National Instruments BNC-208X User Manual

BNC-208X Series

User Manual

Analog BNC Breakout Boards

September 1993 Edition Part Number 320407-01

National Instruments Corporate Headquarters

6504 Bridge Point Parkway Austin, TX 78730-5039 (512) 794-0100 Technical support fax: (800) 328-2203

(512) 794-5678

Branch Offices:

Australia (03) 879 9422, Austria (0662) 435986, Belgium 02/757.00.20, Canada (Ontario) (519) 622-9310, Canada (Québec) (514) 694-8521, Denmark 45 76 26 00, Finland (90) 527 2321, France (1) 48 14 24 24, Germany 089/741 31 30, Italy 02/48301892, Japan (03) 3788-1921, Mexico 95 800 010 0793, Netherlands 03480-33466, Norway 32-84 84 00, Singapore 2265886, Spain (91) 640 0085, Sweden 08-730 49 70, Switzerland 056/20 51 51, Taiwan 02 377 1200, U.K. 0635 523545

Limited Warranty

The BNC-208X Series boards are warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period. This warranty includes parts and labor.

The media on which you receive National Instruments software are warranted not to fail to execute programming instructions, due to defects in materials and workmanship, for a period of 90 days from date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace software media that do not execute programming 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 work. National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty.

National Instruments believes that the information in this manual is accurate. The document has been carefully 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 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.

EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED,

AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OF

NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA, PROFITS ,

USE OF PRODUCTS, OR INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY THEREOF

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.

. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART

NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER.

. This limitation of the liability of National Instruments will apply regardless of the form of action,

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.

Trademarks

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 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 Instruments products 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.

Preface

This manual describes the electrical and mechanical aspects of the BNC-2080 and BNC-2081 boards and contains information about installing and making connections to the boards. The BNC-208X Series boards are analog breakout boards with BNC-style connectors. These breakout boards connect to the National Instruments multifunction data acquisition boards for the IBM PC/XT/AT, Personal System/2, and compatible computers, and Macintosh NuBus computers.

Organization of This Manual

The BNC-208X Series User Manual is organized as follows:

• Chapter 1, Introduction, describes the BNC-208X Series boards; lists the contents of your BNC-2080 and BNC-2081 kits; describes the optional equipment, signal conditioning accessories, and software support; and explains how to unpack your BNC-208X Series board.

• Chapter 2, BNC-2080 Board, describes the BNC-2080 board in detail, including its function, specifications, compatibility, connection, mounting, and application notes.

• Chapter 3, BNC-2081 Board, describes the BNC-2081 board in detail, including its function, specifications, compatibility, connection, mounting, and application notes.

• Chapter 4, Installation and Connections, explains how to install and make connections to the BNC-208X Series boards.

• TheCustomer Communication appendix contains forms you can use to request help from National Instruments or to comment on our products.

• 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: italic Italic text denotes emphasis, a cross reference, or an introduction to a key

concept. Lab board Lab board refers to the Lab-PC, Lab-PC+, Lab-NB, and Lab-LC boards. Macintosh NuBus Macintosh NuBus refers to the Macintosh NuBus family of computers. MIO-16 MIO-16 refers to the AT-MIO-16, AT-MIO-16D, AT-MIO-16F-5,

AT-MIO-16X, MC-MIO-16, NB-MIO-16, NB-MIO-16X, and

PC-LPM-16 boards.

Preface

PC PC refers to PC/XT/AT/EISA and IBM PS/2 computers. SC-205X SC-205X refers to the SC-2050, SC-2051, SC-2052, and SC-2053 boards. SC-206X SC-206X refers to the SC-2060, SC-2061, and SC-2062 boards. SC-207X SC-207X refers to the SC-2070, SC-2071, and SC-2072 boards.

Abbreviations

The following metric system prefixes are used with abbreviations for units of measure in this manual:

Prefix Meaning Value

µ- micro-

m- milli-

k- kilo-

M- mega-

10 10

-6

-3

3 6

The following abbreviations are used in this manual: A amperes

C Celsius dB decibels ° degrees F farads f

c

cutoff frequency Hz hertz

in. inches m meters Ω ohms % percent π pi V volts W watts

Acronyms

The following acronyms are used in this manual: AC alternating current

CMRR common-mode rejection ratio DC direct current DGND digital ground DIFF differential input I/O input/output LED light-emitting diode NRSE nonreferenced single-ended input RSE referenced single-ended input VDC volts direct current

BNC-208X Series User Manual vi © National Instruments Corporation

Preface

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 the appendix at the end of this manual.

Figures

Figure 1-1. BNC-2080 Board Directly Connected to an MIO-16 Board............................1-2

Figure 1-2. BNC-208X, SC-207X, SC-206X, and SC-205X Series Boards

Connected to an MIO-16 Board .......................................................................1-2

Figure 2-1. BNC-2080 Analog Breakout Board..................................................................2-1

Figure 2-2. BNC-2080 Board Parts Locator Diagram.........................................................2-2

Figure 2-3. Onboard Equivalent Circuit for DIFF Mode....................................................2-4

Figure 2-4. W2 Jumper Settings..........................................................................................2-5

Figure 2-5. Direct Connection between an MIO-16 Board and the BNC-2080 Board.......2-8

BNC-208X Series User Manual x © National Instruments Corporation

Contents

Figure 2-6. Connection between an MIO-16 Board, the BNC-2080 Board, and

the SC-2070/72 Board or the MIO-16, and the BNC-2080 and

SC-206X Series Boards via the SC-2050 Board..............................................2-8

Figure 2-7. Switch Configurations for Differential Mode or Single-Ended Mode.............2-10

Figure 2-8. W1 Ground Reference Jumper.........................................................................2-10

Figure 2-9. BNC-2080 Switch Configurations for an MIO-16 Configured in

DIFF Mode (Factory Default Setting)..............................................................2-11

Figure 2-10. BNC-2080 Switch Configurations for an MIO-16 Configured in

RSE and NRSE Modes.....................................................................................2-12

Figure 2-11. Bias Return Resistor for DC-Coupled Floating Source on Channel 1

in DIFF Mode...................................................................................................2-14

Figure 2-12. Normalized Frequency Response of Lowpass Filter........................................2-16

Figure 2-13. Lowpass Filter on Differential Channel 1 ........................................................2-17

Figure 2-14. Normalized Frequency Response of Highpass Filter.......................................2-18

Figure 2-15. Highpass Filter on Differential Channel 1........................................................2-19

Figure 2-16. Attenuator for Use with Differential Inputs......................................................2-21

Figure 2-17. Switch Configurations for SE Mode (PC-LPM-16).........................................2-22

Figure 2-18. Ground Reference Jumper Position for Use with the PC-LPM-16..................2-23

Figure 2-19. Analog Output Schematic for DACs, DAC0 OUT Shown.............................2-23

Figure 3-1. BNC-2081 Analog Breakout Board..................................................................3-1

Figure 3-2. BNC-2081 Board Parts Locator Diagram.........................................................3-2

Figure 3-3. Onboard Equivalent Circuit..............................................................................3-3

Figure 3-4. W1 Jumper Settings..........................................................................................3-4

Figure 3-5. Direct Connection between a Lab Board and the BNC-2081 Board................3-7

Figure 3-6. Connection between a Lab Board, the BNC-2081, and the SC-2071 Board,

or the Connection between a Lab Board, the BNC-2081 and the SC-206X

Series Board, via the SC-2053 Board...............................................................3-7

Figure 3-7. Normalized Frequency Response of Lowpass Filter........................................3-9

Figure 3-8. Lowpass Filter on Channel 1............................................................................3-10

Figure 3-9. Normalized Frequency Response of Highpass Filter.......................................3-11

Figure 3-10. Highpass Filter on Channel 1 ...........................................................................3-12

Figure 3-11. Attenuator for Use with BNC-2081 Board Inputs............................................3-13

Figure 3-12. DAC0 OUT Schematic.....................................................................................3-14

Figure 3-13. Analog Output Schematic for DACs, DAC0 OUT Shown.............................3-14

Figure 4-1. Mounting Locations for the BNC-208X Series Board and SC-207X

Series Board......................................................................................................4-3

Figure 4-2. Mounting Locations for the BNC-208X Series Board and SC-205X

Series Board or SC-206X Series Board............................................................4-3

Figure 4-3. Attaching a Mountable Board to the Chassis ...................................................4-4

Figure 4-4. Double-Height Mounting..................................................................................4-5

Figure 4-5. Connections between Data Acquisition Boards and BNC-208X

Series Boards and between SC-205X Series Boards and BNC-2080

and BNC-2081 Boards......................................................................................4-6

Contents

Tables

Table 1-1. Data Acquisition Boards for Use with BNC-208X Series Boards...................1-1

Table 2-1 Switch S5 Settings for National Instruments Data Acquisition Boards...........2-3

Table 2-2. DIFF Mode Channel Component Positions......................................................2-5

Table 2-3. Data Acquisition Boards Used with the BNC-2080 Board..............................2-7

Table 3-1. Component Positions in Each Channel.............................................................3-4

Table 3-2. Data Acquisition Boards Used with the BNC-2081 Board..............................3-6

BNC-208X Series User Manual xii © National Instruments Corporation

Chapter 1 Introduction

This chapter describes the BNC-208X Series boards; lists the contents of your BNC-2080 and BNC2081 kits; describes the optional equipment, signal conditioning accessories, and software support; and explains how to unpack your BNC-208X Series board.

The BNC-2080 and BNC-2081 boards are two analog breakout boards with signal-labeled BNC connectors and analog signal conditioning areas. The BNC-2080 and BNC-2081 breakout boards simplify the connection of analog signals, some digital signals, and two user-defined connections to the data acquisition board in laboratory, test, and production environments. The BNC-2080 can be configured to use 8 differential or 16 single-ended analog input channels available on the board. The boards have silkscreened component locations for resistors, and capacitors for building single-pole highpass and lowpass filters, and voltage dividers.

Table 1-1 lists the specific data acquisition boards that can currently be used with the BNC-208X Series boards.

Table 1-1. Data Acquisition Boards for Use with BNC-208X Series Boards

NB Series

(Macintosh

NuBus)

BNC-2080 NB-MIO-16

NB-MIO-16X

BNC-2081 Lab-LC

Note: When a board is referred to as an MIO-16 board, the reference applies to the AT-MIO-16,

AT-MIO-16D, AT-MIO-16F-5, AT-MIO-16X, MC-MIO-16, NB-MIO-16, NB-MIO-16X, and PC-LPM-16 boards listed in Table 1-1. Similarly, when a board is referred to simply as a Lab board, the reference applies to the Lab-LC, Lab-NB, Lab-PC+ and Lab-PC boards listed in Table 1-1.

