National Instruments NI 9423, NI 9421 Operating Instructions Manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS

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NI 9421/9423

8-Channel Sinking Digital Input Modules

This document describes how to use the National Instruments 9421
and National Instruments 9423 and includes specifications and
terminal assignments for the NI 9421/9423. In this document, the
NI 9421 with screw terminal, NI 9421 with DSUB, and NI 9423
are referred to inclusively as the NI 9421/9423. Visit

info

and enter rdsoftwareversion to determine which

ni.com/

software you need for the modules you are using. For information
about installing, configuring, and programming the system, refer to
the system documentation. Visit

cseriesdoc for information about C Series documentation.

Note The safety guidelines and specifications in this

ni.com/info and enter

document are specific to the NI 9421/9423. 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 9421/9423 2 ni.com

Safety Guidelines

Operate the NI 9421/9423 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 Voltages

Yo u can connect hazardous voltages to the NI 9421/9423 with
screw terminal only. Do not connect hazardous voltages to the
NI 9421 with DSUB.

If hazardous voltages are connected to the module, take the
following precautions. A hazardous voltage is a voltage greater
than 42.4 V

Caution Ensure that hazardous voltage wiring is

or 60 VDC to earth ground.

pk

performed only by qualified personnel adhering to local
electrical standards.

Caution Do not mix hazardous voltage circuits and

human-accessible circuits on the same module.

© National Instruments Corp. 3 NI 9421/9423

Caution Make sure that devices and circuits connected to

the module are properly insulated from human contact.

Caution When module terminals are hazardous voltage

LIVE (>42.4 V

/60 VDC), you must ensure that devices

pk

and circuits connected to the module are properly
insulated from human contact. You must use the NI 9932
connector backshell kit to ensure that the terminals are
not accessible.

Figure 1 shows the NI 9932 connector backshell.

Note You can use the NI 9932 connector backshell only

with the NI 9421/9423 with screw terminal.

NI 9421/9423 4 ni.com

Figure 1. NI 9932 Connector Backshell

Safety Guidelines for Hazardous Locations

The NI 9421/9423 is suitable for use in Class I, Division 2,
Groups A, B, C, D, T4 hazardous 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 9421/9423 in a potentially explosive environment.
Not following these guidelines may result in serious injury or
death.

© National Instruments Corp. 5 NI 9421/9423

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 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 Ex 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, in ambient temperatures of –40 °C ≤ Ta ≤ 70 °C. If you

NI 9421/9423 6 ni.com

are using the NI 9421/9423 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.

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.

© National Instruments Corp. 7 NI 9421/9423

Connecting the NI 9421/9423

The NI 9421/9423 provides connections for eight digital input
channels.

DI0
DI1
DI2
DI3
DI4
DI5
DI6
DI7
NC
COM

03

47

0
1
2
3
4
5
6
7
8
9

DI0
NC
DI1
DI2
NC
DI3
DI4
NC
DI5
DI6
NC
DI7

03

47

14
15
16
17
18
19
20
21
22
23
24
25

1
2
3
4
5
6
7
8

9
10
11
12
13

COM
NC
COM
COM
NC
COM
COM
NC
COM
COM
NC
COM
COM

Figure 2. NI 9421/9423 Terminal and Pin Assignments

NI 9421/9423 8 ni.com

The NI 9421/9423 with screw terminal has a 10-terminal,
detachable screw-terminal connector. The NI 9421 with DSUB has
a 25-pin DSUB connector.

Each channel of the NI 9421/9423 has a DI terminal or pin to which
you can connect voltage or current signals. The NI 9421/9423 also
has COM, a common terminal or pin that is internally connected to
the isolated ground reference of the module.

Note You must use 2-wire ferrules to create a secure

connection when connecting more than one wire to a
single terminal on the NI 9421/9423 with screw terminal.

The NI 9421/9423 has sinking inputs, meaning that when the
external device drives current or applies voltage to the DI terminal
or pin, DI provides a path to COM for the current or voltage. The
NI 9421/9423 internally limits current signals connected to DI. For
more information about input current levels, refer to the

Specifications section.

Yo u can connect 2-, 3-, and 4-wire sourcing-output devices to the
NI 9421/9423. A sourcing-output device drives current or applies
voltage to DI. An example of a sourcing-output device is an open
collector PNP.

