National Instruments BNC-2140 User Manual

DAQ

BNC-2140 User Manual

Dynamic Signal Acquisition Signal Conditioning Accessory

BNC-2140 User Manual

June 1998 Edition

Part Number 321933B-01

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© Copyright 1998 National Instruments Corporation. All rights reserved.

Important Information

Warranty

The BNC-2140 is warranted against defects in materials and workmanship for a period of one year from the date of
shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace
equipment that proves to be defect ive du ring t he wa rranty period . Th is warranty incl udes parts a nd l abor.

A Return Material Authorization (RMA) number must b e ob tain ed fro m th e facto ry an d clearl y mark ed on t he outsi de
of the package before any equipment wil l be accepted for warranty work. National Instruments will pay the shippi ng costs
of returning to the owner parts which are covered by warran ty.

National Instruments believes that the information in this manual is accurate. The document has been c arefully reviewed
for technical accuracy. In the event that technical or typographical errors exist, National Instruments reserves the right to
make changes to subsequent editions of th is do cume nt with ou t p rio r no ti ce to hold ers o f thi s ed itio n. The read er sh ou ld
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 docume nt o r th e in form ati on con tai ned in i t.

XCEPT AS SPECIFIED HEREIN

E

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, wh ether in con tract or tort , incl udin g n egli gen ce.
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, malfuncti ons, or s ervice failur es caused by own er’s fai lure to fol low
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 photocopying, recording, storing in an information retrieval system, or translating, in whole or in part, without
the prior written consent of National Instruments Corporation.

USTOMER’S RIGHT TO RECOVER DAMAGES CAUSED

. C

. This limitation of the liability of

,

Trademarks

ICP® is a registered trademark of PCB Piezotronics, Inc.
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 com ponent s and tes ting inten ded to ensure a l evel of reliab ilit y
suitable for use in treatment and diagnosis of humans. Applications of National Instruments products invol ving m edical
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 designer. Any use or application of National Instruments products for or involving medical or clinical
treatment must be performed by properly trained and qualified medical personnel, and all traditional medical safeguards,
equipment, and procedures that are appropriate in the particular situation to prevent serious injury or death should always
continue to be used when National Instruments products are being used . National Instrum ents product s are NOT intended
to be a substitute for any form of established process, procedure, or equipment used to monitor or safeguard human health
and safety in medical or clinical treatment.

Contents

About This Manual

Organization of This Manual.........................................................................................vii

Conventions Used in This Manual.................................................................................viii

Related Documentation........................................... .......................................................viii

Customer Communication.............................................................................................viii

Chapter 1
Introduction

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

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

Optional Equipment................................................ .......................................................1-2

Custom Cabling .............................................................................................................1-3

Chapter 2
Installation and Configuration

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

Device Configuration...................................................... ...............................................2-1

Chapter 3
Signal Connections

I/O Connectors...............................................................................................................3-1

Analog Input Signal Connections..................................................................................3-5

Analog Output Signal Connections ...............................................................................3-5

Chapter 4
Theory of Operation

Functional Overview......................................................................................................4-2

Analog Input Circuitry...................................................................................................4-3

Analog Output................................................................................................................4-4

Appendix A
Specifications

Analog Input....................................................................................................A-1

Voltage Input.....................................................................................A-1

Current Excitation........................................................ .....................A-1

Analog Output.................................................................................................A-2

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National Instruments Corporation v BNC-2140 User Manual

Contents

Power Requirement (from DSA board)..........................................................A-2

Physical...........................................................................................................A-2

Environment....................................................................................................A-2

Appendix B
Customer Communication

Glossary

Index

Figures

Figure 2-1. Switch Settings and Signal Connections...............................................2-2

Figure 3-1. BNC-2140 External 68-Pin Analog Connector ....................................3-3

Figure 4-1. BNC-2140 Block Diagram ...................................................................4-2

Tables

Table 3-1. BNC Analog I/O Connector Signal Descriptions ................................3-1

Table 3-2. 68-Pin Analog I/O Connector Signal Descriptions .............................. 3-4

BNC-2140 User Manual vi

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National Instruments Corporation

About This Manual

This manual describes the electrical and mechanical aspects of the
BNC-2140 accessory and contains information concerning its operation.

