National Instruments SC-2040 User Manual

SC-2040

User Manual

Eight-Channel Simultaneous Sample-and-Hold Accessory

September 1994 Edition

Part Number 371191A-01

© Copyright 1994 National Instruments Corporation.

All Rights Reserved.

National Instruments Corporate Headquarters

6504 Bridge Point Parkway
Austin, TX 78730-5039
[phone]
Technical support fax: [phone]

[phone]

Branch Offices:

Australia [phone], Austria [phone], Belgium 02/757.00.20, Canada (Ontario) [phone],
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Germany 089/741 31 30, Italy 02/48301892, Japan [phone], Netherlands 03480-33466, Norway 32-848400,
Spain (91) 640 0085, Sweden 08-730 49 70, Switzerland 056/20 51 51, U.K. 0635 523545

Limited Warranty

The SC-2040 is warranted against defects in materials and workmanship for a period of one year from the date of
shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace
equipment that proves to be defective during the warranty period. This warranty includes parts and labor.

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

LabVIEW®, NI-DAQ®, and RTSI® are trademarks of National Instruments Corporation.
Product names 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.

Contents

About This Manual................................................................................................................ix

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

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

The National Instruments Documentation Set..................................................................x

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

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

Chapter 1
Introduction

About the SC-2040.........................................................................................................1-1

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

Software Programming Choices....................................................................................1-2

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

Unpacking......................................................................................................................1-4

Chapter 2
Configuration and Installation

Board Configuration ......................................................................................................2-1

Installation......................................................................................................................2-8

Power On Sequence.......................................................................................................2-8

..........................................................................................................................1-1

LabVIEW and LabWindows Application Software..........................................1-2

NI-DAQ Driver Software...................................................................................1-2

Register-Level Programming.............................................................................1-4

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

Supplementary Configuration Information........................................................2-6

Power Supply Selection.........................................................................2-6

Shield Selection......................................................................................2-6

DAQ Board Ground Isolation Selection................................................2-6

Gain Selection....................................................................................................2-6

Input Mode Selection.........................................................................................2-7

Chapter 3
Signal Connections

I/O Connector Pin Description.......................................................................................3-1

Signal Connection Description..........................................................................3-4

Analog Signal Input...........................................................................................3-7

Digital Signal Input............................................................................................3-11

Monitoring Signal Outputs.................................................................................3-11

Other Connection Considerations..................................................................................3-11

© National Instruments Corporation v SC-2040 User Manual

.............................................................................................................3-1

DC-Coupled Inputs................................................................................3-7

AC-Coupled Signals ..............................................................................3-8

Analog Input Ranges..................................................................3-10

Contents

Chapter 4
Theory of Operation

Functional Overview......................................................................................................4-1

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

Input Protection..................................................................................................4-3

Amplification.....................................................................................................4-3

Track-and-Hold (T/H) Circuitry........................................................................4-3

..........................................................................................................4-1

Triggering from the DAQ Board ...........................................................4-4

External Triggering................................................................................4-5

Output Connection.................................................................................4-6

Power Supply.........................................................................................4-6

Chapter 5
Calibration Procedures

Software Calibration......................................................................................................5-1

Offset Adjustment..............................................................................................5-1

Gain Adjustment................................................................................................5-2

Linearity Adjustment.........................................................................................5-2

Hardware Calibration.....................................................................................................5-2

.....................................................................................................5-1

Appendix A
Specifications

........................................................................................................................A-1

Appendix B
Customer Communication

...............................................................................................B-1

Glossary........................................................................................................................Glossary-1

Index..................................................................................................................................Index-1

SC-2040 User Manual vi © National Instruments Corporation

Contents

Figures

Figure 1-1. The Relationship between the Programming Environment,

NI-DAQ, and Your Hardware............................................................................. 1-3

Figure 2-1. SC-2040 Parts Locator Diagram..........................................................................2-2

Figure 3-1. SC-2040 I/O Connectors J11 and J12..................................................................3-2

Figure 3-2. SC-2040 Signal Routing......................................................................................3-6

Figure 3-3. Ground-Referenced Signal Connection...............................................................3-7

Figure 3-4. Floating Signal Connection.................................................................................3-8

Figure 3-5. Ground-Referenced AC-Coupled Signal Connection .........................................3-9

Figure 3-6. Ground-Offset AC-Coupled Signal Connection..................................................3-9

Figure 3-7. Floating AC-Coupled Signal Connection............................................................3-10

Figure 4-1. SC-2040 Block Diagram......................................................................................4-2

Figure 4-2. T/H Amplifier Hold Settling Time and Track Acquisition Time........................4-4

Figure 4-3. MIO-16E Controlled Triggering..........................................................................4-5

Figure 4-4. External Triggering..............................................................................................4-6

Tables

Table 2-1. Power Supply Selection.......................................................................................2-3

Table 2-2. Shield Selection...................................................................................................2-4

Table 2-3. DAQ Board Ground Isolation Selection..............................................................2-4

Table 2-4. Channel Gain Selection.......................................................................................2-5

Table 2-5. Channel Input Mode............................................................................................2-5

Table 2-6. Gain Switches for Each Channel.........................................................................2-6

Table 2-7. Switch Settings for Gain Selection......................................................................2-7

Table 2-8. Input Mode Selection Jumpers............................................................................2-7

Table 3-1. Pin Assignments for Connectors J11 and J12......................................................3-3

Table 3-2. Input Connectors Signal Summary......................................................................3-4

Table 3-3. Output Connectors (J11 and J12) Signal Summary.............................................3-4

Table 5-1. Calibration Component Identification.................................................................5-3

© National Instruments Corporation vii SC-2040 User Manual

About This Manual

This manual describes the electrical and mechanical aspects of the SC-2040 and contains
information concerning its configuration and operation. The SC-2040 is an eight-channel
simultaneously sampling differential amplifier for the National Instruments MIO-16E Series
DAQ boards. The SC-2040 samples all eight channels at the same time, preserving interchannel
phase relationships for the MIO-16E.

Organization of This Manual

The SC-2040 User Manual is organized as follows:

• Chapter 1, Introduction, describes the SC-2040, lists what you need to get started with your

SC-2040, describes the optional software and optional equipment, and explains how to
unpack your SC-2040.

• Chapter 2, Configuration and Installation, describes the configuration and installation of

your SC-2040. The topics discussed are switch and jumper configuration, connection of the
SC-2040 to the MIO-16E, and the power-on sequence for your SC-2040 configuration.

• Chapter 3, Signal Connections, describes the signal connections to the SC-2040 board, and

cable wiring.

• Chapter 4, Theory of Operation, contains a functional overview of the SC-2040 board and

explains the operation of each functional unit making up the SC-2040.

• Chapter 5, Calibration Procedures, discusses the calibration procedures for the SC-2040

board.

• Appendix A, Specifications, lists the specifications for the SC-2040.

• Appendix B, Customer Communication, contains forms you can use to request help from

National Instruments or to comment on our products.

• The Glossary contains an alphabetical list and description of terms used in this manual,

including abbreviations, acronyms, metric prefixes, mnemonics, and symbols.

• The Index contains an alphabetical list of key terms and topics used in this manual, including

the page where you can find each one.

© National Instruments Corporation ix SC-2040 User Manual

About This Manual

Conventions Used in This Manual

The following conventions are used in this manual:
bold italic Bold, italic text denotes a note, caution, or warning.
italic Italic text denotes emphasis, a cross reference, or an introduction to a key

concept.

MIO-16E MIO-16E refers to the National Instruments E-Series of MIO-16 DAQ

boards unless otherwise noted.

monospace Lowercase text in this font denotes text or characters that are to be literally

input from the keyboard, sections of code, programming examples, and
syntax examples. This font is also used for the proper names of disk
drives, paths, directories, programs, subprograms, subroutines, device
names, functions, variables, filenames, and extensions, and for statements
and comments taken from program code.

Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in the
Glossary.

The National Instruments Documentation Set

The SC-2040 User Manual is one piece of the documentation set for your system. You could
have any of several types of manuals, depending on the hardware and software in your system.
Use the manuals you have as follows:

• Your DAQ hardware user manuals–These manuals have detailed information about the DAQ

hardware that plugs into or is connected to your computer. Use these manuals for hardware
installation and configuration instructions, specification information about your DAQ
hardware, and application hints.

• Software manuals–Examples of software manuals you might have are the LabVIEW and

LabWindows
system, use either the application software (LabVIEW or LabWindows) manuals or the
NI-DAQ manuals to help you write your application. If you have a large and complicated
system, it is worthwhile to look through the software manuals before you configure your
hardware.

• Accessory manuals–If you are using accessory products, read the terminal block and cable

assembly installation guides or accessory board user manuals. They explain how to
physically connect the relevant pieces of the system together. Consult these guides when you
are making your connections.

