National Instruments PCI-4452, PCI-4451 User Manual

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DAQ

PCI-4451/4452 User Manual

Dynamic Signal Acquisition Device for PCI

April 1998 Edition

Part Number 321891A-01

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Important Information

Warranty

The PCI-4451/4452 is warranted against defe cts in mate ria l s 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 instructions 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 equipment will be accepted for warranty wo rk. National Instru ments will pay the shippi ng costs of returning to the owner part s which are c overed by warranty.

National Instruments believes that the informatio n in this manual is accurate. The document ha s been careful ly reviewed for technical accurac y. In the even t that te chn ical or t ypograp hic al errors ex ist, Nation al Inst rumen ts res erves the righ t to make changes to subsequent editions of this document without prior notice to holders of this edition. The reader should consult National Instruments if errors are suspected. In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it.

XCEPT AS SPECIFIED HEREIN

ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER OR INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY THEREOF

National Instruments will apply regardless of the form of action, whether in contract or tort, including negligence. Any action against National Instruments must be brought within one year after the cause of action accrues. National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control. The warranty provided herein does not cover damages, defects, malfunctions, or service failures caused by owner’s failure to follow the National Instruments installation, operation, or maintenance instructions; owner’s modification of the product; owner’s abuse, misuse, or negligent acts; and power failure or surges, fire, flood, accident, actions of third parties, or other events outside reasonable control.

ATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA, PROFITS, USE OF PRODUCTS

. N

ATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS

, N

Copyright

Under the copyright laws, this publication may not be reproduced or transmitted in any form, electronic or mechanical, including photocopyi ng, recordi ng, sto ring in an inform ati on retriev al syste m, or translat ing , in whole or in part, with out the prior written consent of National Instruments Corporation.

USTOMER’S RIGHT TO RECOVER DAMAGES CAUSED

. C

. This limitation of the liability of

Trademarks

ComponentWorks™, CVI™, LabVIEW™, Measure™, NI-DAQ™, and VirtualBench™ are trademarks of Nationa l Instruments Corporation.

Product and company names listed are trademarks or trade names of their respective companies.

WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS

National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans. Applications of National Instruments products involving medical or clinical treatment can create a potential for accidental injury caused by product failure, or by errors on the part of the user or application des igner. An y use or ap plica tion of Na tiona l Instrume nts p roducts for or inv olvi ng medic al or c linica l treatment must be performed by properly trained and qualifie d medic al pe rsonnel, an d all traditio nal med ical sa feguards, equipment, and p roce dures tha t ar e a ppropria te in th e pa rticula r s itua tion to p revent s erious inju ry or d eath shou ld alway s continue to be used whe n National Instruments pro ducts are being use d. Nation al Instrumen ts product s are NOT inte nded to be a substitute for any fo rm of establis hed process, pro cedure, or e quipment us ed to monito r or safeguard h uman heal th and safety in medical or clinical treatment.

About This Manual

Organization of This Manual.........................................................................................ix

Conventions Used in This Manual.................................................................................x

National Instruments Documentation............. ...... ..... ........................................ ............xi

Related Documentation..................................................................................................xi

Customer Communication.............................................................................................xi

Chapter 1 Introduction

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

Unpacking......................................................................................................................1-2

Software Programming Choices....................................................................................1-3

National Instruments Application Software....................................................1 -3

Optional Equipment.......................................................................................................1-4

Custom Cabling .............................................................................................................1-4

Chapter 2 Installation and Configuration

Software Installation......................................................................................................2-1

Hardware Installation.....................................................................................................2-1

Device Configuration................................................................................... ..................2-2

Chapter 3 Hardware Overview

Analog Input..................................................................................................................3-3

Input Mode ............................................................................... .......................3-3

Input Coupling......................................................... ..... ...................................3-3

Input Polarity and Input Range........................................................................3-3

Considerations for Selecting Input Ranges.....................................................3-4

Analog Output................................................................................................................3-5

Output Mode....................................................................................................3-5

Output Polarity and Output Range..................................................................3-5

Trigger ...........................................................................................................................3-6

RTSI Triggers ..................................................................................................3-9

Digital I/O......................................................................................................................3-10

Timing Signal Routing...................................................................................................3-11

Programmable Function Inputs....................................................................... 3 -11

National Instruments Corporation v PCI-4451/4452 User Manual

Contents

Device and RTSI Clocks.................................................................................3-11

Selecting Sample/Update Clock Frequency..................................................................3-12

Device Configuration Issues......................... ...... ...... ....................................... ..............3-13

Chapter 4 Signal Connections

I/O Connectors...............................................................................................................4-1

Analog I/O Connector Signal Descriptions ....................................................4-2

Digital I/O Connector Signal Descriptions.....................................................4-5

Analog Input Signal Connections..................................................................................4-9

Types of Signal Sources................................................................................................4-10

Floating Signal Sources ..................................................................................4-10

Ground-Referenced Signal Sources................................................................4-10

Analog Output Signal Connections...............................................................................4-11

Analog Power Connections........................................................................................... 4-12

Digital I/O Signal Connections ..................................................................................... 4-12

Digital Power Connections............................................................................................ 4-14

Timing Connections...................................................................................................... 4-14

Programmable Function Input Connections ...................................................4-14

Acquisition Timing Connections.......................... ...... ..... ...............................4-15

Waveform Generation Timing Connections...................................................4-18

General-Purpose Timing Signal Connections.................................................4-19

Field Wiring Considerations..........................................................................................4-24

PFI0/TRIG1 (EXT_TRIG) Signal....................................................4-16

PFI1/TRIG2 (PRETRIG) Signal ...................................................... 4-17

CONVERT* Signal..........................................................................4-17

EXTSTROBE* Signal......................................................................4-18

WFTRIG Signal................................................................................4-18

UPDATE* Signal .............................................................................4-18

GPCTR0_SOURCE Signal ..............................................................4-19

GPCTR0_GATE Signal ........................................................... ...... ..4-20

GPCTR0_OUT Signal......................................................................4-20

GPCTR0_UP_DOWN Signal...........................................................4-20

GPCTR1_SOURCE Signal ..............................................................4-21

GPCTR1_GATE Signal ........................................................... ...... ..4-21

GPCTR1_OUT Signal......................................................................4-22

GPCTR1_UP_DOWN Signal...........................................................4-22

FREQ_OUT Signal....................................... ..... ...... .........................4-24

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Chapter 5 Calibration

Loading Calibration Constants......................................................................................5-1

Self-Calibration..............................................................................................................5-2

External Calibration.......................................................................................................5-2

Traceable Recalibration.................................................................................................5-3

Chapter 6 Theory of Analog Operation

Functional Overview......................................................................................................6-1

Analog Input Circuitry................................................................................................... 6 -1

Input Coupling......................................................... ..... ...................................6-2

Calibration............ ...... ....................................... ..............................................6-2

Antialias Filtering........................................ ...... ...... ....................................... .6-3

The ADC .........................................................................................................6-8

Noise................................................................................................................6-9

Analog Output Circuitry................................................................................................6-10

Anti-Image Filtering........................................................................................6-10

The DAC .........................................................................................................6-12

Calibration.......................................................................................................6-12

Mute Feature........................................... ..... ...... ........................................ ......6-13

Contents

Appendix A Specifications

Appendix B Pin Connections

Appendix C Customer Communication

Glossary

Index

National Instruments Corporation vii PCI-4451/4452 User Manual

Contents

Figures

Figure 3-1. Digital Function Block Diagram...........................................................3-1

Figure 3-2. Analog Function Block Diagram..........................................................3-2

Figure 3-3. Below-Low-Level Triggering Mode.....................................................3-7

Figure 3-4. Above-High-Level Triggering Mode.................................................. ..3-8

Figure 3-5. Inside-Region Triggering Mode ...........................................................3-8

Figure 3-6. High-Hysteresis Triggering Mode........................................................ 3-8

Figure 3-7. Low-Hysteresis Triggering Mode.........................................................3-9

Figure 3-8. RTSI Bus Signal Connection................................................................3-10

Figure 4-1. Analog Pin Connections .......................................................................4-2

Figure 4-2. Digital Pin Connections........................................................................4-5

Figure 4-3. Analog Input Stage ...............................................................................4-9

Figure 4-4. Analog Output Channel Block Diagram............................................... 4-11

Figure 4-5. Digital I/O Connections........................................................................4-13

Figure 4-6. Typical Posttriggered Acquisition ........................................................4-15

Figure 4-7. Typical Pretriggered AcquisitionPFI1.................................................. 4-16

Figure 4-8. EXTSTROBE* Signal Timing .............................................................4-18

Figure 4-9. GPCTR0_SOURCE Signal Timing......................................................4-19

Figure 4-10. GPCTR0_OUT Signal Timing .............................................................4-20

Figure 4-11. GPCTR1_SOURCE Signal Timing......................................................4-21

Figure 4-12. GPCTR1_OUT Signal Timing .............................................................4-22

Figure 4-13. GPCTR Timing Summary ....................................................................4-23

Figure 6-1. Input Frequency Response....................................................................6-5

Figure 6-2. Input Frequency Response Near the Cutoff..........................................6-6

Figure 6-3. Alias Rejection at the Oversample Rate...............................................6-7

Figure 6-4. Comparison of a Clipped Signal to a Proper Signal .............................6-8

Figure 6-5. Signal Spectra in the DAC....................................................................6-11

Figure A-1. Idle Channel Noise (Typical)................................................................A-4

Figure B-1. 68-Pin Digital Connector for any Digital Accessory............................B-2

Tables

Table 3-1. Actual Range and Measurement Precision...........................................3-4

Table 3-2. Actual Range and Measurement Precision...........................................3-6

Table 4-1. Analog I/O Connector Pin Assignment................................................4-3

Table 4-2. Analog I/O Signal Summary.................................................................4-4

Table 4-3. Digital I/O Connector Pin Assignment................................................. 4-6

Table 4-4. Digital I/O Signal Summary .................................................................4-8

PCI-4451/4452 User Manual viii

National Instruments Corporation

About This Manual

This manual describes the electrical and mechanical aspects of the PCI-4451 and PCI-4452 devices and cont ains information co ncerning their operation. Unless otherwise noted, the text applies to both devices.

The PCI-4451 and PCI-4452 are high-performance, high-accuracy analog input/output (I/O) devices for the PCI bus. These devices also support digital I/O (DIO) functions, counter/timer functions, and external trigger functions.

Organization of This Manual

The PCI-4451/4452 User Manual is organized as follows:

• Chapter 1, Introduction, describes the PCI-4451 and PCI-4452 devices, lists what yo u need to get start ed, explains how to u npack your devices, and describes the optional software and optional equipment.

• Chapter 2, Installation and Configuration, explains how to install and configure your PCI-4451/4452 device.

• Chapter 3, Hardware Overview, presents an overview of the hardware functions on your PCI-4451/4452 device.

• Chapter 4, Signal Connections, describes how to make input and output connections to your PCI-4451/4452 device via the analog I/O and digital I/O connectors of the device.

• Chapter 5, Calibration, discusses the calibration procedures for your PCI-4451/4452 device.

• Chapter 6, Theory of Analog Operation, contains a functional overview and explains the operation of each analog functional unit making up the PCI-4451/4452.

• Appendix A, Specifications, lists the specifications of the PCI-4451/4452.

• Appendix B, Pin Connections, describes the pin connections on the optional 68-pin digital accessories for the PCI-4451/4452 devices.

• Appendix C, Customer Communication, contains forms you can use to request help from National I nstruments or to comment on our products and manuals.

National Instruments Corporation ix PCI-4451/4452 User Manual

About This Manual

•The Glossary contains an alphabetical list and description of terms used in this manual, including abbreviations, acronyms, metric prefixes, mnemonics, and symbols.

•The Index contains an alphabetical list of key terms and topics in this manual, including the page where you can find each one.

Conventions Used in This Manual

The following conventions are used in this manual:

<> Angle brackets enclose the name of a key on the keyboard—for example,

<shift>. Angle brackets containing numbers separated by an ellipsis represent a range of values associated with a bit or signal name—for example, DBIO<3..0>.

♦ The ♦ symbol indicates that the text following it applies only to a specific

product, a specific operating system, or a specific software version.

* An asterisk following a signal name denotes an ACTIVE LOW signal.

This icon to the left of bold italicized text denotes a note, which alerts you to important information.

bold italic Bold italic text denotes an activity objective, note, caution, or warning. DSA DSA refers to dynamic signal acquisition. italic Italic text denotes v ariables, emphasis, a cross reference, or an introduction

SE SE means referenced single ended (RSE). SE and RSE are equivilant.

PCI-4451/4452 User Manual x

This icon to the left of bold italicized text denotes a caution, which advises you of precautions to take to avoid injury, data loss, or a system crash.

to a key concept. This font also denotes text from which you supply the appropriate word or value, as in NI-DAQ 6.x.

National Instruments Corporation

National Instruments Documentation

The PCI-4451/4452 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:

• Software documentation—You may have both application software and NI-DAQ software documentation. National Instruments application software includes ComponentWorks, LabVIEW, LabWindows/CVI, Measure, and VirtualBench. After you set up your hardware system, use either your application softw are do cumen t ation or the NI-DAQ 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 your hardware.

• Accessory installation guides or manuals—If you are using accessory products, read the terminal block and cable assembly installation guides. They explain how to physically connect the relevant pieces of the system. Consult these guides when you are making your connections.

About This Manual

Customer Communication

National Instruments wants to receive your comments on our products and manuals. We are interest ed in the applications you develop with our products, and we want to help if you have problems with them. To make it easy for you to contact us, thi s manual contains comment and conf iguration forms for you to complete. These forms are in Appendix C, Customer

Communication, at the end of this manual.

National Instruments Corporation xi PCI-4451/4452 User Manual

Introduction

This chapter describes the PC I-445 1 and PCI -4452 d evices , lists what you need to get started, explains how to unpack you r devices, and describes the optional software and optional equipment.

The PCI-4451/4452 are high-performance, high-accuracy analog I/O devices for the PCI bus. These de vices are members of the PCI-DSA series and are specifically designed for demanding dynamic signal acquisition applications. The PCI-4451 has two channels of 16-bit simultaneously sampled input at 204.8 kS/s and two channels of 16-bit simultaneously updated output at 51.2 kS/s, while the PC I-4452 has four chan nels of 16-bit simultaneously sampled analog input at 204.8 kS/s. Inf ormation on anal og output applies only to the PCI-4451, where as information on anal og input applies to both the PCI-4451 and the PCI-4452.

Both the analog input and the analog output circuitry have oversampling delta-sigma modulating converters. Delta-sigma converters are inherently linear, provide built-in brick-wall anti-aliasing/imaging filters, and have specifications that exceed other conventional technology for this application with regard to THD, SNR, and amplitude flatness. You can use these high-quality specifications and features to acquire or generate signals with high-accuracy and fidelity without introducing n oise or out-of-band aliases.

Applications include audio signal processing and analysis, acoustics and speech research, sonar, audio frequency test and measurement, vibration and modal analysis, or any application requ iring high-fidelity signal acquisition with a bandwidth up to 95 kHz or signal generation with a bandwidth up to 23 kHz.

National Instruments Corporation 1-1 PCI-4451/4452 User Manual

Chapter 1 Introduction

What You Need to Get Started

To set up and use your PCI-4451 or PCI-4452, you will need the following:

❑ One of the following devices:

PCI-4451 PCI-4452

❑ PCI-4451/4452 Series User Manual ❑ You may have one or more of the following software packages and

documentation:

LabVIEW for Windows LabWindows/CVI for Windows NI-DAQ for PC Compatibles VirtualBench-DSA ComponentWorks Measure

❑ Your co mputer

Unpacking

❑

SHC68-C68-A1

analog cable

❑ BNC-2140 accessory

Your PCI-4451/4452 is shipped in an antistatic plastic package to prevent electrostatic damage to the device. Electrostatic discharge can damage components on the instrument. To avoid such damage in handling the device, take the following precautions:

• Ground yourself vi a a grounding strap or by hold ing a grounded obj ect.

• Touch the plastic package to a metal part of your computer chassis before removing the device from the package.

• Remove the device from the package and inspect the device for loose components or any other si gn of damage. Notify National In struments if the device appears damaged in any way. Do not install a damaged device into your computer.

• Never touch the exposed pins of connectors.

PCI-4451/4452 User Manual 1-2

National Instruments Corporation

Software Programming Choices

There are several options to choose from to program and use your National Instruments device. You can use LabVIEW for Windows, LabWindows/CVI for Windows, VirtualBench-DSA, ComponentWorks, and Measure.

National Instruments Application Software

LabVIEW and LabWindows/CVI are innovative program development software packages for data acquisition and control applications. LabVIEW uses graphical programming, whereas LabWindows/CVI enhances traditional programing languages. Both packages include extensive libraries for data acquisition, instrument control, data analysis, and graphical data presentation.

LabVIEW features interactive graphics, a state-of-the-art user interface, and a powerful graphical programming language. The LabVIEW Data Acquisition VI Library, a series of VIs for using LabVIEW with National Instruments device hardware, is included with LabVIEW. The LabVIEW Data Acquisition VI Library is functionally equivalent to the NI-DAQ software.

Chapter 1 Introduction

LabWindows/CVI features interactive graphics, a state-of-the-art user interface, and uses the ANSI C programming language. The LabWindows/CVI Data Acquisition, a series of functions for using LabWindows/CVI with National Instruments device hardware, is included with the NI-DAQ software kit. The LabWindows/CVI Data Acquisition library is functionally equivalent to the NI-DAQ software.

