National Instruments NI 9478 User manual

GETTING STARTED GUIDE
NI 9478
16 DO, 0 V to 50 V, Sinking, 50 μs

This document explains how to connect to the NI 9478.
Note Before you begin, complete the software and
hardware installation procedures in your chassis
documentation.
Note The guidelines in this document are specific to
the NI 9478. The other components in the system might
not meet the same safety ratings. Refer to the
documentation for each component in the system to
determine the safety and EMC ratings for the entire
system.
Safety Guidelines
Operate the NI 9478 only as described in this document.
Caution Do not operate the NI 9478 in a manner not
specified in this document. Product misuse can result in
a hazard. You can compromise the safety protection
built into the product if the product is damaged in any
way. If the product is damaged, return it to NI for
repair.
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Safety Voltages
Connect only voltages that are within the following limits:
Vsup-to-COM 50 VDC maximum,
Measurement Category I
Isolation
Channel-to-channel None
Channel-to-earth ground
Continuous 60 VDC,
Measurement Category I
Withstand 1,000 Vrms, verified by a 5 s
dielectric withstand test
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.
NI 9478 Getting Started Guide | © National Instruments | 3

Caution Do not connect the NI 9478 to signals or use
for measurements within Measurement Categories II,
III, or IV.
Note Measurement Categories CAT I and CAT O are
equivalent. These test and measurement circuits are not
intended for direct connection to the MAINS building
installations of Measurement Categories CAT II,
CAT III, or CAT IV.
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.
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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 IP54
as defined by IEC/EN 60079-15.
Caution For Division 2 and 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 and Internationally
The NI 9478 has been evaluated as Ex nA IIC T4 Gc equipment
under DEMKO Certificate No. 07 ATEX 0626664X and is
IECEx UL 14.0089X certified. Each NI 9478 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 9478
NI 9478 Getting Started Guide | © National Instruments | 5

in Gas Group IIC hazardous locations, you must use the device in
an NI chassis that has been evaluated as Ex nC IIC T4, Ex IIC
T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.
Caution You must make sure that transient
disturbances do not exceed 140% of the rated voltage.
Caution The system shall only be used in an area of
not more than Pollution Degree 2, as defined in
IEC 60664-1.
Caution The system shall be mounted in an
ATEX/IECEx-certified enclosure with a minimum
ingress protection rating of at least IP54 as defined in
IEC/EN 60079-15.
Caution The enclosure must have a door or cover
accessible only by the use of a tool.
Electromagnetic Compatibility Guidelines
This product was tested and complies with the regulatory
requirements and limits for electromagnetic compatibility (EMC)
stated in the product specifications. These requirements and
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limits provide reasonable protection against harmful interference
when the product is operated in the intended operational
electromagnetic environment.
This product is intended for use in industrial locations. However,
harmful interference may occur in some installations, when the
product is connected to a peripheral device or test object, or if the
product is used in residential or commercial areas. To minimize
interference with radio and television reception and prevent
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.
Special Conditions 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.
NI 9478 Getting Started Guide | © National Instruments | 7

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.
Preparing the Environment
Ensure that the environment in which you are using the NI 9478
meets the following specifications.
Operating temperature
(IEC 60068-2-1, IEC 60068-2-2)
-40 °C to 70 °C
Operating humidity
(IEC 60068-2-78)
10% RH to 90% RH,
noncondensing
Pollution Degree 2
Maximum altitude 2,000 m
Indoor use only.
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Note Refer to the device datasheet on ni.com/manuals
for complete specifications.
NI 9478 Getting Started Guide | © National Instruments | 9

NI 9478 Pinout
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
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
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Table 1. NI 9478 Signal Descriptions
Signal Description
COM Common reference connection
DO Digital output signal connection
NC No connection
Vsup Voltage supply connection
Connecting Digital Devices
You can connect a variety of industrial devices, such as solenoids,
motors, actuators, relays, and lamps to the NI 9478. You must
connect an external power supply to the NI 9478. The power
supply provides the current for the output channels.
NI 9478 Getting Started Guide | © National Instruments | 11

Figure 1. Connecting an Industrial Device to the NI 9478
Device +
–
NI 9478
COM
Vsup
DO
External
Power
Supply
Cable
Clamp
Caution Do not install or remove C Series modules
from your system if the external power supply
connected to the Vsup and COM pins is powered on.
Ensure that the devices you connect to the NI 9478 are
compatible with the output specifications of the NI 9478. Refer to
the device datasheet at ni.com/manuals for output specifications.
12 | ni.com | NI 9478 Getting Started Guide