All analog signals from the data acquisition board are made available at BNC connectors. Each of the BNC-208X Series boards is connected directly to the data acquisition board (NB, MC, Lab, PC, or AT Series) by a 50-pin ribbon cable. The AT-MIO-16D requires an NB5 cable. The Lab-LC requires an NB10 cable. If any SC-206X Series digital signal conditioning boards are also being used with the same data acquisition board for conditioning of the digital I/O signals, then an SC-205X Series cable adapter board is required.

MC Series

(IBM PS/2)

MC-MIO-16 AT-MIO-16

PC and AT

Series

(PC/XT/AT)

AT-MIO-16D AT-MIO-16F-5 AT-MIO-16X PC-LPM-16

Lab Series

(PC/XT/AT and

Macintosh

NuBus)

Lab-NB Lab-PC Lab-PC+

Introduction Chapter 1

Art not available in PDF version of this document.

Figure 1-1 shows the BNC-2080 board mounted in a 19-in. rack mount, directly connected to the MIO16 data acquisition board.

Figure 1-1. BNC-2080 Board Directly Connected to an MIO-16 Board

The BNC-208X Series boards can be mounted beside an SC-205X Series cable adapter board, an SC206X Series signal conditioning board, and an SC-207X Series general-purpose termination breadboard in a 19-in. rack-mount chassis. You can mount your BNC-208X Series board on the left or right side of the rack mount. Mounting the BNC-208X Series board on the left side and running the cable under the BNC-208X Series board to connect to the any of the SC Series boards will make access to both boards easier. Figure 1-2 shows the BNC-208X, SC-207X, SC-206X, and SC-205X Series boards connected to an MIO-16 board.

Figure 1-2. BNC-208X, SC-207X, SC-206X, and SC-205X Series Boards

Connected to an MIO-16 Board

BNC-208X Series User Manual 1-2 © National Instruments Corporation

Chapter 1 Introduction

What Your Kit Should Contain

There are three kit versions for each of the BNC-2080 and the BNC-2081 boards–one kit contains a 0.5 m cable, one kit contains a 1.0 m cable, and one kit contains no cable, listed as follows.

Kit Name Kit Part

Number

BNC-2080 kit with 0.5 m cable

BNC-2080 kit with 1.0 m cable

BNC-2080 without cable 776579-90 BNC-2080 board 181630-01 BNC-2081 kit with 0.5 m

cable BNC-2081 kit with 1.0 m

cable BNC-2081 without cable 776599-90 BNC-2081 board 181635-01

You can identify which version of the BNC-208X Series kit you have by looking up the part number in the preceding table.

In addition to the board, each version of the BNC-208X Series kit contains the following component.

776579-05 BNC-2080 board

50-conductor 0.5 m NB1 cable

776579-10 BNC-2080 board

50-conductor 1.0 m NB1 cable

776599-05 BNC-2081 board

50-conductor 0.5 m NB1 cable

776599-10 BNC-2081 board

50-conductor 1.0 m NB1 cable

Kit Component Part Number

Kit Component Board Part

Number

181630-01 180524-05

181630-01 180524-10

181635-01 180524-05

181635-01 180524-10

BNC-208X Series User Manual 320407-01

If your kit is missing any of the components or if you received the wrong version, contact National Instruments.

Optional Equipment

Equipment Part Number

Type NB5 cable (for the AT-MIO-16D)

0.5 m 181304-05

1.0 m 181305-05

Rack-mount chassis kit with acrylic plastic cover

Single height 180636-01 Double height 180636-02

Rack-mount chassis kit with metal wraparound cover

Single height 181080-01 Double height 181080-02

Introduction Chapter 1

Signal Conditioning Accessories

Accessory Part Number

SSR Series eight-channel backplane

with 0.4 m cable for SC-2050 Series

SC-2070 and 50-conductor cable

0.5 m cable

1.0 m cable

SC-2071 and 50-conductor cable

0.5 m cable

1.0 m cable

SC-2072 and 50-conductor cable

0.5 m cable

1.0 m cable

SC-2072D and 50-conductor cable

0.5 m cable

1.0 m cable

776290-18

776358-00 776358-10

776358-01 776358-11

776358-02 776358-12

776358-102 776358-112

SC-2060 and 26-conductor cable

0.2 m cable

0.4 m cable

SC-2061 and 26-conductor cable

0.2 m cable

0.4 m cable

SC-2062 and 26-conductor cable

0.2 m cable

0.4 m cable

SC-2050 and 50-conductor cable

0.5 m cable

1.0 m cable

SC-2051 and 50-conductor cable

0.5 m cable

1.0 m cable

SC-2052 and 50-conductor cable

0.5 m cable

1.0 m cable

776336-00 776336-10

776336-01 776336-11

776336-02 776336-12

776335-00 776335-10

776335-01 776335-11

776335-02 776335-12

SC-2053 and 50-conductor cable

0.5 m cable

1.0 m cable

BNC-208X Series User Manual 1-4 © National Instruments Corporation

776335-03 776335-13

Chapter 1 Introduction

Software Support

The BNC-208X Series boards require no additional software support beyond that provided for the data acquisition board in use.

Unpacking

Your BNC-208X Series board is shipped in an antistatic package to prevent electrostatic damage to the board. Several components on the board can be damaged by electrostatic discharge. To avoid such damage in handling the board, take the following precautions:

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

• Remove the board from the package and inspect the board for loose components or any other sign of damage. Notify National Instruments if the board appears damaged in any way. Do not install a damaged board into your computer.

Chapter 2

Art not available in PDF version of this document.

BNC-2080 Board

This chapter describes the BNC-2080 board in detail, including its function, specifications, compatibility, connection, mounting, and application notes.

The BNC-2080 is an analog breakout board that makes it easy to connect to all MIO-16 or PC-LPM-16 analog signals and a few digital signals via BNC connectors. All other MIO-16 signals are accessible via solder holes in the board next to data acquisition board input connectors. Passive analog input signal conditioning, such as filters and dividers, can also be added.

The BNC-2080 board is used with the National Instruments data acquisition boards for the Macintosh NuBus (NB Series), IBM PS/2 Micro Channel (MC Series), and PC/XT/AT and compatible computers.

Figure 2-1 shows the BNC-2080 board.

Figure 2-1. BNC-2080 Analog Breakout Board

The BNC-2080 board has BNC connectors for all analog signals, a few digital signals, and two userdefined connectors. With open component positions in the input paths, you can insert resistors and capacitors for conditioning the 16 single-ended or 8 differential analog input signals. The BNC-208X Series boards can also be used in conjunction with the other signal conditioning accessories, including the SC-207X Series boards. For connection of multiple signal conditioning accessories, an SC-205X Series cable adapter board must be used.

BNC-2080 Board Chapter 2

Art not available in PDF version of this document.

Figure 2-2 illustrates the parts locator diagram for the BNC-2080 board.

Figure 2-2. BNC-2080 Board Parts Locator Diagram

BNC-208X Series User Manual 2-2 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Power Connections

Because the BNC-2080 board is an analog breakout board for both the MIO-16 and PC-LPM-16 boards, it has a flexible power connection scheme.

Switch S5 is responsible for selecting the power inputs from the I/O cable. Switch S5 is a three-position switch that configures the BNC-2080 to connect to pins 33 (DGND) and 34 (+5 V) in position A, to no I/O pins in position B, and to pins 49 (+5 V) and 50 (DGND) in position C.

Table 2-1 shows the setting to be used with each of the National Instruments data acquisition boards.

Table 2-1. Switch S5 Settings for National Instruments Data Acquisition Boards

Board S5 Setting

AT-MIO-16 AT-MIO-16D AT-MIO-16F-5 AT-MIO-16X MC-MIO-16 A NB-MIO-16 NB-MIO-16X PC-LPM-16

Warning: If the data acquisition board does not use pins 33/34 or pins 49/50 for power connections,

set switch S5 to position B. Failure to set switch S5 to position B under these conditions could result in damage to your external power supply, the BNC-2080, the expansion board connected to the BNC-2080, and/or your computer. National Instruments is not liable for damages resulting from such connections.

A A A A

A A

C

Analog Input

Each differential analog input has seven open positions for signal conditioning components. Six of these positions are designated as resistors, and one is designated as a capacitor. The board is shipped with jumpers in two positions for each input. The equivalent circuit of one input is shown in Figure 2-3. The board can be used when the MIO-16 board is configured for both 16 single-ended inputs and 8 differential inputs. For specific applications illustrating signal conditioning with both single-ended and differential inputs, refer to the section titled Application Notes later in this chapter.

BNC-2080 Board Chapter 2

Input Schematic for ACH1 (DIFF mode)

S2

DIFF SE

32 1

COMMON

Channel 9

Case

BNC Connector

+5 V +5 V

(Center)

R21

C

R15

Case

BNC Connector

Jumpers Installed Here at Factory

AISENSE

AIGND

Channel 1 (Center)

1 2

3

R4

A

R11

NRSE

RSE

W1

D

AIGND AIGND

R20

ACH 9 (-in)

F

C2

G

To Input Multiplexer on MIO-16

R3

ACH 1 (+in)

B

E

Figure 2-3. Onboard Equivalent Circuit for DIFF Mode

The components are numbered differently for each channel. Table 2-2 lists the components in each channel and their correspondence to the circuit shown in Figure 2-3.

BNC-208X Series User Manual 2-4 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Table 2-2. DIFF Mode Channel Component Positions

Channel (Position in Figure 2-3)

Differential Single-Channel A B C D E F G

0 (0, 8) R2 R10 R19 R14 R1 R18 C1 1 (1, 9) R4 R11 R21 R15 R3 R20 C2 2 (2, 10) R6 R12 R23 R16 R5 R22 C3 3 (3, 11) R8 R13 R25 R17 R7 R24 C4 4 (4, 12) R28 R35 R45 R39 R27 R44 C9 5 (5, 13) R30 R36 R47 R40 R29 R46 C10 6 (6, 14) R32 R37 R49 R41 R31 R48 C11 7 (7, 15) R34 R38 R51 R42 R33 R50 C12

When the board is shipped, jumpers are inserted in the E and F positions of the input network, as in Figure 2-3. These jumpers can be easily removed to build analog input signal conditioning circuits. Several applications showing the use of these open component positions are discussed in the section titled Application Notes later in this chapter.

Shield Ground

Jumper W2 is used to connect digital ground (DGND) to a grounded metal case. This option is useful only if the BNC-2080 board is on metal standoffs and is mounted in a grounded metal case. Shield grounding can be selected to reduce noise.