VirtualBench is a suite of VIs that allows you to use your data acquisition products just as you use stand-alone instruments, but you benefit from processing, display, and storage capabilities of PCs. VirtualBench instruments load and save waveform data to disk in the same forms used in popular spreadsheet programs and word processors. A report generation capability complements the raw data storage by adding timestamps, measurements, user name, and comments.

The complete VirtualBench suite contains VirtualBench-Scope, VirtualBench-DSA, VirtualBench-Function Generator, VirtualBench-FG, VirtualBench-Arb, VirtualBench-AODC, VirtualBench-DIO, VirtualBench-DMM, and VitualBench-Logger. Your PCI 4451/4452 comes with VirtualBench-DSA. VirtualBench-DSA is a turnkey

National Instruments Corporation 1-3 PCI-4451/4452 User Manual

Chapter 1 Introduction

application you can use to make measurements as you would with a standard dynamic analyzer.

ComponentWorks contains tools for data acquisition and instrument control built on NI-DAQ driver software. ComponentWorks provides a higher-level programming interface for building virtual instruments with Visual Basic, V isual C++, Borland Delphi, and Microsoft Internet Explorer . With Com ponentW orks, you can use al l of the configurat ion tools, resource management utilities, and interactive control utilities included in NI-DAQ.

Measure is a data acquisition and instrument control add-in for Microsoft Excel. With Measure, you can acquire data directly from plug-in DAQ boards, GPIB instruments, or serial (RS-232) devices. Measure has easy-to-use dialogs for configurin g your measurements. Your data is placed directly into Excel worksheet cells, from which you can perform your analysis and report generations using the full power and flexibility of Excel.

Optional Equipment

National Instruments offers a variety of products to use with your PCI-4451/4452 series devices, including cables and connector blocks as follows:

•

SHC50-68 digital cable

•

Shielded and DIN rail mountable 68-pin connector blocks

•

RTSI cables

Custom Cabling

National Instruments offers cable s of different l engths and the BNC-2140 DSA accessory to connect your analog I/O to the PCI-4451/4452. National Instruments recommends you do not develop your own cabling solution due to the difficulty of working with the high-density connector and the need to maintain high signal integrity . Howeve r, if your application requires that you develop your own cable use the following guidelines:

• Use shielded twisted-pair wires for each differential analog input or output channel pair. Since the signals are differential, using this type of wire yields the best results.

• When connecting the cable shields, be sure to connect the analog input grounds to the AIGND pins and the analog output grounds to the AOGND pins. For a conne ctor pin assignment, refer to Table 4- 1,

Analog I/O Connector Pin Assignment.

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National Instruments Corporation

Chapter 1 Introduction

• To create your own accessories, you can use an AMP 68-pin right-angle PWB receptacle header, part number 787254-1.

• Recommended manufacturer part numbers for the 68-pin mating connector for the cable assembly are as follows:

– AMP 68-position straight cable plug, part number 787131-3 – AMP 68-position backshell with jackscrews, part number

787191-1

National Instruments also offers cables of differ ent lengths and accessories to connect your digital I/O si gn als to th e PC I-4451/4452. To develop your own cable, the mating connector for the digital I/O is a 50-position receptacle. For a connector pinout assignment, refer to Table 4-3, Digital

I/O Connector Pin Assignment. Recommended manufacturer part numbers

for this mating connector are as follows:

• 50-position straight cable plug, part number 787131-1

• 50-position backshell with jackscrews, part number 787233-1

Refer to Appendix B, Pin Connections , for pin assign ments of digital accessories and cables.

National Instruments Corporation 1-5 PCI-4451/4452 User Manual

Installation and Configuration

This chapter explains how to install and configure your PCI-4451/4452 device.

Software Installation

Note

Install your software before you install your PCI-4451/4452 device.

If you are using NI-DAQ, refer to your NI-DAQ release notes. Find the installation section for your operating system and follow the instructions given there. If you are using LabVIEW, LabWindows/CVI, or other National Instruments application software, refer to the appropriate release notes. After you have installed your application software, refer to your NI-DAQ release notes and follow the instructions given there for your operating system and application software package.

Hardware Installation

You can install the PCI-4451/4452 device in any available PCI expansion slot in your computer. However, to achieve the best noise performance, leave as much room as possible between the PCI-4451/4452 device and other devices and hardware. The following are general installation instructions, but consult your computer user manual or techn ical reference manual for specific instructions and warnings:

1. Write down the PCI-4451/4452 device serial number in the

PCI-4451/4452 Hardware and Software Configuration Form in

Appendix C, Customer Communication, of this manual.

2. Turn off and unplug your computer.

3. Remove the top cover or access port to the I/O channel.

4. Remove the expansion slot cover on the back panel of the computer.

5. Insert the PCI-4451/4452 device into a 5 V PCI slot. It should fit snugly, but do not force the device into place.

6. Screw the mounting bracket of the PCI-4451/4452 device to the back panel rail of the computer.

National Instruments Corporation 2-1 PCI-4451/4452 User Manual

Chapter 2 Installation and Configuration

7. Check the installation.

8. Replace the cover.

9. Plug in and turn on your computer. The PCI-4451/4452 de vice is now installe d. Y ou are now ready t o configure

your software.

Device Configuration

The PCI-4451/4452 devices are completely software configurable. However, you must perform two types of configuration—bus-related and data acquisition-related.

The PCI-4451/4452 devices are fully compatible with the industry standard PCI Local Bus Specification Revision 2.0. The PCI system automatically performs all bus-related configurations and requires no interaction from you. Bus-related configuration includes setting the device base memory address and interrupt channel.

Data acquisition related configuration includes such setting s as an alog input polarity and range, analog input mode, and others. You can modify these settings through National Instruments application level software, such as ComponentWorks, LabVIEW, LabWindows/CVI, and VirtualBench or driver software such as NI-DAQ.

PCI-4451/4452 User Manual 2-2

National Instruments Corporation

Hardware Overview

This chapter presents an overview of the hardware functions on your PCI-4451/4452 device. Figure 3-1 shows a block diagram of the digital functions. Figure 3-2 shows a block diagram of the analog functions. The two function blocks connect through the analog mezzanine bus.

Analog Mezzanine Bus (to Analog Section)

Analog Mezzanine Control

Clock Generator

Digital I/O Bus

RTSI Bus

†

PCI-4451 only

Direct Digital

Synthesis

DAQ-STC

Clock Control

General Control

Functions

MITE

PCI Controller

PCI Bus

Figure 3-1.

Parallel <-> Serial

Converter

FIFO and DMA

Control

Digital Function Block Diagram

AI FIFO

AO FIFO

†

National Instruments Corporation 3-1 PCI-4451/4452 User Manual

Chapter 3 Hardware Overview

Analog Bus

ENABLE0

ENABLE1

Output

Enable

DIFF

ATTEN

††

DAC0

ADC0

DIFF

Gain

Filter

AMP

DIFF

ATTEN

††

DAC1

ADC1

DIFF

Gain

Filter

AMP

†

ADC2

Filter

DIFF

Gain

AMP

†

DIFF

Gain

ADC3

Filter

AMP

Control

Attenuation

Calibration

Gain/Offset

Manager

DAC Clock

DAC Control

General Control

Serial Data Manager

Digital

Detect

Overrange

ADC Control

Calibration

Gain/Offset

Detect

Analog

Overrange

Gain

Control

ADC Clock

Manager

Trigger

EEPROM

Control

Analog Mezzanine Bus (to Digital Section)

MUX0

ATTEN

0 dB/20 dB

MUX0

AC/DC

Coupling

MUX0

INPUT/CAL

MUX1

ATTEN

0 dB/20 dB

MUX1

AC/DC

Coupling

MUX1

INPUT/CAL

MUX2

ATTEN

0 dB/20 dB

MUX2

AC/DC

Coupling

MUX2

INPUT/CAL

Analog Bus

Figure 3-2.

PCI-4451/4452 User Manual 3-2

MUX3

ATTEN

0 dB/20 dB

MUX3

AC/DC

Coupling

MUX3

INPUT/CAL

MUX

ATTEN

Control

MUX

AC/DC

Control

MUX

Control

INPUT/CAL

Analog Function Block Diagram

PCI-4451 only

††

PCI-4452 only

†

National Instruments Corporation

Analog Input

Input Mode

Input Coupling

Chapter 3 Hardware Overview

The analog input section of each PCI-4451/4452 device is software configurable. You can select di fferent anal og input con figuratio ns through application software. The following sections describe in detail each of the analog input categories.

The PCI-4451/4452 devices use differential (DIFF) inputs. You can configure the input as a referenced single ended (SE) channel using the BNC-2140 DSA accessory. For more information, please refer to the BNC-2140 Use r Manual. In DIFF mode, one line connects to the positive input of the channel, and the other connects to the negative inp ut of the same channel. You can connect the differential input to SE or DIFF signals, either floating or ground-referenced. However, grounding the negative input from floating sources may impr ove the measurement quality by removing the common-mode noise.

The PCI-4451/4452 has a software-programmable switch that determines whether a capacitor is placed in the signal path. If the switch is set for DC, the capacitor is bypassed and any DC offset present in the source signal is passed to the ADC. If the source has a significant amount of unwanted offset (bias voltage), you must set the switch for AC coupling to place the capacitor in the signal path and take full advantage of the input signal range.

Input Polarity and Input Range

The PCI-4451/4452 devices operate in bipolar mode. Bipolar input means that the input voltage range is between –V The PCI-4451/4452 has a bipolar input range of 20 V (±10 V) for a gain of 1.0 (0 dB).

You can program the range settings on a per channel basis so that you can configure each input channel uniquely. The software-programmable gain on these devices increases their overall flexibility by matching the input signal ranges to those that the ADC can accommodate. With the proper gain setting, you can use the full resolution of the ADC to measure the input signal. Table 3-1 shows the overall input range and precision according to the input range configuration and gain used.

National Instruments Corporation 3-3 PCI-4451/4452 User Manual

/2 and +V

ref

/2.

ref

Chapter 3 Hardware Overview

Table 3-1.

Linear Gain Gain Input Range Precision

0.1 –20 dB ±42.4 V

Actual Range and Measurement Precision

3.0518 mV

0.316 –10 dB ±31.6 V 965.05 µV

1.0 0 dB ±10.0 V 305.18 µV

3.16 10 dB ±3.16 V 96.505 µV 10 20 dB ±1.00 V 30.518 µV

31.6 30 dB ±0.316 V 9.6505 µV

100 40 dB ±0.100 V 3.0518 µV 316 50 dB ±31.6 mV 965.05 nV

1000 60 dB ±10.0 mV 305.18 nV

The value of 1 LSB of the 16-bit ADC; that is, the voltage increment corresponding to a

change of one count in t h e ADC 16-bit count.

The actual input range is by design ±100 V; howe ver, the device is not tested or certified

to operate in this range. See Appendix A,

Specifications

, for absolute ma ximum ratings.

All data read from the ADC is interpreted as two’s complement format. In two’s complement mode, digital data values read from the analog input channel are either positive or negative.

Considerations for Selecting Input Ranges

The input range you select depends on the expected range of the incoming signal. A large input range can accommodate a large signal variation but reduces the voltage resolution. Choosing a smaller input range improves the voltage resolution but can result in the input signal going out of range. For best results, match the input range as closely as possible to the expected range of the input signal.

If the input range is not appropriately chosen, an input signal can be clipped and introduce large errors that are easily identified in the frequency spectrum. The PCI-4451/4452 is equipped with overrange detection circuits in both the analog and digital sections of each input channel. These circuits determine if an input signal has exceeded the selected input voltage. Chapter 6, Theory of Analog Operation, provides a m ore in-depth explanation of how overranges can occur.

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Chapter 3 Hardware Overview

Caution If you exceed the rated input voltages, you can damage the computer and the

connected equipment.

Analog Output

The analog output section of t he PCI-4451 device is software-con figurable. You can select different analog output configurations through application software designed to control the PCI-4451. The followi ng sections describe in detail each of the analog output categories. Th e PCI-4451 device has two channels of analog output voltage at the I/O connector.

Output Mode

The PCI-4451 device uses DIFF outputs. You can configure the outputs as an SE channel using the BNC-21 40 DSA accessory. For more information, please refer to the BNC-2140 User Manual. In DIFF mode, one line connects to the positive input of the channel, and the other connects to the negative input of that same channel. You can connect the differential output to either SE or DIFF loads, either floating or gro und-referenced. Howev er, grounding the ne gative output is recommended w hen driving floating single-ended loads.

Output Polarity and Output Range

The PCI-4451 device operates in bipolar mode. Bipolar outp ut means that the output voltage range is between –V a bipolar output range of 20 V (±10 V) for an attenuation of 1.0 (0 dB).

You can program the range settings on a per channel basis so that you can configure each output channel uniquely. The software-programmable attenuation on these devices increases their overall flexibility by matching the output signal ranges to the your application. Table 3-2 shows the overall output range and precision according to the attenuation used.

National Instruments Corporation 3-5 PCI-4451/4452 User Manual

/2 and +V

ref

/2. The PCI-4451 has

ref

Chapter 3 Hardware Overview

Table 3-2.

Attenuation

Linear

Actual Range and Measurement Precision

Attenuation

1.0 0 dB ±10.0 V 305.18 µV 10 20 dB ±1.00 V 30.158 µV 100 40 dB ±0.100 V 3.0518 µV ∞ ∞ dB 0 V 0 V

The value of 1 LSB of the 16-bit DAC; that is, the voltage increment corresponding to a

change of one count in the DAC 16-bit count. See Appendix A,

Note The device boots in a m ode with the outputs disabled

Specifications

, for absolute ma ximum ratings.

Although these functions appear similar, they are quite distinct and are implemented to protect your external equipment from startup transients.

When the DACs no longer have data written to them, they automatically retransmit the last data point they received. If you are expecting the data to return to 0 V or any other voltage level, you

append the data to make it do so.

MUST

All data written to the DACs are interpreted as two’s complement format. In two’s complement mode, data values written to the analog output channel are either positive or negative.

Range Precision

infinitely (∞) attenuated.

AND

Trigger

In addition to supporting internal software tri ggering and external digital triggering to initiate a data acquisition sequence, the PCI-44 51/4452 also supports analog level triggering. You can configure the trigger circuit to monitor any one of the analog input channels to generate the level trigger. Choosing an input channel as the level trigger channel does not influence the input channel capabilities. The level trigger circuit compares the full 16 bits of the programmed trigger level with the digitized 16-bit sample. The trigger-level range is identical to the analog input voltage range. The trigger-level resolution is the same as the precision for a given input range. Refer to Table 3-1.

The trigger circuit generates an internal digital trigger based on the input signal and the user-defined trigger levels. Any of the timing sections of the DAQ-STC can use th is level trigger, including the analog input, analog output, RTSI, and general-purpose counter/timer sections. For example,

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National Instruments Corporation

Chapter 3 Hardware Overview

you can configure the analog input section to acquire a given number of samples after the analog input signal crosses a specific threshold. As another example, you can configure the analog output section to generate an output waveform whenever the analog input signal crosses a specific threshold.

Due to the nature of delta-sigma con v er ters, the triggering cir cuits o perate on the digital output of the converter. Since the trigger is generated at the output of the converter, triggers can occur only when a sample is actually generated. Placing the triggering circuits on the digital side of the converter does not affect most measurements unless an analog output is generated based on the input trigger. In this case, you must be aware of the inheren t delays of the finite impulse response (FIR) filters internal to the delta-sigma conv erters and you must accoun t for the delays. The delay through th e input converter is 42 sample periods, while the delay through the output converter is 34.6 ±0.5 sample periods.

During repetitive sampling of a waveform, you may observe jitter due to the uncertainty of where a trigger level falls compared to the actual digitized data. Although this trigger jitter is never greater than one sample period, it can seem quite bad when the sample rate is only twice the bandwid th of interest. This jitter has no effect on the processing of the data, and you can decrease this jitter by oversampling.

There are five analog level triggering modes available, as shown in Figures 3-3 throug h 3-7. You can set lowValue and highValue independently in the software.

In below-low-level triggering mode, shown in Figure 3-3, the trigger is generated when the signal value is less than lowValue. HighValue is unused.

lowValue

Trigger

Figure 3-3.

National Instruments Corporation 3-7 PCI-4451/4452 User Manual

Below-Low-Level Triggering Mode

Chapter 3 Hardware Overview

In above-high-level triggering mode, the trigger is generated when the signal value is greater than highValue. LowValue i s unu sed .

highValue

Trigger

Figure 3-4.

Above-High-Level Triggering Mode

In inside-region triggering mode, the trigger is generated when the signal value is between the lowValue and the highValue.

highValue

lowValue

Trigger

Figure 3-5.

Inside-Region Triggering Mode

In high-hysteresi s trigger ing mode, the trigger i s generated when the signal value is greater than highValue, with the hysteresis specified by lowValue.

highValue

lowValue

Trigger

Figure 3-6.

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High-Hysteresis Triggering Mode

National Instruments Corporation

Chapter 3 Hardware Overview

In low-hysteresis triggering mode, the trigger is generated when the signal value is less than lowValue, with the hysteresis specified by highValue.

highValue

lowValue

Trigger

RTSI Triggers

Figure 3-7.

Low-Hysteresis Triggering Mode

Y o u can use digital triggering through the RTSI bus and the external digital 50-pin connector using any one of the eight available programmable function input (PFI) pi ns. PFI0/TRIG1 (EXT_TRIG) is the pin dedicated to external digital triggering.

