shielded cables and install
the system in a metal enclosure. Suppression ferrites
must be installed on power supply inputs near power
entries to modules and controllers. Power supply and
module cables must be separated on opposite sides of
the enclosure and must enter and exit through opposing
enclosure walls.
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Connecting the NI 9478
The NI 9478 has a 37-pin DSUB connector that provides
connections for the 16 digital output channels.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
DO0
DO1
DO2
DO3
DO4
DO5
DO6
DO7
Vsup
Vsup
DO8
DO9
DO10
DO11
DO12
DO13
DO14
DO15
NC
COM
COM
COM
COM
COM
COM
COM
COM
Vsup
Vsup
COM
COM
COM
COM
COM
COM
COM
COM
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
Figure 1. NI 9478 Pin Assignments
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Each channel of the NI 9478 has a DO pin to which you can
connect the load you want to control. Each channel also has a COM
pin. National Instruments recommends you provide independent
COM wiring for each channel to minimize current flow in the
COM wiring. The COM pins are all connected together internally.
You must connect an external power supply to the NI 9478. This
power supply provides the current for the devices you connect to
the module. Connect the positive lead of the power supply to Vsup
and the negative lead of the power supply to COM.
Caution Do not remove or insert modules if the external
power supply connected to the Vsup pin is powered on.
The NI 9478 has current sinking outputs, meaning the DO pin is
driven to COM when the channel is turned on.
You can directly connect the NI 9478 to a variety of industrial
devices such as solenoids, motors, actuators, relays, and lamps.
Make sure the devices you connect to the NI 9478 are compatible
with the output specifications of the module. Refer to the
Specifications section for more information about the output
specifications.
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Connect the device to DO and the positive lead of the power
supply. Refer to Figure 2 for an illustration of how to connect
a device to the NI 9478.
Vsup
Cable
Clamp
DO
Device
External
+
Power
–
Supply
COM
NI 9478
Figure 2. Connecting a Device to the NI 9478
You must connect the Vsup pin to the power supply to enable a
weak cable clamping diode that protects the module from cable
inductance flyback. This flyback voltage results from small
amounts of energy stored in the inductance of the cabling. Refer
to the Using Long Cables section for more information about
protection from cable inductance flyback. You still must install an
external flyback diode when switching inductive loads. Refer to the
Protecting the Module from Flyback Voltages section for more
information about installing a flyback diode.
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Protecting the Module from Flyback Voltages
If the module is switching an inductive or energy-storing device
such as a solenoid, motor, or relay, and the device does not have
flyback protection, install an external flyback diode as shown in
Figure 3. Refer to the Using Long Cables section for more
information about protection from cable inductance flyback.
Vsup
Cable
Device
Clamp
DO
External
Power
Supply
+
–
COM
NI 9478
Figure 3. Connecting a Flyback Diode to the NI 9478
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Using Long Cables
The inductance of the cabling that connects the NI 9478, the loads,
and the external supply stores up energy when a channel is on and
passing current through the cables. Each time a channel is turned
off, the energy stored in the cables is released as flyback voltage
and dissipates as heat in the NI 9478. The total power dissipated in
the module increases with higher switching frequencies, higher
currents, and longer cable lengths. The cable length is the total
distance from the digital output pin of the NI 9478 channel,
through the load, through the external power supply, and back
to the COM pin, as shown in Figure 4.
Vsup
Load
Cable
Clamp
External
Power
Supply
+
–
DO
Cable
Length
NI 9478
COM
Figure 4. Cable Length of the NI 9478
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You can reduce the effective length of the cable by adding a
capacitor close to the NI 9478 across the power supply leads and
adding a diode from the digital output line to the Vsup pin line.
National Instruments recommends that you use a capacitor with a
capacitance of at least 20 μF. In this case, the effective length of the
cable is the distance from the output pin, through the new diode,
through the capacitor, and back to the COM pin, as shown in
Figure 5.
Vsup
Load
Cable
Clamp
External
Power
Supply
+
–
DO
Cable
Length
COM
Figure 5. Cable Length of the NI 9478 with a Capacitor and Diode
NI 9478
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I/O Protection
The NI 9478 provides protection against overcurrent and
short-circuit conditions.
Output Current Limit Thresholds
The NI 9478 provides two configurable current limit thresholds
for the module, Limit A and Limit B. The NI 9478 continuously
monitors the current through each output channel and detects if
the current exceeds either of the current limit thresholds. You can
configure the current limit thresholds and check the current limit
output status in software to determine if the current through each
channel has exceeded the current limit thresholds. Refer to the
software help for more information about configuring current
limits and checking output status. Visit ni.com/info and enter
cseriesdoc for information about C Series documentation.
