National Instruments NI 9421 User manual

NI-9421 Getting
Started
2022-07-06

Contents
Before You Begin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Guidelines for Hazardous Voltages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
NI-9421 with Screw Terminal and NI-9421 with Spring Terminal Safety Voltages
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
NI-9421 with DSUB Safety Voltages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Safety Guidelines for Hazardous Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electromagnetic Compatibility Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Special Conditions for Marine Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Preparing the Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Connecting the NI-9421. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
NI-9421 Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Connecting Sourcing-Output Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
LED Indications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
High-Vibration Application Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Where to Go Next. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
NI Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
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NI-9421 Getting Started

Before You Begin
Read the NI-9421 Safety, Environmental, and Regulatory Information and
complete the soware and hardware installation procedures in your chassis
documentation.
Safety Guidelines
Caution Observe all instructions and cautions in the user documentation.
Using the product in a manner not specified can damage the product and
compromise the built-in safety protection.
Attention Suivez toutes les instructions et respectez toutes les mises
en garde de la documentation d'utilisation. L'utilisation du produit de
toute autre façon que celle spécifiée risque de l'endommager et de
compromettre la protection de sécurité intégrée.
Safety Guidelines for Hazardous Voltages
If hazardous voltages are connected to the product, take the following precautions.
A hazardous voltage is a voltage greater than:
■ 30 V RMS, 42.4 V peak, or 60 V DC in DRY LOCATIONS
■ 16 V RMS, 22.6 V peak, or 35 V DC in WET LOCATIONS
Caution Ensure that hazardous voltage wiring is performed only by
qualified personnel adhering to local electrical standards.
Attention S'assurer que le câblage à tension dangereuse est eectué par
du personnel qualifié respectant les normes électriques locales.
© National Instruments 3
NI-9421 Getting Started

Caution Do not mix hazardous voltage circuits and human-accessible
circuits on the same product.
Attention Ne pas combiner des circuits avec des tensions dangereuses et
des circuits accessibles aux personnes sur le même produit.
Caution When product terminals are hazardous voltage LIVE, you must
ensure that devices and circuits connected to the product are properly
insulated from human contact.
Attention Lorsqu'une haute tension dangereuse est appliquée aux
bornes du produit, vous devez vous assurer que les appareils et les circuits
auxquels il est connecté sont correctement isolés de tout contact humain.
Caution You must use the connector backshell kit to ensure that the
terminals are not accessible.
NI-9421 with Screw Terminal and NI-9421 with Spring Terminal
Safety Voltages
Connect only voltages that are within the following limits:
Channel-to-COM 30 V maximum
Overvoltage protection 40 V maximum
Reverse-biased voltage -30 V maximum
Isolation
Channel-to-channel None
Channel-to-earth ground
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NI-9421 Getting Started

Continuous 250 V RMS, Measurement Category II
Withstand 2,300 V RMS, verified by a 5 s dielectric withstand test
NI-9421 with DSUB Safety Voltages
Connect only voltages that are within the following limits:
Channel-to-COM 30 V maximum
Overvoltage protection 40 V maximum
Reverse-biased voltage -30 V maximum
Isolation
Channel-to-channel None
Channel-to-earth ground
Continuous 60 V DC, Measurement Category I
Withstand 1,000 V RMS, verified by a 5 s dielectric withstand test
Safety Guidelines for Hazardous Locations
The NI-9421 is suitable for use in hazardous locations; , and hazardous locations;
and nonhazardous locations only. Follow these guidelines if you are installing the
NI-9421 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 o or the area is known to be nonhazardous.
Caution Do not remove modules unless power has been switched o or
the area is known to be nonhazardous.
© National Instruments 5
NI-9421 Getting Started

Caution Substitution of components may impair suitability for Class I,
Division 2, or Zone 2.
Caution The system must be installed in an enclosure certified for the
intended hazardous (classified) location, having a tool secured cover/door,
where a minimum protection of at least IP54 is provided.
Caution For Division 2 and Zone 2 applications, connected signals must
be within the following limits.
Capacitance 0.2 µF maximum
Special Conditions for Hazardous Locations Use in Europe and
Internationally
The NI-9421 has been evaluated as equipment under DEMKO ATEX and is IECEx
certified. Each NI-9421 is marked 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-9421
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 Transient protection shall be provided that is set at a level not
exceeding 140% of the peak rated voltage value of 85 V at the supply
terminals to the equipment.
Caution The system shall only be used in an area of not more than
Pollution Degree 2, as defined in IEC/EN 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.
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NI-9421 Getting Started

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 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 approved for marine (shipboard) applications. To verify marine
approval certification for a product, visit ni.com/product-certifications, search by
model number, and click the appropriate link.
Notice 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.
© National Instruments 7
NI-9421 Getting Started

Preparing the Environment
Ensure that the environment in which you are using the NI-9421 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.
Note Refer to the device datasheet on ni.com/manuals for complete
specifications.
Connecting the NI-9421
The NI-9421 provides connections for eight digital input channels.
Figure 1. NI-9421 Pinout
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 with
screw terminal or NI-9421 with spring terminal.
NI-9421 Signals
Each channel of the NI-9421 has a DI terminal or pin to which you can connect
voltage or current signals. The NI-9421 also has COM, a common terminal or pin that
is internally connected to the isolated ground reference of the module.
The NI-9421 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 internally limits current signals connected to DI.
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NI-9421 Getting Started

Connecting Sourcing-Output Devices
You can connect 2-, 3-, and 4-wire sourcing-output devices to the NI-9421. A
sourcing-output device drives current or applies voltage to DI. An example of a
sourcing-output device is an open collector PNP.
Connect the output of the sourcing-output device to DI on the NI-9421. Connect the
common of the external device to the COM terminal or pin.
Figure 2. Connecting a Device to the NI-9421 (3-Wire Device Shown)
The NI-9421 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.
LED Indications
Each channel has an LED that indicates the state of the channel, as the following
table describes. The LEDs are disabled when the chassis is in sleep mode.
LED State Indication
Illuminated Channel is on
Not illuminated Channel is o
Table 1. LED Indications
High-Vibration Application Connections
If your application is subject to high vibration, NI recommends that you follow these
guidelines to protect connections to the NI-9421:
■Use ferrules to terminate wires to the detachable connector.
■Use the backshell kit with the NI-9421 with screw terminal or the backshell
kit with the NI-9421 with spring terminal.
Where to Go Next
© National Instruments 9
NI-9421 Getting Started

NI Services
Visit ni.com/support to find support resources including documentation,
downloads, and troubleshooting and application development self-help such as
tutorials and examples.
Visit ni.com/services to learn about NI service oerings such as calibration options,
repair, and replacement.
Visit ni.com/register to register your NI product. Product registration facilitates
technical support and ensures that you receive important information updates from
NI.
NI corporate headquarters is located at 11500 N Mopac Expwy, Austin, TX,
78759-3504, USA.
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NI-9421 Getting Started
© 2022 National Instruments Corporation.