National Instruments NI PXI-4224 User Manual

PXI

NI PXI-4224 User Manual

NI PXI-4224 User Manual

August 2008
373752G-01

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The NI PXI-4224 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced
by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the
warranty period. This warranty includes parts and labor.

The media on which you receive National Instruments software are warranted not to fail to execute programming instructions, due to defects in
materials and workmanship, for a period of 90 days from date of shipment, as evidenced by receipts or other documentation. National Instruments
will, at its option, repair or replace software media that do not execute programming instruc tions if National Instruments receives notice of such defects
during the warranty period. National Instruments does not warrant that the operation of the software shall be uninterrupted or error free.

A Return Material Authorization (RMA) number must be obtained from the factory and clearly marked on the outside of the package before any
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Conventions

The following conventions are used in this manual:

<> Angle brackets that contain numbers separated by an ellipsis represent a

range of values associated with a bit or signal name—for example,
AO <3. .0>.

» The » symbol leads you through nested menu items and dialog box options

to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.

This icon denotes a note, which alerts you to important information.

This icon denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash. When this symbol is marked on
the product, refer to the Read Me First: Safety and Radio-Frequency
Interference document, shipped with the product, for precautions to take.

When symbol is marked on a product it denotes a warning advising you to
take precautions to avoid electrical shock.

When symbol is marked on a product it denotes a component that may be
hot. Touching this component may result in bodily injury.

bold Bold text denotes items that you must select or click in the software, such

as menu items and dialog box options. Bold text also denotes parameter
names.

italic Italic text denotes variables, emphasis, a cross-reference, hardware labels,

or an introduction to a key concept. Italic text also denotes text that is a
placeholder for a word or value that you must supply.

monospace Text in this font denotes text or characters that you should enter from the

keyboard, sections of code, programming examples, and syntax examples.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames and extensions, and code excerpts.

Contents

Chapter 1
About the NI PXI-4224

What You Need to Get Started ......................................................................................1-2

National Instruments Documentation ............................................................................1-3

Installing the Application Software, NI-DAQ, and the DAQ Device ...........................1-3

Installing the NI PXI-4224 ............................................................................................1-4

LED Pattern Descriptions ..............................................................................................1-4

Chapter 2
Connecting Signals

Connecting Signals to the NI PXI-4224 ........................................................................2-1

Front Signal Connector....................................................................................2-1

Analog Input Connections...............................................................................2-3

Floating Signal Source Connection...................................................2-11

Ground-Referenced Signal Connection ............................................2-12

Shielded Ground-Referenced Signal Connection

(Recommended) .............................................................................2-12

Chapter 3
Configuring and Testing

Verifying and Self-Testing the Signals Using Test Panels ............................................3-1

Configuring the NI PXI-4224 in MAX..........................................................................3-2

Creating a Voltage Task or Global Channel Using NI-DAQmx.....................3-2

Verifying and Self-Testing an NI-DAQmx Task or Global Channel.............. 3-3

Chapter 4
Theory of Operation

Theory of Operation.......................................................................................................4-1

Signal Conditioning Functional Overview ......................................................4-3

Measurement Considerations ..........................................................................4-3

Input Impedance................................................................................4-3

Common-Mode Rejection Ratio .......................................................4-4

Effective CMR ..................................................................................4-5

Timing and Control Functional Overview ......................................................4-5

Programmable Function Inputs .......................................................................4-6

Device and PXI Clocks ...................................................................................4-7

© National Instruments Corporation v NI PXI-4224 User Manual

Contents

Chapter 5
Using the NI PXI-4224

Developing Your Application ....................................................................................... 5-1

Typical Program Flow Chart........................................................................... 5-1

Overview of Typical Flow Chart .................................................................... 5-3

Creating a Task Using DAQ Assistant or Programmatically ........... 5-3

Adjusting Timing and Triggering..................................................... 5-3

Configuring Channel Properties ....................................................... 5-4

Acquiring, Analyzing, and Presenting.............................................. 5-5

Completing the Application.............................................................. 5-5

Developing an Application Using LabVIEW ................................................. 5-5

Using a DAQmx Channel Property Node in LabVIEW................... 5-7

Synchronization and Triggering...................................................................... 5-8