Overcurrent Protection
You can configure each channel on the NI 9478 to disable the
output if the current through the output exceeds either current
limit threshold. This protects the NI 9478 from overcurrent and
short-circuit conditions and provides a way to limit the current
through an external device.
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Some applications require a large inrush current when a channel is
first turned on. If this inrush current exceeds the maximum current
limit threshold, you may need to disable overcurrent protection by
programming the channel to have no current limit. Refer to the
software help for more information about configuring current
limits. Visit ni.com/info and enter cseriesdoc for information
about C Series documentation.
Caution The NI 9478 is not protected against output
overcurrent or short-circuit conditions when overcurrent
protection is disabled. If you disable overcurrent
protection, ensure that the wiring is correct and that you
are operating the NI 9478 within the specifications.
The total amount of current that you can switch with a channel
depends on the duty cycle of the channel, the ambient temperature,
the switching frequency, and the amount of current switched by
other channels within the same module at the same time. Refer to
the Safe Operating Current section for more information about the
current specifications.
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Overcurrent Refresh
The NI 9478 provides an overcurrent refresh setting that enables
a channel to automatically recover within the specified overcurrent
refresh period if the channel exceeds its current limit threshold.
If overcurrent refresh is disabled, the channel remains off after an
overcurrent condition until software sends a command to turn the
channel back on. Refer to the software help for more information
about overcurrent refresh. Visit ni.com/info and enter
cseriesdoc for information about C Series documentation.
Safe Operating Current
The maximum allowable output current depends on the output
frequency and cable lengths. Higher output currents, higher output
frequencies, and longer cable lengths can contribute to power
dissipating and heat increasing in the NI 9478. The Specifications
section gives allowable current and frequency specifications if you
use 2 meters of cabling. For other operating conditions, you can
find the safe operating specifications for the NI 9478 by calculating
the percentage of the total allowable power each output channel
dissipates given the output current, frequency, and cable length
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for that channel. Use the following equation to calculate the
percentage of the total power budget each output channel uses in
your application.
2
2
⎞
⎛
⎞
⎛
P = 4% I
⎝ out ⎠
+
0.12%(length – 0.2) I
⎝ out ⎠
+ 0.04%(I
+ 1) freq
out
where P is the percentage of total allowable power the channel uses
Iout is the output current in amperes while the channel is on
length is the total cable length in meters, shown in Figure 4
freq is the frequency rate in kHz at which the output channel goes
through an on-off cycle
To verify that your application keeps the NI 9478 within safe
operating specifications, calculate the average percentage of
total allowable power each channel uses, then add together the
percentages for all the channels. For operation in ambient
temperatures from 55 to 70 °C, the total average power of all
channels must remain under 100%. For temperatures below 55 °C,
the total average power of all channels can run up to 150%.
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Example One
You are driving a load with 2.0 meters of cable through a cycle in
which the NI 9478 is on and passing 1.25 A of current for 40 μs,
then off for 10 μs. The output period is 50 μs (40 μs + 10 μs) so the
output frequency is 20 kHz. The channel uses 14.8% of the total
power budget, as shown in the following equation.
2
2
4%(1.25 ) + [0.12%(2.0 – 0.2)(1.25 ) + 0.04%(1.25 + 1)]20 = 14.8%
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Example Two
You are driving a load with 2.0 meters of cable through a cycle in
which the NI 9478 first is constantly on and passing 3 A of current
for 0.25 seconds, then drives the load at 20 kHz with 1.25 A current
for 1.25 seconds, then drives the load off for 4 seconds. While the
NI 9478 is constantly on, the output frequency is 0 kHz and the
channel uses 36% (4% × 32) of the total power budget. Example
One shows that while the NI 9478 is driving at 20 kHz, the channel
uses 14.8% of the total power budget. While the NI 9478 is off, the
channel uses 0% of the power budget. The average percentage of
total allowable power over the complete 5.5 second cycle is 5%,
as shown in the following equation.
36%(0.25s) + 14.8%(1.25 s) + 0%(4s)
------------------------------------------------------------------------------------------------- = 5%
5.5s
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Sleep Mode
This module supports a low-power sleep mode. Support for sleep
mode at the system level depends on the chassis that the module is
plugged into. Refer to the chassis manual for information about
support for sleep mode. If the chassis supports sleep mode, refer to
the software help for information about enabling sleep mode. Visit
ni.com/info and enter cseriesdoc for information about
C Series documentation.