You can trigger the PCI-DSA devices from any other PCI-DSA device or any National Instruments device that has the RTSI bus feature. You can connect the devices through the RTSI bus cable. An external digital trigger can also trigger multiple devices simultaneously by distributing that trigger through the RTSI bus. You can select the polarity of the external digital trigger.

The seven RTSI trigger lines on the RTSI bus provide a very flexible interconnection scheme for any PCI-4451/4452 device sharing the RTSI bus. These bidirectional lines can drive any of eight timing signals onto the RTSI bus and can receive any of these timing signals. This signal connection scheme is shown in Figure 3-8.

National Instruments Corporation 3-9 PCI-4451/4452 User Manual

Chapter 3 Hardware Overview

Trigger 7

RTSI Bus Connector

Clock

RTSI Switch

switch

DAQ-STC TRIG1 TRIG2 CONVERT* UPDATE* WFTRIG GPCTR0_SOURCE GPCTR0_GATE GPCTR0_OUT GPCTR1_SOURCE GPCTR1_GATE RTSI_OSC (20 MHz)

Figure 3-8.

RTSI Bus Signal Connection

Refer to the Chapter 4, Signal Connections for a des c ript i on of the signals shown in Figure 3-8.

Digital I/O

The PCI-4451/4452 devices contain eight lines of digital I/O for general-purpose use through the 50-pin connector. You can individually software-configure each line for either input or output.

The hardware up/down control for general-purpose counters 0 and 1 are connected onboard to DIO6 and DIO7, respectively. Thus, you can use DIO6 and DIO7 to control the general-purpose counters. The up/down control signals are input only and do not affect the operation of the DIO lines.

Note At system power-on and reset, the hardware sets both the PFI and DIO lines to

high impedance. This means that the device circuitry is not actively driving the output either high or low. F or example, DIO(0) will be in the high impedance state after power on, and Table 4-4, Digital I/O Signal Summary, shows that there is a 50 kΩ pull-up resistor. This pull-up resistor sets the DIO(0) pin to a logic high when the output is in a high-impedance state. Take careful consideration of the power-on state of the system to prevent any damage to external equipment.

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Timing Signal Routing

The DAQ-STC provides a flexible interface for connecting timing signals to other devices or to external circuitry. Your PCI-4451/4452 device uses the RTSI bus to interconnect timing signals between devices, and uses the PFI pins on the I/O connector to connect the device to external circuitry. These connections enable the PCI-4 451/4452 device to both control and be controlled by other devices and circuits.

There are a total of 13 timing signals internal to the DAQ-STC that you can control by an external source. You can also control these timing signals by signals generated internally to the DAQ-STC, and these selections are fully software configurable. Many of these timing signals are also available as outputs on the RTSI pins, as indicated in the RTSI Triggers section earlier in this chapter, and on the PFI pins, as indicated in Chapter 4, Signal

Connections.

Programmable Function Inputs

The 10 PFIs are connected to the signal routing multiplexer for each timing signal, and software can select one of the PFIs as the external source for a given timing signal . It is im portant to note that you can use any of th e PFIs as an input by any of the timing signals and that multiple timing signals can use the same PFI simultaneously. This flexible routing scheme reduces the need to change physical connections to the I/O connector for different applications. You can also individually enable each of the PFI pins to output a specific internal timing signal. For example, if you need the GPCTR0_SOURCE signal as an output on the I/O connector, software can turn on the output driver for the PFI8/GPCTR0_SOURCE pin.

Chapter 3 Hardware Overview

Note

Two o f the 10 PF I pi n s are n ot avai l ab le for general-purpose input on the di git a l connector . You can confi gure PFI2/C ONVERT * and PFI5 /UPD A TE * as output s only.

Device and RTSI Clocks

Some PCI-4451/4452 device functions require a frequency timebase to generate the necessary timing signals for controlling general-purpose signals at the 50-pin digital I/O connector. You canno t use these signals for the generating the frequency of sample rates or update rates. Refer to

Selecting Sample/Update Cl ock Freq uency section for information on

sample/update clock generation.

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Chapter 3 Hardware Overview

A PCI-4451/4452 device can use either its internal 20 MHz timebase or a timebase received over the RTSI bus. In addition, if you configure the device to use the internal timebase, you can pr ogram the de vi ce to dri v e its internal timebase o ver the RTSI bus to anot her device that you program to receive this timebase signal. The default configuration at startup is to use the internal timebase without driving the RTSI bus timebase signal. This timebase is software-selectable.

Selecting Sample/Update Clock Frequency

The two analog input channels of the PCI-4451 and the four inputs of the PCI-4452 are simultaneously sampled at any software-programmable rate from 5.0 kS/s to 204.8 kS/s in 190.7 µS/s increments (worst case). The devices use direct digital synthesis (DDS) technology so that you can choose the correct sample rate required for your application. All the input channels acquire data at the same rate. One input channel cannot acquire data at a different rate from another input channel.

The two analog output channels of the PCI-4451 are updated simultaneously at any software programmable rate from 1.25 kS/s to

51.2 kS/s in 47.684 µS/s increments (worst case). The input sample rate and output update rate on the PCI-4451 are synchronized and deri ved fro m the same DDS clock. The input and output clocks may differ from each other by a factor of 2 (1, 2, 4, 8, …, 128) while still maintaining their synchronization as lon g as the lower bounds for update and sample rate are maintained. All the output channels update data at the same rate. One output channel cannot update data at a different rate from another output channel.

The DDS clock signal and the synchronization start signal are transmitted to other PCI-DSA devices via the RTSI bus. The PCI-4451/4452 can also receive these signals to syn chronize the acquisition or wa veform generation with other devices. In a multidevice system, a master device would drive the clock and synchronization signal to other slave or receiving devices.

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Device Configuration Issues

Selecting a sample rate that is less than two times the frequency of a band of interest can lead you to believe the board is functioning improperly. By undersampling the signal, you could receive what appears to be a DC signal. This situation is due to the sharp antialiasing filters that remove frequency components above the sampling frequency. If you have a situation where this occurred, simply increase the sample rate until it meets the requirements of the Shannon Sampling Theorem. For more information on the filters and aliasing, refer to Chapter 6, Theory of Analog Opera tio n.

Unlike other converter technologies, delta-sigma converters must be run continuously and at a minimum clock rate. To operate within guaranteed specifications, the A/D con verters should operate at a minimum sample rate of 5.0 kS/s and the D/A converters should operate at a minimum update rate of 1.25 kS/s. This minimum rate is required to keep the internal circuitry of the converters running within specifications. You are responsible for selecting sample and update rates that fall within the specified limits. Failure to do so could greatly affect the specifications.

Chapter 3 Hardware Overview

National Instruments Corporation 3-13 PCI-4451/4452 User Manual

Signal Connections

This chapter describes how to make input and output connections to your PCI-4451/4452 device via th e analog I/O and digital I/ O connectors of t he device.

The analog I/O connector for the PCI-4451/4452 connects to the BNC-2140 DSA accessory through the SHC68-C68-A1 shielded cable. You can access the analog I/O of the PCI-4451/4452 using standard BNC connectors on the BNC-2140. Y ou can connect the analog I/O sign als to the shielded cable through a single 68-pin connector.

The digital I/O connector for the PCI-4451/4452 has 50 pins that you can connect to generic 68-pi n t erm inal blocks through the SHC 50-68 shielded cable. You can connect the digital I/O signals to the shielded cable through a single 50-pin connector.

I/O Connectors

Table 4-1 describes the pin assignments for the 68-pin analog I/O connector. Ta ble 4-3 describes the 50 -pin digital connec tor on the PCI-4451/4452 devices. A signal description follows the connector pinouts.

Caution

National Instruments Corporation 4-1 PCI-4451/4452 User Manual

Connections that exceed any of the maximum ratings of input or output signals on the PCI-4451/4452 devices can damage the PCI-4451/4452 device, the computer , and associated accessories. Maximum input ratings for each signal are given in the Protection column of Table 4-2 and 4-4. National Instruments is not liable for any damages resulting from s uch signal connections.

Chapter 4 Signal Connections

Analog I/O Connector Signal Descriptions

Figure 4-1 shows the analog pin connections for the PCI-4451/4452.

-ACH0 NC

-ACH1 NC

ACH2-

-ACH3 NC NC NC NC NC

NC NC NC NC NC

NC NC

NC NC NC NC

-DAC0 OUT NC

-DAC1 OUT NC NC NC

NC NC

+5 V

GND

135 236 337 438 539 640 741 842

943 10 44 11 45 12 46 13 47 14 48 15 49 16 50 17 51 18 52 19 53 20 54 21 55 22 56 23 57 24 58 25 59 26 60 27 61 28 62 29 63 30 64 31 65 32 66 33 67 34 68

+ACH0 GND +ACH1 GND +ACH2 GND +ACH3 GND NC NC NC NC NC NC NC NC NC

NC NC

NC NC NC NC NC +DAC0 OUT GND +DAC1 OUT GND NC NC NC NC +5 V GND

Figure 4-1.

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Analog Pin Connections

National Instruments Corporation

Chapter 4 Signal Connections

Table 4-1.

Signal Name Reference Direction Description

+ACH<0..3> AIGND Input +Analog Input Channel 0 throu gh 3—The PCI-4451 uses

−ACH<0..3>

AIGND Input

Analog I/O Connector Pin Assignment

+ACH<0..1> and the PCI-4452 uses +ACH<0..3>.

−Analog Input Channel 0 through 3—The PCI-4451 uses

−ACH<0..1> and the PCI-445 2 uses −ACH<0..3>.

AIGND — — Ana log Input Ground—These pins are the reference point for

single-ended measure m ents in SE configuration and t he bias current return point for di fferential measurement s . Al l three ground references—AIGND, AOGND, and DGND—are connected together on your PCI-4451/4452 device, but each serves a separate purpose.

+DAC0OUT

−DAC0OUT

+DAC1OUT

−DAC1OUT

AOGND — — Analog Output Ground—The anal og output voltages are

+5 V DGND Output +5 VDC Source—These pins are fused for up to 0. 5 A and

DGND — — Dig it al Ground—This pin supplies the reference for the +5

−DAC0OUT

+DAC0OUT Output

−DAC1OUT

+DAC1OUT Output

Output +Analog Output Channel 0—T hi s pin supplies the analog

non-inverting output channel 0. This pin is available only on the PCI-4451.

−Analog Output Channel 0—This pin supplies the an al og

inverting output channel 0. This pin is available only on the PCI-4451.

Output +Analog Output Channel 1—T hi s pin supplies the analog

non-inverting output channel 1. This pin is only available on the PCI-4451.

−Analog Output Channel 1—This pin supplies the an al og

inverting output channel 1. This pin is only available on the PCI-4451.

ultimately refere nc ed to this node. All three ground references—AIGND, AOGND, and DGND—are connected together on your PCI-4451/4 452 device, but each serves a separate purpose.

supply power to the DSA signal conditioning accessories. The fuse is s elf resetting.

VDC supply. All three ground references—AIGND, AOGND, and DGND—are connected together on your PCI-4451/4452 device, but each serves a sep ara te purpose.

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Chapter 4 Signal Connections

Table 4-2.

Signal

Signal Name

+ACH<0..3>

ACH<0..3>

−

AIGND +DAC0OUT

DAC0OUT

−

+DAC1OUT

DAC1OUT

−

AOGND DGND +5 V

AI = Analog Input DIO = Digital Input/Outpu t AO = Analog Output DO = Digital Output

†

±400 V/±400 V guarantee d by de sign, but not tested or certi fied to operate beyond ± 42. 4 V

Type and Direction

AI — — — — — —

AO — — — — — —

DIO — — — — — —

Impedance

Input/

Output

1 MΩ in parallel with 50 pF to AIGND

22 Ω to

DAC0OUT,

−

4.55 kΩ to AOGND

22 Ω to +DAC0OUT,

4.55 kΩ to AOGND

22 Ω to

DAC1OUT,

−

4.55 kΩ to AOGND

22 Ω to +DAC1OUT,

4.55 kΩ to AOGND

0.7 Ω Short-circuit to

Analog I/O Signal Summary

Protection

(V olts)

On/Off

±42.4 V/±42.4 V

Short-circuit to

DAC0OUT,

−

ground

Short-circuit to +DAC0OUT, ground

Short-circuit to

DAC1OUT,

−

ground

Short-circuit to +DAC1OUT, ground

ground

Source

(mA at V)

†

— — —

†

— — —

16.7 mA at 10 V

0.5A

Sink

(mA at

— — —

Rise

Time

(ns)

Bias

±100 pA

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National Instruments Corporation

Digital I/O Connector Signal Descriptions

Figure 4-2 shows the digital pin connections for the PCI-4451/4452.

Chapter 4 Signal Connections

FREQ_OUT

GPCTR0_OUT

PFI8/GPCTR0_SOURCE

PFI6/WFTRIG

PFI7

GPCTR1_OUT

PFI3/GPCTR1_SOURCE

PFI1/TRIG2 (PRETRIG)

CONVERT*

DIO(7) DIO(6)

DIO(0) DIO(2) DIO(4) DIO(3)

+5 V +5 V +5 V

N/C N/C N/C N/C N/C N/C N/C

126 227 328 429 530 631 732 833

934 10 35 11 36 12 37 13 38 14 39 15 40 16 41 17 42 18 43 19 44 20 45 21 46 22 47 23 48 24 49 25 50

DGND PFI9/GPCTR0_GATE DGND UPDATE* DGND PFI4/GPCTR1_GATE DGND PFI0/TRIG1(EXT_TRIG)

DGND RESERVED1

DGND DIO(1) DGND EXTSTROBE* DGND DIO(5) N/C +5 V DGND N/C DGND N/C DGND

N/C

DGND

Figure 4-2.

Digital Pin Connections

Refer to Appendix B, Pin Connections , for the digital pin connections of the 68-pin connector.

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Chapter 4 Signal Connections

Table 4-3.

Signal Name Reference Direction De scription

DIO<0..7> DGND Input or

DGND — — Digital Ground—This pin supplies the reference for the digital

+5 V DGND Output +5 VDC Source—These pins are fused for up to 1 A of +5 V

RESERVED1 DGND Output RESERVED—This pin is reserved. This signal is always high. EXTSTROBE* DGND Output Externa l Strobe—This signal can be toggled under software

PFI0/TRIG1 (EXT_TRIG) DGND Input

PFI1/TRIG2 (PRETRIG) DGND Input

CONVERT* DGND Output A high-to-low edge on CONVERT* indicates that an A/D

PFI3/GPCTR1_SOURCE DGND Input

Digital I/O Connector Pin Assignment

Output

Digital I/O channels 0 through 7—Channels 6 and 7 can control the up/down signal of general-purpose counters 0 and 1, respectivel y.

signals at the I/O connector as we ll as the +5 VDC supply.

supply. The fuse is self-resetting.

control to latch sign al s or trigger events on external devices. TRIG1—As an input, this is a source for the data acquisition

trigger. As an output, this signa l can drive external applications to

indicate that a trigger on the device has occurred. TRIG1 is the start acquisi tion signal.

In LabVIEW, referred to as AI Start Trigger for both input and output.

PFI1/TRIG2 (PRETRIG)—As an in put , this is one of the PFIs.

As an output, this is the TRIG2 sig nal . In pre tri gger applications, a low-to-high transition indicates the initiation of the posttrigger conversi ons. TR IG2 is not used in posttrigger applications.

In LabVIEW, referred to as AI Stop Trigger for both input and output.

conversion is oc curring. In LabVIEW, referred to as AI Convert.

PFI3/Counter 1 Source— As an input, this is one of the PFIs.

Output

PFI4/GPCTR1_GATE DGND Input

Output

UPDATE* DGND Output A high-to-low edge on UPDATE* indicates that a D/A

PCI-4451/4452 User Manual 4-6

As an output, this is the GPCTR1_SOURCE signal. This signal reflects the actua l source connected to th e general-purpose counter 1.

PFI4/Counter 1 G ate—As an input , th is is one of the PFIs.

As an output, this is the GPCTR1_GATE signal. This signal reflects the actual gate signal connected to the general-purpose counter 1.

conversion is oc curring. In LabVIEW, referred to as AO Upda te.

National Instruments Corporation

Chapter 4 Signal Connections

Table 4-3.

Signal Name Reference Direction De scription

GPCTR1_OUT DGND Out put General-Purpose Counter 1 Output PFI6/WFTRIG DGND Input

PFI7 DGND Input PFI7—This is one of the PFIs. PFI8/GPCTR0_SOURCE DGND Input

PFI9/GPCTR0_GATE DGND Input

GPCTR0_OUT DGND Out put General-Purpose Counter 0 Output FREQ_OUT DGND Output Frequency Output—This output is from the frequency

Digital I/O Connector Pin Assignment (Continued)

PFI6/Waveform Trigger—As an input, this is one of the PFIs.

Output

As an output, this is the WFTRIG signal. In timed analog output sequences, a low-to-high tran s ition indicates the initiation of the wave form generation.

In LabVIEW, referred to as AO Start Trigger for both input and output.

PFI8/Counter 0 Source—As an input, this is one of the PFIs.

As an output, this is the GPCTR0_SOURCE signal. This signal reflects the actua l source connected to th e general-purpose counter 0.

PFI9/Counter 0 Gate—As a n input, this is one of the PFIs.

As an output, this is the GPCTR0_GATE signal. This signal reflects the actual gate signal connected to the general-purpose counter 0.

generator output.

