National Instruments NI USB-6008 User manual

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USER GUIDE
NI USB-6008/6009
Bus-Powered Multifunction DAQ USB Device
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ni.com/manuals
The National Instruments USB-6008/6009 devices provide eight single-ended analog input
(AI) channels, two analog output (AO) channels, 12 DIO channels, and a 32-bit counter with a
full-speed USB interface. This user guide describes how to use these devices.
For specifications, refer to the NI USB-6008 Device Specifications and the NI USB-6009
Device Specifications available at ni.com/manuals.
The following table compares the NI USB-6008 and NI USB-6009 devices.
Table 1. NI USB-6008 and NI USB-6009 Comparison
Feature NI USB-6008 NI USB-6009
AI resolution 12 bits differential, 11
bits single-ended
14 bits differential, 13 bits
single-ended
Maximum AI sample rate,
single channel1
10 kS/s 48 kS/s
Maximum AI sample rate,
multiple channels (aggregate)1
10 kS/s 48 kS/s
DIO configuration Open collector2Each channel individually
programmable as open collector
or active drive2
The following figure shows key functional components of the NI USB-6008/6009.
1System-dependent.
2This document uses NI-DAQmx naming conventions. Open-drain is called open collector and
push-pull is called active drive.

Figure 1. NI USB-6008/6009 Block Diagram
P1.<0..3>
P0.<0..7>
Digital I/O Terminal Block
AI <0..7>
AO 0
AO 1
Analog I/O Terminal Block
+2.5 V/CAL
+5 V/200 mA
8 Channel
12/14b ADC
12b DAC
12b DAC
USB Microcontroller
SPI
External
Power
Supply
Vbus
Full-Speed USB Interface
USB
PFI 0
Safety Guidelines
The following section contains important safety information that you must follow when
installing and using the NI USB-6008/6009.
Caution Operate the NI USB-6008/6009 only as described in these operating
instructions. Misuse of the device can result in a hazard. You can compromise the
safety protection built into the device if the device is damaged in any way. If the
device is damaged, contact National Instruments for repair.
Caution Do not substitute parts or modify the device except as described in this
user guide. Use the device only with the accessories specified in the installation
instructions.
2| ni.com | NI USB-6008/6009 User Guide

Caution Do not operate the device in an explosive atmosphere or where there may
be flammable gases or fumes. If you must operate the device in such an
environment, it must be in a suitably rated enclosure.
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.
Caution To ensure the specified EMC performance, operate this product only with
shielded cables and accessories.
Caution This product may become more sensitive to electromagnetic disturbances
in the operational environment when test leads are attached or when the product is
connected to a test object.
Caution Emissions that exceed the regulatory requirements may occur when this
product is connected to a test object.
Note Changes or modifications to the product not expressly approved by National
Instruments could void your authority to operate the product under your local
regulatory rules.
Unpacking the Kit
Caution To prevent electrostatic discharge (ESD) from damaging the device,
ground yourself using a grounding strap or by holding a grounded object, such as
your computer chassis.
1. Touch the antistatic package to a metal part of the computer chassis.
2. Remove the device from the package and inspect the device for loose components or any
other sign of damage.
Caution Never touch the exposed pins of connectors.
NI USB-6008/6009 User Guide | © National Instruments | 3

Note Do not install a device if it appears damaged in any way.
3. Unpack any other items and documentation from the kit.
Store the device in the antistatic package when the device is not in use.
Setting Up the NI USB-6008/6009
Complete the following steps to get started with the NI USB-6008/6009.
Note For information about non-Windows operating support, refer to the Getting
Started with NI-DAQmx Base document available from ni.com/manuals.
1. Install the application software (if applicable), as described in the installation instructions
that accompany your software.
2. Install NI-DAQmx3.
Note The NI-DAQmx software is included on the disk shipped with your kit
and is available for download at ni.com/support. The documentation for
NI-DAQmx is available after installation from Start»All Programs»National
Instruments»NI-DAQmx. Other NI documentation is available from
ni.com/manuals.
3. Install the 16-position screw terminal plugs by inserting them into the connector jacks, as
shown in the following figure.
Figure 2. Signal Label Application Diagram
9
0
0
6
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8
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1
3
2
4
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23
1. Overlay Label with Pin Orientation Guides
2. Screw Terminal Connector Plug
3. Signal Label
4. USB Cable
4. Affix the provided signal labels to the screw terminal connector plugs. You can choose
labels with pin numbers, signal names, or blank labels, as shown in the following figure.
3NI USB-6008/6009 devices are supported by NI-DAQmx 7.5 and later.
4| ni.com | NI USB-6008/6009 User Guide