Figure 2-4 details the jumper settings for W2.

W2

• •

W2

• •

Shield Ground Selected Shield Ground Not Selected

Figure 2-4. W2 Jumper Settings

BNC-2080 Board Chapter 2

Fuse and Power LED

The +5-V line from the data acquisition board is protected by a 750-mA fuse. If the red power LED does not light when the data acquisition board is powered on, check both the 750-mA fuse on the BNC2080 board and the output fuse (if any) on the MIO-16 board. Information on connecting power is given in Chapter 4, Installation and Connections.

Digital and Timing Signals

All of the analog signals and a few digital signals from the MIO-16 data acquisition board are made available at BNC connectors on the BNC-2080 board. Because these signals are not conditioned or changed in any way by the BNC-2080 board, refer to your MIO-16 board user manual for information on the use of these signals. If you want optical isolation of or relay control by the digital I/O lines, you must use the SC-2050 cable adapter board and the appropriate SC-2060 digital signal conditioning board. If you want access to all MIO-16 signals via screw terminals, you must use the SC-2070 or SC-2072 board. For more information on the SC-205X Series boards, the SC-206X Series boards, or the SC207X Series boards, refer to either your National Instruments catalog, the SC-205X Series User Manual, the SC-206X Series User Manual, or the SC-207X Series User Manual.

Specifications

This section lists the specifications of the BNC-2080 analog breakout board. These ratings are typical at 25° C unless otherwise stated. The operating temperature range for this board is 0° to 70° C.

Analog Input

Number of channels 8 differential, 16 single-ended Field connections 24 BNC connectors; 18 analog (MIO-16)

16 analog (LPM-16), [See note], 4 digital, and 2 user-defined

Signal conditioning capability Seven open component positions per channel that

include connections from each input to ground, +5 V, each other, and series connections to the inputs of the data acquisition boards

Other signals Solder holes for remaining MIO-16 signals Note: The DAC0 OUT and DAC1 OUT BNC connectors are for use with only the MIO-16 boards.

These connectors are connected to ±12 VDC when the LPM-16 board is in use.

BNC-208X Series User Manual 2-6 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Power Requirements

Power consumption (at +5 VDC ±5%)

Typical 12 mA with no signal conditioning installed Maximum 750 mA from host computer

Note: The power specifications pertain to the power supply of the host computer. The maximum

power consumption of the BNC-2080 board is a function of the signal conditioning components installed. If the board is being powered from the host computer, the maximum +5-V current draw is fuse-limited to 750 mA.

Physical

Board dimensions (including standoffs) 7.9 by 4.9 by 1.725 in. I/O connectors Two 50-pin male ribbon-cable connectors BNC connectors 24

Operating Environment

Temperature 0° to 70° C Relative humidity 5% to 90% noncondensing

Storage Environment

Temperature -55° to 125° C Relative humidity 5% to 90% noncondensing

Board-to-Board Cabling

The BNC-2080 board directly connects to any of the data acquisition boards listed in Table 2-3.

Table 2-3. Data Acquisition Boards Used with the BNC-2080 Board

NB Series MC Series AT Series

(Macintosh NuBus) (IBM PS/2) (PC AT)

BNC-2080 NB-MIO-16 MC-MIO-16 AT-MIO-16

NB-MIO-16X AT-MIO-16D*

AT-MIO-16F-5 AT-MIO-16X PC-LPM-16

*Requires an NB5 cable, available separately.

BNC-2080 Board Chapter 2

The data acquisition boards listed in Table 2-3, except for the AT-MIO-16D, connect to the BNC-2080 board as shown in Figure 2-5. The AT-MIO-16D connects to the BNC-2080 via a 100conductor type NB5 ribbon cable, available separately.

50-Pin I/O Connector

MIO-16 BNC-2080

50-Conductor Cable

Figure 2-5. Direct Connection between an MIO-16 Board and the BNC-2080 Board

If any signal conditioning of the digital I/O ports with the National Instruments SC-206X Series boards is desired, then the SC-2050 cable adapter board must be used with the data acquisition boards listed in Table 2-2.

Figure 2-6 shows a connection using the SC-2050 cable adapter board.

SC-2070/72

SC-2050

Digital I/O

26-Conductor Cable

SC-206X Series or 8-Channel SSR

MIO-16

50-Conductor Cable

BNC-2080

50-Conductor Cable

Figure 2-6. Connection between an MIO-16 Board, the BNC-2080 Board, and the

SC-2070/72 Board or the MIO-16, and the BNC-2080 and SC-206X Series Boards

via the SC-2050 Board

Warning: Do not connect the BNC-2080 board to any board other than a National Instruments MIO-

16 data acquisition board, the SC-2070/72 board, or the SC-2050 cable adapter board. The BNC-2080 board is not compatible with any other data acquisition boards or cable adapter boards. Attempts to use the BNC-2080 board with products for which it is not intended can result in damage to the BNC-2080 board, the data acquisition board, or the host computer. National Instruments is not liable for damages resulting from these connections.

The BNC-2080 board uses a 50-pin ribbon-cable connector to connect to the 50-pin I/O connector on either a data acquisition board, the SC-2070/72, or the SC-2050 cable adapter board. The BNC-2080 has two MIO-16 connectors for connecting to the SC-2070/72 board or the SC-206X Series board via the SC-2050 board. For more information, see Chapter 4, Installation and Connections.

BNC-208X Series User Manual 2-8 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Mounting

The BNC-2080 board is equipped with metal standoffs so the board can be placed on a workbench near the host computer. You can use an optional rack-mount chassis, which can be fitted with a flat, acrylic plastic cover. When the BNC-2080 board is mounted in the chassis, the board can be grounded to its metal standoffs, and therefore to the rack. For more information, see Chapter 4, Installation and Connections.

Application Notes

The open component positions on the BNC-2080 board make adding signal conditioning components to the analog input signals easier. Several applications are covered in this section, including filtering and attenuation.

The figures in this section give examples on a specific input channel. If you want to install the circuit on a different channel, consult Table 2-3 to determine the equivalent component positions for the other channels.

Soldering and Desoldering on the BNC-2080 Board

The applications discussed here require you to make modifications to the printed circuit board, usually by removing jumpers and adding components. The BNC-2080 board is shipped with wire jumpers in the E and F positions (see Table 2-3 and Figure 2-3). Use a low-wattage soldering iron (20 to 30 W) when soldering to the board. To desolder on the BNC-2080, vacuum-type tools work best. Use care when desoldering to avoid damaging component pads. Only rosin-core, electronic-grade solder should be used. Acid-core solder damages the printed circuit board and components.

Channel Configurations

MIO-16 Analog Input

This section discusses the input configuration of the MIO-16 board and the corresponding configurations of the BNC-2080.

The analog input channels of an MIO-16 data acquisition board can be configured for one of three input modes: differential (DIFF) input mode, referenced single-ended (RSE) input mode, or nonreferenced single-ended (NRSE) input mode.

Although the open component positions are placed to facilitate use with differential inputs, any of the three modes can be selected. If the MIO-16 board is configured in the RSE mode, all 16 analog input channels are referenced to AIGND. If the MIO-16 board is configured in the NRSE mode, resistors should not be inserted into positions B or D of Figure 2-3 for any channel. Doing so can cause inaccurate readings because of incorrect ground reference. Resistors can be inserted into these positions in the RSE mode. For information on the input configurations, see your MIO-16 board user manual.

The BNC-2080 board can be configured to work with all three MIO-16 input configurations. The DIFF mode is configured by flipping the switches next to each pair of BNC connectors to DIFF. This must be done to all eight switches in order to have eight differential channels. In DIFF mode, the first eight

BNC-2080 Board Chapter 2

analog (ACH0 through ACH7) BNC connectors are used. The remaining eight analog (ACH8 through ACH15) BNC connectors are not used. The MIO-16 board must also be configured for differential input. The jumper W1 position is irrelevant in DIFF mode.

J3

ACH0

J9

ACH8

DIFF Mode (Factory Default Setting)

SE

S2

DIFF

J3

J9

SE Mode

ACH0

SE

ACH8

DIFF

S2

Figure 2-7. Switch Configurations for Differential Mode or Single-Ended Mode

Note: All of the switches are required to be in the same position; that is, S1 through S4 and S6 through

S9 must all be in either the DIFF position or in the SE position.

The single-ended mode is configured by flipping the switches next to each pair of BNC connectors to SE. This must be done to all eight switches in order to have 16 single-ended channels. In the singleended mode, all 16 BNC connectors are in use. In the single-ended mode, all 16 BNC cases are tied to the COMMON signal. The COMMON signal can be switched between AIGND and AISENSE through jumper W1. See Figure 2-8. AISENSE is tied to COMMON for NRSE mode configuration and AIGND is tied to COMMON for RSE mode configuration.

W1

RSE

• •

AISENSE

COMMON

AIGND

W1

• •

NRSE

Figure 2-8. W1 Ground Reference Jumper

The three configurations of the BNC-2080 board corresponding to the input mode configuration of the MIO-16 are shown in Figure 2-9 and Figure 2-10.

BNC-208X Series User Manual 2-10 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Art not available in PDF version of document.

Figure 2-9. BNC-2080 Switch Configurations for an MIO-16 Configured in DIFF Mode

(Factory Default Setting)

BNC-2080 Board Chapter 2

Art not available in PDF version of document.

Figure 2-10. BNC-2080 Switch Configurations for an MIO-16 Configured in RSE and

NRSE Modes As described in Chapter 2 of your MIO-16 board user manual, the input configuration of the MIO-16 depends on the type of signal source. There are two types of signal sources: nonreferenced or floating signals and ground-referenced signals. To measure floating signal sources, the MIO-16 should be configured for the RSE mode or DIFF mode with bias resistors. To measure ground-referenced signal sources, the MIO-16 should be configured for the NRSE mode or DIFF mode. Both types of signal sources and the recommended methods for MIO-16 board connection are discussed as follows.

Connecting Nonreferenced (or Floating) Signal Sources

A floating signal source is a signal source that is not connected in any way to the building ground system, but has an isolated ground-reference point. If an instrument or device has an isolated output, that instrument or device falls into the floating signal source category. Some examples of floating signal sources are outputs for: thermocouples, transformers, battery-powered devices, optical isolators, and isolation amplifiers. The ground reference of a floating source must be tied to the ground of the data acquisition board to establish a local or onboard reference for the signal.