®

manual sets and the NI-DAQ manuals. After you set up your hardware

SC-2040 User Manual x © National Instruments Corporation

About This Manual

Related Documentation

The following document contains information that you may find helpful as you read this manual:

• Your DAQ hardware user manual

Customer Communication

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

Communication, at the end of this manual.

© National Instruments Corporation xi SC-2040 User Manual

Chapter 1 Introduction

This chapter describes the SC-2040, lists what you need to get started with your SC-2040,
describes the optional software and optional equipment, and explains how to unpack your
SC-2040.

About the SC-2040

The SC-2040 is an eight-channel simultaneously sampling differential amplifier for the National
Instruments MIO-16E Series DAQ boards. Each channel provides DIP-switch-selectable gain
followed by a track-and-hold amplifier. The track-and-hold amplifiers sample all the inputs at
the same time, which is useful for preserving interchannel phase relationships. The MIO-16E
can trigger the track-and-hold amplifiers, or you can supply an external trigger source.

Note: When a board is referred to without an AT prefix (that is, MIO-16E), the reference

applies to the AT versions of that board.

The SC-2040 is a circuitboard assembly that is placed on a workbench or mounted in a 19-in.
rack. You can configure the SC-2040 to draw power from the MIO-16E board or from an
external +5 V supply. A red LED indicates when the board is powered on. Input signal leads are
attached at screw terminals.

What You Need to Get Started

To set up and use your SC-2040, you will need the following components:

• SC-2040 board

• SC-2040 User Manual

• 1.0, 2.0, 5.0, or 10.0 m SH6868 or R6868 cable
Detailed specifications of the SC-2040 are in Appendix A, Specifications.

© National Instruments Corporation 1-1 SC-2040 User Manual

Introduction Chapter 1

Software Programming Choices

Your SC-2040 kit does not include software. There are four options to choose from when
programming your National Instruments DAQ and SCXI hardware. You can use LabVIEW,
LabWindows, NI-DAQ, or register-level programming software.

The SC-2040 works with LabVIEW for Windows, LabVIEW for Macintosh, LabWindows for
DOS, LabWindows/CVI for Windows, NI-DAQ software for PC compatibles, and NI-DAQ
software for Macintosh.

LabVIEW and LabWindows Application Software

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

LabVIEW currently runs on three different platforms–AT/MC/EISA computers running
Microsoft Windows, the Macintosh platform, and the Sun SPARCstation platform. LabVIEW
features interactive graphics, a state-of-the-art user interface, and a powerful graphical
programming language. The LabVIEW Data Acquisition VI Library, a series of VIs for using
LabVIEW with National Instruments DAQ hardware, is included with LabVIEW. The
LabVIEW Data Acquisition VI Libraries are functionally equivalent to the NI-DAQ software,
except that the SCXI functions are not included in the LabVIEW software for Sun.

LabWindows has two versions–LabWindows for DOS is for use on PCs running DOS, and
LabWindows/CVI is for use on PCs running Windows and for Sun SPARCstations.
LabWindows/CVI features interactive graphics, a state-of-the-art user interface, and uses the
ANSI standard C programming language. The LabWindows Data Acquisition Library, a series
of functions for using LabWindows with National Instruments DAQ hardware, is included with
the NI-DAQ software kit. The LabWindows Data Acquisition libraries are functionally
equivalent to the NI-DAQ software, except that the SCXI functions are not included in the
LabWindows/CVI software for Sun.

Using LabVIEW or LabWindows software will greatly reduce the development time for your
data acquisition and control application.

NI-DAQ Driver Software

The NI-DAQ driver software is included at no charge with all National Instruments DAQ
hardware. NI-DAQ is not packaged with SCXI or accessory products. NI-DAQ has an
extensive library of functions that you can call from your application programming environment.
These functions include routines for analog input (A/D conversion), buffered data acquisition
(high-speed A/D conversion), analog output (D/A conversion), waveform generation, digital I/O,
counter/timer operations, SCXI, RTSI, self-calibration, messaging, and acquiring data to
extended memory.

SC-2040 User Manual 1-2 © National Instruments Corporation

Chapter 1 Introduction

NI-DAQ also internally addresses many of the complex issues between the computer and the
DAQ hardware such as programming interrupts and DMA controllers. NI-DAQ maintains a
consistent software interface among its different versions so that you can change platforms with
minimal modifications to your code. Figure 1-1 illustrates the relationship between NI-DAQ and
LabVIEW and LabWindows. You can see that the data acquisition parts of LabVIEW and
LabWindows are functionally equivalent to the NI-DAQ software.

Conventional
Programming

Environment

(PC, Macintosh, or

Sun SPARCstation)

LabVIEW

(PC, Macintosh, or

Sun SPARCstation)

NI-DAQ

Driver Software

LabWindows

(PC or

Sun SPARCstation)

DAQ or

SCXI Hardware

Personal

Computer

or

Workstation

Figure 1-1. The Relationship between the Programming Environment,

NI-DAQ, and Your Hardware

The National Instruments PC, AT, MC, EISA, DAQCard, and DAQPad Series DAQ hardware is
packaged with NI-DAQ software for PC compatibles. NI-DAQ software for PC compatibles
comes with language interfaces for Professional BASIC, Turbo Pascal, Turbo C, Turbo C++,
Borland C++, and Microsoft C for DOS; and Visual Basic, Turbo Pascal, Microsoft C with SDK,
and Borland C++ for Windows. You can use your AT-MIO-16, together with other PC, AT,
MC, EISA, DAQCard, and DAQPad Series DAQ and SCXI hardware, with NI-DAQ software
for PC compatibles.

The National Instruments NB Series DAQ boards are packaged with NI-DAQ software for
Macintosh. NI-DAQ software for Macintosh comes with language interfaces for MPW C,
THINK C, Pascal, and Microsoft QuickBASIC. Any language that uses Device Manager
Toolbox calls can access NI-DAQ software for Macintosh. You can use NB Series DAQ boards
and SCXI hardware with NI-DAQ software for Macintosh.

The National Instruments SB Series DAQ boards are packaged with NI-DAQ software for Sun,
which comes with a language interface for ANSI C.

© National Instruments Corporation 1-3 SC-2040 User Manual

Introduction Chapter 1

Register-Level Programming

There are no register-level programming concerns for the SC-2040. When using the SC-2040,
only the MIO-16E Series board needs to be programmed. Refer to your MIO-16E board manual
for further information on register-level programming.

Optional Equipment

Contact National Instruments to order the following optional equipment:

• CB-50 I/O connector (50-screw terminals) with 0.5 or 1.0 m cable

• Single or double height rack-mount kit with acrylic plastic cover

• Single or double height rack-mount kit with metal wraparound cover

Unpacking

Your SC-2040 board is shipped in an antistatic package to prevent electrostatic damage to the
board. Electrostatic discharge can damage several components on the board. To avoid such
damage in handling the board, take the following precautions:

• Ground yourself via a grounding strap or by holding a grounded chassis such as a computer

chassis.

• 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.

• Never touch the exposed pins of connectors.

SC-2040 User Manual 1-4 © National Instruments Corporation

Chapter 2 Configuration and Installation

This chapter describes the configuration and installation of your SC-2040. The topics discussed
are switch and jumper configuration, connection of the SC-2040 to the MIO-16E, and the power­on sequence for your SC-2040 configuration.

Board Configuration

The SC-2040 has 10 jumpers, eight DIP switches, and one slide switch that you use to configure
the board. These switches and jumpers are shown in Figure 2-1.

© National Instruments Corporation 2-1 SC-2040 User Manual

Configuration and Installation Chapter 2

Figure 2-1. SC-2040 Parts Locator Diagram

SC-2040 User Manual 2-2 © National Instruments Corporation

Chapter 2 Configuration and Installation

The SC-2040 has one switch that controls whether the board is powered from an external supply
or from the MIO-16E board. Furthermore, two jumpers control how the board is shielded and
grounded. Additionally, there are eight sets of switches and jumpers that configure the gain
settings and input modes of the eight SC-2040 channels.

Table 2-1. Power Supply Selection

Switch Description Configuration

INT position—Use this setting
to configure the SC-2040 to

SW1

INT

draw power through the

EXT

A. Internal

Power

SW1

INT

SW1

MIO-16E board. (factory
setting)

J13

EXT position—Use this
setting to draw +5 V power
from an external supply
connected to connector J13.

EXT

B. External

Power

© National Instruments Corporation 2-3 SC-2040 User Manual

Configuration and Installation Chapter 2

Table 2-2. Shield Selection

Jumper Description Configuration

W1

SHLD OFF position—Place
the jumper in this position to
keep the SC-2040 analog

SHLD OFF

W1

ground isolated from the metal
standoffs in the corners of the
board (factory setting).