Choose one of the labels, align the correct label with the terminals printed on the top
panel of your device and apply the label, as shown in the previous figure.
Figure 3. NI USB-6008/6009 Signal Labels
GND +AI0 -+AI1 -+AI2 -+AI3 -AO0 AO1 GND
GND +5V+2.5V PFI0 P1.3 P1.2 P1.1 P1.0 P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0
12345678910 11 12 13 14 15 16
GND AI 0 AI4 GND AI1 AI5 GND AI 2 AI6 GND AI3 AI7 GND AO0 AO1 GND
DIGITAL
ANALOG
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
GND GND GND GND
2
3
4
5
or
1
1
1. User-Defined Custom Label
2. Terminal Number Label
3. Digital I/O Label
4. Analog Input Differential Signal Name Label
5. Analog Input Single-Ended Signal Name Label
Note After you label the screw terminal connector plugs, you must only insert
them into the matching connector jack, as indicated by the overlay label on the
device.
5. Plug one end of the USB cable into the NI USB-6008/6009 and the other end into an
available USB port on the computer.
6. Double-click the NI MAX icon on the desktop to open Measurement & Automation
Explorer (MAX).
7. Expand My System»Devices and Interfaces and verify that the NI USB-6008/6009 is
listed. If your device does not appear, press <F5> to refresh the view in MAX. If your
device is still not recognized, refer to ni.com/support/daqmx for troubleshooting
information.
8. Self-test your device in MAX by right-clicking NI USB-6008 or NI USB-6009 and
selecting Self-Test. Self-test performs a brief test to determine successful device
installation. When the self-test finishes, a message indicates successful verification or if
an error occurred. If an error occurs, refer to ni.com/support/daqmx.
Caution To ensure the specified EMC performance, operate this product only
with shielded cables and accessories.
9. Connect the wires (16 AWG to 28 AWG) of a shielded, multiconductor cable to screw
terminals by stripping 6.35 mm (0.25 in) of insulation, inserting the wires into the screw
terminals, and securely tightening the screws with the flathead screwdriver to a torque of
0.22 N · m to 0.25 N · m (2.0 lb · in. to 2.2 lb · in.). Refer to the Pinout and Signal
Descriptions section for an image of the NI USB-6008/6009 pinout.
If using a shielded cable, connect the cable shield to a nearby GND terminal.
Note For information about sensors, go to ni.com/sensors. For
information about IEEE 1451.4 TEDS smart sensors, go to ni.com/teds.
10. Run a Test Panel in MAX by right-clicking NI USB-6008 or NI USB-6009 and selecting
Test Panels.
NI USB-6008/6009 User Guide | © National Instruments | 5

Click Start to test the device functions, or Help for operating instructions. Click Close to
exit the test panel.
Using the NI USB-6008/6009 in an Application
You can use the DAQ Assistant through many NI application software programs to configure
virtual and measurement channels. The following table lists DAQ Assistant tutorial locations
for NI applications.
Table 2. DAQ Assistant Tutorial Locations
NI Application Tutorial Location
LabVIEW Go to Help»LabVIEW Help. Next, go to Getting Started with
LabVIEW»Getting Started with DAQ»Taking an NI-DAQmx
Measurement in LabVIEW.
LabWindows™/CVI™Go to Help»Contents. Next, go to Using LabWindows/CVI»
Data Acquisition»Taking an NI-DAQmx Measurement in
LabWindows/CVI.
Measurement Studio Go to NI Measurement Studio Help»Getting Started with the
Measurement Studio Class Libraries»Measurement Studio
Walkthroughs»Walkthrough: Creating a Measurement Studio
NI-DAQmx Application.
LabVIEW
SignalExpress
Go to Help»Taking an NI-DAQmx Measurement in
SignalExpress.
Refer to the Where to Go from Here section for information about programming examples for
NI-DAQmx and NI-DAQmx Base.
Features
The NI USB-6008/6009 features a USB connector, USB cable strain relief, two screw terminal
connector plugs for I/O, and an LED indicator, as shown in the following figure.
6| ni.com | NI USB-6008/6009 User Guide