© National Instruments Corp. 9 NI 9421/9423

Connect the output of the sourcing-output device to DI on the
NI 9421/9423. Connect the common of the external device to the
COM terminal or pin. Refer to Figure 3 for an illustration of
connecting a device to the NI 9421/9423.

Sourcing-Output

Device

DI

External

Power

Supply

+

–

COM

NI 9421/9423

Figure 3. Connecting a Device to the NI 9421/9423 (3-Wire Device Shown)

NI 9421/9423 10 ni.com

The NI 9421/9423 channel registers as ON when the
sourcing-output device applies a voltage or drives a current that is
in the input ON range to DI. The channel registers as OFF when the
device applies a voltage or drives a current that is in the input OFF
range to DI. If no device is connected to DI, the channel registers
as OFF. Refer to the Specifications section for more information
about the ON and OFF states.

Each channel has an LED that turns on and off to indicate the state
of that channel. When a channel LED is lit, the channel is on. When
the LED is dark, the channel is off. The LEDs are disabled when
the chassis is in sleep mode. Refer to the Sleep Mode section for
more information about sleep mode.

© National Instruments Corp. 11 NI 9421/9423

Wiring for High-Vibration Applications

If an application using the NI 9421/9423 with screw terminal is
subject to high vibration, National Instruments recommends that
you either use ferrules to terminate wires to the detachable
screw-terminal connector or use the NI 9932 backshell kit to
protect the connections. Refer to Figure 4 for an illustration of
using ferrules. Refer to Figure 1 for an illustration of the NI 9932
connector backshell.

Figure 4. 10-Terminal Detachable Screw-Terminal Connector with Ferrule

NI 9421/9423 12 ni.com

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.

© National Instruments Corp. 13 NI 9421/9423

Specifications

The following specifications are typical for the range –40 to 70 °C
unless otherwise noted. The specifications are the same for the
NI 9421 and the NI 9423 unless otherwise noted. All voltages are
relative to COM unless otherwise noted.

Input Characteristics

Number of channels.......................... 8 digital input channels

Input type .......................................... Sinking

Digital logic levels

OFF state

Input voltage ........................ ≤5V

Input current (NI 9421)........ ≤ 300 μA

Input current (NI 9423)........ ≤ 150 μA

ON state

Input voltage ........................ 11–30 V

Input current......................... ≥3mA

NI 9421/9423 14 ni.com

I/O protection

Input voltage

NI 9421 ................................40 V max

NI 9423 ................................35 V max

Reverse-biased voltage ............... –30 V max

Input current

NI 9421 ................................7 mA max,

NI 9423 ................................8.5 mA max,

Input delay time

NI 9421....................................... 100 μs max

internally limited

internally limited

NI 9423....................................... 1 μs max

MTBF

NI 9421....................................... 2,086,204 hours at 25 °C;

Bellcore Issue 2, Method 1,
Case 3, Limited Part Stress
Method

© National Instruments Corp. 15 NI 9421/9423

NI 9423....................................... 979,623 hours at 25 °C;

Note Contact NI for Bellcore MTBF specifications

at other temperatures or for MIL-HDBK-217F

specifications.

NI 9421 Power Requirements

Power consumption from chassis

Active mode ............................... 240 mW max

Sleep mode .................................7 mW max

Bellcore Issue 2, Method 1,
Case 3, Limited Part Stress
Method

Thermal dissipation (at 70 °C)

Active mode ............................... 1.3 W max

Sleep mode .................................1.1 W max

NI 9423 Power Requirements

Power consumption from chassis

Active mode ............................... 290 mW max

Sleep mode .................................7 mW max

NI 9421/9423 16 ni.com

Thermal dissipation (at 70 °C)

Active mode ............................... 1.5 W max

Sleep mode .................................1.3 W max

Physical Characteristics

If you need to clean the module, wipe it with a dry towel.

Note For two-dimensional drawings and

three-dimensional models of the C Series module and

connectors, visit ni.com/dimensions and search by

module number.

Screw-terminal wiring ...................... 12 to 24 AWG copper

conductor wire with 10 mm
(0.39 in.) of insulation
stripped from the end

Torque for screw-terminals ............... 0.5 to 0.6 N · m

(4.4 to 5.3 lb · in.)