Differential Inputs

To provide a return path for the instrumentation amplifier bias currents, floating sources must have a 10kΩ to 100-kΩ resistor to AIGND on one input if DC-coupled, or both inputs if AC-coupled. For more detailed information on connections to floating signal sources and differential inputs, refer to the configuration chapter in your MIO-16 board user manual. These bias resistors can be installed in positions B and D (Table 2-2 and Figure 2-3) of the BNC-2080 board. Figure 2-11 shows both the schematic and the component placement for a single 100-kΩ bias return resistor on the negative input from a floating source connected to Channel 1 (the D position in Table 2-2). Additional signal conditioning circuitry, such as filters and attenuators, as described in the sections Building Lowpass Filters, Building Highpass Filters, and Building Attenuators (Voltage Dividers) later in this chapter, can be built in the open component positions.

BNC-208X Series User Manual 2-12 © National Instruments Corporation

Chapter 2 BNC-2080 Board

+

To Input Multiplexer

G

R3

C2

R20

G (C2)

R4

E

D

F

R3

E

AIGND

R11

R21

Input Schematic for ACH1

A

B

R15

C

Channel 1 (+in)

BNC Connector

100-kΩ Resistor

Channel 1 (+in {Center})

BNC Connector

Channel 9 (-in)

R15 = 100 kΩ

F

R20

D

Channel 9 (-in {Case})

Figure 2-11. Bias Return Resistor for DC-Coupled Floating Source on Channel 1 in

DIFF Mode

Single-Ended Inputs

When measuring floating signal sources, the MIO-16 board should be configured to supply a ground reference. Therefore, the MIO-16 should be configured for RSE mode. In this configuration, the negative input of the MIO-16 instrumentation amplifier is tied to the analog ground. Therefore, the BNC-2080 board should be used in its factory configuration. In the factory configuration, jumpers are in the two series positions, E and F (see Table 2-2). In this configuration, all of the signal grounds should be tied to AIGND. Signal conditioning circuitry such as filters and attenuators, as described in the sections titled Building Lowpass Filters, Building Highpass Filters, and Building Attenuators (Voltage

Dividers) later in this chapter, can be built in the open component positions.

BNC-2080 Board Chapter 2

Connecting Ground-Referenced Signal Sources

A grounded signal source is connected in some way to the building system ground; therefore, the signal source is already connected to a common ground point with respect to the data acquisition board (assuming the host computer is plugged into the same power system). The nonisolated outputs of instruments and devices that plug into the building power system fall into this category.

Differential Inputs

If the MIO-16 data acquisition board is configured for differential inputs, ground-referenced signal sources connected to the BNC-2080 board need no special components added to the BNC-2080 board. The inputs of the BNC-2080 board can be left in the factory-original condition, that is, with only jumpers in the two series positions, E and F (see Table 2-3). Signal conditioning circuitry, such as filters and attenuators, as described in the sections titled Building Lowpass Filters, Building Highpass Filters, and Building Attenuators (Voltage Dividers) later in this chapter, can be built in the open component positions.

Single-Ended Inputs

When measuring ground-referenced signals, the external signal supplies its own reference ground point and the MIO-16 should not supply one. Therefore, the MIO-16 board should be configured for the NRSE mode. In this configuration, all of the signal grounds should be tied to AISENSE, which connects to the negative input of the instrumentation amplifier on the MIO-16 board. The inputs of the BNC-2080 board can be left in the factory-original condition, that is, with jumpers in the series position (E or F, depending on the channel). The open positions that connect the input to AIGND, B and D (see Table 2-2 and Figure 2-3), should not be used in this configuration. Referencing the signal to AIGND can cause inaccurate measurements resulting from an incorrect ground reference.

Building Lowpass Filters

Simple, R-C lowpass filters are easily installed in the BNC-2080 board on any differential input channel. The filters are useful for accurate measurement and noise rejection. By substituting resistance and capacitance values into the following formula (hereafter referred to as Formula 2-1), you can calculate a simple, one-pole R-C filter to have a -3-dB point cutoff frequency (fc):

fc =

The frequency response rolls off at a rate of -20 dB per decade of increase thereafter. A Bode plot of the amplitude versus normalized frequency is shown in Figure 2-12.

1

(2πRC)

(Formula 2-1)

BNC-208X Series User Manual 2-14 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Amplitude

0.1

0.01

0.001

0.0001

1

| | | | | |

0.1 1 10 100 1,000 10,000 (f )

c

Normalized Frequency

dB

0

-20

-40

-60

-80

Figure 2-12. Normalized Frequency Response of Lowpass Filter

When measuring low-frequency signals (about 4 Hz), if you have 400-Hz noise on your inputs, you can add a lowpass filter with a cutoff frequency of 4 Hz. The 400-Hz noise then attenuates by 40 dB. Notice that your 4-Hz signal also attenuates, but by only 3 dB. Do not neglect any potential attenuation of signals of interest by this low-order filter.

You must also choose the filter component values. The resistance or the capacitance can be selected arbitrarily; one value determines the other. Picking the capacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available. If a capacitance of 1 µF is available, the resistance is (by substitution into Formula 2-1) 39,789 Ω, or about 39.8 kΩ. This resistance must be divided by two to get the resistor value on each input of a differential channel. Therefore, in this example, each input has a 19.89-kΩ resistor (or the closest standard value) in its series positions, E and F. The closest standard 5% tolerance resistors are 20 kΩ. The closest standard 0.5% resistors are 19.8 kΩ. National Instruments recommends using 1% or better tolerance resistors in this application because differences between the resistor values degrade the common-mode rejection ratio (CMRR). Figure 2-13 shows both the schematic and the component placement for a 4-Hz lowpass filter placed on differential input Channel 1. If the input signal source is floating, a bias return resistor must be placed in the D position (R15 in this case).

The BNC-2080 board open component locations do not facilitate R-C lowpass filters with the MIO-16 board configured for single-ended inputs. Therefore, if the MIO-16 board is configured for single-ended inputs, lowpass filters must be built on the custom breadboard area.

BNC-2080 Board Chapter 2

R3

C2

R20

To Input Multiplexer

R4

E

G

F

R3 = 19.8 kΩ

+

G

C2 = 1 µF

R11

R15

R21

Input Schematic for ACH1

E

Channel 1

A

(+in)

B

D

C

19.8-kΩ Resistor

BNC Connector

Channel 1 (+in {Center})

Channel 9 (-in)

1-µF Capacitor

BNC Connector

Channel 9

F

-

R20 = 19.8 kΩ

(-in {Case})

Figure 2-13. Lowpass Filter on Differential Channel 1

Building Highpass Filters

Simple, R-C highpass filters are easily installed in the BNC-2080 board on any differential input channel. The filters are useful for accurate high-frequency measurement and low-frequency noise rejection. By substituting resistance and capacitance values into the following formula, hereafter referred to as Formula 2-2, you can calculate a simple, one-pole R-C filter to have a -3-dB point fc:

fc =

The frequency response rolls off at a rate of -20 dB per decade decrease thereafter. A Bode plot of the amplitude versus normalized frequency is shown in Figure 2-14.

1

(2πRC)

(Formula 2-2)

BNC-208X Series User Manual 2-16 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Amplitude

0.01

0.001

0.0001

1

0.1

| | | | | |

0.0001 0.001 0.01 0.1 1 10 Normalized Frequency

(f )

c

dB

0

-20

-40

-60

-80

Figure 2-14. Normalized Frequency Response of Highpass Filter

When measuring high-frequency signals (about 50 kHz), if you have 50-Hz noise on your inputs, you can add a highpass filter with a cutoff frequency of 50 kHz. The 50-Hz noise then attenuates by 60 dB. Notice that your 50-kHz signal also attenuates, but by only 3 dB. Do not neglect any potential attenuation of signals of interest if you add a low-order filter.

You must also choose the filter component values. The resistance or the capacitance can be selected arbitrarily; one value determines the other. Picking the capacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available. The filter circuit has one series capacitor on each input of the differential channel. Because the two capacitors are in series, the capacitance value that must be substituted into Formula 2-2 is the series capacitance of the two capacitors in series. For two capacitors in series, the net capacitance is the reciprocal of the sum of the reciprocals of the two capacitances. For example, two 0.001-µF capacitors in series have a net capacitance of 0.0005 µF. The two capacitors should be the same value, or the CMRR is degraded. If capacitors of 0.001 µF are available, the resistance is (by substitution into Formula 2-2) 6,366 Ω, or about 6.4 kΩ. Therefore, in this example, the input channel has a 6.37-kΩ resistor (or the closest standard value) in its capacitor position, G. The closest standard 5% tolerance resistors are 6.2 kΩ. The closest standard 1% resistors are 6.34 kΩ. Figure 2-15 shows both the schematic and the component placement for a 50-kHz highpass filter placed on differential input Channel 1. If the input signal source is floating, a bias return resistor must be placed in the D position (R15 in this case).

Note: Highpass filters generally exhibit poorer common-mode rejection characteristics than lowpass

filters because capacitors are in the series input paths. Capacitors have poorer tolerances than resistors, and matching of the input impedances is crucial for good common-mode rejection.

The BNC-2080 board open component locations do not facilitate R-C highpass filters with the MIO-16 board configured for single-ended inputs. Therefore, if the MIO-16 board is configured for single-ended inputs, highpass filters must be built on the custom breadboard area.

Note: Due to space constraints, when a resistor is inserted in position G (capacitor position) it must be

inserted vertically before bending the other lead to the board.

BNC-2080 Board Chapter 2

R3

C2

R20

To Input Multiplexer

R4

E

R11

G

F

Input Schematic for ACH1

+

G

R15

R21

R3 = 0.001 µF (Capacitor)

E

C2 = 6.34 kΩ (Resistor)

Channel 1

A

(+in)

B

D

C

6.34-kΩ Resistor

BNC Connector

Channel 1 (+in {Center})

Channel 9 (-in)

0.001-µF Capacitor

BNC Connector

Channel 9 (-in {Case})

F

-

R20 = 0.001 µF (Capacitor)

Figure 2-15. Highpass Filter on Differential Channel 1

BNC-208X Series User Manual 2-18 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Building Attenuators (Voltage Dividers)

Attenuators can be connected to the analog inputs of the BNC-2080 board when the inputs from its data acquisition board are in DIFF mode. The BNC-2080 board open component positions do not facilitate voltage dividers with the MIO-16 board configured for single-ended inputs. Therefore, if the MIO-16 board is configured for single-ended inputs, attenuators must be built on a separate breadboard. Attenuators can be used to reduce a signal that is outside the normal input range of the data acquisition board (±10 V maximum).