National Instruments Corporation 4-7 PCI-4451/4452 User Manual

Chapter 4 Signal Connections

Table 4-4.

Signal

Signal Name

DGND +5 V

DIO<0..7>

RESERVED1 EXTSTROBE*

PFI0/TRIG1 (EXT_TRIG)

PFI1/TRIG2 (PRETRIG)

CONVERT*

PFI3/GPCTR1_SOURCE

PFI4/GPCTR1_GATE

GPCTR1_OUT

UPDATE*

PFI6/WFTRIG

PFI7 PFI8/GPCTR0_SOURCE

PFI9/GPCTR0_GATE

GPCTR0_OUT

FREQ_OUT

DIO = Digital Input/Output pu = pullup DO = Digital Output DI = Digital Input

Note: The tolerance on the 50 kΩ pullup and pulldown resistors is very large. Actual value may range between 17 and 100 kΩ.

Type and Direction

DIO — DIO 0.15 Ω

DIO —

DO — DO —

DIO —

DO —

DIO —

DO —

DIO —

DI —

DIO —

DO —

Digital I/O Signal Summary

Impedance

Input/

Output

Protection

(V olts)

On/Off

— — — Short-circuit

to ground Vcc +0.5 13 at

— — — — 3.5 at

Vcc +0.5 3.5 at

— 3.5 at

Vcc +0.5 3.5 at

— 3.5 at

Vcc +0.5 3.5 at

Vcc +0.5 — — Vcc +0.5 3.5 at

Vcc +0.5 3.5 at

— 3.5 at

Source

(mA at V)

1A —

24 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc -0.4)

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

5 at 0.4

(Vcc

0.4)

−

Sink

(mA at

Rise

Time

(ns)

— —

1.1

—

1.5

—

1.5

Bias

— —

50 kΩ pu

50 kΩ pu 50 kΩ pu

50 kΩ pu

50 kΩ pu 50 kΩ pu

50 kΩ pu

PCI-4451/4452 User Manual 4-8

National Instruments Corporation

Analog Input Signal Connections

The analog input signals for the PCI-4451 /4452 d evices are +ACH<0..3>,

−ACH<0..3>, and AIGND. The + analog input channels of your PCI-4451, and ±ACH<0..3> are tied to the four analog input channels of your PCI-4452 device.

Chapter 4 Signal Connections

ACH<0..1> signals are tied to the two

+ACH

-ACH

AIGND

Caution

Calibration Multiplexer

Exceeding the differential and common-mode input ranges distorts your input signals.

AIGND is an analog input common signal that connects directly to the ground system on the PCI -4451/44 52 de vices. You can use t his sign al for a general analog ground tie point to your PCI-4451/4452 de vice if necessary , but connecting AIGND to other earth-connected grounds is not recommended. AIGND is not directly available if you are using a BNC-2140 accessory.

Figure 4-3 shows a diagram of your PCI-4451/4452 device analog input stage.

20 dB

Attenuator

AIGND

Differential

Amplifier

–

Gain = 0 dB Gain = 10 dB Gain = 20 dB Gain = 30 dB Gain = 40 dB Gain = 50 dB Gain = 60 dB

Analog

Lowpass

Filter

A/D

Converter

0.047 F

1 GΩ

0.047 F

= 3.4 Hz

DC/AC

Coupling

900 kΩ

100 kΩ

900 kΩ

Gain = 0 dB Gain = -20 dB

Figure 4-3.

Analog Input Stage

The analog input stage applies gain and common-mode voltage rejection and presents high input impedance to the analog input signals connected to your PCI-4451/4452 de vice. Si gnals are rou ted di rectly to t he positive and negative inputs of the analog input stage on the device. The analog input stage converts two input signals to a signal that is the difference between the two input signals multiplied by the gain setting of the amplifier. The

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Chapter 4 Signal Connections

amplifier output voltage is referenced to the ground for the device. Your PCI-4451/4452 device A/D converter (ADC) measu res t his o ut put voltage when it performs A/D conversi ons.

Connection of analo g input s ignals to your PCI -4451/4 452 de vice dep ends on the configuration of the input signal sources. For most signals, you use a DIFF configuration and simply connect the signal to +ACHx (where x is the PCI-4451/4452 channel) and the signal ground (or signal minus, as appropriate) to −ACHx. However, if a signal has a high output impedance (greater than 1 kΩ) and is floating, you may find it useful to use an SE configuration and tether the signal minus to AIGND to reduce common-mode interference. You can make the DIFF and SE connections through the BNC-2140 accessory.

Types of Signal Sources

When configuring the input ch annels and mak i ng s ignal co nnecti on s, f irst determine whether the signal sources are floating or ground-referenced. The following sections describe these two types of signals.

Floating Signal Sources

A floating signal sou rce does not connect in any way to the building ground system but instead has an isolated ground-reference point. Some examples of floating signal sources are outputs of transformers, thermocouples, battery-powered devices, o ptical i solator ou tputs, and is olation am plifi ers. An instrument or device that has an isolat ed output is a floating signal source.

Ground-Referenced Signal Sources

A ground-referenced signal source connects in some way to the building system ground and is, therefore, already connected to a common ground point with respect to the PCI-4451/4452 device, assuming that you plug the computer into the same power s ystem. Noni solat ed out puts of i nstrumen ts 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 po wer system is typicall y between 1 and 100 mV but can be much higher if power distribution circuits are not properly connected. For this reason, National Instruments does not recommend connecting AIGND to the source signal ground system, since the difference between the grounds can induce currents in the PCI-4451/4452 ground system.

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National Instruments Corporation

Analog Output Signal Connections

The analog output signals for the PCI-4451 device are +DAC0OUT,

−DAC0OUT, +DAC1OUT, -DAC1OUT, and AOGND. +DAC0OUT and

−DAC0OUT are the plus and minus voltage output signals for analog

output channel 0. +DAC1OUT and −DAC1OUT are the plus and minus voltage output signal, for analog output channel 1.

AOGND is a ground -reference signal for b oth analog output chann els. It is connected directly to the ground system on the PCI-4451 device. You can use this signal for a general analog ground tie point to your PCI-4451 device if necessary, but connecting AOGND to other earth-connected grounds is not recommended. AOGND is not directly available if you are using the BNC-2140 accessory.

The PCI-4451 has two analog output channels, either of which is illustrated in Figure 4-4.

Chapter 4 Signal Connections

D/A

Converter

Gain = 0 dB Gain = -20 dB Gain = -40 dB Gain = -∞ dB

100 kΩ

+DACxOUT

10 kΩ

-DAC

100 kΩ

AOGND

OUT

Attenuator

Balanced

Differential

Driver

Figure 4-4.

11 Ω

Analog Output Channel Block Diagram

The analog output stage is differential and balanced. Each output signal consists of a plus connection, a minus connection, and a ground (A OGND) connection. The actual output signal is the dif ference between the plus and minus connections. The pair is balanced, meaning that, if the impedances from each of the pair to AOGND is the same (or inf i nite), then the vo ltage at the plus and minus terminals are equal but opposite, so that their difference is the desired signal and their sum (or average) is zero. If impedances from each of the pair to AOGND is not the same, the connection is unbalanced, but the difference between the plus and minus

National Instruments Corporation 4-11 PCI-4451/4452 User Manual

Chapter 4 Signal Connections

terminals is still equal to the desired signal. If the minus side is grounded, the plus voltage is equal to the signal. Conversely, if the plu s sid e is grounded, the minus voltage is equal to the negative of the signal. In all cases, the difference is equal to the signal.

Connection of analog output signals from your PCI-4451 device depends on the configuration of the devices receiving the signals. For most sig nals, you use a DIFF configuration and simply connect +D A CxOUT (wher e x is the PCI-4451 channel) to the signal and −DACxOUT to the signal ground (or signal minus, as appropriate). When driving some floating devices, however , you may sometimes find it helpful to use the SE configuration and connect the floating ground system of the device to AOGND to reduce common-mode noise coupled from an interfering source to the de v ice.You can make DIFF and SE connections through the BNC-2140 accessory.

Analog Power Connections

Two pins on the analog I/O connector supply +5 V from the computer power supply via a self-resetting fuse. The fuse will reset automatically within a few seconds after the overcurrent condition is removed. These pins are referenced to DGND and you can use them to power external analog accessories like the BNC-2140.

• Power rating +4.65 to +5.25 VDC at 0.5 A

Caution

Do not under any circumstances connect these +5 V power pins directly to analog ground, digital ground, or to any other voltage source on the PCI-4451/4452 device or any other device. Doing so can damage the PCI-4451/4452 device and the computer. National Instruments is not liable for damages resulting from such a connection.

Digital I/O Signal Connections

The digital I/O signals are DIO<0..7> and DGND. DIO<0..7> are the signals making up the DIO por t. DGND is the ground-reference signal fo r the DIO port. You can p rogram all lines in dividually to be inputs or o utputs.

PCI-4451/4452 User Manual 4-12

National Instruments Corporation

LED

Chapter 4 Signal Connections

Figure 4-5 shows signal connections for three typical digital I/O applications.

+5 V

DIO<4..7>

+5 V

Switch

I/O Connector

TTL Signal

Figure 4-5.

DGND

Digital I/O Connections

DIO<0..3>

Figure 4-5 shows DIO<0..3> configured for digital input and DIO<4..7> configured for digital output. Digital input applications include receiving TTL signals and sensing external device states such as the state of the switch shown in Figure 4-5. Digital output applications include s e nding TTL signals and driving external devices such as the LED shown in Figure 4-5.

National Instruments Corporation 4-13 PCI-4451/4452 User Manual

Chapter 4 Signal Connections

Digital Power Connections

Four pins on the digital I/O connector supply +5 V from the computer power supply via a self-resetting fuse. The fuse will reset automatically within a few seconds after the overcurrent condition is removed. These pins are referenced to DGND and you can use them to power external digital circuitry.

• Power rating +4.65 to +5.25 VDC at 1 A

Caution

Timing Connections

All external control over the timing o f your PCI-4451/44 52 device is routed through the 10 programmable function inputs labeled PFI0 through PFI9 (excluding PFI2 and PF I5). These signals are explained in detail in the next section, Programmable Function Input Connections. Most of these PFIs are bidirectional. As outputs they are not programmable and reflect the state of acquisition, waveform generation, and general-purpose timing signals. As inputs, the PFI signals are programmable and can control any acquisition, waveform generation, and general-purpose timing signals.

The acquisition signals are explained in the Acquisition Timing

Connections section later in this chapter. The wa veform generation signals

are explained in the Waveform Generation Timing Connections section later in this chapter. The general-purpose timing signals are explained in the

General-Purpose Timing Signal Connections section later in this chapter.

All digital timing connections are referenced to DGND.

Programmable Function Input Connections

You can individually enable each of the PFI pins to output a specific internal timing signal. For example, if you need the GPCTR1_SOURCE signal as an output on the I/O connector, software can turn on the output driver for the PFI3/GPCTR1_SOURCE pin.

Caution

Be careful not to drive a PFI signal externally when it is configured as an output.

PCI-4451/4452 User Manual 4-14

National Instruments Corporation

As an input, you can individually configure each PFI for edge or level detection and for polarity selection as well. You can use the polarity selection for any of the timing signals, but the edge or level detection depends upon the particular timing signal being controlled. The detection requirements for each timing signal are listed within the section that discusses that individual signal.

In edge-detection mode, the minimum pulse width required is 10 ns. This applies for both rising-edge and falling-edge polarity settings. There is no maximum pulse-width requirement in edge-detect mode.

In level-detection mode, there are no minimum or maximum pulse-width requirements imposed by the PFIs themselves, but there can be limits imposed by the particular timing signal being controlled. These requirements are listed later in this chapter.

Acquisition Timing Connections

The acquisition timing signals are PFI0/TRIG1, PFI1/TRIG2, CONVERT*, and EXTSTROBE*.

Posttriggered data acquis ition allo ws you to vie w only data that is acquired after a trigger event is received. A typical posttriggered acquisition sequence is shown in Figure 4-6.

Chapter 4 Signal Connections

TRIG1

CONVERT*

Scan Counter

Figure 4-6.

National Instruments Corporation 4-15 PCI-4451/4452 User Manual

Typical Posttriggered Acquisition

13042

Chapter 4 Signal Connections

TRIG1

Pretriggered data acquisition allows you to view data that is acquired b efore the trigger of interest in addition to data acquired after the trigger. Figure 4-7 shows a typical pretriggered acquisition sequence. The description for each signal shown in these figures is included later in this chapter.

TRIG2

CONVERT*

Sample Counter

Don't Care

01231 0222

Figure 4-7.

Typical Pretriggered Acquisition

Don't Care

PFI1

PFI0/TRIG1 (EXT_TRIG) Signal

Any PFI pin can externally input the PFI0/TRIG1 (EXT_TRIG) signal, which is available as an output on the PFI0/TR IG 1 (EXT_TR I G) pin .

Refer to Figures 4-6 and 4-7 for the relationship of PFI0/TRIG1 to the acquisition sequence.

As an input, the PFI0/TRIG1 signal is configured in the edge-detection mode. You can select any PFI pin as the source for PFI0/TRIG1 and configure the polarity selection for either rising or falling edge. The selected edge of the PFI0/TRIG1 signal starts the data acqu isition sequence for both posttriggered and pretriggered acquisitions. The PCI-4451/4452 supports analog level triggering on the PFI0/TRIG1 p in. See Chapter 3,

Hardware Overview, for more information on analog level triggering.

As an output, the PFI0/TRIG1 signal reflects the action that initiates an acquisition sequence. This is true even if the acquisition is externally triggered by another PFI signal. The output is an active high pulse with a pulse width of 50 to 100 ns. This ou tput is set to tri-state at startup.

The device also uses the PFI0/TRIG1 signal to initiate pretriggered acquisition operations. In most pretriggered applications, the PFI0/TRIG1 signal is generated by a software trigger. Refer to the PFI1/TRIG2 signal description for a complete description of the use of PFI0/TRIG1 and PFI1/TRIG2 in a pretriggered acquisition operation.

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National Instruments Corporation

Chapter 4 Signal Connections

PFI1/TRIG2 (PRETRIG) Signal

Any PFI pin can externally input the PFI/1TRIG2 (PRETRIG) signa l, which is available as an output on the PFI1/TR IG 2 (PR E TRIG) pin.

Refer to Figure 4-7 for the relationship of PFI1/TRIG2 to the acquisition sequence.

As an input, the P F I1/ TR IG2 si gn al is co nfigured in edge-detection mode. Y o u can select any PFI pin as the source for PFI1/TRIG2 and conf igure the polarity selection for either rising or falling edge. The selected edge of the PFI1/TRIG2 signal initiates the posttriggered phase of a pretriggered acquisition sequence. In pretriggered mode, the PFI0/TRIG1 signal initiates the data acquisition. The scan counter indicates the minimum number of scans before PFI1/TRIG2 is recognized. After the scan counter decrements to zero, it is loaded with the number of posttrigger scans to acquire while the acquisition continues. The device ignores the PFI1/TRIG2 signal if it is asserted prior to the scan counter decrementing to zero. After the selected edge of PFI1/TRIG2 is received, the device acquires a fixed number of scans and the acquisition stops. After PFI1/TRIG2 is received, any additional PFI1/TRIG2 signals are ignored until the acquisition is restarted. This mode acquires data both before and after receiving PFI1/TRIG2.

As an output, the PFI1/TRIG2 signal reflects the posttrigger in a pretriggered acquisition sequence. This is true even if the acquisition is externally triggered by another PFI signal. The PFI1/TRIG2 signal is not used in posttriggered data acquisition. The output is an active high pulse with a pulse width of 50 to 100 ns. This output is set to tri-state at startup.

CONVERT* Signal

The CONVERT* signal is only available as an output on the CONVERT* pin. The CONVERT* signal reflects the end of delta-sigma conversion on the ADC. The output is an active-low pulse with a pulse width of 70 to 100 ns. This output is set to tri-state at startup.

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Chapter 4 Signal Connections

EXTSTROBE* Signal

EXTSTROBE* is an output-only signal that generates either a single pulse or a sequence of eight pulses in the hardware-strobe mode. An external device can use this signal to latch signals or to trigger events. In single-pulse mode, software controls the level of the EXTSTRO BE* signal. A 10 µs and a 1.2 µs clock is available for generating a sequence of eight pulses in hardware-strobe mode. Figure 4-8 shows the timing for hardware-strobe mode EXTSTROBE* signal.

= 600 ns or 5 µs

Figure 4-8.

EXTSTROBE* Signal Timing

Waveform Generation Timing Connections

The waveform generation timing signals are WFTRIG and UPDATE*.

WFTRIG Signal

Any PFI pin can externally input the WFTRIG signal, which is available as an output on the PFI6/WFTRIG pin.

As an input, the WFTRIG signal is configured in the edg e-detection mode. You can select any PFI pin as the source for WFTRIG and configure the polarity selection for either rising or falling edge. The selected edge of the WFTRIG signal starts the waveform generation for the DACs.

As an output, the WFTRIG signal reflects the trigge r that in itiates waveform generation. This is true even if the waveform generation is externally triggered by another PFI signal. The output is an active high pulse with a pulse width of 50 to 100 ns. This output is set to tri-state at startup.

UPDATE* Signal

The UPDATE* signal is only availabl e as an o utput on t he UPDATE* pin . The UPDATE* signal reflects the end of a delta-sigma conversion on the DACs. The output is an active-low pulse with a pulse width of 70 to 100 ns. This output is set to tri-state at startup.