Synchronizing the NI PXI-4224 ..................................................................... 5-8

Synchronizing the NI PXI-4224 Using LabVIEW ........................... 5-10

Other Application Documentation and Material ........................................................... 5-11

Calibrating the NI PXI-4224 ......................................................................................... 5-12

Loading Calibration Constants........................................................................ 5-12

Self-Calibration............................................................................................... 5-12

External Calibration ........................................................................................ 5-13

Appendix A
Specifications

Appendix B
Timing Signal Information

Appendix C
Removing the NI PXI-4224

Appendix D
Common Questions

Glossary

Index

NI PXI-4224 User Manual vi ni.com

Figures

Contents

Figure 2-1. NI PXI-4224 Front Label ......................................................................2-3

Figure 2-2. Unshielded Floating Signal Source Connection

Using a D-SUB Connector ....................................................................2-4

Figure 2-3. Unshielded Grounded Signal Source Connection

Using a D-SUB Connector ....................................................................2-5

Figure 2-4. Shielded Floating Signal Source Connection

Using a D-SUB Connector ....................................................................2-6

Figure 2-5. Shielded Grounded Signal Source Connection

Using a D-SUB Connector ....................................................................2-7

Figure 2-6. Unshielded Floating Signal Source Connection

Using a Terminal Block ........................................................................2-8

Figure 2-7. Unshielded Grounded Signal Source Connection

Using a Terminal Block ........................................................................2-9

Figure 2-8. Shielded Floating Signal Source Connection

Using a Terminal Block ........................................................................2-10

Figure 2-9. Shielded Grounded Signal Source Connection

Using a Terminal Block ........................................................................2-11

Figure 4-1. Block Diagram of NI PXI-4224 ............................................................4-2

Figure 4-2. Effect of Input Impedance on Signal Measurements ............................4-4

Figure 4-3. AI CONV CLK Signal Routing ............................................................4-6

Figure 4-4. NI PXI-4224 PXI Trigger Bus Signal Connection................................4-8

Figure 5-1. Typical Program Flowchart...................................................................5-2

Figure 5-2. General Synchronizing Flowchart.........................................................5-9

Figure A-1. PXI-4224 Dimensions ...........................................................................A-4

Figure B-1. Typical Posttriggered Sequence ............................................................B-2

Figure B-2. Typical Pretriggered Sequence..............................................................B-2

Figure B-3. AI START TRIG Input Signal Timing .................................................B-3

Figure B-4. AI START TRIG Output Signal Timing...............................................B-3

Figure B-5. AI REF TRIG Input Signal Timing.......................................................B-4

Figure B-6. AI REF TRIG Output Signal Timing ....................................................B-5

Figure B-7. AI SAMP CLK Input Signal Timing ....................................................B-6

Figure B-8. AI SAMP CLK Output Signal Timing..................................................B-6

Figure B-9. AI CONV CLK Input Signal Timing ....................................................B-7

Figure B-10. AI CONV CLK Output Signal Timing .................................................B-8

Figure B-11. AI SAMPLE CLK TIMEBASE Signal Timing....................................B-9

Figure B-12. AI HOLD COMPLETE Signal Timing.................................................B-10

Figure C-1. Injector/Ejector Handle Position Before Device Removal....................C-2

© National Instruments Corporation vii NI PXI-4224 User Manual

Contents

Tables

Table 2-1. NI PXI-4224 25-Pin D-SUB Terminal Pin Assignments ..................... 2-2

Table 4-1. Signal Conditioning Functional Blocks ................................................ 4-3

Table 4-2. PXI Trigger Bus Timing Signals .......................................................... 4-9

Table 5-1. NI-DAQmx Properties .......................................................................... 5-4

Table 5-2. Programming a Task in LabVIEW ....................................................... 5-6

Table 5-3. Synchronizing the NI PXI-4224 Using LabVIEW ............................... 5-10

Table A-1. Maximum Sampling Rates.................................................................... A-1

NI PXI-4224 User Manual viii ni.com

About the NI PXI-4224

This chapter provides an introduction to the NI PXI-4224 device and its
installation.