Figure 4. NI USB-6008/6009 Top and Back Views
NI USB-6009
8 Inputs, 14-bit, Multifunction I/O
32 Digital 17
1 Analog 16
1
2 2 4
3
1. USB Cable Strain Relief
2. Screw Terminal Connector Plug
3. LED Indicator
4. USB Connector
USB Connector and USB Cable Strain Relief
The NI USB-6008/6009 features a USB connector for full-speed USB interface. You can
provide strain relief for the USB cable by threading a zip tie through the USB cable strain
relief ring and tightening around a looped USB cable, as shown in the following figure.
Figure 5. NI USB-6008/6009 Strain Relief
1
LED Indicator
The NI USB-6008/6009 device has a green LED indicator that indicates device status, as listed
in the following table. When the device is connected to a USB port, the LED blinks steadily to
indicate that the device is initialized and is receiving power from the connection.
NI USB-6008/6009 User Guide | © National Instruments | 7

Table 3. LED State/Device Status
LED State Device Status
Not lit Device not connected or in suspend
On, not blinking Device connected but not initialized, or the computer is in standby mode.
In order for the device to be recognized, the device must be connected to a
computer that has NI-DAQmx installed on it.
Single-blink Operating normally
Screw Terminal Connector Plugs
The NI USB-6008/6009 ships with one detachable screw terminal connector plug for analog
signals and one detachable screw terminal connector plug for digital signals. These screw
terminal connectors provide 16 connections that use 16 AWG to 28 AWG wire. Refer to step 4
of the Setting Up the NI USB-6008/6009 section for information about selecting labels for the
screw terminal connector plugs. Refer to the Pinout and Signal Descriptions section for the
device pinout and signal descriptions.
You can order additional connectors and labels for your device. Refer to the Cables and
Accessories section for ordering information.
Firmware
The firmware on the NI USB-6008/6009 refreshes whenever the device is connected to a
computer with NI-DAQmx. NI-DAQmx automatically uploads the compatible firmware
version to the device. The firmware version may be upgraded when new versions of
NI-DAQmx release.
Cables and Accessories
The following table contains information about cables and accessories available for the
NI USB-6008/6009. For a complete list of accessories and ordering information, refer to the
pricing section of the NI USB-6008 or NI USB-6009 product page at ni.com.
8| ni.com | NI USB-6008/6009 User Guide

Table 4. NI USB-6008/6009 Cables and Accessories
Accessory Part Number Description
USB-6008/6009 Accessory
Kit
779371-01 Four additional screw-terminal
connectors, connector labels, and a
screwdriver
USB-6000 Series
Prototyping Accessory
779511-01 Unshielded breadboarding accessory for
custom-defined signal conditioning and
prototyping. You can use up to two
accessories per device.
Hi-Speed USB Cable 184125-01,
184125-02
1 m and 2 m lengths
Caution For compliance with Electromagnetic Compatibility (EMC) requirements,
this product must be operated with shielded cables and accessories. If unshielded
cables or accessories are used, the EMC specifications are no longer guaranteed
unless all unshielded cables and/or accessories are installed in a shielded enclosure
with properly designed and shielded input/output ports.
Pinout and Signal Descriptions
The following figure shows the pinout of the NI USB-6008/6009. Analog input signal names
are listed as single-ended analog input name, AI x, and then differential analog input name,
(AI x+/-). Refer to the following table for a detailed description of each signal.
NI USB-6008/6009 User Guide | © National Instruments | 9

Figure 6. NI USB-6008/6009 Pinout
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
GND
AI 0 (AI 0+)
AI 4 (AI 0–)
GND
AI 1 (AI 1+)
AI 5 (AI 1–)
GND
AI 2 (AI 2+)
AI 6 (AI 2–)
GND
AI 3 (AI 3+)
AI 7 (AI 3–)
GND
AO 0
AO 1
GND
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
P1.0
P1.1
P1.2
P1.3
PFI 0
+2.5 V
+5 V
GND
Table 5. Signal Descriptions
Signal
Name
Reference Direction Description
GND — — Ground—The reference point for the single-ended
analog input measurements, analog output voltages,
digital signals, +5 VDC supply, and +2.5 VDC at
the I/O connector, and the bias current return point
for differential mode measurements.
AI <0..7> Varies Input Analog Input Channels 0 to 7—For single-ended
measurements, each signal is an analog input
voltage channel. For differential measurements,
AI 0 and AI 4 are the positive and negative inputs
of differential analog input channel 0. The
following signal pairs also form differential input
channels: AI <1, 5>, AI <2, 6>, and AI <3, 7>.
Refer to the Analog Input section for more
information.
10 | ni.com | NI USB-6008/6009 User Guide