Warning: The BNC-2080 board is not designed for any input voltages greater than 42 V, even if a

user-installed voltage divider reduces the voltage to within the input range of the data acquisition board. Input voltages greater than 42 V can result in damage to the BNC-2080 board, any and all boards connected to it, and the host computer. Overvoltage can also cause an electric shock hazard for the operator. National Instruments is not liable for damage or injury resulting from such misuse.

A three-resistor circuit for attenuating voltages at the differential inputs of the BNC-2080 board is shown in Figure 2-16. The figure also shows the placement of the resistors on the open component positions for differential Channel 1. The gain G of this attenuator is given by the following formula:

R

G =

(RE + RF + RG)

Therefore, the input to the MIO-16 board (V

V

= VSC * G

MIO

where V

SC

G

(Formula 2-3)

) is as follows:

MIO

is the voltage applied to the BNC connectors of the BNC-2080. The accuracy of this gain

equation depends on the tolerances of the resistors used. Note: Due to space constraints, when a resistor is to be inserted in position G (capacitor

position) it must be inserted vertically before bending the other lead to the board.

BNC-2080 Board Chapter 2

R3

Channel 9 (-in)

C2

R4

E

R11

G

F

R15

A

C

D

Channel 1 (+in)

BNC Connector

To Input Multiplexer

+

-

R20

G

R21

Input Schematic for ACH1

R3 = 10 kΩ

E

C2 = 10 kΩ (Resistor)

F

B

10-kΩ Resistor

Channel 1 (+in {Center})

BNC Connector

Channel 9 (-in {Case})

R20 = 10 kΩ

Figure 2-16. Attenuator for Use with Differential Inputs

BNC-208X Series User Manual 2-20 © National Instruments Corporation

Chapter 2 BNC-2080 Board

Example:

Using the values in Figure 2-13,

G =

10 kΩ

(10 kΩ + 10 kΩ + 10 kΩ)

=

1 3

Therefore,

1

V

=

MIO

V

3

SC

When the MIO-16 is configured for ±10-V inputs, the board can acquire ±30-V signals with this attenuator circuit.

If the use of thermocouples is required in your applications, using National Instruments SC-2070 board is better suited for the task. The SC-2070 board is equipped with an onboard temperature sensor for use with thermocouple cold-junction compensation.

PC-LPM-16

The analog input section of an PC-LPM-16 data acquisition board consists of 16 ground-referenced singleended channels; therefore, the only valid configuration for the BNC-2080 is also RSE mode. In this mode, all 16 analog input BNC connectors are used. Switches S1 through S4 and S6 through S9 must be in the SE position, and jumper W1 should be in the AIGND-COMMON position, as shown in Figure 217 and Figure 2-18, respectively.

J3

ACH0

SEDIFF

S2

J9

ACH8

Single-Ended Mode

Figure 2-17. Switch Configurations for SE Mode (PC-LPM-16)

Note: All the switches are required to be in the same position; that is, S1 through S4 and S6 through S9

must all be in the SE position for use with the PC-LPM-16.

BNC-2080 Board Chapter 2

W1

AISENSE

• •

COMMON

AIGND

RSE

Figure 2-18. Ground Reference Jumper Position for Use with the PC-LPM-16

The application information given for MIO-16 in the RSE input mode also applies to the PC-LPM-16.

MIO-16 Analog Output

Analog output BNC connectors each have two open component positions for optional signal conditioning components. One of these is designated as a resistor and the other as a capacitor. The equivalent circuit for DAC0 OUT is shown in Figure 2-19. DAC1 OUT circuitry is identical to that of DAC0 OUT.

When the board is shipped, 0-Ω jumpers are inserted into the R9 position. These can be easily removed to build passive analog output signal conditioning circuits such as voltage dividers and lowpass filters.

R9

DAC0 OUT

AOGND

Jumpers Installed Here at Factory

C5

DAC0 OUT

BNC Connector

Figure 2-19. Analog Output Schematic for DACs, DAC0 OUT Shown

BNC-208X Series User Manual 2-22 © National Instruments Corporation

Chapter 3

Art not available in PDF version of document.

BNC-2081 Board

This chapter describes the BNC-2081 board in detail, including its function, specifications, compatibility, connection, mounting, and application notes.

The BNC-2081 is an analog breakout board that makes it easy to connect to all Lab data acquisition board analog signals, a few digital signals, and two user-defined connectors via BNC-type connectors. Analog input signal conditioning can be added, such as filters and dividers. All other Lab signals can be accessed by solder holes in the board located next to the Lab input connectors. In addition, there is a connector to provide access to all digital I/O ports. This connector is in the standard pinout for connection to one of National Instruments DIO-24 boards.

The BNC-2081 board is used with the National Instruments Lab data acquisition boards for the Macintosh (Lab-NB and Lab-LC), IBM PC/XT/AT, and compatible computers (Lab-PC and Lab-PC+).

Figure 3-1 shows the BNC-2081 board.

Figure 3-1. BNC-2081 Analog Breakout Board

The BNC-2081 board has BNC connectors for eight single-ended input channels. Open component positions at each analog input facilitate the addition of user-selected signal conditioning. With open component positions in the input paths, you can insert user-supplied resistors and capacitors for conditioning the eight single-ended analog input signals.

BNC-2081 Board Chapter 3

Art not available in PDF version of document.

Figure 3-2 illustrates the parts locator diagram for the BNC-2081 board.

Figure 3-2. BNC-2081 Board Parts Locator Diagram

Analog Input

Each analog input has four open positions for signal conditioning components. All signal conditioning components are designated as resistors, but capacitors can be inserted for the construction of R-C filters. The board is shipped with wire jumpers in one position for each input. The equivalent circuit of one input is shown in Figure 3-3. For specific applications illustrating signal conditioning with single-ended inputs, refer to Application Notes later in this chapter.

BNC-208X Series User Manual 3-2 © National Instruments Corporation

Chapter 3 BNC-2081 Board

Input Schematic for ACH1

Channel 1

Case

BNC Connector

R4

A

+5 V

(Center)

R5

B

Jumper Installed Here at Factory

AIGND

J4

R14

D

To Input Multiplexer on MIO-16

C

R6

ACH 1

Figure 3-3. Onboard Equivalent Circuit

The components are numbered differently for each channel. Table 3-1 is a listing of the components in each channel and their correspondence to the circuit shown in Figure 3-3.

BNC-2081 Board Chapter 3

Table 3-1. Component Positions in Each Channel

Position in Figure 3-3

Channel A B C D

0 R1 R2 R3 R13 1 R4 R5 R6 R14 2 R7 R8 R9 R15 3 R10 R11 R12 R16 4 R19 R20 R21 R31 5 R22 R23 R24 R32 6 R25 R26 R27 R33 7 R28 R29 R30 R34

When the board is shipped, a jumper is inserted in the C position of the input network. The jumper can be easily removed to build analog input signal conditioning circuits. A few specific applications showing the use of these open component positions are discussed in Application Notes later in this chapter.

Shield Ground

Jumper W1 is used to connect digital ground (DGND) to a grounded metal case. This option is useful only if the BNC-2081 board is on metal standoffs and mounted in a grounded metal case. Shield grounding can be selected to reduce noise.

Figure 3-4 shows the jumper settings for W1.

W2

• •

W2

• •

Shield Ground Selected Shield Ground Not Selected

Figure 3-4. W1 Jumper Settings

BNC-208X Series User Manual 3-4 © National Instruments Corporation

Chapter 3 BNC-2081 Board

Fuse and Power LED

The +5-V line from the data acquisition board is protected by a 750-mA fuse. If the red power LED does not light when the data acquisition board is powered on, check the 750-mA fuse on the BNC-2081 board and the output fuse (if any) on the Lab data acquisition board. Information on power connection is given in Chapter 4, Installation and Connections.

Digital and Timing Signals

All of the signals from the Lab data acquisition board are made available either by BNC connectors or via solder holes on the BNC-2081 board. Because these signals are not conditioned or changed in any way by this board, refer to your Lab board user manual for information on the use of these signals. If you want screw terminal access to all signals, a National Instruments SC-2071 board can be used in conjunction with the BNC-2081 board. If you want optical isolation of or relay control by the digital I/O lines, you must use a National Instruments SC-2053 cable adapter board and the appropriate SC-206X Series digital signal conditioning board. For more information on these products, refer to either your National Instruments catalog, the SC-205X Series User Manual, the SC-206X Series User Manual, or the SC-207X Series User Manual.

Specifications

This section lists the specifications of the BNC-2081 analog breakout board. These ratings are typical at 25° C unless otherwise stated. The operating temperature range for this board is 0° to 70° C.

Analog Input

Number of channels Eight single-ended Field connections 15 BNC connectors Signal conditioning capability Four open component positions per channel that

include connections from the input to ground, +5 V, and a series connection to the input of the data acquisition board

Other signals Solder holes for remaining Lab board

I/O signals

DIO connector DIO-24 connector for digital ports

Power Requirements

Power consumption (at +5 VDC ±5%)

Typical 12 mA with no user circuitry connected Maximum 750 mA from host computer

BNC-2081 Board Chapter 3

Note: The power specifications pertain to the power supply of the host computer. The maximum

power consumption of the BNC-2081 board is a function of the signal conditioning components installed. If the board is being powered from the host computer, the maximum +5-V current is fuse-limited to 750 mA.

Physical

Board dimensions (including standoffs) 7.9 by 4.9 by 1.725 in. I/O connectors Three 50-pin male ribbon-cable connectors BNC connectors 15

Operating Environment

Temperature 0° to 70° C Relative humidity 5% to 90% noncondensing

Storage Environment

Temperature -55° to 125° C Relative humidity 5% to 90% noncondensing

Board-to-Board Cabling

The BNC-2081 board directly connects to any of the data acquisition boards listed in Table 3-2.

Table 3-2. Data Acquisition Boards Used with the BNC-2081 Board

Lab Board

(PC/XT and Macintosh NuBus)

BNC-2081 Board Lab-LC

Lab-NB

Lab-PC

Lab-PC+

The BNC-2081 board directly connects to the Lab-PC, Lab-PC+ and Lab-NB using the 50-pin NB1 cable supplied with the BNC-2081. The Lab-LC board connects to the BNC-2081 using an NB10 cable, available separately.

BNC-208X Series User Manual 3-6 © National Instruments Corporation

Chapter 3 BNC-2081 Board

50-Pin I/O Connector

Lab Board BNC-2081

NB1 (Lab-PC, Lab-PC+, Lab-NB)

or

NB10 (Lab-LC) cable

Figure 3-5. Direct Connection between a Lab Board and the BNC-2081 Board

For digital signal conditioning with the National Instruments SC-206X Series boards, the SC-2053 cable adapter board must be used with the Lab board. Figure 3-6 shows a connection using the SC-2053 cable adapter board.