The NI PXI-4224 is part of the NI PXI-4200 series of data acquisition
(DAQ) devices with integrated signal conditioning. The PXI-4200 series
reduces measurement setup and configuration complexity by integrating
signal conditioning and DAQ on the same product.

The NI PXI-4224 is an 8-channel isolated analog input device with a ±10 V
input range. It allows isolated analog measurements directly on the PXI
platform.

The NI PXI-4224 has the following characteristics:

• Each channel has a gain of either 1 or 10.

• An isolation rating of 42.4 V

• The front connector is a 25-pin D-SUB connector, with 16 pins for
analog input.

or 60 VDC, Category I.

peak

1

Signal connections are made through a TB-2725 terminal block that
provides connections for all eight analog input channels. You can
optionally connect a standard 25-pin D-SUB cable to the device and cable
it as needed for your application.

Note Go to ni.com/products to determine if newly developed terminal blocks are

available.

You can configure most settings on a per-channel basis through software.
The NI PXI-4224 is configured using Measurement & Automation
Explorer (MAX) or through function calls to NI-DAQmx.

Note The NI PXI-4224 is supported in NI-DAQmx only.

© National Instruments Corporation 1-1 NI PXI-4224 User Manual

Chapter 1 About the NI PXI-4224

What You Need to Get Started

To set up and use the NI PXI-4224, you need the following:

❑ Hardware

–NIPXI-4224

– One of the following:

• TB-2725 terminal block

• 25-pin D-SUB female connector

– PXI or PXI/SCXI combination chassis

❑ Software

– NI-DAQ 7.3.1 or later

– One of the following:

•LabVIEW

• Measurement Studio

• LabWindows

❑ Documentation

– NI PXI-4224 User Manual

– Read Me First: Safety and Radio-Frequency Interference

– DAQ Getting Started Guide

– PXI or PXI/SCXI combination chassis user manual

– Documentation for your software

™

/CVI

™

❑ Tools

– 1/8 in. flathead screwdriver

You can download NI documents from

NI PXI-4224 User Manual 1-2 ni.com

ni.com/manuals.

National Instruments Documentation

The NI PXI-4224 User Manual is one piece of the documentation set for
your DAQ system. You could have any of several types of manuals
depending on the hardware and software in your system. Use the manuals
you have as follows:

• DAQ Getting Started Guide—This document describes how to install
NI-DAQ devices and NI-DAQ. Install NI-DAQmx before you install
the SCXI module.

• SCXI Quick Start Guide—This document describes how to set up an
SCXI chassis, install SCXI modules and terminal blocks, and
configure the SCXI system in MAX.

• PXI or PXI/SCXI combination chassis manual—Read this manual for
maintenance information about the chassis and for installation
instructions.

• Accessory installation guides or manuals—If you are using accessory
products, read the terminal block installation guides. They explain how
to physically connect the relevant pieces of the system.

• Software documentation—You may have both application software
and NI-DAQmx software documentation. NI application software
includes LabVIEW, Measurement Studio, and LabWindows/CVI.
After you set up the hardware system, use either your application
software documentation or the NI-DAQmx documentation to help you
write your application. If you have a large, complicated system, it is
worthwhile to look through the software documentation before you
configure the hardware.

Chapter 1 About the NI PXI-4224

Installing the Application Software, NI-DAQ, and the DAQ Device

Refer to the DAQ Getting Started Guide, packaged with the NI-DAQ
software, for instructions for installing your application software, NI-DAQ
driver software, and the DAQ device to which you will connect the
NI PXI-4224.

NI-DAQ 7.3.1 or later is required to configure and program the
NI PXI-4224 device. If you do not have NI-DAQ 7.3.1 or later, you can
either contact an NI sales representative to request it on a CD or download

ni.com.

it from

© National Instruments Corporation 1-3 NI PXI-4224 User Manual

Chapter 1 About the NI PXI-4224

Installing the NI PXI-4224

Note Refer to the Read Me First: Radio-Frequency Interference document before

removing equipment covers or connecting or disconnecting any signal wires.

Refer to the DAQ Getting Started Guide to unpack, install, and configure
the NI PXI-4224 in a PXI chassis, and then to the SCXI Quick Start Guide
if you are using a PXI/SCXI combination chassis.