SHLD ON position—Place
the jumper in this position to

SHLD ON

W1

SHLD OFF

connect the SC-2040 analog
ground to the metal standoffs
or to a rack-mount kit, which

SHLD ON

may provide shielding for the
SC-2040.

Table 2-3. DAQ Board Ground Isolation Selection

Jumper Description Configuration

W10

AIGND-AIGND position—
Use this setting if you are
using a MIO-16E DAQ board.

W10

AIGND

Place the jumper in this
position to keep the SC-2040

AIGND

digital ground and analog
grounds isolated (factory
setting).

DGND

AIGND-DGND position—
Place the jumper in this
position to connect the
SC-2040 analog ground to

W10

DGNDAIGND

AIGND

digital ground.

SC-2040 User Manual 2-4 © National Instruments Corporation

Chapter 2 Configuration and Installation

Table 2-4. Channel Gain Selection

Switch Description Configuration

U2
U6
U9
U14
U17
U21
U24
U28

Unity gain position—For
unity gain (gain = 1), open all
the switches by pushing down
the OFF end of the switches.
(factory setting)

The unity gain position has

Gain Table

A B C D

1234

OFF

the number side up.

Other gains—Refer to

Supplementary Configuration
Information, later in the

chapter, and the gain table on
the board itself.

Table 2-5. Channel Input Mode

Switch Description Configuration

W2
W3

W4
W5
W6
W7

W8
W9

A-B position—Use this
setting for connecting ground­referenced signals to the
SC-2040 (factory setting).

B-C position—Use this setting
for connecting floating (non­ground referenced) sources.
A 100 kΩ resistor is
connected from the negative
channel input to the SC-2040
analog ground.

A B C

W2

A B C

W2

The W3–W9 jumper
positions are the same
as on W2.

© National Instruments Corporation 2-5 SC-2040 User Manual

Configuration and Installation Chapter 2

Supplementary Configuration Information

Power Supply Selection

Set switch SW1 to the INT position to connect the SC-2040 power converter to the +5 V lines on
the MIO-16E board. Set switch SW1 to the EXT position to draw power from an external +5 V
power supply connected to J13.

The MIO-16E is fused to provide 5 W of power (at +5 V and 1 A). The SC-2040 consumes
nearly all of this available power. Therefore, if you have other DAQ accessories that you would
like to power from the MIO, you should switch the SC-2040 to external power and provide an
external +5 V power source. In external power mode, the SC-2040 is fuse limited to 1 A at
+5 V.

Shield Selection

If you are using a rack-mount kit, shield the SC-2040 from unwanted noise by connecting the
analog ground on the board to the metal chassis of the rack using jumper W1. When you set W1
to the SHLD ON position, the jumper connects the analog ground to the metal standoffs used to
mount the board in a rack. In the SHLD OFF position, the SC-2040 analog ground is isolated
from the metal standoffs.

DAQ Board Ground Isolation Selection

You can use jumper W10 to connect the SC-2040 digital and analog grounds. If you are using a
MIO-16E board, you must isolate the grounds by leaving the jumper in its default position.

Gain Selection

The gain selection switches can select gains of 1, 10, 100, 200, 300, 500, 600, 700, and 800 for
each channel, as shown in Table 2-6.

Table 2-6. Gain Switches for Each Channel

Channel Close Switches

0U2
1U6
2U9
3 U14
4 U17
5 U21
6 U24
7 U28

SC-2040 User Manual 2-6 © National Instruments Corporation

Chapter 2 Configuration and Installation

To close a switch, push down the number side. Closing switch A selects a gain of 500. Closing
switch B selects a gain of 200. Closing switch C selects a gain of 100. Closing switch D selects
a gain of 10. Opening all the switches selects a gain of 1. You can select other gains by closing
more than one switch, as shown in Table 2-7.

Table 2-7. Switch Settings for Gain Selection

Desired Gain Close Switches

1 None

10 D
100 C
200 B
300 B and C
500 A
600 A and C
700 A and B
800 A, B, and C

Input Mode Selection

Jumpers W2 through W9 select the input mode for each channel on the SC-2040. Position A-B
leaves the negative input of the instrumentation amplifier connected only to the front connector.
This is the factory-default setting. Position B-C connects the negative input of the
instrumentation amplifier to the board analog ground through a 100 kΩ resistor. This setting is
useful for keeping floating, or nonground-referenced, sources from saturating the instrumentation
amplifier. Table 2-8 shows the input mode jumper and channel selections.

Table 2-8. Input Mode Selection Jumpers

Channel Use Jumper

0W2
1W3
2W4
3W5
4W6
5W7
6W8
7W9

© National Instruments Corporation 2-7 SC-2040 User Manual

Configuration and Installation Chapter 2

Installation

Note: You must turn off power to the PC, and to the SC-2040 board if the board is externally

powered, before installing the board or making any connections to it.

To install the SC-2040, connect the 68-pin ribbon from the MIO-16E I/O connector to connector
J12 on the SC-2040. The SC-2040 can be mounted in a rack-mount chassis using the mounting
holes (indicated with an arrow on the board) in the four corners of the SC-2040 board.

The SC-2040 is installed. You are now ready to install and configure your software.
If you are using NI-DAQ, refer to your NI-DAQ manual. The software installation and

configuration instructions are in Chapter 1, Introduction to NI-DAQ. Find the installation and
system configuration section for your operating system and follow the instructions given there.

If you are using LabVIEW, the software installation instructions are in your LabVIEW release
notes. After you have installed LabVIEW, refer to the Configuring LabVIEW section of
Chapter 1 of your LabVIEW user manual for software configuration instructions.

If you are using LabWindows, the software installation instructions are in Part 1, Introduction to
LabWindows, of the Getting Started with LabWindows manual. After you have installed
LabWindows, refer to Chapter 1, Configuring LabWindows, of the LabWindows User Manual
for software configuration instructions.

Power-on Sequence

If the SC-2040 is powered by an external power source, you must turn on power to the SC-2040
before turning on the computer. Similarly, you must turn off power to the SC-2040 after turning
off the computer. The red LED labeled DS1 indicates when power is applied to the board.

SC-2040 User Manual 2-8 © National Instruments Corporation

Chapter 3 Signal Connections

This chapter describes the signal connections to the SC-2040 board, and cable wiring.

I/O Connector Pin Description

Warning: Connections that exceed any of the maximum ratings of input or output signals on

the MIO-16 can result in damage to the MIO-16 board and to the personal
computer. This includes connecting any power signals to ground and vice versa.
National Instruments is not liable for any damages resulting from any such signal
connections.

Corresponding signals on connectors J11 and J12 are connected together through the SC-2040.
Connector J12 carries the signals to and from the MIO-16E board. Use connector J11 to access
these signals. You can use this connector to monitor these signals, using a National Instruments
CB-50, for example, or you can use this connector to connect to other DAQ accessories.
Figure 3-1 shows these connectors.

© National Instruments Corporation 3-1 SC-2040 User Manual

Signal Connections Chapter 3

2

11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49

1

4

3

6

5

8

7

10

9

12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50

34
33

32
31
30
29
28
27
26
25

24
23

22
21
20

19
18
17
16
15
14
13
12
11
10

9
8

7
6
5

4
3
2
1

68
67
66
65
64
63

62

61

60
59
58

57
56
55
54
53

52

51
50
49
48

47
46

45
44

43
42

41
40

39
38
37
36
35

A. Breakout Connector J11

B. I/O Connector J12

Figure 3-1. SC-2040 I/O Connectors J11 and J12

Table 3-1 lists the pin assignments for the breakout connector J11 and the I/O connector J12 on
the SC-2040 and the corresponding and MIO-16E Series signal names.

SC-2040 User Manual 3-2 © National Instruments Corporation

Chapter 3 Signal Connections

Table 3-1. Pin Assignments for Connectors J11 and J12

Breakout Connector J11

Pin Numbers

1, 2 AIGND AIGND 24, 27, 29, 32, 56, 59, 64, 67

3 ACH0 ACH0 68
4 AIGND ACH8 34
5 ACH1 ACH1 33
6 AIGND ACH9 66
7 ACH2 ACH2 65
8 AIGND ACH10 31

9 ACH3 ACH3 30
10 AIGND ACH11 63
11 ACH4 ACH4 28
12 AIGND ACH12 61
13 ACH5 ACH5 60
14 AIGND ACH13 26
15 ACH6 ACH6 25
16 AIGND ACH14 58
17 ACH7 ACH7 57
18 AIGND ACH15 23
19 NC AISENSE 62
20 NC DAC0OUT 22
21 NC DAC1OUT 21
22 NC EXTREF 20
23 NC AOGND 54, 55

24, 33 DGND DGND 4, 7, 9, 12, 13, 15, 18, 35, 36, 39,

25 NC DIO0 52
26 NC DIO4 19
27 NC DIO1 17
28 NC DIO5 51
29 NC DIO2 49
30 NC DIO6 16
31 NC DIO3 47
32 NC DIO7 48

34, 35 +5V +5V 8, 14

36 NC SCANCLK 46
37 NC EXTSTROBE* 45
38 NC PFI0/TRIG1 11
39 NC PFI1/TRIG2 10
40 TRIG PFI2/CONVERT* 43
41 NC PFI3/GPCTR1_SOURCE 42
42 NC PFI4/GPCTR1_GATE 41
43 NC GPCTR1_OUT 40
44 NC PFI5/UPDATE* 6
45 NC PFI6/WFTRIG 5
46 TRACK*/HOLD PFI7/STARTSCAN 38
47 NC PFI8/GPCTR0_SOURCE 37
48 NC PFI9/GPCTR0_GATE 3
49 NC GPCTR0_OUT 2
50 NC FREQ_OUT 1

SC-2040

Signal Names

MIO-16E Series

1

Signal Names

I/O Connector J12

Pin Numbers

44, 50, 53

1

All signals labeled NC are unused by the SC-2040.