Table 5. Signal Descriptions (Continued)
Signal
Name
Reference Direction Description
AO <0, 1> GND Output Analog Output Channels 0 and 1—Supplies the
voltage output of AO channel 0 or AO channel 1.
Refer to the Analog Output section for more
information.
P0.<0..7> GND Input or
Output
Port 0 Digital I/O Channels 0 to 7—You can
individually configure each signal as an input or
output. Refer to the Digital I/O section for more
information.
P1.<0..3> GND Input or
Output
Port 1 Digital I/O Channels 0 to 3—You can
individually configure each signal as an input or
output. Refer to the Digital I/O section for more
information.
PFI 0 GND Input PFI 0—This pin is configurable as either a digital
trigger or an event counter input. Refer to the PFI 0
section for more information.
+2.5 V GND Output +2.5 V External Reference—Provides a reference
for wrap-back testing. Refer to the +2.5 V External
Reference section for more information.
+5 V GND Output +5 V Power Source—Provides +5 V power up to
200 mA. Refer to the +5 V Power Source section
for more information.
Analog Input
The NI USB-6008/6009 has eight analog input channels that you can use for four differential
analog input measurements or eight single-ended analog input measurements.
The following figure shows the analog input circuitry of the NI USB-6008/6009.
NI USB-6008/6009 User Guide | © National Instruments | 11

Figure 7. NI USB-6008/6009 Analog Input Circuitry
AI
+2.5 VREF
39.2 kΩ
127 kΩ
30.9 kΩPGA
Input Range
Selection
AI FIFO
ADC
MUX
The main blocks featured in the NI USB-6008/6009 analog input circuitry are as follows:
•MUX—The NI USB-6008/6009 has one analog-to-digital converter (ADC). The
multiplexer (MUX) routes one AI channel at a time to the PGA.
•PGA—The programmable-gain amplifier provides input gains of 1, 2, 4, 5, 8, 10, 16, or
20 when configured for differential measurements and gain of 1 when configured for
single-ended measurements. The PGA gain is automatically calculated based on the
voltage range selected in the measurement application.
•ADC—The analog-to-digital converter (ADC) digitizes the AI signal by converting the
analog voltage into digital code.
•AI FIFO—The NI USB-6008/6009 can perform both single and multiple analog-to-
digital conversions of a fixed or infinite number of samples. A first-in-first-out (FIFO)
buffer holds data during AI acquisitions to ensure that no data is lost.
Analog Input Modes and Signal Sources
You can configure the AI channels on the NI USB-6008/6009 to take differential or referenced
single-ended (RSE) measurements. The following table summarizes the recommended analog
input mode(s) for floating signal sources and ground-references signal sources. Refer to the
table in the Pinout and Signal Descriptions section for more information about I/O
configurations for single-ended or differential measurements.
12 | ni.com | NI USB-6008/6009 User Guide

Table 6. Analog Input Configurations
Analog Input
Mode
Floating Signal Sources (Not
Connected to Building Ground)
Ground-Referenced Signal Sources
Examples • Ungrounded thermocouples
• Signal conditioning with
isolated outputs
• Battery devices
Plug-in instruments with non-isolated
outputs
Differential
(DIFF)
+
–
+
–
AI+
AI–
GND
Signal Source NI USB-6008/6009
+
–
+
–
AI+
AI–
GND
Signal Source NI USB-6008/6009
Referenced
Single-Ended
(RSE)
+
–
+
–
AI
GND
Signal Source NI USB-6008/6009
Ground-loop potential (VA– VB) are added
to measured signal.
NOT RECOMMENDED
+
–
+
–
AI
GND
VB
VA
Signal Source NI USB-6008/6009
Floating Signal Sources
A floating signal source is not connected to the building ground system, but has an isolated
ground-reference point. Some examples of floating signal sources are outputs of transformers,
thermocouples, battery-powered devices, optical isolators, and isolation amplifiers. An
instrument or device that has an isolated output is a floating signal source.
Refer to Field Wiring and Noise Considerations for Analog Signals for more information. To
access this document, go to ni.com/info and enter the Info Code rdfwn3.
When to Use Differential Connections with Floating Signal Sources
Use DIFF input connections for any channel that meets any of the following conditions:
• Your application requires input ranges other than ±10 V.
• The input signal is low level and requires greater accuracy.
NI USB-6008/6009 User Guide | © National Instruments | 13