SC-2071

50-Conductor Cable

OR

PORT-C-

SC-206X Series

Lab Board BNC-2081

SC-2053

PORT-B-

PORT-A-

Digital I/O

SC-206X Series

Figure 3-6. Connection between a Lab Board, the BNC-2081, and the SC-2071 Board,

or the Connection between a Lab Board, the BNC-2081, and the

SC-206X Series Board, via the SC-2053 Board

Warning: Do not connect the BNC-2081 board to any board other than a National Instruments Lab

data acquisition board, the SC-2053 cable adapter board, or the SC-2071 board. The BNC2081 board is not compatible with any other data acquisition boards or cable adapter boards. Attempts to use the BNC-2081 board with products for which it was not intended can result in damage to the BNC-2081 board, the data acquisition board, or the host computer. National Instruments is not liable for damages resulting from these connections.

The BNC-2081 board uses a 50-pin ribbon-cable connector to connect to the 50-pin I/O connector on either a Lab data acquisition board, an SC-2053 cable adapter board, or the SC-2071. If the BNC-2081 board is to be used with the SC-2053 or the SC-2071 boards and is mounted in a rack, the cable should run underneath the BNC-2081 board for easier access to the BNC-2081. For more information, see Chapter 4, Installation and Connections.

BNC-2081 Board Chapter 3

Mounting

The BNC-2081 board is equipped with metal standoffs so the board can be placed on a workbench near the host computer. You can use an optional rack-mount chassis, which can be fitted with a flat, acrylic plastic cover. When the BNC-2081 board is mounted in the chassis, the board can be grounded to its metal standoffs, and therefore to the rack. For more information, see Chapter 4, Installation and Connections.

Application Notes

The open component positions on the BNC-2081 board make adding signal conditioning components to the analog input signals easier. Several applications are covered in this section, including filtering and attenuation.

The figures in this section give examples on a specific input channel. If you want to install the circuit on a different channel, consult Table 3-1 to determine the equivalent component positions for the other channels.

Soldering and Desoldering on the BNC-2081 Board

With the applications discussed here, you must make modifications to the printed circuit board, usually by removing jumpers and adding components. The BNC-2081 board is shipped with one jumper in the C position (see Table 3-1 and Figure 3-3). Use a low-wattage soldering iron (20 to 30 W) when soldering to the board. To desolder on the BNC-2081, vacuum-type tools work best. Use care when desoldering to avoid damaging component pads. Only rosin-core, electronic-grade solder should be used. Acid-core solder damages the printed circuit board and components.

Connecting Nonreferenced (or Floating) Signal Sources

A floating signal source is a signal source that is not connected in any way to the building ground system, but has an isolated ground-reference point. If an instrument or device has an isolated output, that instrument or device falls into the floating signal source category. Some examples of floating signal sources are outputs for: thermocouples, transformers, battery-powered devices, optical isolators, and isolation amplifiers. The ground reference of a floating source must be tied to the ground of the data acquisition board.

No special components are needed to measure signals from floating sources connected to the BNC-2081 board. Because the negative side of the single-ended inputs is grounded, all floating sources are referenced to the same ground. The inputs of the BNC-2081 board can be left in the factory-original condition, that is, with a jumper in the series position, C (see Table 3-1). Signal conditioning circuitry, such as the filters and attenuators described in Building Lowpass Filters, Building Highpass Filters, and Building Attenuators (Voltage Dividers) later in this chapter, can be used.

Connecting Ground-Referenced Signal Sources

BNC-208X Series User Manual 3-8 © National Instruments Corporation

Chapter 3 BNC-2081 Board

A grounded signal source is connected in some way to the building system ground; therefore, the signal source is already connected to a common ground point with respect to the data acquisition board, assuming the host computer is plugged into the same power system. The nonisolated outputs of instruments and devices that plug into the building power system fall into this category.

In the case of grounded signal sources connected to the single-ended inputs of the BNC-2081 board, a small DC error can be measured because of differences between the ground potentials of the signal source and the Lab board. This error is unavoidable with the BNC-2081 board because the Lab data acquisition board is configured only for RSE. No special components are needed to measure signals from grounded sources connected to the BNC-2081 board. The inputs of the BNC-2081 board can be left in the factory-original condition, that is, with a jumper in the series position C (see Table 3-1 and Figure 3-3). Signal conditioning circuitry such as the filters and attenuators as described in the sections titled Building Lowpass Filters, Building Highpass Filters, and Building Attenuators (Voltage Dividers) later in this chapter, can be used.

Building Lowpass Filters

Simple, R-C lowpass filters are easily installed in the BNC-2081 board on any input channel. The filters are useful for accurate measurement and noise rejection. By substituting resistance and capacitance values into the following formula (hereafter referred to as Formula 3-1), you can calculate a simple, onepole R-C filter to have a -3-dB point fc:

fc =

The frequency response rolls off at a rate of -20 dB per decade of increase thereafter. A Bode plot of the amplitude versus normalized frequency is shown in Figure 3-7.

1

(2πRC)

Amplitude

(Formula 3-1)

1

0.1

0.01

0.001

0.0001

dB

0

-20

-40

-60

-80

| | | | | |

0.1 1 10 100 1,000 10,000 (f )

c

Normalized Frequency

Figure 3-7. Normalized Frequency Response of Lowpass Filter

BNC-2081 Board Chapter 3

When measuring low-frequency signals (about 4 Hz), if you have 400-Hz noise on your inputs, you can add a lowpass filter with a cutoff frequency of 4 Hz. The 400-Hz noise then attenuates by 40 dB. Notice that your 4-Hz signal also attenuates, but by only 3 dB. Do not neglect any potential attenuation of signals of interest by this low-order filter.

You must also choose the filter component values. The resistance or the capacitance can be selected arbitrarily; one value determines the other. Picking the capacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available. If a capacitance of 1 µF is available, then the resistance is, by substitution into Formula 3-1, 39,789 Ω, or about 39.80 kΩ. Therefore, in this example, the input has a 39.80-kΩ resistor (or the closest standard value) in its series position, C. The closest standard 5%-tolerance resistor is 39 kΩ. For a lowpass filter on a single-ended input, 5%-tolerance resistors suffice. Figure 3-8 shows both the schematic and the component placement for a 4-Hz lowpass filter placed on Channel 1.

R14

+

To Input Multiplexer

D

R5

R6

Input Schematic for ACH1

D

R14 = 1 µF (Capacitor)

R4

R6 = 39 kΩ

C

A

B

C

39-kΩ Resistor

Channel 1 (Center)

ACH1

AIGND (Case)

BNC Connector

1-µF Capacitor

Channel 1 (Center)

BNC Connector

AIGND

(Case)

Figure 3-8. Lowpass Filter on Channel 1

BNC-208X Series User Manual 3-10 © National Instruments Corporation

Chapter 3 BNC-2081 Board

Building Highpass Filters

Simple, R-C highpass filters are easily installed in the BNC-2081 board on any input channel. The filters are useful for accurate high-frequency measurement and low-frequency noise rejection. By substituting resistance and capacitance values into the following formula (hereafter referred to as Formula 3-2), you can calculate a simple, one-pole R-C filter to have a -3-dB point f

c:

fc =

The response rolls off at a rate of -20 dB per decade drop in frequency thereafter. A Bode plot of the amplitude versus normalized frequency is shown in Figure 3-9.

1

(2πRC)

Amplitude

(Formula 3-2)

1

0.1

0.01

0.001

0.0001

dB

0

-20

-40

-60

-80

| | | | | |

0.0001 0.001 0.01 0.1 1 10 (f )

Normalized Frequency

c

Figure 3-9. Normalized Frequency Response of Highpass Filter

When measuring high-frequency signals (about 20 kHz), if you have 20-Hz noise on your inputs, you can add a highpass filter with a cutoff frequency of 20 kHz. The 20-Hz noise then attenuates by 60 dB. Notice that your 20-kHz signal also attenuates, but by only 3 dB. Do not neglect any potential attenuation of signals of interest if you add a low-order filter.

You must also choose the filter component values. The resistance or the capacitance can be selected arbitrarily; one value determines the other. Picking the capacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available. If a 0.001-µF capacitor is available, the resistance is (by substitution into Formula 3-2) 7,958 Ω, or about 8.0 kΩ. Therefore, in this example, the input channel has a 7.96-kΩ resistor (or the closest standard value) in position D and a 0.001-µF capacitor in position C. The closest standard 5% tolerance resistor is 8.2 kΩ. Resistor tolerance is not a concern in this application because most capacitors have poor tolerances (for example, 20% to 30%). Figure 3-10 illustrates both the schematic and the component placement for a 20-kHz highpass filter placed on input Channel 1.

BNC-2081 Board Chapter 3

R14

D

R4

R5

R6

Input Schematic for ACH1

+

A

B

C

8.2-kΩ Resistor

R6 = 0.001µF (Capacitor)

Channel 1 (Center)

C

ACH1

AIGND (Case)

BNC Connector

0.001-µF Capacitor

Channel 1 (Center)

To Input Multiplexer

AIGND

D

R14 = 8.2 kΩ

BNC Connector

AIGND (Case)

Figure 3-10. Highpass Filter on Channel 1

Building Attenuators (Voltage Dividers)

Attenuators can be connected to the analog inputs of the BNC-2081 board. Attenuators can be used to reduce a signal that is outside the normal input range of the data acquisition board (±10 V maximum).

Warning: The BNC-2081 board is not designed for any input voltages greater than 42 V, even if a

user-installed voltage divider reduces the voltage to within the input range of the data acquisition board. Input voltages greater than 42 V can result in damage to the BNC-2081 board, any and all boards connected to it, and the host computer. Overvoltage can also cause an electric shock hazard for the operator. National Instruments is not liable for damage or injury resulting from such misuse.

Chapter 3 BNC-2081 Board

A two-resistor circuit for attenuating voltages at the single-ended inputs of the BNC-2081 board is shown in Figure 3-11. The figure also shows the placement of the resistors on the open component positions for Channel 1. The gain, G, of this attenuator is given by the following formula:

R

G =

D

(RC + RD)

(Formula 3-3)

Therefore, the input to the Lab board (V

V

Lab

where V

= V

is the voltage applied to the BNC connectors of the BNC-2081 board. The accuracy of this

SC

SC *

G

) is as follows:

Lab

gain equation depends on the tolerances of the resistors used. The input impedence of the channel with the voltage attenuator is RC + R

D. This should be kept sufficiently high to avoid any loading effect on

the voltage you are measuring.