© National Instruments Corporation 3-3 SC-2040 User Manual

Signal Connections Chapter 3

Signal Connection Description

Table 3-2. Input Connectors Signal Summary

Connector Signal Name Description

J5 AIGND Analog Input Ground—These inputs provide a bias current return point

for AC-coupled signals.

J1, J2, J3, J4,
J6, J7, J8, J9

J1, J2, J3, J4,
J6, J7, J8, J9

J10, J13 DGND Digital Ground—These inputs provide the reference for all digital signals

J10 TRIG Trigger—This input, which is connected directly to the PFI2 pin on

J13 +5 V +5 VDC Source—When external power is selected, this input provides

CH+<0..7> Positive Inputs—These inputs are the positive signal inputs for

channels 0 through 7.

CH-<0..7> Negative Inputs—These inputs are the negative signal inputs for

channels 0 through 7.

and the reference for the +5 V power source.

connectors J11 and J12, is a trigger input for the MIO-16E. A low-to­high transition on TRIG alerts the MIO-16E to place the SC-2040 into
hold mode and start acquiring data.

DC power for the SC-2040 from an external +5 V. The SC-2040 fuses
the input to 1 A of the +5 V supply.

Table 3-3. Output Connectors (J11 and J12) Signal Summary

J11 Pin
(50-pin)

1, 2, 4, 6, 8,
10, 12, 14, 16,
18

3, 5, 7, 9, 11,
13, 15, 17

24, 33 4, 7, 9, 12, 13,

34, 35 8, 14 +5 V +5 VDC Source—When internal power is selected,

40 43 TRIG (PFI2) Trigger—This pin, which is connected directly to the

J12 Pin
(68-pin)

23, 24, 26, 27,
29, 31, 32, 34,
56, 58, 59, 61,
63, 64, 66, 67

68, 33, 65, 30,
28, 60, 25, 57

15, 18, 35, 36,
39, 44, 50, 53

Signal Name Description

AIGND Analog Input Ground—These pins establish the

reference point for the SC-2040 outputs (ACH<0..7>).
They are also connected directly to the AIGND input
connector J5 for use with AC-coupled signals.

ACH<0..7> Analog Channels 0 through 7—These pins carry the

outputs of the SC-2040 eight channels to the DAQ
board. They are referenced to AIGND.

DGND Digital Ground—These pins are the reference for the

+5 V power source and for the digital signals used by
the SC-2040: TRIG (PFI2) and TRACK*/HOLD
(PFI7/STARTSCAN).

these pins provide DC power for the SC-2040 from
the MIO-16E board. The MIO-16E pins are fused to
1 A of +5 V supply.

TRIG input on screw terminal connector J10, is a
trigger input to the MIO-16E PFI2 line. A low-to­high transition on PFI2 alerts the MIO-16E to place
the SC-2040 into hold mode and start acquiring data.

(continues)

SC-2040 User Manual 3-4 © National Instruments Corporation

Chapter 3 Signal Connections

Table 3-3. Output Connectors (J11 and J12) Signal Summary (Continued)

J11 Pin
(50-pin)

46 38 TRACK*/HOLD

others others compatibility The remaining pins provide 50 pin compatibility with

J12 Pin
(68-pin)

Signal Name Description

Track-or-hold—This pin, used as an output from the

(PFI7/STARTSCAN)

MIO-16E, controls whether the SC-2040 is in hold
mode or track mode. A high level output from the
DAQ board places the SC-2040 into hold mode, while
a low level returns the SC-2040 into track mode. With

an MIO-16E attached, pin 46 on J11 should be used
for monitoring purposes only.

the 68 pin MIO-16E. They can be monitored from
connector J11. Refer to Figure 3-1 for pin locations
and to Chapter 3, Signal Connections, in your MIO­16E manual for pin descriptions.

The signals from the SC-2040 screw terminal connectors are connected to the MIO-16E via J12
as shown in Figure 3-2. Observe that the PFI7/STARTSCAN signal returns from the MIO-16E
as a level-sensitive track-and-hold signal to the SC-2040. Notice also that AISENSE is
disconnected.

© National Instruments Corporation 3-5 SC-2040 User Manual

Signal Connections Chapter 3

J5

J1

J2

J9

SC-2040
Input Signals

AIGND

CH0+
CH0-

CH1+
CH1-

.
.
.
.
.
.

CH7
CH7

T/H

T/H

T/H

Signals Sent
to MIO-16

AIGND
AISENSE

ACH0

ACH1

.
.
.
.
.
.
.
.

ACH7

J10

TRIG
DGND

SC-2040
Screw Terminals

Track*/Hold

Figure 3-2. SC-2040 Signal Routing

PFI2/
STARTSCAN

PFI7
DGND
J11 and J12

Connectors on SC-2040

SC-2040 User Manual 3-6 © National Instruments Corporation

Chapter 3 Signal Connections

Analog Signal Inputs

Connect the differential signals to be measured to the screw terminal connectors J1 through J4
and J5 through J9.

DC-Coupled Inputs
Note: If all your inputs are DC-coupled, leave connector J5 disconnected.

All eight channels have fully differential inputs, so the signals you are measuring should be
ground referenced. If they are not, set jumpers W2 through W9 of the nonreferenced channels to
position B-C to create a DC path for the input bias currents. If you do not do this, the bias
currents of the instrumentation amplifiers of the nonreferenced channels produce stray
capacitances, resulting in uncontrollable drift and possible saturation.

Figure 3-3 illustrates how to connect a ground-referenced signal.

CH+

IN+

Vin

CH-

A B C

100 kΩ

A

IN-

SC-2040

Figure 3-3. Ground-Referenced Signal Connection

© National Instruments Corporation 3-7 SC-2040 User Manual

Signal Connections Chapter 3

Figure 3-4 illustrates how to connect a floating signal.

CH+

IN+

Vin

CH-

A B C

100 kΩ

A

IN-

SC-2040

Figure 3-4. Floating Signal Connection

AC-Coupled Signals
Note: For AC-coupled signals, you must reference the analog ground of your

instrumentation to the DAQ board. The SC-2040 connector J5 provides the analog
reference, connecting directly to the MIO-16E board as shown in Figure 3-2.

For AC-coupled signals, set jumpers W2 through W9 to position B-C with an external resistor
from the positive input channel connected to its negative ground. Doing this creates the DC path
for the positive input bias current. Typical resistor values range from 100 kΩ to 10 MΩ. This
solution, although necessary in this case, lowers the input impedance of the channel and
introduces an additional offset voltage proportional to the product of the input bias current and
the resistor value used. The inputs of the SC-2040 have a typical bias current of about ±100 pA.
When you use a 1 MΩ resistor, the result is ±100 µV of offset, which is insignificant in most
applications. However, if you use larger valued bias resistors, significant input offset may result.
Lower valued bias resistors will increase loading of the source, possibly resulting in gain error.

SC-2040 User Manual 3-8 © National Instruments Corporation

Chapter 3 Signal Connections

Figures 3-5 through 3-7 illustrate how to connect AC-coupled signals.

CH+

IN+

Vin

CH-

A B C

100 kΩ

A

IN-

SC-2040

Figure 3-5. Ground-Referenced AC-Coupled Signal Connection

CH+

IN+

Vin

CH-

A B C

IN-

Analog

GND

100 kΩ

A

SC-2040

A

Figure 3-6. Ground-Offset AC-Coupled Signal Connection

© National Instruments Corporation 3-9 SC-2040 User Manual

Signal Connections Chapter 3

CH+

IN+

Vin

CH-

A B C

100 kΩ

IN-

SC-2040

A

Figure 3-7. Floating AC-Coupled Signal Connection

Analog Input Ranges

Warning: Exceeding the differential and common-mode input ranges results in distorted

input signals. Exceeding the maximum input voltage rating can result in damage
to the SC-2040 board, and the DAQ board. National Instruments is

NOT liable for

any damages resulting from such signal connections.