LED Pattern Descriptions

The following LEDs on the NI PXI-4224 front panel confirm the system is
functioning properly:

• The ACCESS LED is normally green and blinks yellow for a minimum
of 100 ms during the NI PXI-4224 configuration.

• The ACTIVE LED is normally green and blinks yellow for a minimum
of 100 ms during data acquisition.

NI PXI-4224 User Manual 1-4 ni.com

Connecting Signals

This chapter provides details about the front signal connector of the
NI PXI-4224 and how to connect signals to the NI PXI-4224.

Connecting Signals to the NI PXI-4224

After you have verified that the NI PXI-4224 is installed correctly and
self-tested the device, refer to the following sections to connect signals to
the device.

Caution Refer to the Read Me First: Safety and Radio-Frequency Interference document

before removing equipment covers, or connecting or disconnecting any signal wires.

Front Signal Connector

The NI PXI-4224 connection interface consists of a 25-pin D-SUB
connector and one SMB connector. You can program SMB connector
as a PFI 0 line or for external calibration. Table 2-1 shows the signal
assignments of the D-SUB connector for the NI PXI-4224. Figure 2-1
shows the front label, with each set of screw terminals labeled according
to the corresponding differential input signal for the NI PXI-4224.

2

To connect a signal to the NI PXI-4224, use a TB-2725 terminal block
designed specifically for the NI-PXI-4224, or use a 25-pin D-SUB to build
a connector to suit your application. Refer to the TB-2725 Terminal Block
Installation Guide if you are using the TB-2725 terminal block. Use
Table 2-1 to make the signal connections if you are constructing a
connector using a 25-pin D-SUB connector.

Connect a timing or triggering signal to the PFI 0/CAL SMB connector
using a cable with an SMB signal connector.

© National Instruments Corporation 2-1 NI PXI-4224 User Manual

Chapter 2 Connecting Signals

Caution The PFI 0/CAL SMB connector is for low-voltage timing and calibration signals

only. Voltages greater than ±15 V can damage the device.

If you are building a 25-pin D-SUB connector for your application, make sure you use a
connector and wires that are safety rated for the voltage and category of the signals in your
application.

Table 2-1. NI PXI-4224 25-Pin D-SUB Terminal Pin Assignments

Front Connector

Diagram

14 15 16 17 18 19 20 21 22 23 24 25

12345678910111213

Pin Number Signal Names Pin Number Signal Names

14 AI 0 – 1 AI 0 +

15 AI 1 – 2 AI 1 +

16 AI 2 – 3 AI 2 +

17 AI 3 – 4 AI 3 +

18 AI 4 – 5 AI 4 +

19 AI 5 – 6 AI 5 +

*

NC—No Connection

20 AI 6 – 7 AI 6 +

21 AI 7 – 8 AI 7 +

22 No Pin 9 No Pin

23 NC

*

10 D GND

24 SPI CLK 11 MISO

25 SELECT 12 MOSI

N/A N/A 13 +5 V

NI PXI-4224 User Manual 2-2 ni.com

Chapter 2 Connecting Signals

NI PXI-4224

8 Chan Isolation Amp

ACCESS ACTIVE

2

PFI 0/

CAL

12345678910111213

14 15 16 17 18 19 20 21 22 23 24 25

1

3

1 ACCESS and ACTIVE LEDs
2 SMB PFI 0/CAL Connector

3 25-Pin D-SUB or TB-2725 Terminal

Block Connector

Figure 2-1. NI PXI-4224 Front Label

Analog Input Connections

The following sections provide a definition of the signal source
characteristics, descriptions of various ways to connect signals to the
NI PXI-4224, and electrical diagrams showing the signal source and
connections. Whenever possible, use shielded twisted-pair field wiring
and grounding to reduce the effects of unwanted noise sources.

© National Instruments Corporation 2-3 NI PXI-4224 User Manual

Chapter 2 Connecting Signals

Caution If you are building a 25-pin D-SUB connector for your application, make sure

you use a connector and signal wires that are safety rated for the voltage and category of
the signals in your application.

