National Instruments NI 9481 User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9481
4-Channel SPST Electromechanical Relay Module
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NI 9481 Operating Instructions and Specifications 2 ni.com
This document describes how to use the National Instruments 9481
and includes specifications and terminal assignments for the NI 9481.
Visit ni.com/info and enter rdsoftwareversion to determine
which software youneed for the modules youare using. For
information about installing, configuring, and programming the
system, refer to the system documentation. Visit ni.com/info and
enter cseriesdoc for information about C Series documentation.
Note The safety guidelines and specifications in this
document are specific to the NI 9481. 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.

© National Instruments Corp. 3 NI 9481 Operating Instructions and Specifications
Safety Guidelines
Operate the NI 9481 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
If hazardous voltages are connected to the module, take the
following precautions. A hazardous voltage is a voltage greater
than 42.4 Vpk or 60 VDC to earth ground.
Caution Ensure that hazardous voltage wiring is
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.
Caution Make sure that devices and circuits connected to
the module are properly insulated from human contact.

NI 9481 Operating Instructions and Specifications 4 ni.com
Caution When module terminals are hazardous voltage
LIVE (>42.4 Vpk/60 VDC), youmust ensure that devices
and circuits connected to the module are properly
insulated from human contact. Youmust use the NI 9932
connector backshell kit to ensure that the terminals are
not accessible.
Figure 1 shows the NI 9932 connector backshell.
Figure 1. NI 9932 Connector Backshell

© National Instruments Corp. 5 NI 9481 Operating Instructions and Specifications
Safety Guidelines for Hazardous Locations
The NI 9481 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
hazardous locations; and nonhazardous locations only. Follow
these guidelines if youare installing the NI 9481 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 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.

NI 9481 Operating Instructions and Specifications 6 ni.com
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 9481 Operating Instructions and Specifications
Connecting the NI 9481
The NI 9481 has a 10-terminal detachable screw-terminal connector
that provides connections for 4 electromechanical relay channels.
Figure 2. NI 9481 Terminal Assignments
03
0
1
2
3
4
5
6
7
8
9
CH0a
CH0b
CH1a
CH1b
CH2a
CH2b
CH3a
CH3b
NC
NC

NI 9481 Operating Instructions and Specifications 8 ni.com
Each electromechanical relay channel has two interchangeable
terminals, CHa and CHb.
Each channel has an LED that indicates the state of the 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.
When connecting a load to the NI 9481, connect the positive lead
of the load to either the CHa or the CHb terminal, and the ground
of the load to one of the leads of the power supply. Connect the
remaining CHa or CHb terminal to the other lead of the power
supply. Figure 3 shows a possible configuration.
Figure 3. Connecting a Load to the NI 9481
NI 9481
+
–
CHa
CHbAC
or
Load

© National Instruments Corp. 9 NI 9481 Operating Instructions and Specifications
Note Youmust use 2-wire ferrules to create a secure
connection when connecting more than one wire to a
single terminal on the NI 9481.
When the channel is turned on, the terminal connected to the load
drives current or applies voltage to the load. When the channel is
off, the terminal does not drive current or apply voltage to the load.
Wiring for High-Vibration Applications
If an application is subject to high vibration, National Instruments
recommends that youeither 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.

NI 9481 Operating Instructions and Specifications 10 ni.com
Figure 4. 10-Terminal Detachable Screw-Terminal Connector with Ferrule
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.