PCI-4451/4452 User Manual 4-18

National Instruments Corporation

General-Purpose Timing Signal Connections

The general-purpose timing signals are GPCTR0_SOURCE, GPCTR0_GATE, GPCTR0_OUT, GPCTR0_UP_DOWN, GPCTR1_SOURCE, GPCTR1_GATE, GPCTR1_OUT, GPCTR1_UP_DOWN, and FREQ_OUT.

GPCTR0_SOURCE Signal

Any PFI pin can externally input the GPCTR0_SOURCE signal, which is available as an output on the PFI8/GPCTR0_SOURCE pin.

As an input, the GPCTR0_SOURCE signal is configured in the edge-detection mode. You can select any PFI pin as the source for GPCTR0_SOURCE and configure the polarity selection for either rising or falling edge.

As an output, the GPCTR0_SOURCE signal reflects the actual clock connected to general-purpose counter 0. This is true even if another PFI signal is externally inputting the source clock. This output is set to tri-state at startup.

Figure 4-9 shows the timing requirements for the GPCTR0_SOURCE signal.

Chapter 4 Signal Connections

Figure 4-9.

= 50 ns minimum

= 23 ns minimum

GPCTR0_SOURCE Signal Timing

The maximum allowed frequen cy is 20 MHz, with a minimum pulse width of 23 ns high or low. There is no minimum frequency limitation.

The 20 MHz or 100 kHz timebase normally generates the GPCTR0_SOURCE signal unless you select some external source.

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Chapter 4 Signal Connections

GPCTR0_GATE Signal

Any PFI pin can externally input the GPCTR0_GATE signal, which is available as an output on the PFI9/GPCTR0_GATE pin.

As an input, the GPCTR0_GATE signal is configured in the edge-detection mode. You can select any PFI pin as the source for GPCTR0_GATE and configure the polarity selection for either rising or falling edge. Y ou can use the gate signal in a variety of different applications to perform actions such as starting and stopping the counter, generating interrupts, saving the counter contents, and so on.

As an output, the GPCTR0_GATE signal reflects the actual gate signal connected to general-purpose counter 0. This is true even if the gate is being externally generated by another PFI signal. This output is set to tri-state at startup.

GPCTR0_OUT Signal

This signal is available only as an output on the GPCTR0_OUT pin. The GPCTR0_OUT signal reflects the terminal count (TC) of general-p urp ose counter 0. You have two software-s electable ou tput o ption s—pulse o n TC and toggle output po larity on TC. The out put polarity is software selectable for both options. This output is set to tri-state at startup. Figure 4-10 shows the timing of the GPCTR0_OUT signal.

GPCTR0_SOURCE

GPCTR0_OUT

(Pulse on TC)

GPCTR0_OUT

(Toggle output on TC)

Figure 4-10.

GPCTR0_UP_DOWN Signal

This signal can be externally input on the DIO6 pin and is no t available as an output on the I/O connector. The general-purpose counter 0 will count down when this pin is at a logic low and count u p when it is at a logic high . You can disable this input so that software can control the up-down functionality and leave the DIO6 pin free for general use.

PCI-4451/4452 User Manual 4-20

GPCTR0_OUT Signal Timing

National Instruments Corporation

Chapter 4 Signal Connections

GPCTR1_SOURCE Signal

Any PFI pin can externally input the GPC TR1_SOURCE signal, which is available as an output on the PFI3/GPCTR1_SOURCE pin.

As an input, the GPCTR1_S OURCE signal is conf igured in edge-detect ion mode. Y ou can select an y PFI pin as the source for GPCTR1_SOURCE and configure the polarity selection for either rising or falling edge.

As an output, the GPCTR1_SOURCE monitors the actual clock connected to general-purpose counter 1. This is true even if the source clock is externally generated by another PFI signal. This output is set to tri-state at startup.

Figure 4-11 shows the ti ming requirements for the GP CTR1_SOURCE signal.

Figure 4-11.

= 50 ns minimum

= 23 ns minimum

GPCTR1_SOURCE Signal Timing

The maximum allowed frequen cy is 20 MHz, with a minimum pulse width of 23 ns high or low. There is no minimum frequency limitation.

The 20 MHz or 100 kHz timebase normally generates the GPCTR1_SOURCE unless you select some external source.

GPCTR1_GATE Signal

Any PFI pin can externally input the GPCTR1_GATE signal, which is available as an output on the PFI4/GPCTR1_GATE pin.

As an input, the GPCTR1_GATE signal is configured in edge-detection mode. You can select any PFI pin as the source for GPCTR1_GATE and configure the polarity selection for either rising or falling edge. Y ou can use the gate signal in a variety of different applications to perform such actions as starting and stopping the counter, generating interrupts, saving the counter contents, and so on.

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Chapter 4 Signal Connections

GPCTR1_SOURCE

GPCTR1_OUT

(Pulse on TC)

GPCTR1_OUT

(Toggle output on TC)

As an output, the GPCTR1_GATE signal monitors the actual gate signal connected to general-purpose counter 1. This is true even if the gate is externally generated by another PFI signal. This output is set to tri-state at startup.

GPCTR1_OUT Signal

This signal is available only as an output on the GPCTR1_OUT pin. The GPCTR1_OUT signal monitors the TC device general-purpose counter 1. You have two software-selectable o utput options—puls e on TC and toggle output polarity on TC. The output polarity is software selectable for bo th options. This output is set to tri-state at startup. Figure 4-12 shows the timing requirements for the GPCTR1_OUT signal.

Figure 4-12.

GPCTR1_UP_DOWN Signal

This signal can be externally input on the DIO7 pin and is no t available as an output on the I/O connector. General-purpose counter 1 counts down when this pin is at a logic low and counts up at a logic high. This input can be disabled so that software can control the up-down functionality and leave the DIO7 pin free for general use. Figure 4-13 requirements for the GATE and SOURCE input signals and the timing specifications for the OUT output signals of your PCI-4451/4452 device.

PCI-4451/4452 User Manual 4-22

GPCTR1_OUT Signal Timing

shows the timing

National Instruments Corporation

Chapter 4 Signal Connections

SOURCE

GATE

OUT

gsu

Source Clock Period Source Pulse Width Gate Setup Time Gate Hold Time Gate Pulse Width Output Delay Time

out

t 50 ns minimum t

t t t t

Figure 4-13.

sc sp gsu gh gw out

GPCTR Timing Summary

23 ns minimum 10 ns minimum 0 ns minimum 10 ns minimum 80 ns maximum

The GA TE and OUT signal transitions shown in Figure 4-13 are referenced to the rising edge of the SOURCE signal. This timing diagram assumes that you programmed the counters to count rising edges. The same timing diagram, but with the source signal inverted and referenced to the falling edge of the source signal , would apply when you programmed the counter to count falling edges .

The GATE input timing parameters are referenced to the signal at the SOURCE input or to one of the internally generated signals on your PCI-4451/4452 device. Figure 4-13 shows the GATE signal referenced to the rising edge of a source signal. The gate must be valid (either high or low) for at least 10 ns before the rising or falling edge of a source signal for the gate to take effect at that source edge, as shown by t

and tgh in

gsu

Figure 4-13. The gate signal is not required to be held af ter t he active edge of the source signal.

If you use an internal timebase clock, the gate signal cannot be synchronized with the clock. In this case, gates applied close to a source edge take effect either on that source edge or on the next one. This arrangement results in an uncertainty of one source clock period with respect to unsynchronized gating sources.

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Chapter 4 Signal Connections

The OUT output timing parameters are referenced to the signal at the SOURCE input or to one of the internally generated clock signals on the PCI-4451/4452 devices. Figure 4-13 shows the OUT signal referenced to the rising edge of a source signal. Any OUT signal state changes occur within 80 ns after the rising or falling edge of the source signal.

FREQ_OUT Signal

This signal is available only as an output on the FREQ_OUT pin. The PCI-4451/4452 device frequency generator outputs the FREQ_OUT pin. The frequency generator is a 4-bit counter that can divide its input clock b y the numbers 1 through 16. The input clock of the frequency generator is software-selectable from the internal 10 MHz and 100 k Hz timebases. The output polarity is software selectable. This output is set to tri-state at startup.

Field Wiring Considerations

Environmental noise can seriously influence the accuracy of measurements made with your PCI-445 1/4452 device if you do not take pro per care when running signal wires between sign al sources an d the devi ce. The follo wing recommendations apply mainly to analog input signal routing to the device, although they also apply to signal routing in general.

Minimize noise pickup and maximize measurement accuracy by taking the following precautions:

• Use differential analog input connections to reject common-mode noise.

• Use individually shielded, twisted-pair wires to connect analog input signals to the device. W ith this type of wire, the signals attached to the +ACHx and −ACHx inputs are twisted together and then covered with a shield. You then connect this shield only at one point to the signal source ground. This kind of connection is requi red for signals tra veling through areas with large magnetic fields or high electromagnetic interference.

• Route signals to the device carefully. Keep cabling away from noise sources. The most common noise source in a PCI data acquisition system is the video monitor. Separate the monitor from the analog signals as much as possible.

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National Instruments Corporation

Chapter 4 Signal Connections

The following recommendations apply for all signal connections to digital signal routing from your PCI-4451/4452 device:

• The digital output signal integrity is greatly influenced by the length of the cable being driven. Minimize cable lengths and use schmitt-trigger devices to deglitch signals. Further conditioning may be req uired to create a clean signal.

• Always try to couple a ground wi th a signal to minimize noi se pickup and radiation.

The following recommendations apply for all signal connections to your PCI-4451/4452 device:

• Separate PCI-4451/4452 device signal lines from high-current or high-voltage lines. These lines can induce currents in or voltages on the PCI-4451/4452 de v ice si gnal line s if th e y run i n parall el paths at a close distance. To reduce the magnetic coupling between lines, separate them by a reasonable distance if they run in parallel, or run the lines at right angles to each other.

• Do not run signal lines through cond ui ts th at als o co ntai n p ower lines.

• Protect signal lines from magnetic fields caused by electric motors, welding equipment, breakers, or transf ormers by running them through special metal conduits.

For more information, refer to the application note, Field Wiring and Noise Consideration for Analog Signals, available from National Instruments.

National Instruments Corporation 4-25 PCI-4451/4452 User Manual

Calibration

This chapter discusses the calibration procedures for your PCI-4451/4452 device. Your PCI-4451/4452 is shipped with a calibration certificate. The traceability information is stored in National Instruments corporate databases and is not actually shown on your certificate. The certificate contains a unique tracking nu mber linking your device to the database. You can get a detailed calibration report from National Instruments for an additional charge.

If you are using the NI-DAQ device driver, that software includes calibration functions for performing all o f the steps in the calibration process. Calibration refers to the process of minimizing measurement and output voltage errors by making small circuit adjustments. On the PCI-4451/4452 de vi ces , thes e adjus tment s ta k e the form of writing values to onboard calib rati on DACs (CalD ACs). Some form of device calibration is required for all but the most forgiving applications. If you do not calibrate your device, your signals and measurements could have very large offset and gain errors. The four lev els of calibration av ailable are described in this chapter. Th e first le vel is the fastest, easiest, and least accurate, whereas the last level is the slowest, most difficult, and most accurate.

Loading Calibration Constants

Your PCI-4451/4452 device is factory calibrated before shipment at approximately 25° C to the levels indicated in Appendix A, Specifications. The associated calibration constants—the values that were written to the CalDACs to achieve calibration in the factory—are stored in the onboard nonvolatile memory (EEPROM). Because the CalDACs have no memory capability, they do not retain calibration information wh en the device is unpowered. Loading calibration co nstants refers to the process of loading the CalDACs with the values stored in the EEPROM. NI-DAQ software determines when this is necessary and does it automatically.

The EEPROM contains a user-modifiable calibration area in addition to the p ermanent factory calibration area. This means that you can load the CalDA Cs with values either from the original factory calibration or from a calibration that you subsequently performed. This method of calibration is

National Instruments Corporation 5-1 PCI-4451/4452 User Manual

Chapter 5 Calibration

Self-Calibration

not very accurate because it does not take into account the fact that the device measurement and output volt age errors can vary with time and temperature. It is better to self-calibrate when you install the device in your environmen t.

Your PCI-4451/4452 device can measure and correct for almost all of its calibration-related errors without any external signal connections. Your National Instruments software provides a self-calibration method. This self-calibration process, which generally takes less than a minut e , is the preferred method of assuring accuracy in your application. Initiate self-calibration to minimize the effects of any offset and gain drifts, particularly those due to warmup.

Your PCI-4451/4452 device has an o nboard calibration refere nce to ensure the accuracy of self-calibration. Its specifications are listed in Appendix A,

Specifications. The reference voltage is measured at the factory and stored

in the EEPROM for subsequent self-calibrations. Immediately after self-calibration, the only significant residual calibration

error could be gain error due to time or temperature drift of the onboard voltage reference. This error is addressed by ex ternal calibration , which is discussed in the following section, External Calibration. If you are interested primarily in relative measurements, you can ignore a small amount of gain error, and self-calibration should be sufficient.

If you calibrate your PCI-4451/4452 device while it is connected to a BNC-2140 accessory, set each input channel to SE and connect each channel + terminal to a channel - terminal through a BNC shunt. You can also calibrate your PCI-4451/4452 device by removing the external cable connected to the BNC-2140 accessory.

External Calibration

The onboard calibration reference voltage is stable enough for most applications, but if you are using your device at an extreme temperature or if the onboard reference has not been measured for a year or more, you may wish to externally calibrate your device.

An external calibration refers to calibrating your device with a known external reference rather than relying on the onboard reference. Redetermining the value of the onboard reference is part of this process and

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National Instruments Corporation

you can sav e the resul ts in the EEP ROM, so you shou ld not ha ve to per form an external calibration very often. You can externally calibrate your de vice by calling the NI-DAQ calibration function. To externally calibrate your device, be sure to use a ver y accurate external DC referen ce. The reference should be several times more accurate than the device itself. For example, to calibrate the PCI-4451/4452, the external reference should have a DC accuracy better than ±115 ppm (±0.001 dB).

Traceable Recalibration

Traceable recalibration is divided into three different areas—factory, on-site and third party. Devices typically require this type of recalibration every year.

If you require factory recalibration, send your PCI-4451/4452 back to National Instruments. The device will be sent back to you with a new calibration certificate. A detailed report may be requested for an additional fee. Please check with National Instruments for additional information such as cost and delivery times.

If your company has a metrology laboratory, you can recalibrate the PCI-4451/4452 at your location (on-site). You can also send out your PCI-4451/4452 for recalibration by a third party. Please contact National Instruments for approved third-party calibration service providers.

Chapter 5 Calibration

National Instruments Corporation 5-3 PCI-4451/4452 User Manual

Theory of Analog Operation

This chapter contains a functional overview and explains the operation of each analog functional unit making up the PCI-4451/4452.

Functional Overview

See Figure 3 -2, Analog Function Block Diagram, for a general block diagram of the PCI-4451/4452 analog functions.

Analog Input Circuitry

The PCI-4451 has two identical analog input channels. The PCI-4452 has four identical analog input channels. An analog input channel is illustrated in Figure 4-3, Analog Input Stage.

These input channels have 16-bit resolution and are simultaneously sampled at softwar e-programmable rates from 5 t o 204.8 kS/s in 190.7µS/s increments. This flexibility in sample rates makes the device well suited for a wide variety of applications, including audio and vibration analysis.

The differential analog inputs have AC/DC coupling. You can use a programmable gain amplifier stage on the inputs to select gains from

-20 to 60 dB in 10 dB steps. The input stage has differential connections,

allowing quiet measurement of either single-ended or differential signals. The analog inputs have both analog and real-time digital filters

implemented in hardware to prevent aliasing. Input signals first pass through lowpass analog filters to attenuate signals with frequency components beyond the range of the ADCs. Then digital antialiasing filters automatically adjust their cutoff frequency to remove frequency components above half the programmed sampling rate. Because of this advanced analog input design, you do not have to add any filters to prevent aliasing. These filters do cause a delay of 42 conversion periods between the input analog data and the digitized data.

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Chapter 6 Theory of Analog Operation

The 90 dB dynamic range of the PCI-44 51/4452 devi ces is the result of low noise and distortion and makes possible high-accuracy measurements. The devices ha ve excelle nt amplitude flatness of ±0.1 dB, and have a maximum total harmonic distortion (THD) specification of −92 dB at 1 kHz and a worst case THD of −80 dB at higher frequencies.

State-of-the-art, 128-times oversampling, delta-sigma modulating ADCs achieve the low noise and low distortion of the PCI-4451/4452. Because these ADCs sample at 128 times the specified sampling rate with 1-bit resolution, they produce nearly perfect linearity. Extremely flat, linear-phase, lowpass digital filters then remove the quantization noise from outside the band of interest, divide the sample rate by 128, and increase the resolution to 16 bits. Using the delta-sigma modulating ADCs, the PCI-4451/4452 are immune to the DNL distortion associated with conventional data acquisition devices.

Input Coupling

The PCI-4451/4452 has a software programmable switch to individually configure each input channel for AC or DC coupling. If the switch is set for DC, the capacitor is bypassed, and any DC offset present in the source signal being used passes to the ADC. The DC configuration is preferred because it places one less component in the signal path and thus has higher fidelity. The DC configuration is recommended if the signal source has only small amounts of offset voltage (less than ±100 mV), or if the DC content of the acquired signal is important.