In the electrical diagrams, two different ground symbols are used. These
symbols indicate that you cannot assume that the indicated grounds are at
the same potential. Refer to Appendix A, Specifications, for maximum
working voltage specifications.

You can make signal connections to the NI PXI-4224 through either an
NI terminal block, such as the TB-2725, or you can build a connector using
a 25-pin D-SUB.

Figures 2-2 through 2-5 illustrate connecting signals using a D-SUB
connector.

Signal Source

+

V

SIG

–

Tw isted-Pair

Wiring

AI 0 +

AI 0 –

AI 7 +

AI 7 –

CH 0

CH 7

Figure 2-2. Unshielded Floating Signal Source Connection Using a D-SUB Connector

NI PXI-4224 User Manual 2-4 ni.com

Chapter 2 Connecting Signals

Signal Source

+

V

SIG

–

V

Ground

SIG

Reference

Tw isted-Pair

Wiring

AI 0 +

CH 0

AI 0 –

CH 7

AI 7 +

AI 7 –

Figure 2-3. Unshielded Grounded Signal Source Connection Using a D-SUB Connector

© National Instruments Corporation 2-5 NI PXI-4224 User Manual

Chapter 2 Connecting Signals

Signal Source

+

V

SIG

–

Shielding

Wiring

CH 0

AI 0 +

AI 0 –

CH 7

AI 7 +

AI 7 –

Figure 2-4. Shielded Floating Signal Source Connection Using a D-SUB Connector

Tw isted-Pair

NI PXI-4224 User Manual 2-6 ni.com

Chapter 2 Connecting Signals

Signal Source

+

V

SIG

–

V

Ground

SIG

Reference

Shielding

Wiring

CH 0

AI 0 +

AI 0 –

CH 7

AI 7 +

AI 7 –

Figure 2-5. Shielded Grounded Signal Source Connection Using a D-SUB Connector

Tw isted-Pair

© National Instruments Corporation 2-7 NI PXI-4224 User Manual

Chapter 2 Connecting Signals

Figures 2-6 through 2-9 illustrate connecting signals using a terminal
block.

Signal Source

+

V

SIG

–

Tw isted-Pair

Wiring

Terminal Block

AI 0 +

AI 0 –

AI 7 +

AI 7 –

CH 0

CH 7

Figure 2-6. Unshielded Floating Signal Source Connection Using a Terminal Block

NI PXI-4224 User Manual 2-8 ni.com

Chapter 2 Connecting Signals

Signal Source

+

V

SIG

–

V

Ground

SIG

Reference

Tw isted-Pair

Wiring

Terminal Block

AI 0 +

CH 0

AI 0 –

CH 7

AI 7 +

AI 7 –

Figure 2-7. Unshielded Grounded Signal Source Connection Using a Terminal Block

© National Instruments Corporation 2-9 NI PXI-4224 User Manual

Chapter 2 Connecting Signals

Signal Source

+

V

SIG

–

Tw isted-Pair

Wiring

Shielding

Terminal Block

CH 0

AI 0 +

AI 0 –

CH 7

AI 7 +

AI 7 –

Figure 2-8. Shielded Floating Signal Source Connection Using a Terminal Block

NI PXI-4224 User Manual 2-10 ni.com

Chapter 2 Connecting Signals

Signal Source

+

V

SIG

–

V

Ground

SIG

Reference

Tw isted-Pair

Wiring

Shielding

Terminal Block

CH 0

AI 0 +

AI 0 –

CH 7

AI 7 +

AI 7 –

Figure 2-9. Shielded Grounded Signal Source Connection Using a Terminal Block

Floating Signal Source Connection

Figures 2-2, 2-4, 2-6, and 2-8 illustrate floating signal source connections.
In this configuration, the signal source being measured is a floating signal
source, such as a battery. A floating signal source is not connected in
any way to the building ground system.

To connect a floating signal source connection to the NI PXI-4224, the
signal (V
signal reference (V

© National Instruments Corporation 2-11 NI PXI-4224 User Manual

+) is connected to the NI PXI-4224 channel (AI X +). The

SIG

–) is connected to the channel reference (AI X –).