The SC-2040 instrumentation amplifiers can reject any voltage within their common-mode input
range caused by ground-potential differences between the signal source and the board. In
addition, the amplifiers can reject common-mode noise pickup in the leads connecting the signal
sources to the SC-2040 board. However, you should be careful to minimize noise pickup. The
common-mode rejection of the instrumentation amplifiers decreases significantly at high
frequencies. The amplifiers do not reject normal-mode noise.

The common-mode input range of the SC-2040 instrumentation amplifiers is defined as the
magnitude of the greatest common-mode signal that can be rejected. Thus the common-mode
input range for the SC-2040 depends on the gain and size of the differential input signal:

(V

diff

= V

+

in

- V

-

).

in

The exact formula for the permissible common-mode input range is as follows:

diff

V

cm-allowed

= ± (12 V -

Thus, with a differential voltage of 10 V and a gain of G

G V

).

2

= 1, the maximum possible common-

mode voltage would be ±7 V. The same range would apply for a differential input of 100 mV
and a gain of 100. The range increases to ±12 V for zero differential input voltage. The actual
common-mode voltage available at the input is measured with respect to the SC-2040 ground,
and can be calculated by the following formula:

+

V

V

cm-actual

SC-2040 User Manual 3-10 © National Instruments Corporation

()

=

−

in

−V

in

2

.

Chapter 3 Signal Connections

where V

+

is the signal at the positive input (IN0+ through IN7+), and V

n

i

corresponding negative input (IN0- through IN7-). Both V

+

i

and V

n

-

is the signal at the

n

i

-

are measured with respect

n

i

to the SC-2040 chassis ground.

Digital Signal Inputs

If you are using an external trigger, connect the trigger source and the digital reference to screw
connector J9. This signal should be in the range 0 to +5 V, with switching occurring around

1.5 V.

Note: All digital signals on the SC-2040 are referenced to the +5 V power supply. If the

MIO-16E supplies power, it provides this reference. If an external supply provides
power, it provides this reference through connector J13.

A rising edge on the trigger will place the SC-2040 into hold mode, and the SC-2040 will return
to track mode when the MIO-16E indicates that the data acquisition is complete.

Although the TRIG signal is a digital signal, it is still susceptible to noise, particularly at its
transitions. This noise can cause the SC-2040 to enter hold mode on the wrong edge. Two
possible sources of noise are interference and reflection. The best way to reduce noise
corruption is to minimize the distance that the signal must travel. Furthermore, you can
minimize interference by properly shielding the incoming trigger signal. You can minimize
reflection by ensuring that the impedance of the source of the trigger signal matches the
impedance of the cable used to transmit the signal; inserting a small resistor (about 50 Ω) in
series with the signal source will minimize reflection.

Monitoring Signal Outputs

You can use connector J11 to monitor the signals being sent to and from the MIO-16E board.
Figure 4-3 shows a sampled analog signal as the SC-2040 channel output.

You can also monitor the state of the SC-2040 through line PFI7/STARTSCAN. A high level on
PFI7/STARTSCAN indicates the SC-2040 is in hold mode, while a low level indicates that the
SC-2040 is in track mode.

Other Connection Considerations

Refer to the sections titled Analog Input Signal Connections and Cabling and Field Wiring in
Chapter 3 of your MIO-16E board user manual for additional signal connection information.

© National Instruments Corporation 3-11 SC-2040 User Manual

Chapter 4 Theory of Operation

This chapter contains a functional overview of the SC-2040 board and explains the operation of
each functional unit making up the SC-2040.

Functional Overview

The SC-2040 consists of eight channels, each one comprising an instrumentation amplifier with
DIP switch-programmable gains of 1, 10, 100, 200, 300, 500, 600, 700, or 800, and a track-and­hold amplifier. The analog inputs are overvoltage protected. The DAQ board or a user-supplied
external trigger switches the SC-2040 between hold mode and track mode as desired. All eight
channels are simultaneously placed in hold mode.

The block diagram in Figure 4-1 illustrates the key functional components of the SC-2040.

© National Instruments Corporation 4-1 SC-2040 User Manual

Theory of Operation Chapter 4

68-Pin I/O Connector

50-Pin Breakout Connector

PFI7

ACH0

ACH7

PFI2

(Track/Hold Signal)

+5 V

Power-On

LED

External

+5 V

T/H

Inst.

Amp

+

Input

Protection

CH0+

• • • • •

• • •

Gains

-

• • •

A

• • •

CH0-

T/H

Inst.

Amp

+

Input

Protection

CH7+

-

CH7-

Gains

Power

Converter

+15 V

-15 V

(External Trigger)

A

External

Track/Hold

Trigger

Figure 4-1. SC-2040 Block Diagram

SC-2040 User Manual 4-2 © National Instruments Corporation

Chapter 4 Theory of Operation

Analog Circuitry

The analog input circuitry consists of eight channels with DIP-switch-programmable
instrumentation amplifiers followed by buffered track-and-hold amplifiers. In addition, you can
include the voltage-regulation circuitry and input protection in the analog section. Each block is
described in the following paragraphs.

Input Protection

The first block an incoming analog signal encounters is the input protection. Each input terminal
is protected against input voltages up to ±15 V powered off and ±30 V powered on. The input
protection consists of a 1 kΩ resistor in series with each input line followed by low-leakage
diodes to the supply rails (±15 V).

Amplification

Next in the signal path are the instrumentation amplifiers, which fulfill two purposes on the
SC-2040 board. First, the instrumentation amplifiers convert differential input signals into
single-ended signals referred to the SC-2040 analog ground for input common-mode signal
rejection. With this conversion, the SC-2040 can extract the analog input signals from common­mode noise voltages before the DAQ board samples and converts the signals. Second, the
instrumentation amplifiers amplify input signals, resulting in an increase in measurement
resolution and accuracy. Furthermore, the amplifiers exhibit low bias currents and good
bandwidth, even at high gains.

You can select gains for each channel independently with separate DIP switches. Gains are 1,
10, 100, 200, and 500, although gains of 300, 600, 700, and 800 are available with reduced
accuracy. See Appendix A, Specifications, for details on the performance of the instrumentation
amplifiers.

Track-and-Hold (T/H) Circuitry

The track-and-hold amplifiers operate as simple buffers when in track mode, but freeze their
outputs when placed into hold mode. Because all of the track-and-hold amplifiers in each
SC-2040 board enter hold mode at the same time, they implement simultaneous sampling of all
channels. Simultaneous sampling is useful for preserving phase relationships between channels.

The track-and-hold amplifiers are subject to various imperfections, which are listed in
Appendix A, Specifications. The most relevant of these performance specifications are the track­mode acquisition time and the hold-mode settling time, as these parameters affect how the DAQ
board acquires the data, most noticeably through the sampling rate.

The hold-mode settling time refers to how long it takes the T/H amplifiers to settle a stable value.
Thus, the hold-mode settling time affects how long the DAQ board must wait before attempting
to acquire data. The track-mode acquisition time refers to how long it takes the T/H amplifiers to

© National Instruments Corporation 4-3 SC-2040 User Manual

Theory of Operation Chapter 4

find the inputs again after having been in hold mode. Therefore, this delay indicates how long
the SC-2040 must remain in track mode before it is ready to re-enter hold mode. Returning the
SC-2040 to hold mode before the track-mode acquisition delay has elapsed will cause the
SC-2040 to "hold" erroneously. Figure 4-2 illustrates these timing concerns. Typical hold mode
settling times and track acquisition times for 12-bit and 16-bit accuracies are given in
Appendix A, Specifications.

differential channel

input

T/H output

hold setting time

hold

track*/hold signal
(PF17)

track

hold setting
time

hold

track acquisition
time

track

Figure 4-2. T/H Amplifier Hold Settling Time and Track Acquisition Time

Triggering from the DAQ Board

This section applies to you only if you are triggering the SC-2040 from the MIO-16E board.

Note: No signal should be connected to connector J10 for MIO-16E triggering.

You can place the SC-2040 into hold mode on command using the MIO-16E DAQ board. You
must either program the MIO-16E board for this purpose or use the NI-DAQ software included
with your MIO board. After placing the SC-2040 into hold mode, the MIO-16E board performs
data acquisition and conversion. Once this process is complete, the MIO-16E board releases the
SC-2040 into track mode.

The MIO-16E board uses line PFI7/STARTSCAN to indicate to the SC-2040 whether it should
track the input signals or hold them at a constant level. A logic zero (low level) on
PFI7/STARTSCAN indicates track mode, while a logic one (high level) indicates hold mode, as
indicated in Figure 4-3.