Typically, when a system is in sleep mode, you cannot
communicate with the modules. In sleep mode, the system
consumes minimal power and may dissipate less heat than it
does in normal mode. Refer to the Specifications section for more
information about power consumption and thermal dissipation.
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Specifications
The following specifications are typical for the range –40 to 70 °C
unless otherwise noted. All voltages are relative to COM unless
otherwise noted.
Output Characteristics
Number of channels..........................16 digital output channels
Output type .......................................Sinking
Power-on output state .......................Channels off
Output voltage (V0)...........................I0R0
External power supply
voltage range (Vsup)...........................0–50 VDC
Continuous output current (I0)1, per channel
All channels on...........................1.2 A max
Four channels on ........................2.5 A max
One channel on...........................5 A max
1
Refer to the Safe Operating Current section for more information about safe
operating current.
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Switched output current (10 kHz)1, per channel
All channels on...........................1 A max
Four channels on ........................2 A max
One channel on...........................4 A max
Switched output current (20 kHz)1, per channel
All channels on...........................0.75 A max
Four channels on ........................1.67 A max
One channel on...........................3.33 A max
Output impedance (R0) .....................50 mΩ max
Reversed-voltage protection .............None
Number of current limit settings.......2 (Limit A and Limit B)
Current limit range............................0–5.1 A
Current limit resolution.....................8-bit, 20 mA per LSB
Current limit accuracy ......................130 mA + 3% of setting, max
1
Using up to 2 meters of cabling on each output channel. Refer to the Safe Operating
Current section for more information.
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Overcurrent protection threshold
selection per channel.........................Limit A, Limit B, or
No Limit
Overcurrent shutoff response time....1 μs
Overcurrent refresh configuration ....Enabled or Disabled
Overcurrent refresh period................20–2550 μs in 10 μs
increments
Overcurrent refresh period
accuracy ............................................ 7% max
Propagation delay .............................250 ns max
MTBF ...............................................823,106 hours at 25 °C;
Bellcore Issue 6, Method 1,
Case 3, Limited Part Stress
Method
Note Contact NI for Bellcore MTBF specifications
at other temperatures or for MIL-HDBK-217F
specifications.
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Power Requirements
Power consumption from chassis
Active mode ...............................1 W max
Sleep mode .................................25 μW max
Thermal dissipation (at 70 °C)
Active mode ...............................1.5 W max
Sleep mode .................................25 μW max
Physical Characteristics
If you need to clean the module, wipe it with a dry towel.
Weight...............................................148 g (5.2 oz)
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Safety
Maximum Voltage1
Connect only voltages that are within the following limits.
Vsup-to-COM.....................................50 VDC,
Measurement Category I
Measurement Category I is for measurements performed on
circuits not directly connected to the electrical distribution system
referred to as MAINS voltage. MAINS is a hazardous live electrical
supply system that powers equipment. This category is for
measurements of voltages from specially protected secondary
circuits. Such voltage measurements include signal levels, special
equipment, limited-energy parts of equipment, circuits powered by
regulated low-voltage sources, and electronics.
Caution Do not connect the NI 9478 to signals or use for
measurements within Measurement Categories II, III,
or IV.
1 The maximum voltage that can be applied or output between Vsup and COM without
creating a safety hazard.
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Isolation Voltages
Channel-to-channel...........................No isolation between
channels
Channel-to-earth ground
Continuous .................................60 VDC,
Measurement Category I
Withstand....................................1,000 V, verified by a 5 s
dielectric withstand test
Safety Standards
This product is designed to meet the requirements of the following
standards of safety for electrical equipment for measurement,
control, and laboratory use:
•
•
IEC 61010-1, EN 61010-1
UL 61010-1, CSA 61010-1
Note For UL and other safety certifications, refer to the
product label or visit ni.com/certification, search
by module number or product line, and click the
appropriate link in the Certification column.
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Hazardous Locations
U.S. (UL) ..........................................Class I, Division 2,
Groups A, B, C, D, T4;
Class I, Zone 2,
AEx nA IIC T4
Canada (C-UL) .................................Class I, Division 2,
Groups A, B, C, D, T4;
Class I, Zone 2,
Ex nA IIC T4
Europe (DEMKO).............................Ex nA IIC T4
Environmental
National Instruments C Series modules are intended for indoor use
only but may be used outdoors if installed in a suitable enclosure.
Refer to the manual for the chassis you are using for more
information about meeting these specifications.