Protecting the Digital Outputs from Flyback
Voltages
If the channel 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.
Figure 2. Connecting a Flyback Diode
+
–
NI 9478
COM
DO External
Power
Supply
Vsup
Cable
Clamp Device
Cable Inductance
The inductance of the cabling stores energy when a channel is on
and driving current. When a channel turns off, energy in the
NI 9478 Getting Started Guide | © National Instruments | 13

cabling is released as flyback voltage, which dissipates as heat in
the NI 9478. The heat dissipated increases with higher switching
frequencies, higher currents, and longer cables.
Reducing Cable Length
The effective cable length is the total distance from DO to COM.
Figure 3. Cable Length of the NI 9478
NI 9478 COM
Vsup
DO
+
–
External
Power
Supply
Cable
Length
Load
Cable
Clamp
NI recommends adding a capacitor across the power supply leads
and a diode from the DO lead to the Vsup lead. Connecting a
capacitor and a diode reduces the effective cable length and
dissipated heat.
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Figure 4. Cable Length of the NI 9478 with a Capacitor and Diode
Load
NI 9478 COM
Vsup
DO
+
–
External
Power
Supply
Cable
Clamp
Cable
Length
Note NI recommends that you use a capacitor with a
capacitance of at least 20 µF.
I/O Protection
The NI 9478 provides protection against overcurrent and short-
circuit conditions.
Overcurrent Protection
The NI 9478 provides two configurable current limit thresholds,
Limit A and Limit B. The device monitors each output channel.
NI 9478 Getting Started Guide | © National Instruments | 15

You can review the output status in software to determine if the
current has exceeded the limit threshold.
You can configure each channel on the NI 9478 to disable the
output that exceeds the current limit threshold. Some applications
require a large inrush current that may exceed the current limit
threshold. You can disable overcurrent protection by setting no
current limit for that channel.
Caution If you disable overcurrent protection, the
NI 9478 is no protected against overcurrent or short-
circuit conditions. Verify the wiring is correct and that
you are operating the NI 9478 within the specifications.
Overcurrent Refresh
The NI 9478 provides an overcurrent refresh setting. This setting
enables the channel to recover within a specified refresh period.
If the refresh setting is disabled, the channel remains off until it
receives a command from the software.
Safe Operating Conditions
The total amount of current that you can switch with a channel
depends on the duty cycle of the channel, the ambient
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temperature, the switching frequency, and the amount of current
switched by other channels within the same module at the same
time.
NI recommends using 2 meters of cable for safe operating
conditions. Higher currents, higher frequencies, and longer cables
contribute to increased heat in the NI 9478. Refer to the device
datasheet at ni.com/manuals for safe operating conditions.
You can determine safe operating specifications for the NI 9478
by using the following equation.
Figure 5. Safe Operating Conditions Equation
= 4 % 
2+ 0.12 % ℎ0.2  2
+ 0.04 %  + 1 
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
freq is the frequency rate in kHz at which the output channel
goes through an on-off cycle
NI 9478 Getting Started Guide | © National Instruments | 17

Calculate the percentage of total allowable power each channel
uses then add the percentages for all the channels. For ambient
temperatures from 55 °C to 70 °C, the total power for all
channels must remain under 100%. For temperatures below
55 °C, the total power of all channels can run up to 150%.
Example One
The NI 9478 passes 1.25 A current through 2.0 meters of cable.
The channel cycles on for 40 μs and off for 10 μs for a total
output period of 50 μs. This yields an output frequency of
20 kHz, using 14.8% of the total power budget.
Figure 6. Example Equation One
4 % 1.252+ 0.12 % 2.0 0.2 1.252
+ 0.04 % 1.25 + 1 20 = 14.8 %
Example Two
The NI 9478 is on and passing 3 A of current through 2.0 meters
of cable for 0.25 seconds. The channel passes 1.25 A of current at
20 kHz for 1.25 seconds. The channel then drives the load off for
4 seconds.
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While the channel is on, the output frequency is 0 kHz and the
channel uses 36% of the total power budget. The channel uses
14.8% of the total power budget driving at 20 kHz and 0% when
the channel is off. The total percentage of allowable power over
the complete 5.5 second cycle is 5%.
Figure 7. Example Equation Two
36 % 0.25+ 14.8 % 1.25+ 0 % 4
5.5= 5 %
NI 9478 Getting Started Guide | © National Instruments | 19

Where to Go Next
Located at ni.com
/
manuals Installs with the software
CompactRIO NI CompactDAQ
RELATED INFORMATION
NI 9478 Datasheet
NI-RIO Help
LabVIEW FPGA Help
NI 9478 Datasheet
NI-DAQmx Help
LabVIEW Help
C Series
Documentation
& Resources
ni.com
/
info
cseriesdoc
Servi ces
ni.com/services
20 | ni.com | NI 9478 Getting Started Guide