If the source has a significant amount of unwan ted of fset (o r bias voltage), you must set the switch for AC coupling to take full advantage of the input signal range. Using AC coupling results in a drop in the low-frequency response of the analog input. The −3 dB cut of f f requ ency is appr oximate ly

3.4 Hz, but the −0.01 dB cutoff frequency, for instance, is considerably higher at approximately 70.5 Hz. The input coupling switch can connect the input circuitry to ground instead of to the si gnal source. This connection is usually made during of fset cal ib rat ion, which is described in Chapter 5,

Calibration.

Calibration

The PCI-4451/4452 analog inputs have calibration adjustments. Onboard calibration DACs remove the offset and gain errors for each channel. For complete calibration instructions, refer to Chapter 5, Calibration.

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National Instruments Corporation

Antialias Filtering

Chapter 6 Theory of Analog Operation

A sampling system (such as an ADC) can represent signals of only limited bandwidth. Specifically, a sampling rate of Fs can only represent signals with a maximum frequency of Fs/2. This maximum frequency is known as the Nyquist frequency. If a signal is input to the sampling system with frequency components that exceed the Nyquist frequency, the sampler cannot distinguish these parts of the signal from some signals with frequency components less than the Nyquist frequency.

For example, suppose a sampler (such as an ADC) is sampling at 1,000 S/s. If a 400 Hz sine wave is input, then the resulting samples accurately represent a 400 Hz sine wave. Howev er, if a 600 Hz sine wav e is input, the resulting samples again appear to represent a 400 Hz sine wave because this signal exceeds the Nyquist frequenc y (500 Hz) by 10 0 Hz. In f act, any sine wave with a frequency greater than 500 Hz that is input is represented incorrectly as a signal between 0 and 500 Hz. The apparent frequency of this sine wave is the absolute v alue of the dif ference between the frequ ency of the input signal and the closest integer multiple of 1,000 Hz (the sampling rate). Therefore, if a 2,325 Hz sine wave is input, its apparent frequency is:

2,325 − (2)(1,000) = 325 Hz.

If a 3,975 Hz sine wave is input, its apparent frequency is:

(4)(1,000) − 3,975 = 25 Hz.

The process by which the sampler modulates these higher frequency signals back into the 0 to 500 Hz baseband is called aliasing.

If the signal in the previous example is not a sine wa ve, the sign al can hav e many components (harmonics) that lie above the Nyquist frequency. If present, these harmonics are erroneously aliased back into the baseband and added to the parts of the signal that are sampled accu rately, producing a distorted sampled data se t. Input to the sampler only those signals that can be accurately represented. All frequency components of such signals lie below the Nyquist frequ e nc y. T o mak e s ure t hat only those signals go into the sampler, a lowpass filter is applied to signals before they reach the sampler. The PCI-4451/4452 has complete antialiasing filters.

The PCI-4451/4452 includes two stages of antialias filtering in each input channel lowpass filter. This filter has a cutoff frequency of about 4 MHz and a rejection of greater than 40 dB at 20 MHz. Because its cutoff frequency is significantly higher than the data sample rate, the analog filter

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Chapter 6 Theory of Analog Operation

has an extremely flat frequency response in the bandwidth of interest, and it has very little phase error.

The analog filter precedes the analog sampler, which oper ates at 128 times the selected sample rate (26.2144 MS/s in the case of a 204.8 kS/s sample rate) and is actually a 1-bit ADC. The 1-bit, 128-times oversampled data that the analog sampler produces is passed on to a digital antialiasing f ilter that is built into the ADC chip. This filter also has extremely flat frequency response and no phase error , but its roll-of f near the cutof f frequency (abou t

0.493 times the sample rate) is extremely sharp, and the rejection above

0.536 times the sample rate is greater than 85 dB. The output stage of the digital filter resamples the higher frequency data stream at the output data rate, producing 16-bit digital samples.

With the PCI-4451/4452 filters, you have the complete antialiasing protection needed to sample signals accurately. The digital filter in each channel passes only those signal components with frequencies that lie below the Nyquist frequency or within one Nyquist bandwidth of multiples of 128 times the sample rate. The analog filter in each channel rejects possible aliases (mostly noise) from signals that lie near these multiples. Figures 6-1 and 6-2 show the frequency response of the PCI-4451/4452 input circuitry.

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National Instruments Corporation

Chapter 6 Theory of Analog Operation

Amplitude (dB)

0.00

–20.00

–40.00

–60.00

–80.00

–100.00

–120.00

0.00 0.20 0.40 0.60 0.80 1.00 Frequency/Sample Rate (f

)

Figure 6-1.

Input Frequency Response

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Chapter 6 Theory of Analog Operation

Amplitude (dB)

0.00

–1.00

–2.00

–3.00

–4.00

–5.00

–6.00

0.43 0.44 0.45 0.46 0.47 0.48 0.49 0.50 Frequency/Sample Rate (f

)

Figure 6-2.

Input Frequency Response Near the Cutoff

Because the ADC samples at 128 times the data rate, frequency components above 64 times the data rate can alias. The digital filter rejects most of the frequency range over which aliasing can occur. However, the filter can do nothing about components that lie close to 128 times the data rate, 256 times the data rate, and so on, because it cannot distinguish these components from components in the baseband (0 Hz to the Nyquist frequency). If, for instance, the sample rate is 200 kS/s and a signal component lies within 100 kHz of 25.6 MHz (128 × 200 kHz), this signal is aliased into the passband region of the digital filter and is not attenuated. The purpose of the analog filter is to remove these higher frequency components near multiples of the oversampling rate before they get to the sampler and the digital filter.

While the frequency response of the digital filter scales in proportion to the sample rate, the frequency response of the analog filter remains fixed. The response of the filter is optimized to produce good high-frequency alias rejection while having a flat in-band frequency respo nse. Because this filter is third order, its roll-off is rather slow . This means that, although the filter has good alias rejection for high sample rates, it does not reject as well at lower sample rates. The alias rejection near 128 times the sample rate

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National Instruments Corporation

Alias Rejection (dB)

0.00

–10.00

–20.00

–30.00

–40.00

–50.00

–60.00

–70.00

–80.00

Sample Rate

Over-Sample

Frequency

Chapter 6 Theory of Analog Operation

versus sample rate is illustrated in Figure 6-3. For frequencies not near multiples of the oversample rate, the rejection is better than 85 dB.

1 kS/s 10 kS/s 100 kS/s 1 MS/s

128 kHz

1.28 MHz

12.8 MHz 128 MHz

Figure 6-3.

Alias Rejection at the Oversample Rate

There is a form of aliasing that no filter can prevent. When a waveform exceeds the voltage range of the ADC, it is said to be clipped or overranged. When clipping occurs, the ADC assumes the closest value in its digital range to the actual value of the signal, which is always either −32,768 or +32,767. Clipping nearly alwa ys results in an abrupt change in th e slope of the signal and causes the corrupted digital data to have high-frequency energy. This energy is spread throughout the frequency spectrum, and because the clipping happens after the antialiasing filters, the energy is aliased back into the baseband. The remedy for this problem is simple: do not allow the signal to exceed the nominal input range. Figure 6-4 shows the spectra of 10.5 V

and 10.0 V

rms

, 3.0 kHz sine waves digiti zed at

rms

48 kS/s. The signal-to-THD plus noise ratio is 35 dB for the clipped waveform and 92 dB for the properly ranged waveform. Notice that aliases of all the harmonics due to clipping appear in Figure 6-4.

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Chapter 6 Theory of Analog Operation

-0

-20

-40

-60

-80

-100

-120

-140 0 5000 10000 15000 20000 25000

a. Clipped Signal b. Proper Signal

Figure 6-4.

An overrange can occur on the analog signal as well as on the digitized signal. Furthermore, an analog overrange can occur independently from a digital overrange and vice-versa. For example, a piezoelectric accelerometer may have a resonant frequency that, when stimulated, can produce an overrange in the analog signal, but because the delta-sigma technology of the ADC uses very sharp antialiasing f ilters, the overr ange is not passed into the digitized signal. Conversely, a sharp transient on the analog input may not ov errange, b ut due to the step r esponse of those same delta-sigma antialiasing filters, the digitized data may be clipped.

-0

-20

-40

-60

-80

-100

-120

-140 0 5000 10000 15000 20000 25000

Comparison of a Clipped Signal to a Proper Signal

The ADC

The PCI-4451/4452 ADCs use a method of A/D conversion known as delta-sigma modulation. If the data rate is 204.8 kS/s, each ADC actually samples its input signal at 26.2144 MS/s (128 times the data rate) and produces 1-bit samples that are applied to the digital filter. This filter then expands the data to 16 bits, rejects signal components greater than

102.4 kHz (the Nyquist frequency), and resamples the data at the more conventional rate of 204.8 kS/s.

Although a 1-bit quantizer intr oduces a lar ge amou nt of quan tiza tion error to the signal, the 1-bit, 26 MS/s from the ADC carry all the information used to produce 16-bit samples at 204.8 kS/s. The delta-sigma ADC achieves this conversion from high speed to high resolution by ad ding a large amount of random noise to t he signal so that the resulting quantizati on noise, although large, is restricted to frequencies above 102.4kHz. This noise is not correlated with the input signal and is almost completely rejected by the digital filter.

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National Instruments Corporation

Noise

Chapter 6 Theory of Analog Operation

The resulting output of the filter is a band-limited signal with a dynamic range of over 90 d B. One of th e adv antages of a delta-sigma ADC is that it uses a 1-bit DAC as an internal reference, whereas most 16-bit ADCs use 16-bit resistor-network DACs or capacitor-network D ACs. As a result, the delta-sigma ADC is free from the kind of differential nonlinearity (DNL) that is inherent in most high-resolution ADCs. This lack of DNL is especially beneficial when the ADC is converting low-level signals, in which noise and distortion are directly affected by converter DNL.

The PCI-4451/4452 an alog inp uts typical ly ha ve a dynamic r ange o f more than 90 dB. The dynamic range of a circuit is the ratio of the magnitudes of the largest signal the circuit can carry and the r esidual noise in the absence of a signal. In a 16-bit system, the largest signal is taken to be a ful l-scale sine wave that peaks at the codes +32,767 and −32,768. Such a sine wave has an rms magnitude of 32,768/1.414 = 23,170.475 least significant bits (LSBs).

A grounded channel of the PCI-4451/4452 has a noise level of about

0.65 LSB rms (this amount fluctuates). The ratio of 23,170.475 / 0.65 is about 35647, or 91.0 dB— the dynamic range. Se veral factors can degrade the noise performance of the inputs.

First, noise can be picked up from nearby electronics. The PCI -44 51/4 452 works best when it is kept as far away as possible from other plug-in devices, power supplies, disk drives, and computer monitors. Cabling is also critical. Make sure to use well-shielded coaxial or balanced cables fo r all connections, and route the cables away from sources of interference such as computer monitors, switching power supplies, and fluorescent lights.

Finally, choose the sample rate carefully. Take advantage of the antialias filtering that removes signals beyond the band of interest. Computer monitor noise, for example, typically occurs at frequencies between 15 and 50 kHz. If the signal of interest is restricted to below 10 kHz, for example, the antialias filters reject the monitor noise outside the frequency band of interest. The frequency response inside the band of interest is not influenced if the sample rate were between roughly 21.6 and 28 kS/s.

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Chapter 6 Theory of Analog Operation

Analog Output Circuitry

The PCI-4451 has two an alog output channels , either of which is illustrated in Figure 4-4, Analog Output Channel Block Diagram.

A common application for the analog output is to stimulate a system under test while measuring the response with the analog inputs. The inpu t and output sample clocks are synchronized and derived from the same DDS clock. The input and output clocks can differ from each other by a factor of 2 (1, 2, 4, 8, ... 128) while still maintaining their synchronization. Output conversions occur simultaneously at software-programmable rates from

1.25 to 51.2 kS/s, in increments of 47.684 µS/s. The analog output circuitry uses eight-times oversampling interpolators

with 64-times oversampling delta-sigma modulators to generate high-quality signals. The output chann el has a range up to ±10 V (7.07 V attenuation stage so you can choose attenuation of 0, −20, or −40 dB.

Because of the delta-sigma modulating DAC, the device is immune to DNL distortion. The analog output stage generates signals with extremely low noise and low distortion. Because the device has a 93 dB dynamic range , it is possible to generate lo w- noise wa ve forms. The de vice al so has e xcellent amplitude flatness of ±0. 2 dB wit hin the frequen c y range o f DC to 2 3 kHz and has a total harmonic di s t orti on (T HD) of −95 dB at 1 kHz. With these specifications, you are assured of the quality and integrity of the output signals generated.

) and can be dri ven as SE or DIFF. The analog output also has an

rms

Anti-Image Filtering

A sampled signal repeats itself throughout the frequency spectrum. These repetitions begin above one-h alf the sample rate (Fs) and, at least in theory, continue up through the spectrum to infinity, as shown in Figure 6-5a. Because the sample data actually represents only the frequency components below one-half the sample rate (the baseband), it is desirable to filter out all these extra images of the signal. The PCI-44 51 accomplishes this filtering in two stages.

First, the Then, a linear-phase digital filter removes almost all energy above one-half the original sample rate and sends the data at the eight-times rate to the DAC, as shown in Figure 6-5b. Some further (inherent) filtering occurs at the DA C because the data is digitally sampled and held at eight times the sample rate. This filtering has a sin x / x response, yielding nulls at multiples

PCI-4451/4452 User Manual 6-10

data is digitally resampled at eight times the original sample rate.

National Instruments Corporation

of eight times the sample rate, as shown in Figure 6-5c. Still, images remain and they must be filtered out. Each output channel of the PCI-4451 has discrete-time (switched-capacitor) and continuous-time analog filters that remove the high-frequency images, as shown in Figure 6-5d.

Baseband Signal Images

Amplitude

8 F

a. Spectrum of Sampled Signal

Chapter 6 Theory of Analog Operation

16 F

Frequency

Baseband Signal

AmplitudeAmplitude

Baseband Signal

Amplitude

Images After the Digital Filter

8 F

b. Spectrum of Signal After Digital Filter

Images After the DAC

8 F

c. Spectrum of Signal After DAC

8 F

d. Spectrum of Signal After Analog Filters

16 F

Frequency

Figure 6-5.

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Signal Spectra in the DAC

Chapter 6 Theory of Analog Operation

The DAC

The 64-times oversampling delta-sigma DACs on the PCI-4451 work in the same way as delta-sigma ADCs, only in reverse. The digital data fi rst passes through a digital lowpass filter and then goes to the d elta-sigma modulator.

In the ADC the delta-sigma modulator is analog circuitry that converts high-resolution analog signals to high-rate, 1-bit digital da ta, w hereas in the DAC the delta-sigma modulator is digital circuitry that converts high-resolution digital data to high-rate, 1-bit digital data. As in the ADC, the modulator frequency-shapes the quantization n oise so that almost all of its energy is above the signal frequency (refer to The ADC, earlier in this chapter).

The digital 1-bit data is then sent directly to a simple 1 -bit DAC. This DAC can have only one of two analog values, and therefore is inherently perfectly linear. The output of the DAC, however, has a large amount of quantization noise at higher frequencies, and, as described in the section,

Anti-Image Filtering, some images still remain near multiples of eight

times the sample rate. Two anal og filters eliminate the quantization noise and the images. The

first is a fifth-order, switched-capacitor filter in which the cutoff frequency scales with the sample frequency and is approximately 0.52 times the sample frequency. This filter has a four-pole Butterworth response and an extra pole at about 1.04 times the sample frequency.

The second filter is a continuous-time, second-order Butterworth filter in which the cutoff frequency (at 80 kHz) does not scale with the sample frequency. This filter mainly removes high-frequency images from the 64-times oversampled switched-capacitor filter. These filters cause a delay between the input digital data and the output analog data of

34.6 ±0.5 sample periods.

Calibration

The PCI-4451 analog outputs h ave calibration ad justments. Onbo ard calibration DACs remove the offset and gain errors for each channel. For complete calibration instructions, refer to Chapter 5, Calibration.

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National Instruments Corporation

Mute Feature

Chapter 6 Theory of Analog Operation

The two-channel DAC chip on the PCI-4451 goes into mute mode if the chip receives at least 4,096 consecutive zero values on both channels at once. In mute mode, the outputs clamp to ground and the nois e floor drops from about 92 dB belo w full-s cale to about 12 0 dB b elow ful l-scale. Upon receiving any nonzero data, the DAC instantly reverts to normal mode. Mute mode is designed to quiet the background noise to extremely low levels when no waveforms are being generated. Mute mode has a slig htly different offset from the normal offset when zeros are being sent. As a result, the DAC has one offset for th e first 4, 096 zero sa mples and ano ther offset in mute mode for as long as zeros are sent. This difference is usually less than 1 mV.

National Instruments Corporation 6-13 PCI-4451/4452 User Manual

Specifications

This appendix lists the specifications of the PCI-4451/44 52. These specifications are typical at 25° C unless otherwise noted. The system must be allowed to warm-up for 15 minutes to achieve the rated accuracy.

Note

Analog Input

Be sure to keep the cover on your computer to maintain forced air cooling.