R14

D

Channel 1 (Center)

10-kΩ Resistor

R6

R4

R5

A

B

C

ACH1

AIGND (Case)

BNC Connector

To Input Multiplexer

AIGND

Input Schematic for ACH1

+

C

D

R14 = 10 kΩ

Channel 1 (Center)

AIGND (Case)

Figure 3-11. Attenuator for Use with BNC-2081 Board Inputs

BNC Connector

BNC-2081 Board Chapter 3

Example:

Using the values in Figure 3-12,

G =

10 kΩ + 10 kΩ

Therefore, V

10 kΩ

= (1/2) V

Lab

=

1 2

SC

When the Lab board is configured for ±5-V inputs, the board can acquire ±10-V signals with this attenuator circuit. The input impedence of the circuit is 10 kΩ + 10 kΩ = 20 kΩ. The source impedence of the circuit is as follows:

10 kΩ

10 kΩ = 5 kΩ.

Lab Board Analog Output

Analog output BNC connectors each have two open component positions for optional signal conditioning components. One of these is designated as a resistor and the other as a capacitor. The equivalent circuit for DAC0 OUT is shown in Figure 3-12. Circuitry for DAC1 OUT is the same.

When the board is shipped, 0-Ω jumpers are inserted into the R17 an R18 positions. These can be easily removed to build passive analog output signal conditioning circuits such as voltage dividers and lowpass filters. Figure 3-12 shows the DAC0 OUT schematic. Figure 3-13 shows the analog output schematic for DACs with DAC0 OUT shown.

DAC0 OUT

Jumpers Installed Here at Factory

AOGND

R17

DAC0 OUT

BNC Connector

C1

Figure 3-12. DAC0 OUT Schematic

Chapter 3 BNC-2081 Board

R9

DAC0 OUT

Jumpers Installed Here at Factory

AOGND

C5

Figure 3-13. Analog Output Schematic for DACs, DAC0 OUT Shown

Additional Signal Connection Information

DAC0 OUT

BNC Connector

For more information about signal connection, refer to Chapter 2 of your Lab board user manual.

Chapter 4 Installation and Connections

This chapter explains how to install and make connections to the BNC-208X Series boards.

Hardware Installation

Most of the sections that follow apply to all the BNC-208X Series boards. However, several topics are more board-specific than others. Unless a given topic is delineated by board, the topic applies to all BNC-208X Series boards.

Hardware Installation for the BNC-2080 and the BNC-2081

The following are general instructions for installing your BNC-2080 or BNC-2081 board in your computer data acquisition system. Consult the user manual or technical reference manual of your computer for specific instructions and warnings. Notice that the installation instructions are the same for both BNC-2080 and the BNC-2081 boards.

Caution: Turn the host computer off before making any connections.

1. Determine what signal conditioning is desired for the analog inputs and install the necessary components into the open component positions. If no signal conditioning is needed on an input, then the factory-installed jumpers (on the BNC-2080) or jumper (on the BNC-2081) must be in place.

2. Check that jumpers W1 and W2 (on the BNC-2080) and jumper W1 (on the BNC-2081) are set correctly for the current application.

3. Mount the BNC-208X Series board into a 19-in. rack (optional).

4. Connect the BNC-208X Series board to the data acquisition board using a 50-pin ribbon cable. (If an SC-205X Series board or SC-207X Series board is used with the BNC-208X Series board, install and mount the SC-205X Series and SC-207X Series boards as instructed in the SC-205X Series User Manual and the SC-207X Series User Manual. Then connect the SC-207X Series board and the SC-205X Series board to the BNC-208X Series board using the 50-pin cable. Connect the BNC-208X Series board to the data acquisition board.)

5. Connect field signals to the BNC-208X Series board at the BNC connectors or solder holes in the board for remaining digital signals.

Installation and Connections Chapter 4

6. Attach the appropriate cover to the rack mount (optional).

7. Turn the computer on.

8. When finished, turn off any powered external signals to the BNC-208X Series board before turning off the computer.

Warning: The BNC-208X Series boards have not been designed for use with high voltage. Although

the open component positions are configured so that voltage dividers can be installed to reduce a high input voltage to within the ±10-V data acquisition board input range, the maximum safe input voltage at any point on the BNC-208X Series boards is 42-V peak. Input voltages larger than 42 V, even if attenuated by a voltage divider on the BNC-208X Series board, can result in damage to the BNC-208X Series board, the data acquisition boards, or the host computer. High voltage can also cause an electric shock hazard to you. National Instruments is not liable for damages or injuries resulting from these connections.

Installing the SC-205X Series Cable Adapter Boards

Consult the SC-205X Series User Manual for instructions on the installation of your SC-205X Series board if any of these boards are being used.

Installing the SC-207X General-Purpose Termination Breadboards

Consult the SC-207X Series User Manual for instructions on the installation of your SC-207X Series board if any of these boards are being used.

Rack Mounting

Your BNC-208X Series board can be installed on half of a 19-in. rack-mount chassis. You can mount one BNC-208X Series board alongside an SC-205X Series cable adapter board, an SC-206X Series digital signal conditioning board, or an SC-207X Series general-purpose termination breadboard. You can mount your BNC-208X Series board on the left or right side of the 19-in. rack mount. Mounting the BNC-208X Series board on the left side of the rack and any other of the SC Series boards on the right side of the rack will make access to both boards easier. Run the connecting 50-position cable underneath the BNC-208X Series board to the adjoining board. The BNC-208X Series board occupies half of a 19-in. rack, as shown in Figure 4-1 and Figure 4-2.

Chapter 4 Installation and Connections

BNC-208X Series Board SC-207X Series Board

Left-Hand Mounting Position

Right-Hand Mounting Position

Figure 4-1. Mounting Locations for the BNC-208X Series Board and SC-207X Series Board

SC-205X Series Board

BNC-208X Series Board

SC-206X Series Board

Left-Hand Mounting Position

or

Right-Hand Mounting Position

Figure 4-2. Mounting Locations for the BNC-208X Series Board and SC-205X Series Board or SC-

206X Series Board

Installation and Connections Chapter 4

Mount the BNC-208X Series board in the chassis by removing the screws on the bottoms of the four standoffs attached to the board and using the same screws to attach the board to the mounting rack. The two standoffs in the center of the board are for support only and have no screws to attach the board to the rack as shown in Figure 4-3.

Top Washers and Screw

Metal Standoff

Rack Mount

Washer Lock Washer

Screw

Circuit Board

Figure 4-3. Attaching a Mountable Board to the Chassis

Be sure to include the washers around the screws when attaching your board to the rack mount as shown in Figure 4-3.

Notice that jumper W2 (BNC-2080) and jumper W1 (BNC-2081) can connect the digital ground for both boards to the metal standoffs attached to the board. Rack mounting does not automatically ground the boards to the metal chassis unless the appropriate jumper is set.

If two BNC-208X Series boards connected to different data acquisition boards need to be stacked, double-height mounting within one rack-mount chassis is possible. Because only one BNC-208X Series board can be used with each data acquisition board, this situation occurs only if two or more data acquisition boards are being used. You need a hardware kit for double-height mounting consisting of two brackets that are installed in the rack mount. A second row of boards can be mounted on these brackets in the same way as the first row.

Chapter 4 Installation and Connections

Art not available in PDF version of document.

Figure 4-4 illustrates double-height mounting.

Figure 4-4. Double-Height Mounting

External Power Connection (If Necessary)

Your BNC-208X Series board draws very little current from the computer power supply. If several high-current SC-206X Series digital signal conditioning boards, such as the SC-2062 board, are being used on the same data acquisition board as the BNC-208X Series board, some of these boards need to be powered by an external +5-VDC supply. Because the SC-206X Series boards draw much more current than the SC-207X Series or the BNC-208X Series, the SC-206X Series boards should be powered from the external supply, and the SC-207X Series board or the BNC-208X Series board can be run from the host computer power supply. If an external power supply is needed for the SC-206X or SC-207X Series boards, see the External Power Connection section of the SC-206X Series User Manual and the

SC-207X Series User Manual.

Installation and Connections Chapter 4

BNC-208X Series Board Connection

Figure 4-5 illustrates the connections from the BNC-2080 or BNC-2081 boards directly to data acquisition boards via a 50-conductor cable and to other SC-Series boards, using an appropriate cable.

MIO-16

50-Conductor Cable

OR

50-Conductor Cable

OR

MIO-16 BNC-2080

Lab Board BNC-2081

50-Conductor Cable

SC-2050

Digital I/O

BNC-2080

SC-2070 SC-2072

SC-206X Series

SC-2071

OR

Lab Board BNC-2081

50-Conductor Cable

OR

SC-2053

Port -A-

Port -B-

Port -C-

Digital I/O

SC-2072

SC-206X Series

Figure 4-5. Connections between Data Acquisition Boards and BNC-208X Series Boards

and between SC-205X Series Boards and BNC-2080 and BNC-2081 Boards

Chapter 4 Installation and Connections

A 50-pin ribbon cable connects your BNC-208X Series board to either an SC-205X Series board, an SC-207X Series board, or directly to the data acquisition board. Remember to turn the host computer off before making any connections. One end of the ribbon cable connects to the BNC-208X Series board at connector J1 or J2. The other end of the ribbon cable connects either to the data acquisition board or to one of the two 50-pin headers on the SC-205X Series board or the SC-207X Series board you installed for use with the data acquisition board. Connecting the data acquisition board to J2 and using J1 (running cable under board) to daisy chain to any other board in the rack is the easiest method for connecting two or more boards to the MIO-16.

Signal Connections

Ribbon-Cable Connectors

The pinout for the 50-pin ribbon-cable connector on the BNC-2080 board is exactly the same as the 50-pin connector on the MIO-16 and LPM-16 data acquisition boards. The pinout for the 50-pin ribboncable connector on the BNC-2081 board is exactly the same as the 50-pin connector on the Lab data acquisition board. For more information on these connectors, refer to your data acquisition board user manual.

Rack-Mount Chassis Cover Attachment

The optional 19-in. rack-mount accessory includes a flat, acrylic plastic cover that can be installed using the four screws included in the kit. Covering the top and bottom is required for safety reasons if an SC-206X Series board in the same enclosure is to be used in high-voltage situations. Remember that voltages above the 42-V peak cannot be applied to the SC-207X Series inputs.

Warning: The SC-206X Series boards must be completely enclosed if any onboard voltages or any

voltages connected to the relays can exceed 42 V.