• The leads connecting the signal to the device are greater than 3 m (10 ft).
• The input signal requires a separate ground-reference point or return signal.
• The signal leads travel through noisy environments.
• Two analog channels, AI+ and AI-, are available for the signal.
DIFF signal connections reduce noise pickup and increase common-mode noise rejection.
DIFF signal connections also allow input signals to float within the working voltage of the
device.
Refer to the Taking Differential Measurements section for more information about differential
connections.
When to Use Referenced Single-Ended (RSE) Connections with Floating
Signal Sources
Only use RSE input connections if the input signal meets all of the following conditions:
• The input signal can share a common reference point, GND, with other signals that use
RSE.
• Your application permits the use of the ±10 V input range.
• The leads connecting the signal to the device are less than 3 m (10 ft).
DIFF input connections are recommended for greater signal integrity for any input signal that
does not meet the preceding conditions.
In the single-ended modes, more electrostatic and magnetic noise couples into the signal
connections than in DIFF configurations. The coupling is the result of differences in the signal
path. Magnetic coupling is proportional to the area between the two signal conductors.
Electrical coupling is a function of how much the electric field differs between the two
conductors.
With this type of connection, the PGA rejects both the common-mode noise in the signal and
the ground potential difference between the signal source and the device ground.
Refer to the Taking Referenced Single-Ended Measurements section for more information
about RSE connections.
Ground-Referenced Signal Sources
A ground-referenced signal source is a signal source connected to the building system ground.
It is already connected to a common ground point with respect to the device, assuming that the
computer is plugged into the same power system as the source. Non-isolated outputs of
instruments and devices that plug into the building power system fall into this category.
The difference in ground potential between two instruments connected to the same building
power system is typically between 1 mV and 100 mV, but the difference can be much higher if
power distribution circuits are improperly connected. If a grounded signal source is incorrectly
measured, this difference can appear as measurement error. Follow the connection instructions
14 | ni.com | NI USB-6008/6009 User Guide

for grounded signal sources to eliminate this ground potential difference from the measured
signal.
Refer to Field Wiring and Noise Considerations for Analog Signals for more information. To
access this document, go to ni.com/info and enter the Info Code rdfwn3.
When to Use Differential Connections with Ground-Reference Signal Sources
Use DIFF input connections for any channel that meets any of the following conditions:
• Your application requires input ranges other than ±10 V.
• The input signal is low level and requires greater accuracy.
• The leads connecting the signal to the device are greater than 3 m (10 ft).
• The input signal requires a separate ground-reference point or return signal.
• The signal leads travel through noisy environments.
• Two analog channels, AI+ and AI-, are available for the signal.
DIFF signal connections reduce noise pickup and increase common-mode noise rejection.
DIFF signal connections also allow input signals to float within the working voltage of the
device.
Refer to the Taking Differential Measurements section for more information about differential
connections.
When to Use Referenced Single-Ended (RSE) Connections with
Ground-Referenced Signal Sources
Do not use RSE connections with ground-referenced signal sources. Use differential
connections instead.
As shown in the table in the Analog Input Modes and Signal Sources section, there can be a
potential difference between GND and the ground of the sensor. In RSE mode, this ground
loop causes measurement errors.
Taking Differential Measurements
For differential signals, connect the positive lead of the signal to the AI+ terminal, and the
negative lead to the AI- terminal.
Figure 8. Connecting a Differential Voltage Signal
AI+
NI USB-6008/6009
AI–
Voltage
Source
NI USB-6008/6009 User Guide | © National Instruments | 15