Organization of This Manual

The BNC-2140 User Manual is organized as follows:

• Chapter 1, Introduction, describes the BNC-2140 accessory, lists what
you need to get started, explains how to unpack your BNC-2140, and
describes optional equipment.

• Chapter 2, Installation and Configuration, explains how to install and
configure your BNC-2140 accessory.

• Chapter 3, Signal Connections, describes how to make input and
output signal connections to your BNC-2140.

• Chapter 4, Theory of Operation, contains a functional overview of the
BNC-2140.

• Appendix A, Specifications, lists the specifications of the BNC-2140.

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

• 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.

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National Instruments Corporation vii BNC-2140 User Manual

About This Manual

Conventions Used in This Manual

The following conventions are used in this manual:

<> Angle brackets containing numbers separated by an ellipsis represent a

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

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

!

bold italic Bold italic text denotes a note or caution.

italic Italic text denotes a variable, emphasis, a cross reference, or an introduction

SE SE means referenced single ended (RSE).

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.

Related Documentation

The following documents contain information you may find helpful:

• National Instruments Application Note 025, Field Wiring and Noise

Considerations for Analog Signals

• PCI-4451/4452 User Manual

• NI 4551/4552 User Manual

Customer Communication

National Instruments wants to receive your comments on our products
and manuals. We are interested 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, this manual contains comment and configuration
forms for you to complete. These forms are in Appendix B, Customer

Communication, at the end of this manual.

BNC-2140 User Manual viii

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National Instruments Corporation

Introduction

This chapter describes the BNC-2140 accessory, lists what you need to get
started, explains how to unpack your BNC-2140, and describes optional
equipment.

Thank you for buying the BNC-2140 accessory for DSA.The BNC-2140 is
a signal conditioning accessory specifically designed for use with a
dynamic signal acquisition (DSA) series device. It interfaces four BNC
signal inputs and two BNC signal outputs directly to National Instruments
DSA products including the PCI-4451, PCI-4452, NI 4551, and NI 4552.
The BNC-2140 connects to Integrated Circuit Piezoelectric (ICP
accelerometers and microphone preamplifiers as well as any other voltage
source whose output is less than ±42.4 V.

Each input channel consists of an independent 4 mA current source suitable
for use with ICP type accelerometers and microphone preamplifiers. You
can manually enable or disable the ICP signal conditioning on a per channel
basis. When disabled, the BNC-2140 acts as a direct voltage input. You can
manually switch each input channel and each output channel from
differential (DIFF) to single-ended (SE) mode. In SE mode, the BNC shell
tethers to a clean analog ground through a 50 Ω resistor.

1

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)

The BNC-2140 receives power for the ICP signal conditioning from the
DSA plug-in board via the 68-pin high-density connector. A green LED
indicates when the ICP circuitry is powered on. When you do not require
ICP signal conditioning, you can manually turn off the power to the
circuits.

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National Instruments Corporation 1-1 BNC-2140 User Manual

Chapter 1 Introduction

What You Need to Get Started

To set up and use your BNC-2140 device, you will need the following:

❑ BNC-2140
❑ One of the following DSA devices:

PCI-4451
PCI-4452
NI 4551
NI 4552

❑ BNC-2140 User Manual
❑ Your computer
❑ SHC68-C68-A1 analog cable

Unpacking

Your BNC-2140 is shipped in an antistatic plastic package to prevent
electrostatic damage to the device. Several components on the device can
be damaged by electrostatic discharge. To avoid such damage in handling
the device, take the following precautions:

• Ground yourself via a grounding strap or by holding a grounded object.

• 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 sign of damage. Notify National Instruments
if the device appears damaged in any way. Do not install a damaged
device.