Channel Characteristics

Number of channels...............................2 (PCI-4451) or 4 (PCI-4452),

simultaneously sampled

Input configuration.................................true differential

Resolution ..............................................16 bits

Type of ADC..........................................Delta-sigma, 128-times

oversampling

Sample rates ...........................................5 kS/s to 204.8 kS/s in increments

of 190.735 µS/s

Frequency accuracy................................±100 ppm

Input signal ranges.............................. ...software-selectable

Gain

Full-Scale Range (Peak)Linear Log

0.1

0.316 1 0 dB ±10.0

3.16 +10 dB ±3.16 V 10 +20 dB ±1.00 V

National Instruments Corporation A-1 PCI-4451/4452 User Manual

−20 dB

−10 dB

±42.4 V ±31.6 V

Appendix A Specifications

Gain

Full-Scale Range (Peak)Linear Log

31.6 +30 dB ±0.316 V 100 +40 dB ±0.100 V 316 +50 dB ±0.0316 V

1000 +60 dB ±0.0100 V

FIFO buffer size......................................512 samples

Data transfers..........................................DMA, programmed I/O, interrupt

Transfer Characteristics

INL (relative accuracy)...........................±2 LSB

DNL........................................................±0.5 LSB typ, ±1 LSB max,

no missing codes

Offset (residual DC)

Gain Max Offset

−20 dB ±30 mV

−10 dB ±10 mV

0 dB ±3 mV +10 dB ±1 mV +20 dB ±300 µV

+30, +40, +50, +60 dB ±100 µV

Gain (amplitude accuracy)......................±0.1 dB, f

PCI-4451/4452 User Manual A-2

= 1 kHz

National Instruments Corporation

Appendix A Specifications

Amplifier Characteristics

Input impedance.....................................1 MΩ in parallel with 50 pF

(+ and − each to AIGND)

Frequency response

Gain

0, +10, +20, +30, +40 dB................±0.1 dB, 0 to 95 kHz, 204.8 kS/s,

DC coupling

−20, −10, +50, +60 dB....................±1 dB, 0 to 95 kHz, ±0.1 dB,

0 to 20 kHz

−3 dB bandwidth....................................0.493 f

Input coupling.......................... .............. AC or DC, software-selectable

AC −3 dB cutoff frequency ............ 3.4 Hz

Common-mode range

Gain ≥0 dB................................... ...both + and − should remain within

±12 V of AIGND

Gain < 0 dB.....................................both + and − should remain within

±42.4 V of AIGND

Overvoltage protection...........................±42.4 V, powered on or off

(±400 V guarant eed by design, but not tested or certified to operate beyond ±42.4 V)

Inputs protected...............................ACH0, ACH1, ACH2, ACH3

Common mode rejection ratio

< 1 kHz)............................................90 dB, Gain ≥0 dB

60 dB, Gain < 0 dB

National Instruments Corporation A-3 PCI-4451/4452 User Manual

Appendix A Specifications

Noise

(dB Full-Scale) –65.0

–70.0

–75.0

–80.0

–85.0

–90.0

–95.0

Gain = +60 dB

Gain = +50 dB

Gain = +40 dB

Gain = All Others

1,000,0001,000 10,000 100,000

Sample Rate (S/s)

Figure A-1.

Input noise spectral density ....................8 nV/ (achievable only at

Idle Channel Noise (Typical)

Gain = +50 dB or +60 dB)

Dynamic Characteristics

Alias-free bandwidth ..............................DC to 0.464 f

Alias rejection.........................................80 dB, 0.536 fs < fin < 63.464 f

Spurious-free dynamic range..................95 dB

THD........................................................−80 dB; −90 dB for f

IMD ........................................................−1 00 dB (CCI F 14 kHz + 15 kHz)

Crosstalk (channel separation)................−100 dB, DC to 100 kHz

PCI-4451/4452 User Manual A-4

signal < 1 V

rms

National Instruments Corporation

< 20 kHz or

Phase linearity........................................±1°, Gain ≥ 0 dB,

Interchannel phase..................................±1°, Gain ≥ 0 dB,

Interchannel gain mismatch...................±0.1dB, for all gains

Signal delay............................................42 sample periods, any sample

Onboard Calibration Reference

DC level .................................................5.000 V ±2.5 mV

Temperature coefficient.........................±5 ppm/° C max

Appendix A Specifications

±2°, Gain < 0 dB

±2°, Gain < 0 dB (same configuration all input channels)

(same configuration for all input channels)

rate (time from when signal enters analog input to when digital data is available)

Long-term stability.................................±15 ppm/

1000 h,

Analog Output

♦ PCI-4451 only

Channel Characteristics

Number of channels...............................2 simultaneously updated

Output configuration..............................balanced differential

Resolution ..............................................16 bits

Type of DAC..........................................Delta-sigma, 64-times

oversampling

Sample rates...........................................1.25 to 51.2 kS/s in increments

of 47.684 µS/s

Frequency accuracy................................±100 ppm

National Instruments Corporation A-5 PCI-4451/4452 User Manual

Appendix A Specifications

Output signal range, software-selectable

Attenuation

Linear Log

Full

-scale Range

1 0 dB ±10.0 V

10 20 dB ±1.00 V

100 40 dB ±0.100 V

FIFO buffer size......................................512 samples

Data transfers..........................................DMA, programmed I/O, Interrupt

Transfer Characteristics

Offset (residual DC) ...............................±5 mV max, any gain

Gain (amplitude accuracy)......................±0.1 dB, f

= 1 kHz

out

Voltage Output Characteristics

Output impedance...................................22 Ω between + and −

DACxOUT, 4.55 kΩ to AOGND

Frequency response ................................±0.2 dB, 0 to 23 kHz, 51.2 kS/s

−3 dB bandwidth.....................................0.492 f

Output coupling......................................DC

Short-circuit protection...........................yes (+ and − may be shorted

Outputs protected....................................±DAC0OUT, ±DAC1OUT

Idle channel noise ...................................−91 dB f

PCI-4451/4452 User Manual A-6

together indefinitely)

, DC to 23 kHz

measurement bandwidth

National Instruments Corporation

Appendix A Specifications

Dynamic Characteristics

Image-free bandwidth............................DC to 0.450 f

Image rejection.......................................90 dB, 0.550 fs < f

< 63.450 f

out

Spurious-free dynamic range................. 90 dB, DC to 100 kHz

THD .......................................................−80 dB; −90 dB for f

or signal < 1 V

rms

< 5 kHz

out

IMD........................................................−90 dB (CCIF 14 kHz + 15 kHz)

Crosstalk (channel separation)...............−80 dB, DC to 23 kHz

Phase linearity........................................±1°

Interchannel phase..................................±1°

(same configuration both output channels)

Interchannel gain mismatch...................±0.1 dB, for all attenuations

(same configuration both output channels)

Signal delay............................................34.6 ±0.5 sample periods, any

sample rate (time from when digital data is expressed to when analog signal appears at output terminals)

Digital I/O

Number of channels...............................8 input/output

Compatibility .........................................TTL/CMOS

National Instruments Corporation A-7 PCI-4451/4452 User Manual

Appendix A Specifications

Digital logic levels

Level Min Max

Timing I/O

Input low voltage Input high voltage Input low current (V Input high current (V

= 0 V)

= 5 V)

Output low voltage (IOL = 24 mA) Output high voltage (I

= 13 mA)

0.0 V

2.0 V — —

—

4.35 V

0.8 V

5.0 V

−320 µA

10 µA

0.4 V

Power-on state ........................................Input (High-Z)

Data transfers..........................................Programmed I/O

Number of channels................................2 up/down counter/timers,

1 frequency scaler

Resolution

Counter/timers.................................24 bits

Frequency scaler..............................4 bits

Compatibility..........................................TTL/CMOS

—

Base clocks available

Counter/timers.................................20 MHz, 100 kHz

Frequency scaler..............................10 MHz, 100 kHz

Base clock accuracy................................±0.01%

Max source frequency.............................20 MHz

Min source pulse duration .....................10 ns, edge-detect mode

Min gate pulse duration .........................10 ns, edge-detect mode

Data transfers..........................................DMA, interrupts,

PCI-4451/4452 User Manual A-8

programmed I/O

National Instruments Corporation

Triggers

Appendix A Specifications

DMA modes...........................................Scatter gather

Analog Trigger

Source

PCI-4451.........................................ACH<0..1>

PCI-4452.........................................ACH<0..3>

Level.......................................................± full-scale

Slope.......................................................Positive or negative

(software selectable)

Resolution ..............................................16 bits

Hysteresis...............................................Programmable

Digital Trigger

Compatibility .........................................TTL

Bus Interface

Power Requirement

Response ................................................Rising or falling edge

Pulse width.............................................10 ns min

Type .......................................................PCI Master/Slave

Power (PCI-4451)..................................+5 V, 1.7 A idle, 2.0 A active

+12 V, 11 mA typical

(not including momentary relay

switching)

−12 V, 40 mA typical

+3.3 V, unused

Power (PCI-4452)..................................+5 V, 2.2 A idle, 2.5 A active

+12 V, 150 mA typical

(not including momentary relay

switching)

−12 V, unused

+3.3 V, unused

National Instruments Corporation A-9 PCI-4451/4452 User Manual

Appendix A Specifications

Physical

Environment

Available power......................................+4.65 to +5.25 VDC at 0.5 A

(analog I/O connector)

Available power......................................+4.65 to +5.25 VDC at 1.0 A

(digital I/O connector)

Dimensions (not including connectors)..10.65 by 31.19 by 1.84cm

(4.19 by 12.28 by 0.73 in.)

Digital I/O connector..............................50-pin VHDIC female type

Analog I/O connector .............................68-pin VHDIC female type

Operating temperature............................0° C to +40° C

Storage temperature range......................−25° C to +85° C

Relative humidity ...................................10% to 95%, no condensation

Calibration

Calibration interval.................................1 year

PCI-4451/4452 User Manual A-10

National Instruments Corporation

Pin Connections

This appendix describes the pin connections on the optional 68-pin digital accessories for the PCI-4451 and PCI-4452 devices.

National Instruments Corporation B-1 PCI-4451/4452 User Manual

Appendix B Pin Connections

FREQ_OUT

PFI9/GPCTR0_GATE

GPCTR0_OUT

PFI8/GPCTR0_SOURCE

UPDATE*

PFI6/WFTRIG

PFI7

PFI4/GPCTR1_GATE

GPCTR1_OUT

PFI3/GPCTR1_SOURCE

PFI0/TRIG1 (EXT_TRIG)

PFI1/TRIG2 (PRETRIG)

CONVERT*

RESERVED1

DIO(7) DIO(6)

DIO(5)

DIO(4) DIO(3)

EXTSTROBE*

DIO(2) DIO(1) DIO(0)

+5 V

N/C N/C

N/C N/C N/C N/C N/C N/C N/C N/C

135 236 337 438 539 640 741 842

943 10 44 11 45 12 46 13 47 14 48 15 49 16 50 17 51 18 52 19 53 20 54 21 55 22 56 23 57 24 58 25 59 26 60 27 61 28 62 29 63 30 64 31 65 32 66 33 67 34 68

DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND

DGND DGND

DGND DGND DGND DGND +5 V DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND

Figure B-1.

68-Pin Digital Connector for any Digital Accessory

PCI-4451/4452 User Manual B-2

National Instruments Corporation

Customer Communication

For your convenience, this appendix contains forms to help you gather the information necessary to help us solve your technical problems and a form you can use to comment on the product documentation. When you contact us, we need the information on the Technical Support Form and the configuration form, if your manual contains on e, about your system configuration to answer your questions as quickly as possible.

National Instruments has technical assistance through electronic, fax , and telephone systems to quickly provide the information you need. Our electronic services include a b ulletin board service, an FTP site, a fax-on-demand system, and e-mai l support. If you ha ve a hard ware or softw are problem, first try the electronic support systems. If the information available on these systems does not answer your questions, we of fer fax and tel ephone suppo rt through ou r technical sup port center s, which are staf fed by applications engineers.

Electronic Services

Bulletin Board Support

National Instruments has BBS and FTP si tes dedicated for 24-hour support with a collection of files and documents to answer most common customer questions. From these sites, you can also download the latest instrument drivers, updates, and e xample program s. Fo r recorded instructions on h o w to use the bulletin board and FTP services and for BBS automated information, call 512 795 6990. You can access these services at:

United States: 512 7945422

Up to 14,400 baud, 8 data bits, 1 stop bit, no parity

United Kingdom: 01635 551422

Up to 9,600 baud, 8 data bits, 1 stop bit, no parity

France: 01 48 65 15 59

Up to 9,600 baud, 8 data bits, 1 stop bit, no parity

FTP Support

To access our FTP site, log on to our Internet host, ftp.natinst.com, as anonymous and use your Internet address, such as documents are located in the

National Instruments Corporation C-1 PCI-4451/4452 User Manual

joesmith@anywhere.com, as your password. The support files and

/support directories.

Fax-on-Demand Support

Fax-on-Demand is a 24-h our information ret riev al system co ntaining a library of documents on a wide range of technical information. You can access Fax-on-Demand from a touch-tone telephone at 512 418 1111.

E-Mail Support (Currently USA Only)

You can submit technical support questions to the applications engineering team through e-mail at the Internet address listed below. Remember to include your name, address, and phone number so we can contact you with solutions and suggestions.

support@natinst.com

Telephone and Fax Support

National Instruments has branch offices all over the world. Use the list below to find the technical support number for your countr y. If there is no Na tional Instrume nts office in your country, contact the source from which you purchased your software to obtain support.

Country Telephone Fax

Australia 03 9879 5166 03 9879 6277 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Brazil 011 288 3336 011 288 8528 Canada (Ontario) 905 785 0085 905 785 0086 Canada ( Denmark 45 76 26 00 45 76 26 02 Finland 09 725 725 11 09 725 725 55 France 01 48 14 24 24 01 48 14 24 14 Germany 089 741 31 30 089 714 60 35 Hong Kong 2645 3186 2686 8505 Israel 03 6120092 03 6120095 Italy 02 413091 02 41309215 Japan 03 5472 2970 03 5472 2977 Korea 02 596 7456 02 596 7455 Mexico 5 520 2635 5 520 3282 Netherlands 0348 433466 0348 430673 Norway 32 84 84 00 32 84 86 00 Singapore 2265886 2265887 Spain 91 640 0085 91 640 0533 Sweden 08 730 49 70 08 730 43 70 Switzerland 056 200 51 51 056 200 51 55 Taiwan 02 377 1200 02 737 4644 United Kingdom 01635 523545 01635 523154 United States 512 795 8248 512 794 5678

) 514 694 8521 514 694 4399

Québec

PCI-4451/4452 User Manual C-2

National Instruments Corporation

Technical Support Form

Photocopy this form and update it each time y ou make chan ges to your sof tware or har dware, an d use the completed copy of this form as a reference for your current configuration. Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.

If you are using any National Instruments hardware or software products related to this problem, include the configuration forms from their user manuals. Include additional pages if necessary.

Name __________________________________________________________________________ Company _______________________________________________________________________ Address ________________________________________________________________________

_______________________________________________________________________________ Fax ( ___ )________________Phone ( ___ ) __________________________________________ Computer brand____________Model ___________________Processor _____________________ Operating system (include version number) ____________________________________________ Clock speed ______MHz RAM _____MB Display adapter __________________________ Mouse ___yes ___no Other adapters installed_______________________________________ Hard disk capacity _____MB Brand_________________________________________________ Instruments used _________________________________________________________________

_______________________________________________________________________________ National Instruments hardware product model_____________ Revision ____________________ Configuration ___________________________________________________________________ National Instruments software product___________________ Version _____________________ Configuration ___________________________________________________________________ The problem is: __________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________ List any error messages: ___________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________ The following steps reproduce the problem: ___________________________________________

_______________________________________________________________________________

PCI-4451/4452 Hardware and Software Configuration Form

Record the settings and revisions of your hardware and software on the line to the right of each item. Complete a new copy o f this for m each time you revise your software or hardware configuration, an d use this form as a reference for your current configuration. Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.

National Instruments Products

PCI-4451/4452 device ____________________________________________________________ PCI-4451/4452 device serial number _________________________________________________ Base memory address of the PCI-4451/4452 device _____________________________________ Programming choice and version (NI-DAQ, LabVIEW, or other) __________________________ Other boards in system ____________________________________________________________ Base I/O address of other boards ____________________________________________________ DMA channels of other boards _____________________________________________________ Interrupt level of other boards ______________________________________________________

Other Products

Computer make and model ________________________________________________________ Microprocessor __________________________________________________________________ Clock frequency or speed __________________________________________________________ Type of video board installed _______________________________________________________ Operating system version __________________________________________________________ Operating system mode ___________________________________________________________ Programming language ___________________________________________________________ Programming language version _____________________________________________________ Other boards in system ____________________________________________________________ Base I/O address of other boards ____________________________________________________ DMA channels of other boards _____________________________________________________ Interrupt level of other boards ______________________________________________________

Documentation Comment Form

National Instruments encourages you to comment on the documentation supplied with our products. This information helps us provide quality products to meet yo ur needs.

Title:

PCI-4451/4452 User Manual

Edition Date:

Part Number:

Please comment on the completeness, clarity, and organization of the manual.

_______________________________________________________________________________

_______________________________________________________________________________ If you find errors in the manual, please record the page numbers and describe the errors.