Operating temperature
(IEC 60068-2-1, IEC 60068-2-2) .....–40 to 70 °C
Storage temperature
(IEC 60068-2-1, IEC 60068-2-2) .....–40 to 85 °C
Ingress protection..............................IP 40
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Operating humidity
(IEC 60068-2-56)..............................10 to 90% RH,
noncondensing
Storage humidity
(IEC 60068-2-56)..............................5 to 95% RH,
noncondensing
Maximum altitude.............................2,000 m
Pollution Degree (IEC 60664)..........2
Shock and Vibration
To meet these specifications, you must panel mount the system.
Operating vibration
Random (IEC 60068-2-64).........5 grms, 10 to 500 Hz
Sinusoidal (IEC 60068-2-6) .......5 g, 10 to 500 Hz
Operating shock
(IEC 60068-2-27)..............................30 g, 11 ms half sine,
50 g, 3 ms half sine,
18 shocks at 6 orientations
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Electromagnetic Compatibility
This product is designed to meet the requirements of the following
standards of EMC for electrical equipment for measurement,
control, and laboratory use:
•
•
•
EN 61326 EMC requirements; Industrial Immunity
EN 55011 Emissions; Group 1, Class A
CE, C-Tick, ICES, and FCC Part 15 Emissions; Class A
Note For EMC compliance, operate this device with
shielded cabling.
CE Compliance
This product meets the essential requirements of applicable
European directives, as amended for CE markings, as follows:
•
•
2006/95/EC; Low-Voltage Directive (safety)
2004/108/EC; Electromagnetic Compatibility Directive
(EMC)
Note Refer to the Declaration of Conformity (DoC) for
this product for any additional regulatory compliance
information. To obtain the DoC for this product, visit
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ni.com/certification, search by module number
or product line, and click the appropriate link in the
Certification column.
Environmental Management
National Instruments is committed to designing and manufacturing
products in an environmentally responsible manner. NI recognizes
that eliminating certain hazardous substances from our products is
beneficial not only to the environment but also to NI customers.
For additional environmental information, refer to the NI and the
Environment Web page at ni.com/environment. This page
contains the environmental regulations and directives with which
NI complies, as well as other environmental information not
included in this document.
Waste Electrical and Electronic Equipment (WEEE)
EU Customers At the end of their life cycle, all products
must be sent to a WEEE recycling center. For more
information about WEEE recycling centers and National
Instruments WEEE initiatives, visit ni.com/
environment/weee.htm.
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(RoHS)
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RoHS
National Instruments
ni.com/environment/rohs_chinaDŽ
about China RoHS compliance, go to
environment/rohs_china
(For information
ni.com/
.)
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Where to Go for Support
The National Instruments Web site is your complete resource for
technical support. At ni.com/support you have access to
everything from troubleshooting and application development
self-help resources to email and phone assistance from
NI Application Engineers.
National Instruments corporate headquarters is located at
11500 North Mopac Expressway, Austin, Texas, 78759-3504.
National Instruments also has offices located around the world to
help address your support needs. For telephone support in the
United States, create your service request at ni.com/support
and follow the calling instructions or dial 512 795 8248. For
telephone support outside the United States, contact your local
branch office:
Australia 1800 300 800, Austria 43 662 457990-0,
Belgium 32 (0) 2 757 0020, Brazil 55 11 3262 3599,
Canada 800 433 3488, China 86 21 5050 9800,
Czech Republic 420 224 235 774, Denmark 45 45 76 26 00,
Finland 358 (0) 9 725 72511, France 01 57 66 24 24,
Germany 49 89 7413130, India 91 80 41190000,
Israel 972 3 6393737, Italy 39 02 41309277, Japan 0120-527196,
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Korea 82 02 3451 3400, Lebanon 961 (0) 1 33 28 28,
Malaysia 1800 887710, Mexico 01 800 010 0793,
Netherlands 31 (0) 348 433 466, New Zealand 0800 553 322,
Norway 47 (0) 66 90 76 60, Poland 48 22 3390150,
Portugal 351 210 311 210, Russia 7 495 783 6851,
Singapore 1800 226 5886, Slovenia 386 3 425 42 00,
South Africa 27 0 11 805 8197, Spain 34 91 640 0085,
Sweden 46 (0) 8 587 895 00, Switzerland 41 56 2005151,
Taiwan 886 02 2377 2222, Thailand 662 278 6777,
Turkey 90 212 279 3031, United Kingdom 44 (0) 1635 523545
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product and company names mentioned herein are trademarks or trade names of their respective companies.
For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software,
the patents.txt file on your CD, or ni.com/patents.
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