SC-2040 User Manual 4-4 © National Instruments Corporation

Chapter 4 Theory of Operation

Differential Channel Input

. . . . . . . . .

PFI7 (track*/hold)

. . . . . .

SC-2040 Channel Output

. . . . . .

hold hold track

. . . . . .

. . . . . .

. . . . . . . .

. . . . . .

. . . . . . . . . . .

t

DAQ Conversion

(DAQ board is scanning)

t

DAQ Conversion

Figure 4-3. MIO-16E Controlled Triggering

External Triggering

This section applies to you only if you are triggering the board from an external signal
connected to J10.

You can connect an external trigger to place the SC-2040 into hold mode on command. A rising
edge on the external trigger signal places the SC-2040 into hold mode and alerts the MIO-16E
board to start scanning the SC-2040 outputs. After the MIO-16E board has acquired data from
all of the channels, it returns the SC-2040 to track mode. The external trigger signal is a digital
input and must conform to digital logic levels.

Because the SC-2040 track-and-hold circuitry must re-acquire the input signals at the conclusion
of each hold mode operation, the external trigger source should not return the SC-2040 to hold
mode until after the SC-2040 has had time to re-acquire the signals. The acquisition times for
the SC-2040 at various accuracies are given in Appendix A, Specifications.

The external trigger is connected directly to signal PFI2 on the DAQ board. A rising edge alerts
the DAQ board to place the SC-2040 into hold mode. The DAQ board then begins scanning the
channels. After the scanning process is complete, the board returns the SC-2040 to track mode
using PFI7/STARTSCAN. Notice that additional rising edges from the external trigger are
ignored while the MIO-16E is scanning. Figure 4-4 illustrates the external triggering process.

© National Instruments Corporation 4-5 SC-2040 User Manual

Theory of Operation Chapter 4

Differential Channel Input

. . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . .

PFI2 (external trigger)

. . . . .

. . . . . . . . . . . .

. . . .

PFI7 (track*/hold)

SC-2040 Channel Output

hold hold

track

. . . . . .

track

. . . . .

. . . . . . . .

t

DAQ Conversion

(DAQ board is scanning)

t

DAQ Conversion

Figure 4-4. External Triggering

Output Connection

The output of every channel is connected to the 68-pin rear signal connector and the 50-pin
supplemental I/O connector. The 68-pin connector carries signals to and from the DAQ board,
and also provides +5 V power if selected by the power switch. The corresponding pins of the
50-pin connector are tied to those of the 68-pin connector so that you can monitor these signals
on the 50-pin connector. The pin connections of these connectors are given in Chapter 3, Signal

Connections.

Power Supply

The SC-2040 contains an onboard power switch to either power the SC-2040 from the MIO-16E
board or to draw power from an external +5 V supply. From the +5 V power, an onboard
DC-to-DC converter generates a ±15 V source, which is used to power the analog circuitry. A
red LED indicates that the board is receiving power.

SC-2040 User Manual 4-6 © National Instruments Corporation

Chapter 5 Calibration Procedures

This chapter discusses the calibration procedures for the SC-2040 board.

Note: In many applications, the SC-2040 factory-hardware calibration is sufficient to meet

accuracy requirements, and no further calibration, either hardware or software, is
needed.

Although hardware calibration is discussed in greater detail than software calibration, software
calibration is the preferred choice for the following reasons:

• The calibration adjustments on the SC-2040 are inaccessible under most normal operating
circumstances.

• With software calibration, the board is calibrated in the exact environment in which it will be
operating. Software calibration compensates for system-introduced, in addition to board­introduced, errors. You can perform software calibration fairly frequently, which helps
reduce drift effects.

Because board-introduced errors are minimal with the SC-2040, the use of software rather than
hardware calibration does not significantly reduce dynamic range. The main drawback of
software calibration is reduced throughput due to the increased processing time.

Software Calibration

Software calibration is very simple. Depending on your accuracy requirements, you may want to
perform only offset adjustment; offset and gain adjustments; or offset, gain, and linearity
adjustments.

Offset Adjustment

Offset adjustment requires you to apply an input signal of zero to the channel to be calibrated.
Zero input can mean shorting the board inputs to zero, or it can mean applying zero excitation to
the transducer being used. In the former case, you can remove only board and DAQ board
offset; in the latter case, transducer offset is removed as well. In either case, measurements are
taken with the zero input signal. Average these measurements to reduce uncertainty. This
average represents the offset. Next, subtract the offset from all subsequent measurements.
Notice that offset changes with gain; thus, during calibration, set the channel to the gain at which
the subsequent measurements will be taken.

© National Instruments Corporation 5-1 SC-2040 User Manual

Calibration Procedures Chapter 5

Gain Adjustment

Gain adjustment requires you to apply two different input signals. One of the two points is
typically zero, because zero is easy to generate with a high degree of accuracy. The other should
be near full scale, either a DC-voltage from a precision calibrator or a voltage generated by
applying a known excitation to the transducer being used. Of course, you should generate both
signals—zero and full scale—from the same source.

Take measurements on both signals and compute separate averages. Then combine the averages
with the known input signals to generate linear correction factors for all subsequent
measurements. Specifically, if the input X yields measurement x, and the input Y yields
measurement y, then you should process measurement z as shown in the following equation to
yield the corrected measurement Z:

Z = X +

(Y − X)(z− x)

(y − x)

.

Linearity Adjustment

The SC-2040 seldom needs linearity adjustment because its linearity is quite good, especially at
low gains. Linearity error is often caused by the nonlinearity of the DAQ board you use. If
necessary, the method described previously for correcting gain and offset error may be extended
to include linearity by taking more points along the transfer function and processing the
subsequently acquired data according to a polynomial fit of the calibration points.

Alternatively, and preferably for DAQ boards with no more than 12 bits of resolution, you can
determine the nonlinearity of the system on a code-by-code basis, and you can subtract the error
of each code from any measurement that returns that value. This method has the advantage of
correcting differential as well as integral linearity errors. However, this method may be time­consuming. If time permits, you may determine the nonlinearity of your system on a code-by­code basis with even higher resolution DAQ boards. Describing methods of measuring system
nonlinearity is beyond the scope of this manual. If linearity correction becomes necessary, refer
to your DAQ board user manual.

Hardware Calibration

There are two potentiometers (pots) to adjust for each channel. These are set at the factory and
should not need to be readjusted for most applications. The pots adjust input offset voltage and
output offset voltage for each of the eight channels. Gain error and linearity are not adjustable.
For detailed specifications of offset, gain, and linearity error, see Appendix A, Specifications.

Input offset is any error voltage that appears to be added to the input signal; that is, its effect is
multiplied by the gain of the instrumentation amplifier. Output offset is any error voltage that
appears to be added to the output signal; that is, its effect is independent of the gain of the
instrumentation amplifier. At a fixed gain, these errors are indistinguishable; thus, it is necessary
to switch between gains to properly calibrate the SC-2040.

SC-2040 User Manual 5-2 © National Instruments Corporation

Chapter 5 Calibration Procedures

Your accuracy needs determine how carefully the offsets need to be calibrated. A typical
requirement might be for total offset referred to output to be less than half of an LSB of the DAQ

board being used. For example, a 12-bit, 20 V system has a resolution of 20 V/212 = 4.88 mV.
Calibration to under 2 mV would thus be sufficient for most applications. The SC-2040 is
factory calibrated to have total offset referred to output of less than 2 mV at low gains.

Table 5-1 shows which pots to adjust for each type of offset for each channel and which DIP
switch selects the gain for each channel. Refer to the parts locator diagram in Chapter 2,
Configuration and Installation, to determine the location of each component.

Table 5-1. Calibration Component Identification

Channel Output Offset Adjust Input Offset Adjust Gain DIP Switch

0R1 R4 U2
1 R7 R11 U6
2 R13 R16 U9
3 R18 R22 U14
4 R25 R29 U17
5 R32 R35 U21
6 R37 R41 U24
7 R45 R48 U28

A complicating factor in the calibration of the board is that the output offset is not the same in
track mode as in hold mode. This difference is because of a phenomenon known as hold step, in
which a small amount of charge is transferred to the track-and-hold amplifier hold capacitor
during the transition from track mode to hold mode. This charge transfer slightly changes the
voltage at the output of the track-and-hold amplifier.

The magnitude of the hold step on the SC-2040 is approximately 5 mV, enough to make it
necessary to calibrate output offset in hold mode rather than track mode. You may calibrate
input offset without switching the board to hold mode.

To calibrate the SC-2040 board, the following steps are required:

1. If you are using a rack-mount kit, remove the cover to expose the DIO switches and jumpers.
Connect the board so that the pots and DIP switches are readily accessible.

