This document describes how to use the National Instruments 9401
and includes specifications and pin assignments for the NI 9401.
Vis it ni.com/info and enter rdsoftwareversion to determine
which software you need for the modules you are using. For
information about installing, configuring, and programming the
system, refer to the system documentation. Visit
and enter
cseriesdoc for information about C Series
ni.com/info
documentation.
Note The safety guidelines and specifications in this
document are specific to the NI 9401. The other
components in the system might 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. Visit
ni.com/info and enter cseriesdoc for information
about C Series documentation.
NI 9401 Operating Instructions and Specifications 2ni.com
Page 3
Safety Guidelines
Operate the NI 9401 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 9401 is suitable for use in Class I, Division 2, Groups A, B,
C, D, T 4 ha zar dous locations; Class I, Zone 2, AEx nC IIC T4, and
Ex nC IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if you are installing the NI 9401 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 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, connected signals must
be within the following limit:
Capacitance .......................... 0.2 μF max
Special Conditions for Hazardous Locations Use in Europe
This equipment has been evaluated as EEx nC IIC T4 equipment
under DEMKO Certificate No. 03 ATEX 0324020X. Each module
is marked II 3G and is suitable for use in Zone 2 hazardous
locations. If you are using the NI 9401 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.
NI 9401 Operating Instructions and Specifications 4ni.com
Page 5
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.
The NI 9401 has a 25-pin DSUB connector that provides
connections for eight digital input/output channels.
1
14
DIO0
15
NC
16
DIO1
17
DIO2
18
NC
19
DIO3
20
DIO4
21
NC
22
DIO5
23
DIO6
24
NC
25
DIO7
Figure 1. NI 9401 PinAssignments
NI 9401 Operating Instructions and Specifications 6ni.com
COM
2
NC
3
COM
4
COM
5
NC
6
COM
7
COM
8
NC
9
COM
10
COM
11
NC
12
COM
13
COM
Page 7
Each channel has a DIO pin to which you can connect a digital
input or output device. The eight DIO channels are internally
referenced to COM, so you can use any of the nine COM lines as
a reference for the external signal.
The DIO channels are grouped in two ports, one containing
channels 0, 1, 2, and 3, and one containing channels 4, 5, 6, and 7.
Yo u can independently configure each digital port in software for
input or output. Note that all four channels in the port must share
the same line direction. Refer to the software help for information
about configuring ports on the NI 9401.
Each channel also has a pull-down resistor and includes
overvoltage, overcurrent, and short-circuit protection. Refer to the
Specifications section for more information about input thresholds
and overvoltage protection. Refer to the Overcurrent Protection
section for more information about overcurrent protection.
Figure 2 illustrates how to connect an SPI device to the NI 9401.
In this example, the three channels assigned to output signals are
on one port and the channel assigned to an input signal is on the
other port.
SS
SCLK
MOSI
MISO
SPI Device
Figure 2. Connecting an SPI Device to the NI 9401
NI 9401 Operating Instructions and Specifications 8ni.com
DIO3:0
Configured
for Output
DIO7:4
Configured
for Input
NI 9401
Page 9
Figure 3 illustrates how to connect several types of digital devices
to the NI 9401.
DIO0 as Input
Dev 1
TTL Signal
+5 V
Dev 2
+5 V
LED
Dev 3
DIO1 as Input
COM
DIO7 as Output
NI 9401
Figure 3. Connecting Digital Devices to the NI 9401
Overcurrent protection on the NI 9401 allows only a specified
amount of current for switching DIO channels or sourcing the
output load. If the NI 9401 goes into an overcurrent state, by
exceeding the specified maximum switching frequency or the
output load, the module power supply begins to drop in voltage
until it completely turns off or the overcurrent condition is
removed. When the module is in this state, it can accept new line
direction configuration and output state data but cannot pass valid
input data to the software. Refer to the Specifications section for
more information about the maximum switching frequency and
output load for each channel.
NI 9401 Operating Instructions and Specifications 10ni.com
Page 11
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.
Withstand.................................... 1,000 V
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
1
The maximum voltage that can be applied or output between any channel and COM
without damaging the module or other devices.
NI 9401 Operating Instructions and Specifications 16ni.com
1
at a time, Measurement
Category I
Category I
, verified by a 5 s
rms
dielectric withstand test
Page 17
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 9401 to signals or use
for measurements within Measurement Categories II,
III, or IV.
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
by modu le number or product line, and click the
appropriate link in the Certification column.
U.S. (UL) .......................................... Class I, Division 2,
Canada (C-UL) ................................. Class I, Division 2,
Europe (DEMKO)............................. EEx nC IIC T4
Groups A, B, C, D, T4;
Class I, Zone 2,
AEx nC IIC T4
Groups A, B, C, D, T4;
Class I, Zone 2,
Ex nC 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
NI 9401 Operating Instructions and Specifications 18ni.com
Page 19
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 g
Sinusoidal (IEC 60068-2-6) .......5 g, 10 to 500 Hz
Operating shock
(IEC 60068-2-27).............................. 30 g, 11 ms half sine,
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:
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
NI 9401 Operating Instructions and Specifications 20ni.com
Page 21
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
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
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
and follow the calling instructions or dial 512 795 8248. For
NI 9401 Operating Instructions and Specifications 22ni.com
ni.com/support
Page 23
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,
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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For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software,
patents.txt file on your media, or ni.com/patents.