The differential input mode can measure ±20 V signals in the ±20 V range. However, the
maximum voltage on any one pin is ±10 V with respect to GND. For example, if AI 1 is +10 V
and AI 5 is -10 V, then the measurement returned from the device is +20 V.
Figure 9. Example of a Differential 20 V Measurement
–5
–10
–15
–20
20
15
10
5
0
Amplitude (V)
AI 1
AI 5
Result
Connecting a signal greater than ±10 V on either pin results in a clipped output.
Figure 10. Exceeding ±10 V on AI Returns Clipped Output
–5
–10
–15
–20
20
15
10
5
0
Amplitude (V)
AI 1
AI 5
Result
Taking Referenced Single-Ended Measurements
To connect referenced single-ended (RSE) voltage signals to the NI USB-6008/6009, connect
the positive voltage signal to an AI terminal, and the ground signal to a GND terminal, as
shown in the following figure.
16 | ni.com | NI USB-6008/6009 User Guide

Figure 11. Connecting a Referenced Single-Ended Voltage Signal
AI
NI USB-6008/6009
GND
Voltage
Source
When no signals are connected to the analog input terminal, the internal resistor divider may
cause the terminal to float to approximately 1.4 V when the analog input terminal is
configured as RSE. This behavior is normal and does not affect the measurement when a
signal is connected.
Digital Trigger
You can configure PFI 0 as a digital trigger input for analog input tasks. Refer to the Using
PFI 0 as a Digital Trigger section for more information.
Analog Output
The NI USB-6008/6009 has two independent analog output channels that can generate outputs
from 0 V to 5 V. All updates of analog output channels are software-timed. GND is the
ground-reference signal for the analog output channels.
The following figure shows the circuitry of one analog output channel on the
NI USB-6008/6009.
Figure 12. Circuitry of One Analog Output Channel
REF(+) REF(–)
12-Bit
DAC
50 Ω
AO
+5 V
GND
The main block featured in the NI USB-6008/6009 analog output circuitry is the
digital-to-analog converter (DAC), which converts digital codes to analog voltages. There is
one DAC for each analog output line.
NI USB-6008/6009 User Guide | © National Instruments | 17

Connecting Analog Output Loads
To connect loads to the NI USB-6008/6009, connect the positive lead of the load to the AO
terminal, and connect the ground of the load to a GND terminal, as shown in the following
figure.
Figure 13. Connecting a Load
NI USB-6008/6009
GND
AO
Load
Minimizing Glitches on the Output Signal
When you use a DAC to generate a waveform, you may observe glitches in the output signal.
These glitches are normal; when a DAC switches from one voltage to another, it produces
glitches due to released charges. The largest glitches occur when the most significant bit of the
DAC code changes. You can build a lowpass deglitching filter to remove some of these
glitches, depending on the frequency and nature of the output signal. For more information
about minimizing glitches, refer to the KnowledgeBase document, Reducing Glitches on the
Analog Output of MIO DAQ Devices. To access this document, go to ni.com/info and enter
the Info Code exszek.
Digital I/O
The NI USB-6008/6009 has 12 digital lines on two ports, Port 0 has eight lines, P0.<0..7>, and
Port 1 has four lines, P1.<0..3>. GND is the ground-reference signal for the digital I/O ports.
You can individually program all lines as inputs or outputs.
The following figure shows P0.<0..7> connected to example signals configured as digital
inputs and digital outputs. You can configure P1.<0..3> similarly.
18 | ni.com | NI USB-6008/6009 User Guide

Figure 14. Example of Connecting a Load
+5 V
LED
Switch
I/O Connector
GND
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
+5 V
LED
1
2
3
4
TTL Signal
NI USB-6008/6009
1. P0.0 configured as an open collector digital output
driving an LED
2. P0.2 configured as an active drive digital output
driving an LED
3. P0.4 configured as a digital input receiving a TTL
signal from a gated invertor
4. P0.7 configured as a digital input receiving a 0 V
or 5 V signal from a switch
Caution Exceeding the maximum input voltage ratings or maximum output ratings
can damage the device and the computer. National Instruments is not liable for any
damage resulting from such signal connections. Refer to the NI USB-6008 Device
Specifications or NI USB-6009 Device Specifications for more information.
Source/Sink Information
The default configuration of the NI USB-6008/6009 digital I/O ports is open collector,
allowing 5 V operation, with an onboard 4.7 kΩ pull-up resistor. An external user-provided
pull-up resistor can be added to increase the source current drive up to a 8.5 mA limit per line,
as shown in the following figure.4
4This document uses NI-DAQmx naming conventions. Open-drain is called open collector and
push-pull is called active drive.
NI USB-6008/6009 User Guide | © National Instruments | 19