2. Short each input of the board to ground.
At low gains, more alternatives exist to serve as a short circuit, but at a gain of 500, 1 mV

referred to the output is only 2 µV referred to the input. Thermoelectric effects make it
difficult to keep a short circuit from generating such voltages. The best solution is to use
short lengths of heavy copper wire, and to keep the short away from heat sources.

3. Program the DAQ board to take data in the differential input mode.
The SC-2040 should switch between track mode and hold mode, with the DAQ board

sampling occurring while the board is in hold mode.

© National Instruments Corporation 5-3 SC-2040 User Manual

Calibration Procedures Chapter 5

4. Set the DAQ board to a high gain and measure its offset by shorting its input.
You must subtract this measured offset from all subsequent board measurements to ensure

accuracy.
For the offset of the DAQ board not to affect the calibration, you must subtract the offset

from all board offset measurements. Thus, you must first measure the offset to an accuracy
better than that to which the board is to be calibrated. Furthermore, setting the DAQ board to
a high gain (100, for example) makes it possible to resolve offset changes that would be
indiscernible at lower gains. Because the DAQ board offset will not be independent of gain,
you should set the gain first, and then measure the offset. To measure the offset, disconnect
the board from the DAQ board, short circuit the board inputs to ground, and take some data.
The measured value is the offset. For a reliable value, use software to average a few hundred
readings. After you have measured and recorded the offset, remove the short circuits and
reconnect the board.

5. Measure the output of the first channel with its gain set to one and adjust its output offset pot
until the output is close to zero.

At this gain, most of the board offset is due to output offset. The input offset adjustment has
minimal effect. Set the DAQ board to read the channel. Acquire the data, averaging as in
step 4. Adjust the output offset pot until the difference between the measured offset and the
DAQ board offset is close to zero. There is no need to adjust it perfectly because the input
offset adjustment in the next step might make a slight change in the measured gain-of-one
offset.

6. Measure the output of the same channel with its gain set to 500 and adjust its input offset pot
until the output is close to zero.

At this gain, the input offset adjustment has the dominant effect. Acquire the data and
average as before. Adjust the input offset pot until the difference between the measured
offset and the DAQ board offset is close to zero. Again, it is not necessary to adjust the input
offset perfectly because there will be a slight interdependence between the two offsets.

7. Repeat step 5, adjusting the offset as carefully as desired. Then repeat step 6, adjusting the
offset as carefully as desired. Switch back to a gain of one to ensure that the low-gain offset
is still calibrated. If necessary, repeat steps 5 and 6 until the offset is calibrated at both gains.

8. Repeat steps 5 through 7 for the additional channels you want to calibrate. There is no
calibration interdependence among the channels.

9. Replace the rack-mount chassis cover, if used.

SC-2040 User Manual 5-4 © National Instruments Corporation

Appendix A Specifications

This appendix lists the specifications for the SC-2040. These are typical at 25° C unless otherwise stated. The
operating temperature range is 0° to 50° C.

Analog Input

Input Characteristics

Number of channels 8 differential

Input signal ranges Board Gain

(Hardware

Selectable)

1 ±10 V

10 ±1 V
100 ±100 mV
200 ±50 mV
300 ±33.3 mV
500 ±20 mV
600 ±16.67 mV
700 ±14.29 mV
800 ±12.5 mV

Input coupling DC
Max working voltage

(signal + common mode) Average of 2 inputs should remain within ±7 V of ground

Overvoltage protection ±30 V powered on, ±15 V powered off

Inputs protected ACH<0..7>

Board Range

Max Output Range ±10 V

Transfer Characteristics

Offset error

Pregain error after calibration ±100 µV max
Postgain error after calibration ±2 mV max

Gain error and nonlinearity Gain

(DIP-switch-

selectable)

1 ±0.05% ±25 ppm/°C ±0.01%
10 ±0.1% ±25 ppm/°C ±0.01%
100 ±0.2% ±45 ppm/°C ±0.02%
200 ±0.4% ±60 ppm/°C ±0.02%
300 -0.3%, ±0.6% ±80 ppm/°C ±0.03%
500 ±1.0% ±100 ppm/°C ±0.04%
600 -0.2%, ±1.5% ±120 ppm/°C ±0.05%
700 -0.1%, ±2.0% ±150 ppm/°C ±0.06%
800 -0.3%, ±3.0% ±200 ppm/°C ±0.07%

Max

Gain Error

Max

Gain Tempco

Max

Nonlinearity

© National Instruments Corporation A-1 SC-2040 User Manual

Specifications Appendix A

Amplifier Characteristics

Input impedance

Normal powered on 100 GΩ in parallel with 20 pF
Input bias current ±100 pA, ±10 mA max
Input offset current ±10 pA

CMRR Gain dB (min and typ)

Gain = 1 70 dB min, 90 dB typ
Gain = 10 87 dB min, 104 dB typ
Gain ≥ 100 100 dB min, 110 dB typ

Output range ±10 V

Dynamic Characteristics

Bandwidth Gain -3 dB

Bandwidth

1

10 800 kHz
100 500 kHz
200 300 kHz
300 180 kHz
500 120 kHz
600 100 kHz
700 80 kHz
800 70 kHz

2 MHz

System noise Gain Filter

1 175 µVrms

10 50 µVrms
100 45 µVrms
200 40 µVrms
300 35 µVrms
500 33 µVrms
600 30 µVrms
700 29 µVrms
800 27 µVrms

Noise spectral density

Input noise (gain = 1) 12 nV/√Hz
Output noise 85 nV/√Hz
Slew rate 8 V/µs

SC-2040 User Manual A-2 © National Instruments Corporation

Appendix A Specifications

S/H Characteristics

Measurement 0.012% 0.003% 0.0015% 0.00076%

Track mode
acquisition
time

Hold mode
settling time

Hold step -5 mV — — —
Droop rate ±10 mV/s — — —
Aperture time 250 ns — — —
Interchannel

skew

7 µs 10 µs 50 µs 1 ms

1 µs1 µs1 µs2 µs

±50 ns — — —

Stability

Recommended warm-up time 15 min
Offset temperature coefficient ±(10 + 150/gain) µV/°C

Gain temperature coefficient Gain

(DIP-switch-

selectable)

1 ±25 ppm/°C
10 ±25 ppm/°C
100 ±45 ppm/°C
200 ±60 ppm/°C
300 ±80 ppm/°C
500 ±100 ppm/°C
600 ±120 ppm/°C
700 ±150 ppm/°C
800 ±200 ppm/°C

Max

Gain Tempco

Power Requirement

+5 VDC (±10 %) 800 mA
Total power dissipation 4 W

Physical

Dimensions 1.8 by 7.9 by 4.9 in. (4.6 by 20.1 by 12.4 cm)
I/O connectors

Input 20-screw terminals
Output 50-pin male ribbon-cable rear connector

68-pin male ribbon-cable rear connector

Environment

Operating temperature 0° to 50° C
Storage temperature -55° to 150° C
Relative humidity 5% to 90% noncondensing

© National Instruments Corporation A-3 SC-2040 User Manual

Appendix B 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

[phone]
Technical support fax: [phone]

[phone]

Branch Offices Phone Number Fax Number

Australia [phone] (03) 879 9179
Austria [phone] (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 [phone] (03) 3788-1923
Netherlands 03480-33466 03480-30673
Norway 32-848400 32-848600
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
U.K. 0635 523545 0635 523154

© National Instruments Corporation B-1 SC-2040 User Manual

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

SC-2040 Hardware and Software
Configuration Form

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

National Instruments Products

• DAQ Hardware Revision __________________________________________________

• Interrupt Level of Hardware __________________________________________________

• DMA Channels of Hardware

• Base I/O Address of Hardware __________________________________________________

• NI-DAQ Version __________________________________________________

Other Products

• Computer Make and Model __________________________________________________

• Microprocessor __________________________________________________

• Clock Frequency __________________________________________________

• Type of Video Board Installed

• Operating System __________________________________________________

• Operating System Version __________________________________________________

• Operating System Mode __________________________________________________

• Programming Language __________________________________________________

• Programming Language Version __________________________________________________

• Other Boards in System __________________________________________________

• Base I/O Address of Other Boards __________________________________________________

• DMA Channels of Other Boards __________________________________________________

• Interrupt Level of Other Boards __________________________________________________

Documentation Comment Form

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

Title: SC-2040 User Manual
Edition Date: September 1994
Part Number: 371191A-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 [phone]

Glossary

___________________________________________________

Prefix Meaning Value

p- pico­n- nano­µ- micro-

m- milli-

k- kilo-

M- mega-

10

10
10
10

-12

10
10

˚ degrees

Ω ohms
A amperes
ACH# DAQ board analog input channel number
A/D analog-to-digital
Arms amperes, root mean square
AWG American Wire Gauge
C Celsius
CH#+ module positive input channel number
CH#- module negative input channel number
CMOS complementary metallic oxide semiconductor
cps counts per second
D/A digital-to-analog
DAQ data acquisition
dB decibels
DC direct current
DIN Deutsche Industrie Norme
DIP dual inline package
FIFO first-in-first-out
hex hexadecimal
Hz hertz
in. inches
I