SIG

Chapter 2 Connecting Signals

Ground-Referenced Signal Connection

Figures 2-3, 2-5, 2-7, and 2-9 illustrate the ground-referenced signal
connection. In this configuration, the voltage source being measured is
referenced to its own ground reference that is connected through a
conductive path to the instrument ground reference. For example, the path
can be through a common earth ground or through the power line ground.

To connect a ground-reference signal source to the NI PXI-4224, the signal

+) is connected to the NI PXI-4224 channel (AI X +). The signal

(V

SIG

reference (V

–) is connected to the channel reference (AI X –).

SIG

Shielded Ground-Referenced Signal Connection (Recommended)

Figures 2-5 and 2-9 illustrate shielded ground-referenced signal
connections. The connection to this signal source is identical to the
ground-referenced signal connection with the addition of shielding
around the field wiring. The shielding is grounded at the signal source
ground (V

Ground Reference). Connect the signal (V

SIG

NI PXI-4224 channel (AI X +). Connect the signal reference (V
channel reference (AI X –).

+) to the

SIG

–) to the

SIG

This shielding scheme is effective at reducing capacitive or electrically
coupled noise. The same concerns regarding the difference in ground
potentials, discussed in the Ground-Referenced Signal Connection section,
also apply to this configuration.

For more information about the function of the NI PXI-4224 and other
measurement considerations, refer to Chapter 4, Theory of Operation.

NI PXI-4224 User Manual 2-12 ni.com

3

Configuring and Testing

This chapter provides details about configuring and testing the
NI PXI-4224 in MAX, including how to use device test panels and create
and configure NI-DAQmx Tasks and NI-DAQmx Global Channels.

Verifying and Self-Testing the Signals Using Test Panels

After you have successfully installed the NI PXI-4224, verified the
installation, and connected the signals, use the NI PXI-4224 device test
panels to verify the device is measuring signals properly.

The test panels allow you to measure the signal connected to the
NI PXI-4224 directly as well as configure some of the properties of your
measurement. To open the NI PXI-4224 device test panels when in MAX,
complete the following steps:

1. Expand Devices and Interfaces to display the list of devices and

interfaces.

2. Expand NI-DAQmx Devices to display the list of NI-DAQmx devices.

3. Click PXI-4224.

4. Click the Test Panels button in the device toolbar.

5. Configure the settings on the screen, and click Start to take a

measurement.

To measure scaled voltages, further configure channel properties, and
configure timing settings, use an NI-DAQmx Task or NI-DAQmx Global
Channel.

© National Instruments Corporation 3-1 NI PXI-4224 User Manual

Chapter 3 Configuring and Testing

Configuring the NI PXI-4224 in MAX

This section describes how to create NI-DAQmx Tasks and NI-DAQmx
Global Channels in MAX that allow you to take measurements with the
NI PXI-4224.

Creating a Voltage Task or Global Channel Using NI-DAQmx

An NI-DAQmx Global Channel gives a physical channel a name and
provides scaling. An NI-DAQmx Task is a collection of channels with
timing and triggering configured. To create a new NI-DAQmx Task or
NI-DAQmx Global Channel, complete the following steps:

1. Double-click the Measurement & Automation Explorer icon on the
desktop.

2. Right-click Data Neighborhood and select Create New.

3. Select NI-DAQmx Task or NI-DAQmx Global Channel and
click Next.

4. Select Analog Input and select Voltage.

5. If you are creating a channel, you can select only one channel. If you
are creating a task, select the channels to add to the task. You can select
a range of channels by holding down the <Shift> key while selecting
the channels. You can select multiple individual channels by holding
down the <Ctrl> key while selecting channels. Click Next.

6. Enter the name of the task or channel, and click Finish.

7. Select the channel(s) you want to configure for input voltage range.
While making the selections you can select blocks of channels by
pressing the <Shift> key or individual channels by pressing the
<Ctrl> key.

8. Under the Settings tab, set the input range by entering the Min and
Max values.

9. Click the Device tab and select the Autozero mode.

10. Repeat steps 7 through 9 until you have configured all the channels.

Note For more information about how to further configure the NI PXI-4224, or how to use

LabVIEW to configure the device and take measurements, refer to Chapter 4, Theory of

Operation.

NI PXI-4224 User Manual 3-2 ni.com