Ferrules ............................................. 0.25 mm

© National Instruments Corp. 17 NI 9421/9423

2

to 2.5 mm

2

Weight

NI 9421/9423 with

screw-terminal ............................ 150 g (5.3 oz)

NI 9421 with DSUB................... 145 g (5.1 oz)

Safety

NI 9421/9423 with Screw-Terminal Safety Voltages

Connect only voltages that are within the following limits.

Channel-to-COM .............................. 30 V max

Isolation

Channel-to-channel .................... None

Channel-to-earth ground

Continuous ........................... 250 V

rms

,

Measurement Category II

Withstand ............................. 2,300V

, verified by a 5 s

rms

dielectric withstand test

Measurement Category II is for measurements performed on
circuits directly connected to the electrical distribution system.
This category refers to local-level electrical distribution, such as

NI 9421/9423 18 ni.com

that provided by a standard wall outlet, for example, 115 V for U.S.
or 230 V for Europe.

Caution Do not connect the NI 9421/9423 with screw

terminal to signals or use for measurements within

Measurement Categories III or IV.

NI 9421 with DSUB Safety Voltages

Connect only voltages that are within the following limits.

Channel-to-COM .............................. 30 V max

Isolation

Channel-to-channel .................... None

Channel-to-earth ground

Continuous ........................... 60 VDC,

Measurement Category I

Withstand ............................. 1,000 V

, verified by a 5 s

rms

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

© National Instruments Corp. 19 NI 9421/9423

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.

Note Do not connect the NI 9421 with DSUB to

signals or use for measu rements within Measurement

Categories II, III, or IV.

Hazardous Locations

U.S. (UL) .......................................... Class I, Division 2,

Groups A, B, C, D, T4;
Class I, Zone 2,
AEx nC IIC T4

Canada (C-UL) ................................. Class I, Division 2,

Groups A, B, C, D, T4;
Class I, Zone 2,
Ex nC IIC T4

Europe (DEMKO)............................. Ex nC IIC T4

NI 9421/9423 20 ni.com

Safety Standards

This product meets 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 the Online Product Certification section.

Electromagnetic Compatibility

This product meets the requirements of the following EMC
standards for electrical equipment for measurement, control, and
laboratory use:

• EN 61326 (IEC 61326): Class A emissions; Industrial
immunity

• EN 55011 (CISPR 11): Group 1, Class A emissions

• AS/NZS CISPR 11: Group 1, Class A emissions

• FCC 47 CFR Part 15B: Class A emissions

• ICES-001: Class A emissions

© National Instruments Corp. 21 NI 9421/9423

Note For the standards applied to assess the EMC of this

product, refer to the Online Product Certification section.

Note For EMC compliance, operate this device with

double-shielded cables.

CE Compliance

This product meets the essential requirements of applicable
European Directives as follows:

• 2006/95/EC; Low-Voltage Directive (safety)

• 2004/108/EC; Electromagnetic Compatibility Directive
(EMC)

Online Product Certification

Refer to the product Declaration of Conformity (DoC) for
additional regulatory compliance information. To obtain product
certifications and the DoC for this product, visit ni.com/

certification

click the appropriate link in the Certification column.

NI 9421/9423 22 ni.com

, search by module number or product line, and

Shock and Vibration

To meet these specifications, you must panel mount the system. If
you are using the NI 9421/9423 with screw terminal, you also must
either affix ferrules to the ends of the terminal wires or use the
NI 9932 backshell kit to protect the connections.

Operating vibration

Random (IEC 60068-2-64)......... 5 g

, 10 to 500 Hz

rms

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

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

© National Instruments Corp. 23 NI 9421/9423

Storage temperature

(IEC 60068-2-1, IEC 60068-2-2) .....–40 to 85 °C

Ingress protection.............................. IP 40

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 ............................... 2

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 to the environment and to NI customers.

NI 9421/9423 24 ni.com

For additional environmental information, refer to the NI and the

RoHS

˅

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National Instruments

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ѻકЁ䰤ࠊՓ⫼ᶤѯ᳝ᆇ⠽䋼ᣛҸ

(RoHS)

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RoHS

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ni.com/environment/rohs_china

DŽ

(For information

about China RoHS compliance, go to

ni.com/

environment/rohs_china

.)

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 the 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

environment/weee

.

ni.com/

© National Instruments Corp. 25 NI 9421/9423

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,

NI 9421/9423 26 ni.com

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 22 328 90 10,
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

© National Instruments Corp. 27 NI 9421/9423

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