_______________________________________________________________________________

April 1998 321891A-01

Thank you for your help. Name _________________________________________________________________________ Title __________________________________________________________________________ Company _______________________________________________________________________ Address ________________________________________________________________________

_______________________________________________________________________________ E-Mail Address __________________________________________________________________ Phone ( ___ ) __________________________ Fax ( ___ ) _______________________________

Mail to:

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Technical Publications

Glossary

Prefix Meanings Value

p- pico 10 n- nano- 10 µ- micro- 10

m- milli- 10

k- kilo- 10

M- mega- 10

G- giga- 10

t- tera- 10

Numbers/Symbols

°degree

–12

–9

–6

–3

Ωohm % percent + positive of, or plus – negative of, or minus /per

A amperes AC alternating current AC coupled allowing the transmission of AC signals while blocking DC signals A/D analog-to-digital

National Instruments Corporation G-1 PCI-4451/4452 User Manual

Glossary

ADC analog-to-digital converter—an electronic device, often an integrated

circuit, that converts an analog voltage to a digital number

ADC resolution the size of the discrete steps in the ADC’s input-to-output transfer function;

therefore, the smallest voltage diff erence an ADC can discriminate with a

single measurement AI Convert LabVIEW name for CONVERT*. See CONVERT* AI Start Trigger LabVIEW name for TRIG1. See TRIG1 AI Stop Trigger LabVIEW name for TRIG2. SeeTRIG2 alias a false lower frequency component that appears in sampled data acquired

at too low a sampling rate amplification a type of signal conditioning that improves accuracy in the resulting

digitized si gnal and reduces noise amplitude flatness a measure of how close to constant the gain of a circuit remains over a range

of frequencies AO Start Trigger LabVIEW name for WFTRIG. See WFTRIG AO Update LabVIEW name for UPDATE*. See UPDATE* ASIC Application-Specific Integrated Circuit—a proprietary semiconductor

component designed and manufactured to perform a set of specific

functions for a specific customer asynchronous (1) hardware—a property of an event that occurs at an arbitrary time,

without synchronizatio n to a r eferen ce clock (2 ) sof tware—a p ropert y of a

function that begins an operation and returns prior to the completion or

termination of the operation attenuate to decrease the amplitude of a signal attenuation ratio the factor by which a signal’s amplitude is decreased

PCI-4451/4452 User Manual G-2

National Instruments Corporation

Glossary

b bit—one binary digit, eith er 0 or 1 B byte—eight related bits of data, an eight-bit binary number. Also used to

denote the amount of memory required to store one byte of data

bandwidth the range of frequencies present in a signal, or the range of frequencies to

which a measuring device can respond

base address a memory address that serves as the starting address for programmable

registers. All other addresses are located by adding to the base address. binary a number system with a base of 2 bipolar a signal range that includes both positi v e and negati v e values (for example,

–5 V to +5 V) BNC a type of coaxial signal connector buffer temporary storage for acquired or generated data (software) burst-mode a high-speed data transfer in which the address of the data is sent followed

by back-to-back data words while a physical signal is asserted bus the group of conductors that interconnect individual circui try in a computer .

Typically, a bus is the expansion vehicle to which I/O or other devices are

connected. Examples of PC buses are the ISA and PCI bus. bus master a type of a plug-in board or controller with the ability to read and write

devices on the computer bus

CCelsius Ca lDAC cal ib ration DAC channel pin or wire lead to which you apply or from which you read the analog or

digital signal. Analog signals can be single-ended or differential. For digital

signals, you group channels to form ports. Ports usually consist of either

four or eight digital channels. circuit trigger a condition for starting or stopping clocks

National Instruments Corporation G-3 PCI-4451/4452 User Manual

Glossary

clip clipping occurs when an input signal exceeds the input range of the

amplifier

clock hardware component that controls timing for reading from or writing to

groups CMOS complementary metal-oxide semiconductor CMRR common-mode rejection ratio—a measure of an in strument’s ability to

reject interference from a common-mode signal, usually expressed in

decibels (dB) code width the smallest detectable change in an input voltage of a DAQ device common-mode range the input range over which a circuit can handle a common-mode signal common-mode signal the mathematical average voltage, relativ e to the computer’ s ground, of the

signals from a differential input common-mode voltage any voltage present at the instrumentation amplifier inputs with respect to

amplifier ground compensation range the range of a parameter for which compensating adjustment can be made conditional retrieval a method of triggering in which you simulate an analo g trigger using

software. Also called software triggering. conversion device device that transforms a signal from one form to another. For example,

analog-to-digital converters (ADCs) for analog input, digital-to-analog

converters (DACs) for analog output, digital input or output ports, and

counter/timers are conversion devices. conversion time the time required, in an analog inpu t or outp ut system, from th e moment a

channel is interrogated (such as with a read instruction) to the moment that

accurate data is available CONVERT* convert signal counter/timer a circuit that counts external pulses or clock pulses (timing) coupling the manner in which a signal is connected from one location to another crosstalk an unwanted signal on one channel due to an input on a different channel

PCI-4451/4452 User Manual G-4

National Instruments Corporation

Glossary

current drive capability th e amount o f current a digital or analog output channel is capable of

sourcing or sinking while still operating within voltage range specifications

current sinking the ability of a DA Q board to dissipate current for analog or digital output

signals

current sourcing the ability of a DAQ board to supply current for analog or digital output

signals

D/A digital-to-analog DAC digital-to-analog converter—an electronic device, often an integrated

circuit, that converts a digital number into a corresponding analog voltage or current

daisy-chain a method of propagating signals along a bus, in which the devices are

prioritized on the basis of their position on the bus

DAQ data acquisition—(1) collecting and measuring electrical signals from

sensors, transducers, and test probes or fixtures and inputting them to a computer for processing; (2) collecting and measuring the same kinds of electrical signals with A/D and/or DIO boards plugged into a computer , and possibly generating control signals with D/A and/or DIO boards in the same computer

dB decibel— the unit for expressing a logarithmic measure of the ratio of two

signal levels: dB=20log

(V1/V2), for signals in volts

DC direct current DC coupled allowing the transmission of both AC and DC signals default setting a default parameter value recorded in the driv er. In many cases, the default

input of a control is a certain value (often 0) that means use the current

default setting. For example, the default input for a parameter may be do not change current setting, and the default setting m a y be no AMUX-64T boards. If you do change the value of such a parameter, the new value

becomes the new setting. You can set default settings for some parameters in the configuration utility or manually using switches located on the device.

National Instruments Corporation G-5 PCI-4451/4452 User Manual

Glossary

delta-sigma modulating ADC

a high-accuracy circuit that samples at a higher rate and lower resolution

than is needed and (by means of feedback loops) pushes the quantization

noise above the frequency range of interest. This out-of-band noise is

typically removed by digital filters. device a plug-in data acquisition board, card, or pad that can contain multiple

channels and conversion devices. Plug-in boards, PCMCIA cards, and

devices such as the DAQPad-1200, which connects to your computer

parallel port, are all examples of DAQ devices. SCXI modules are distinct

from devices, with the exception of the SCXI-1200, which is a hybrid. DIFF differential mode differential input an analog input consisting of two terminals, both of which are isolated from

computer ground, whose difference is measured differential measurement

system

a way you can configure your device to read signals, in which you do not

need to connect either input to a fixed reference, such as the earth or a

building ground digital port See port. digital trigger a TTL level signal having two discrete levels—a high and a low level DIO digital input/output DMA direct memory access—a method by which data can be transferred to/fro m

computer memory from/to a device or memory on the bus while the

processor does something else. DMA is the fastest method of transferring

data to/from computer memory. DNL differential nonlinearity—a measure in least significant bit of the

worst-case deviation of code widths from their ideal value of 1 LSB down counter performing frequency division on an internal signal drivers software that controls a specific hardware device such as a DAQ board or

a GPIB interface board dynamic range the ratio of the largest signal level a circuit can handle to the smallest signal

level it can handle (usually taken to be the noise level), normally expressed

in decibels

PCI-4451/4452 User Manual G-6

National Instruments Corporation

Glossary

EEPROM electrically erasable programmable read-only memory—ROM that can be

erased with an electrical signal and reprogrammed EMC electromechanical compliance encoder a device that converts linear or rotary displacement into digital or pulse

signals. The most popular type of encoder is the optical encoder , which uses

a rotating disk with alternating opaque areas, a light source, and a

photodetector. EPROM erasable programmable read-only memory—ROM that can be erased

(usually by ultraviolet light exposure) and reprogrammed event the condition or state of an analog or digital signal expansion ROM an onboard EEPROM that may contain device-specific initialization and

system boot functionality external trigger a voltage pulse from an external source that triggers an event such as A/D

conversion EXTSTROBE* external strobe signal

false triggering triggering that occurs at an unintend ed time FIFO first-in first-out memory buf fer—the first data stored is the first data sent to

the acceptor. FIFOs are often used on DAQ devices to temporarily store

incoming or outgoing data until that data can be retrieved or output. For

example, an analog input FIFO stores the results of A/D conversions until

the data can be retrieved into system memory, a process that requires the

servicing of interrupts and often the programming of the DMA controller.

This process can take several milliseconds in some cases. During this time,

data accumulates in the FIFO for future retrieval. With a larger FIFO,

longer latencies can be tolerated. In the case of analog output, a FIFO

permits faster update rates, because the wa veform d ata can be stored on the

FIFO ahead of time. This again reduces the effect of latencies associated

with getting the data from system memory to the DAQ device.

National Instruments Corporation G-7 PCI-4451/4452 User Manual

Glossary

filtering a type of signal conditioning that allows you to attenuate unwanted portions

of the signal you are trying to measure FIR finite impulse response—a non recursive digital filter with linear phase flash ADC an ADC whose output code is determined in a single step by a bank of

comparators and encoding logic floating signal sources signal sources wi th voltage signals that are not connected to an absolute

reference or system ground. Also called nonreferenced signal sources.

Some common example of floating signal sources are batteries,

transformers, or thermocouples. FREQ_OUT frequency signal ft feet

gain the factor by which a signal is amplified, sometimes expressed in decibels gain accuracy a measure of deviation of the gain of an amplifier from the ideal gain GPCTR0_GATE general-purpose counter timer 0 gate signal GPCTR0_OUT general-purpose counter timer 0 output signal GPCTR0_SOURCE general-purpose counter timer 0 clock source signal GPCTR1_GATE general-purpose counter timer 1 gate signal GPCTR1_OUT general-purpose counter timer 1 output signal GPCTR1_SOURCE general-purpose counter timer 1 clock source signal grounded measurement

See SE. system

PCI-4451/4452 User Manual G-8

National Instruments Corporation

Glossary

h hour half-power bandwidth the frequency range over which a circuit maintains a level of at least –3 dB

with respect to the nominal level

handshaked digital I/O a type of digital acquisition/generation where a device or module accepts

or transfers data after a digital pulse has been received. Also called latched digital I/O.

hardware the physical components of a computer system, such as the circuit boards,

plug-in boards, chassis, enclosures, peripherals, and cables

hardware triggering a form of triggering where you set the start time of an acquisition and gather

data at a known position in time relative to a trigger signal

Hz hertz—cycles per second. Specifically refers to the repetition frequency of

a waveform.

IC integrated circuit IMD intermodulation distortion—the ratio, in dB, of the total rms signal level of

harmonic sum and difference distortion pro ducts, to th e o verall rms signal level. The test signal is two sine waves added together according to the following standards:

SMPTE—A 60 Hz sine wave and a 7 kHz sine wave added in a 4:1 amplitude ratio.

DIN—A 250 Hz sine wave and an 8 kHz sine wave added in a 4:1 amplitude ratio.

CCIF—A 14 kHz sine wave and a 15 kHz sine wave added in a

1:1 amplitude ratio. in. inches INL integral nonlinearity—a measure in LSB of the worst-case deviation from

the ideal A/D or D/A transfer characteristic of the analog I/O circuitry

input bias current the current that flows into the inputs of a circuit

National Instruments Corporation G-9 PCI-4451/4452 User Manual

Glossary

input impedance the measured resistance and capacitance between the input terminals of a

circuit

input offset current the difference in the input bias currents of the two inputs of an

instrumentation amplifier

instrument driver a set of high-level software functions that controls a specific GPIB, VXI,

or RS-232 programmable instrument or a specific plug-in DAQ board. Instrument drivers are available in several forms, ranging from a function callable language to a virtual instrument (VI) in LabVIEW.

instrumentation amplifier

a circuit whose output v oltage with respect to grou nd is prop ortional to t he difference between the voltages at its two inputs

integrating ADC an ADC whose output code represents the average value of the input

voltage over a given time interval

interrupt a computer signal indicating that the CPU should suspend its current task

to service a designated activity interrupt level the relative priority at which a device can interrupt I/O input/output—the transfer of data to/from a computer system involving

communications channels, operator interface devices, and/or data

acquisition and control interfaces I

current, output high

current, output low IRQ interrupt request isolation a type of signal conditioning in which you isolate the transducer signals

from the computer for safety purposes. This protects you and your

computer from large voltage spikes and makes sure the measurements from

the DAQ device are not affected by differences in ground potentials. isolation voltage the voltage that an isolated circuit can normally withstand, usually

specified from inpu t to input and/ or from an y input to the amp lif ier output ,

or to the computer bus

PCI-4451/4452 User Manual G-10

National Instruments Corporation

Glossary

k kilo—the standard metric prefix for 1,000, or 103, used with units of

measure such as volts, hertz, and meters

K kilo—the prefix for 1,024, or 2

, used with B in quantifying data or

computer memory kbytes/s a unit for data transf er that means 1,024 bytes/s kS 1,000 sa mples Kword 1,024 words of memory

LabVIEW laboratory virtual instrument engineering workbench latched digital I/O a type of digital acquisition/generation where a device or module accepts

or transfers data after a digital pulse has been received. Also called

handshaked d i gital I/O. library a file containing compiled object modules, each comprised of one of more

functions, that can be linked to other object modules that make use of these

functions. NIDAQMSC.LIB is a library that contains NI-DAQ functions.

The NI-DAQ function set is broken down into object modules so that only

the object modules that are rele van t to your application ar e linked in, while

those object modules that are not relevant are not linked. linearity the adherence of device response to the equation R = KS, where

R = response, S = stimulus, and K = a constant linearization a type of signal conditioning in which software linearizes the voltage levels

from transducers, so the voltages can be scaled to measure physical

phenomena low frequency corner in an AC -coupled circuit, the frequency belo w which signals are attenuated

by at least 3 dB LSB least significant bit

National Instruments Corporation G-11 PCI-4451/4452 User Manual

Glossary

m meters

M (1) Mega, the standard metric prefix for 1 million or 10

units of measure such as v olts and hertz; (2 ) mega, the pref ix for 1,048,57 6,

, when used with B to quantify data or computer memory

or 2 Mbytes/s a unit for data transfer that means 1,048,576 bytes/s memory buffer See buffer. MITE MXI Interface to Everything—a custom ASIC designed by National

Instruments that implements the PCI bus interface. The MITE supports bus

mastering for high-speed data transfers over the PCI bus. MS million samples MSB most significant bit MTBF mean time between failure MTTR mean time to repair—predicts downtime and how long it takes to fix a

product

, when used with

NC normally closed, or not connected NI-DAQ National Instrument s driver software for DAQ hardware NIST National Institute of Standards and Technology noise an undesirable electrical signal—Noise comes from external sources such

as the AC power line, moto rs, generato rs, transform ers, fluor escent lights,

soldering irons, CR T displays, comp uters, electrical storms, welders, radio

transmitters, and internal sources such as semicond uctors, resistors, and

capacitors. Noise corrupts signals you are trying to send or receive. nonlatched digital I/O a type of digital acquisition/generation where LabVIEW updates the digital

lines or port states immediately or returns the digital value of an input line.

Also called immediate digital I/O or non-handshaking.

PCI-4451/4452 User Manual G-12

National Instruments Corporation

National Instruments PCI-4452, PCI-4451 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

PCI-4451/4452 User Manual

Internet Support

Bulletin Board Support

Fax-on-Demand Support

Telephone Support (USA)

International Offices

National Instruments Corporate Headquarters

Important Information

Warranty

Copyright

Trademarks

WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS

Contents

Figures

Tables

About This Manual

Organization of This Manual

Conventions Used in This Manual

National Instruments Documentation

Related Documentation

Customer Communication

What You Need to Get Started

Unpacking

Software Programming Choices

National Instruments Application Software

Optional Equipment

Custom Cabling

Software Installation

Hardware Installation

Device Configuration

Analog Input

Input Mode

Input Coupling

Input Polarity and Input Range

Considerations for Selecting Input Ranges

Analog Output

Output Mode

Output Polarity and Output Range

Trigger

RTSI Triggers

Digital I/O

Timing Signal Routing

Programmable Function Inputs

Device and RTSI Clocks

Selecting Sample/Update Clock Frequency

Device Configuration Issues

I/O Connectors

Analog I/O Connector Signal Descriptions

Digital I/O Connector Signal Descriptions

Analog Input Signal Connections

Types of Signal Sources

Floating Signal Sources

Ground-Referenced Signal Sources

Analog Output Signal Connections

Analog Power Connections

Digital I/O Signal Connections

Digital Power Connections

Timing Connections

Programmable Function Input Connections

Acquisition Timing Connections

PFI0/TRIG1 (EXT_TRIG) Signal

PFI1/TRIG2 (PRETRIG) Signal

CONVERT* Signal

EXTSTROBE* Signal

Waveform Generation Timing Connections

WFTRIG Signal

UPDATE* Signal

General-Purpose Timing Signal Connections

GPCTR0_SOURCE Signal

GPCTR0_GATE Signal

GPCTR0_OUT Signal

GPCTR0_UP_DOWN Signal

GPCTR1_SOURCE Signal

GPCTR1_GATE Signal

GPCTR1_OUT Signal

GPCTR1_UP_DOWN Signal