National Instruments NI 9481E User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9481E
4-Channel SPST Electromechanical Relay Module

NI 9481E Operating Instructions and Specifications 2 ni.com
This document describes how to use the National Instruments 9481E
and includes dimensions, terminal assignments, and specifications for
the NI 9481E. Visit 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 ni.com/info and
enter cseriesdoc for information about C Series documentation.
Caution National Instruments makes no electromagnetic
compatibility (EMC) or CE marking compliance claims
for the NI 9481E. The end-product supplier is responsible
for conformity to any and all compliance requirements.
Caution The NI 9481E must be installed inside a suitable
enclosure prior to use. Hazardous voltages may be present.

© National Instruments Corp. 3 NI 9481E Operating Instructions and Specifications
NI 9481E Dimensions
The following figure shows the dimensions of the NI 9481E.
Figure 1. NI 9481E Dimensions in Millimeters (Inches)
73.4 (2.89)
0.0 (0.00)
26.7 (1.05) 58.4 (2.30) 66.0 (2.60)
0.0 (0.00)

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

© National Instruments Corp. 5 NI 9481E Operating Instructions and Specifications
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 9481E, 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 9481E
NI 9481E
+
–
CHa
CHbAC
or
Load

NI 9481E Operating Instructions and Specifications 6 ni.com
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 9481E.
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.
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. 7 NI 9481E Operating Instructions and Specifications
Specifications
The following specifications are typical for the range –40 to 85 °C
unless otherwise noted.
Output Characteristics
Number of channels.......................... 4 electromechanical relay
channels
Relay type ......................................... Single pole single throw
(SPST)
Power-on output state ....................... Channels off
Switching capacity (resistive load)
Switching voltage ....................... 60 VDC max, 250 Vrms max
Switching current, per channel
One channel on .................... 4 A max at 30 VDC,
1 A max at 60 VDC,
4 A max at 250 Vrms
All channels on .................... 2 A max at 30 VDC,
1 A max at 60 VDC,
2 A max at 250 Vrms

NI 9481E Operating Instructions and Specifications 8 ni.com
Resistance per channel,
channel on......................................... 50 mΩ
Switching rate ................................... 1 operation per second
Relay release time............................. 5 ms max
Relay operate time ............................ 10 ms max
Relay bounce time ............................ 3 ms
Off state leakage ............................... 10 μAmax
Life expectancy
Mechanical (no load).................. 20,000,000 operations
Electrical (connecting to load) ... 100,000 operations
MTBF ............................................... 460,321 hours at 25 °C;
Bellcore Issue 2, Method 1,
Case 3, Limited Part Stress
Method
Note Contact NI for Bellcore MTBF specifications
at other temperatures or for MIL-HDBK-217F
specifications.

© National Instruments Corp. 9 NI 9481E Operating Instructions and Specifications
Power Requirements
Power consumption from chassis
Active mode ............................... 580 mW max
Sleep mode ................................. 5 mW max
Thermal dissipation (at 70 °C)
Active mode ............................... 1.5 W max
Sleep mode ................................. 5 mW max
Physical Characteristics
Use a dry, low-velocity stream of air to clean the module. If
needed, use a soft-bristle brush for cleaning around components.
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.)
Weight............................................... 76 g (2.7 oz)

NI 9481E Operating Instructions and Specifications 10 ni.com
Safety
Safety Voltages
Connect only voltages that are within the following limits.
CHa-to-CHb...................................... 250 Vrms max,
Measurement Category II
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
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 9481E to signals or use
for measurements within Measurement Categories III
or IV.
Isolation
Channel-to-channel
Continuous ........................... 250 Vrms
(Basic insulation)
Withstand ............................. 1,400 Vrms, verified by a 5 s
dielectric withstand test