National Instruments NI 9401 User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9401
8-Channel, TTL Digital Input/Output Module
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NI 9401 Operating Instructions and Specifications 2 ni.com
This document describes how to use the National Instruments 9401
and includes specifications and pin assignments for the NI 9401.
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 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.

© National Instruments Corp. 3 NI 9401 Operating Instructions and Specifications
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, 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 youare 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.

NI 9401 Operating Instructions and Specifications 4 ni.com
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 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 youare 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.

© National Instruments Corp. 5 NI 9401 Operating Instructions and Specifications
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.

NI 9401 Operating Instructions and Specifications 6 ni.com
Connecting the NI 9401
The NI 9401 has a 25-pin DSUB connector that provides
connections for eight digital input/output channels.
Figure 1. NI 9401 Pin Assignments
COM
NC
COM
COM
NC
COM
COM
NC
COM
COM
NC
COM
COM
DIO0
NC
DIO1
DIO2
NC
DIO3
DIO4
NC
DIO5
DIO6
NC
DIO7
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

© National Instruments Corp. 7 NI 9401 Operating Instructions and Specifications
Each channel has a DIO pin to which youcan connect a digital
input or output device. The eight DIO channels are internally
referenced to COM, so youcan 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 ucan 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.

NI 9401 Operating Instructions and Specifications 8 ni.com
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.
Figure 2. Connecting an SPI Device to the NI 9401
NI 9401
DIO3:0
Configured
for Output
DIO7:4
Configured
for Input
SCLK
MOSI
MISO
SS
SPI Device

© National Instruments Corp. 9 NI 9401 Operating Instructions and Specifications
Figure 3 illustrates how to connect several types of digital devices
to the NI 9401.
Figure 3. Connecting Digital Devices to the NI 9401
TTL Signal
+5 V
+5 V
LED
DIO0 as Input
DIO1 as Input
COM
DIO7 as Output
NI 9401
Dev 3
Dev 2
Dev 1

NI 9401 Operating Instructions and Specifications 10 ni.com
Overcurrent Protection
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.