• Never touch the exposed pins of connectors.

Optional Equipment

If your application requires that you use transducers with microdot
connectors, use the BNC plug screw-on receptacle, part number
033-0101-0001, from Microdot Connector Company. This accessory
allows you to conect BNC and microdot connectors.

BNC-2140 User Manual 1-2

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National Instruments Corporation

Custom Cabling

Chapter 1 Introduction

If your application requires that you use a prepolarized microphone with a
microphone preamplifier, contact Brüel and Kjær.

National Instruments offers cables of different lengths for the BNC-2140
accessory to connect your analog I/O signals to the DSA devices. National
Instruments recommends that you not develop your own cabling solution
due to the high-density connector that is required and the necessity to
maintain high signal integrity.

If your application requires you to 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 pin s. For a co nnector pino ut descripti on refer to Table 3-2 in
Chapter 3, Signal Connections.

• You can create your own accessories by using a 68-pin very high
density cable interconnect (VHDCI) receptacle header using AMP
68-position right-angle PWB receptacle header 787254-1.

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

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

787191-1

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National Instruments Corporation 1-3 BNC-2140 User Manual

Installation and Configuration

This chapter explains how to install and configure your BNC-2140
accessory.

Installation

2

Note

You must turn the power off to your computer before installing the BNC-2140.

The following are general installation instructions.

1. Insert either end of your SHC68-C68-A1 analog cable into the 68-pin
connector on the BNC-2140. Insert the other end into the 68-pin
connector on the DSA plug-in device.

2. Tighten the jack screws finger-tight on both ends of the cable.

3. Check the installation.

4. Turn on your computer.

The BNC-2140 accessory is now installed.

Device Configuration

You must manually configure the BNC-2140 accessory by setting the
channel switches. You can configure each input channel to have ICP signal
conditioning enabled or disabled, and for DIFF and SE measurements. Y ou
can also configure each output channel for DIFF or SE measurements. You
can turn the power on or off for the ICP signal conditioning circuitry. If you
do not require ICP signal conditioning, turn off the ICP power. Refer to
Figure 2-1 for the location of the switches.

Note

You can connect or disconnect BNC cables carrying signals without turning off
the computer.

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National Instruments Corporation 2-1 BNC-2140 User Manual

Chapter 2 Installation and Configuration

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Figure 2-1. Switch Settings and Signal Connections

BNC-2140 User Manual 2-2

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National Instruments Corporation

Signal Connections

This chapter describes how to connect input and output signals to your
BNC-2140.

You can connect the external analog signals through six BNC connectors.
Four BNC connectors are for input signals and two connectors are for
output signals.

The SHC68-C68-A1 shielded cable connects the BNC-2140 internal
analog signal connector to the DSA plug-in device. A single 68-pin 0.8 mm
VHDCI connector connects the analog I/O signals to the shielded cable.

I/O Connectors

Table 3-1 shows the pin assignments for the six external I/O BNC
connectors.

3

Table 3-1.

Signal Name Reference Direction Description

+ACH<0..3> AIGND Input +Analog Input Channel 0 through 3—Each channel

–ACH<0..3> AIGND Input

+DAC0OUT –DAC0OUT Output +Analog Output Channel 0—This pin supplies the

–DAC0OUT +DAC0OUT Output

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National Instruments Corporation 3-1 BNC-2140 User Manual

BNC Analog I/O Connector Signal Descriptions

can have ICP enabled or disabled. This signal passes
through the BNC internal conductor.

–Analog Input Channel 0 through 3—In SE mode
the inverting (–) terminal is tethered to ground
through a 50 Ω resistor. This signal passes through
the external BNC shell.

analog non-inverting output channel 0. This signal
passes through the internal BNC conductor.

–Analog Output Channel 0—This pin supplies the
analog inverting output channel 0. This signal
passes through the external BNC shell. In SE mode,
the inverting (–) terminal is tethered to ground
through a 50 Ω resistor.