Appendix Customer Communication

___________________________________________________

For your convenience, this appendix contains forms to help you gather the information necessary to help us solve technical problems you might have as well as a form you can use to comment on the product documentation. Filling out a copy of the Technical Support Form before contacting National Instruments helps us help you better and faster.

National Instruments provides comprehensive technical assistance around the world. In the U.S. and Canada, applications engineers are available Monday through Friday from 8:00 a.m. to 6:00 p.m. (central time). In other countries, contact the nearest branch office. You may fax questions to us at any time.

Corporate Headquarters

(512) 795-8248 Technical support fax: (800) 328-2203

(512) 794-5678

Branch Offices Phone Number Fax Number

Australia (03) 879 9422 (03) 879 9179 Austria (0662) 435986 (0662) 437010-19 Belgium 02/757.00.20 02/757.03.11 Denmark 45 76 26 00 45 76 71 11 Finland (90) 527 2321 (90) 502 2930 France (1) 48 14 24 00 (1) 48 14 24 14 Germany 089/741 31 30 089/714 60 35 Italy 02/48301892 02/48301915 Japan (03) 3788-1921 (03) 3788-1923 Mexico 95 800 010 0793 95 800 010 0793 Netherlands 03480-33466 03480-30673 Norway 32-848400 32-848600 Singapore 2265886 2265887 Spain (91) 640 0085 (91) 640 0533 Sweden 08-730 49 70 08-730 43 70 Switzerland 056/20 51 51 056/20 51 55 Taiwan 02 377 1200 02 737 4644 U.K. 0635 523545 0635 523154

Technical Support Form

___________________________________________________

Photocopy this form and update it each time you make changes to your software or hardware, and 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 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 will reproduce the problem

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 your needs.

Title: BNC-208X Series User Manual Edition Date: September 1993 Part Number: 320407-01 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.

Thank you for your help. Name Title Company Address

Phone ( ) Mail to: Technical Publications Fax to: Technical Publications

National Instruments Corporation National Instruments Corporation 6504 Bridge Point Parkway, MS 53-02 MS 53-02 Austin, TX 78730-5039 (512) 794-5678

Index

A

abbreviations used in the manual, vi acronyms used in the manual, vii analog breakout board, 2-1 analog input, 2-3, 2-6, 3-2

field connections, 2-6 MIO-16, 2-9 to 2-13 number of channels, 2-6 other signals, 2-6 signal conditioning capability, 2-6

analog output

lab board, 3-14 MIO-16, 2-23 schematic for DACs, DAC0 OUT, 2-23, 3-15

attenuators

building

BNC-2080, 2-20 BNC-2081, 3-12

for use with differential inputs, 2-21

B

bias return resistor, 2-14 BNC-2080, 2-1

connected to MIO-16, 1-2 parts locator diagram, 2-2

BNC-2081, 3-1

analog breakout board, 3-1 parts locator diagram, 3-2

BNC-208X

board connection, 4-6 connected to MIO-16, 1-2 contents of kit, 1-3 unpacking, 1-5

board dimensions

BNC-2080, 2-7 BNC-2081, 3-6

C

cable adapter boards, installing, 4-2 cabling, board-to-board

Index

BNC-2080, 2-7

BNC-2081, 3-6 channel configurations, 2-9 channels, number of

BNC-2080, 2-6

BNC-2081, 3-5 CMRR, vii connections, 4-1

D

DAC0 OUT schematic, 3-14 data acquisition boards, 2-1, 4-6

for use with BNC-208X, 1-1

used with BNC-2081, 3-6

used with SC-2080, 2-7 desoldering

BNC-2080, 2-9

BNC-2081, 3-8 DGND, vii DIFF, vii DIFF mode, 2-11

channel component positions, 2-5

onboard equivalent circuit, 2-4 differential inputs, 2-13, 2-15 differential mode

switch configurations, 2-10 digital and timing signals

BNC-2080, 2-6

BNC-2081, 3-5 DIO connector, 3-5 double-height mounting, 4-5

E

external power connection, 4-5

F

field connections

BNC-2080, 2-6

BNC-2081, 3-5 filters. See also highpass filters.; lowpass filters.

highpass

BNC-2080, 2-17 BNC-2081, 3-11

lowpass

BNC-2080, 2-15 BNC-2081, 3-9

fuse and power LED

BNC-2080, 2-6

BNC-2081, 3-5

G

general-purpose termination breadboards

SC-207X, 4-2 ground reference jumper, 2-10

for use with LPM-16, 2-23 ground-referenced signal sources

BNC-2080, 2-15

BNC-2081, 3-8

H

Index

hardware installation, 4-1 highpass filters

BNC-2080, on differential channel 1, 2-19

BNC-2081, on channel 1, 3-12

building

BNC-2080, 2-17 BNC-2081, 3-11

normalized frequency response

BNC-2080, 2-18 BNC-2081, 3-11

I

I/O connectors, 2-7 installation, 4-1

L

lowpass filters

building

BNC-2080, 2-15

BNC-2081, 3-9 normalized frequency response, 2-16, 3-9 on channel 1, 3-10 on differential channel 1, 2-17

Index

M

MIO-16, 2-1

analog input, 2-9 analog output, 2-23

mounting. See also rack mounting.

BNC-2080, 2-9 BNC-2081, 3-8 double-height, 4-5 locations, 4-3

N

NRSE, vii

mode, 2-12

O

onboard equivalent circuit

BNC-2081, 3-3 for DIFF mode, 2-4

operating environment

BNC-2080, 2-7 BNC-2081, 3-6

optional equipment, 1-3

P

PC-LPM-16, 2-1, 2-22

switch configurations, 2-22

physical specifications

BNC-2080, 2-7

power and fuse LED

BNC-2080, 2-6 BNC-2081, 3-5

power connections, 2-3 power consumption, 2-7

BNC-2081, 3-5

power requirements, 2-7

BNC-2081, 3-5

R

rack mounting, 4-2

chassis cover attachment, 4-7

ribbon-cable connectors, 4-7 RSE, vii

mode, 2-12

S

SC-205X

connected to MIO-16, 1-2 installation, 4-2

SC-206X

connected to MIO-16, 1-2

SC-207X

connected to MIO-16, 1-2 installation, 4-2

SE mode switch configurations, 2-22 shield ground

BNC-2080, 2-5 BNC-2081, 3-4

signal conditioning accessories, 1-4 signal conditioning capability

BNC-2080, 2-6 BNC-2081, 3-5

signal connections

BNC-2081, 4-7

signal sources

floating

BNC-2080, 2-13

BNC-2081, 3-8 ground-referenced (BNC-2080), 3-8 nonreferenced

BNC-2080, 2-13

BNC-2081, 3-8

single-ended

inputs, 2-14, 2-15 mode switch configurations, 2-10

soldering

BNC-2080, 2-9 BNC-2081, 3-8

specifications

BNC-2080, 2-6 BNC-2081, 3-5

storage environment

BNC-2080, 2-7 BNC-2081, 3-6

Index

switch configurations

BNC-2080

MIO-16 in DIFF mode, 2-11

MIO-16 in RSE and NRSE modes, 2-12 differential mode, 2-10 for SE mode (LPM-16), 2-22 single-ended mode, 2-10

switch S5, 2-3

settings, 2-3 settings for data acquisition boards, 2-3

T

timing and digital signals, 3-5

U

unpacking BNC-208X, 1-5

V

VDC, vii voltage dividers. See attenuators.

W

W1 ground reference jumper, 2-10 W1 jumper settings, 3-4 W2 jumper settings, 2-5

National Instruments BNC-208X User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

National Instruments Corporate Headquarters

Limited Warranty

Copyright

Trademarks

Preface

Organization of This Manual

Conventions Used in This Manual

Abbreviations

Acronyms

Related Documentation

Customer Communication

Contents

Figures

Tables

Chapter 1 Introduction

Table 1-1. Data Acquisition Boards for Use with BNC-208X Series Boards

Figure 1-1. BNC-2080 Board Directly Connected to an MIO-16 Board

Figure 1-2. BNC-208X, SC-207X, SC-206X, and SC-205X Series Boards

What Your Kit Should Contain

Optional Equipment

Signal Conditioning Accessories

Software Support

Unpacking

Figure 2-1. BNC-2080 Analog Breakout Board

Figure 2-2. BNC-2080 Board Parts Locator Diagram

Power Connections

Table 2-1. Switch S5 Settings for National Instruments Data Acquisition Boards

Analog Input

Figure 2-3. Onboard Equivalent Circuit for DIFF Mode

Table 2-2. DIFF Mode Channel Component Positions

Shield Ground

Figure 2-4. W2 Jumper Settings

Fuse and Power LED

Digital and Timing Signals

Specifications

Analog Input

Power Requirements

Physical

Operating Environment

Storage Environment

Board-to-Board Cabling

Table 2-3. Data Acquisition Boards Used with the BNC-2080 Board

Figure 2-5. Direct Connection between an MIO-16 Board and the BNC-2080 Board

Figure 2-6. Connection between an MIO-16 Board, the BNC-2080 Board, and the

Mounting

Application Notes

Soldering and Desoldering on the BNC-2080 Board

Channel Configurations

MIO-16 Analog Input

Figure 2-7. Switch Configurations for Differential Mode or Single-Ended Mode

Figure 2-8. W1 Ground Reference Jumper

Figure 2-9. BNC-2080 Switch Configurations for an MIO-16 Configured in DIFF Mode

Figure 2-10. BNC-2080 Switch Configurations for an MIO-16 Configured in RSE and

Connecting Nonreferenced (or Floating) Signal Sources

Differential Inputs

Figure 2-11. Bias Return Resistor for DC-Coupled Floating Source on Channel 1 in

Single-Ended Inputs

Connecting Ground-Referenced Signal Sources

Differential Inputs

Single-Ended Inputs

Building Lowpass Filters

Figure 2-12. Normalized Frequency Response of Lowpass Filter

Figure 2-13. Lowpass Filter on Differential Channel 1

Building Highpass Filters

Figure 2-14. Normalized Frequency Response of Highpass Filter

Figure 2-15. Highpass Filter on Differential Channel 1

Building Attenuators (Voltage Dividers)

Figure 2-16. Attenuator for Use with Differential Inputs

PC-LPM-16

Figure 2-17. Switch Configurations for SE Mode (PC-LPM-16)

Figure 2-18. Ground Reference Jumper Position for Use with the PC-LPM-16

MIO-16 Analog Output

Figure 2-19. Analog Output Schematic for DACs, DAC0 OUT Shown

Figure 3-1. BNC-2081 Analog Breakout Board

Figure 3-2. BNC-2081 Board Parts Locator Diagram

Analog Input