I

I

in

I/O input/output
I

out

LED light-emitting diode
LSB least significant bit
m meters
MB megabytes
MSB most significant bit
ppm parts per million

input current leakage
input current

output current

-9

-6

-3

3
6

© National Instruments Corporation Glossary-1 SC-2040 User Manual

Glossary

RAM random-access memory
rms root mean square
s seconds
SPI serial peripheral interface
tempco temperature coefficient
T/H track-and-hold
UL Underwriters Laboratory
V volts
VI virtual instrument
V

IH

IL volts input low

V
V

in

V

OH

V

OL

V

out

volts input high

volts in
volts output high
volts output low
volts out

VAC volts alternating current
VDC volts direct current
Vrms volts, root mean square

SC-2040 User Manual Glossary-2 © National Instruments Corporation

Index

Numbers/Symbols

+5 V signal

input connector summary (table), 3-4
output connector summary (table), 3-4

to 3-5

A

AC-coupled inputs, 3-8 to 3-11

common-mode input range, 3-10 to 3-11
exceeding differential and

common-mode ranges (warning), 3-10

floating AC-coupled signal connection

(illustration), 3-8

ground-offset AC-coupled signal

connection (illustration), 3-9

ground-referenced AC-coupled signal

connection (illustration), 3-9

referencing analog ground to DAQ

board (note), 3-8
AIGND-AIGND position (table), 2-4
AIGND-DGND position (table), 2-4
AIGND signal

input connector summary (table), 3-4
output connector summary (table), 3-4

to 3-5
analog circuitry, 4-2 to 4-6

amplification, 4-3
external triggering, 4-5 to 4-6
input protection, 4-3
output connection, 4-6
power supply, 4-6
track-and-hold (T/H) circuitry, 4-3 to 4-4
triggering from DAQ board, 4-4 to 4-5

analog input specifications

amplifier characteristics, A-2
dynamic characteristics, A-2
input characteristics, A-1
S/H characteristics, A-3
stability, A-3
transfer characteristics, A-1

analog signal inputs, 3-7 to 3-11

AC-coupled inputs, 3-8 to 3-11

common-mode input range, 3-10

to 3-11

exceeding differential and

common-mode ranges
(warning), 3-10

floating AC-coupled signal

connection (illustration), 3-10

ground-offset AC-coupled signal

connection (illustration), 3-9

ground-referenced AC-coupled

signal connection (illustration), 3-9

referencing analog ground to DAQ

board (note), 3-8
analog input ranges, 3-10 to 3-11
DC-coupled inputs, 3-7 to 3-8

floating signal connection

(illustration), 3-8

ground-referenced signal connection

(illustration), 3-7

leaving connector J5 disconnected

(note), 3-7

B

block diagram of SC-2040, 4-2
board configuration. See configuration.

C

calibration procedures

hardware calibration, 5-2 to 5-4

calibration component identification

(table), 5-3

steps for, 5-3 to 5-4
overview, 5-1
software calibration

gain adjustment, 5-2

linearity adjustment, 5-2

offset adjustment, 5-1

CH-(0..7) signal (table), 3-3
channel gain selection

gain switches for each channel

(table), 2-6

© National Instruments Corporation Index-1 SC-2040 User Manual

Index

procedure for, 2-6 to 2-7
switch settings (table), 2-7

table, 2-5
channel input mode (table), 2-5
CH+(0..7) signal (table), 3-4
common-mode input range, 3-10 to 3-11
configuration

channel gain selection

gain switches for each channel

(table), 2-6
procedure for, 2-6 to 2-7
switch settings (table), 2-7
table, 2-5

channel input mode (table), 2-5
DAQ board ground isolation selection

procedure for, 2-6
table, 2-4

input mode selection, 2-7
parts locator diagram, 2-2
power supply selection

procedure for, 2-6
table, 2-3

shield selection

procedure for, 2-4
table, 2-4

connectors J11 and J12

overview, 3-1
pin assignments (illustration), 3-2

(table), 3-3

signal routing (illustration), 3-6
signal summary (table), 3-4

customer communication, xi, B-1

output connector summary (table), 3-4

to 3-5
digital signal inputs, 3-9
documentation

conventions used in manual, x
National Instruments documentation

set, x

organization of manual, ix
related documentation, xi

E

environment specifications, A-3
equipment, optional, 1-4
EXT switch position (table), 2-3

F

floating AC-coupled signal connection

(illustration), 3-10

floating signal connection (illustration), 3-8

G

gain selection. See channel gain selection.
ground-offset AC-coupled signal connection

(illustration), 3-9

ground-referenced AC-coupled signal

connection (illustration), 3-9

ground-referenced signal connection

(illustration), 3-7

D

H

DAQ board ground isolation selection

procedure for, 2-6
table, 2-4

DC-coupled inputs, 3-7 to 3-8

floating signal connection

(illustration), 3-8

ground-referenced signal connection

(illustration), 3-7

leaving connector J5 disconnected

(note), 3-7

DGND signal

input connector summary (table), 3-4

SC-2040 User Manual Index-2 © National Instruments Corporation

hardware calibration.

See calibration procedures.

hold-mode settling time, 4-3

I

input connectors signal summary (table), 3-4
input mode selection, 2-7
installation

power-on sequence, 2-8
steps for, 2-8

Index

unpacking the SC-2040, 1-4
instrumentation amplifiers, 4-3
INT switch position (table), 2-3

J

J11 and J12 connectors. See connectors J11

and J12.

jumpers and switches. See configuration.

L

LabVIEW and LabWindows application

software, 1-2

M

manual. See documentation.
MIO-16E DAQ board, triggering, 4-4 to 4-5
monitoring signal inputs, 3-11

O

operation of SC-2040. See theory

of operation.
output connection, 4-6
output connectors (J11 and J12) signal

summary (table), 3-4 to 3-5

P

parts locator diagram, 2-2
physical specifications, A-3
pin assignments for SC-2040 I/O connectors

J11 and J12 (table), 3-3
power-on sequence, 2-8
power supply

description, 4-6
selecting

procedure for, 2-6
table, 2-3

specifications, A-3

R

register-level programming, 1-4

S

SC-2040

block diagram, 4-2
features, 1-1
I/O connectors (J11 and J12),

(illustration), 3-2
optional equipment, 1-4
required components, 1-1
software programming choices

LabVIEW and LabWindows

application software, 1-2
NI-DAQ driver software, 1-2 to 1-3
register-level programming, 1-4

unpacking, 1-4

shield selection

procedure for, 2-4

table, 2-4
SHLD OFF jumper position (table), 2-4
SHLD ON jumper position (table), 2-4
signal connections

analog signal inputs, 3-7 to 3-1

AC-coupled inputs, 3-10 to 3-11
analog input ranges, 3-10 to 3-11
DC-coupled inputs, 3-7 to 3-8

connections exceeding maximum ratings

(warning), 3-1
digital signal inputs, 3-11
input connectors signal summary

(table), 3-4
monitoring signal inputs, 3-11
other connection considerations, 3-11
output connectors (J11 and J12) signal

summary (table), 3-4 to 3-5
SC-2040 I/O connectors J11 and J12

(illustration), 3-2
signal routing (illustration), 3-6

signal outputs, monitoring, 3-11
software calibration.

See calibration procedures.

software programming choices

LabVIEW and LabWindows application

software, 1-2
NI-DAQ driver software, 1-2 to 1-3

© National Instruments Corporation Index-3 SC-2040 User Manual

Index

register-level programming, 1-4

specifications

analog input

amplifier characteristics, A-2
dynamic characteristics, A-2
input characteristics, A-1
S/H characteristics, A-3
stability, A-3

transfer characteristics, A-1
environment, A-3
physical, A-3
power requirements, A-3

T

technical support, B-1
theory of operation

analog circuitry, 4-2 to 4-6

amplification, 4-3

external triggering, 4-5 to 4-6

input protection, 4-3

output connection, 4-6

power supply, 4-6

track-and-hold (T/H) circuitry, 4-3

to 4-4

triggering from DAQ board, 4-4

to 4-5
block diagram, 4-2
functional overview, 4-1

track-and-hold (T/H) circuitry, 4-3 to 4-4
TRIG signal

description (table), 3-4
susceptibility to noise, 3-11

TRIG (PF12) signal (table), 3-4
triggering

from DAQ board, 4-4 to 4-5
external

digital signal inputs, 3-11
illustration, 4-6
theory of operation, 4-5 to 4-6

U

unity gain position (table), 2-5
unpacking the SC-2040, 1-4

SC-2040 User Manual Index-4 © National Instruments Corporation