National Instruments SCXI-1120 User Manual

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SCXI-1120

User Manual

Eight-Channel Isolated Analog Input Module for Signal Conditioning

August 1994 Edition

Part Number 320425B-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, 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 SCXI-1120 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 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............................................................................................................. xi

Organization of This Manual ......................................................................................... xi

Conventions Used in This Manual................................................................................. xii

Related Documentation.................................................................................................. xiii

Customer Communication ............................................................................................. xiii

Chapter 1 Introduction

What Your Kit Should Contain...................................................................................... 1-2

Optional Software .......................................................................................................... 1-2

Optional Equipment ....................................................................................................... 1-3

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

Chapter 2 Configuration and Installation

Module Configuration.................................................................................................... 2-1

Hardware Installation..................................................................................................... 2-11

Signal Connections ........................................................................................................ 2-11

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

Custom Cables ................................................................................................... 1-4

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

Digital Signal Connections ................................................................................ 2-4

Jumper W44 ........................................................................................... 2-5

Jumper W43 ........................................................................................... 2-5

Jumper W42 ........................................................................................... 2-5

Using Jumpers W42 and W43 ............................................................... 2-5

Analog Configuration ........................................................................................ 2-7

Grounding, Shielding, and Reference-Mode Selection ......................... 2-7

Jumper W46 ............................................................................... 2-7

Direct Temperature Connection............................................................. 2-8

Jumper 41................................................................................... 2-8

Gain Jumpers.......................................................................................... 2-9

Filter Jumpers......................................................................................... 2-10

Front Connector ................................................................................................. 2-12

Front Connector Signal Descriptions................................................................. 2-13

Analog Input Channels........................................................................... 2-13

Temperature Sensor Connection............................................................ 2-15

Connector-and-Shell Assembly ............................................................. 2-16

SCXI-1320 and SCXI-1328 Terminal Blocks ....................................... 2-17

Terminal Block Temperature Sensor ......................................... 2-18

Terminal Block Jumper Configuration ...................................... 2-19

Terminal Block Signal Connection............................................ 2-20

Terminal Block Installation ....................................................... 2-23

Rear Signal Connector ....................................................................................... 2-23

Rear Signal Connector Signal Descriptions....................................................... 2-25

Analog Output Signal Connections........................................................ 2-26

Contents

Digital I/O Signal Connections.............................................................. 2-26

Timing Requirements and Communication Protocol............................. 2-28

Communication Signals ......................................................................... 2-28

Chapter 3 Theory of Operation

Functional Overview...................................................................................................... 3-1

SCXIbus Connector ........................................................................................... 3-2

SCXIbus Connector Signal Descriptions........................................................... 3-4

Digital Interface ............................................................................................................. 3-6

Digital Control Circuitry................................................................................................ 3-7

Analog and Timing Circuitry......................................................................................... 3-8

Analog Input Channels....................................................................................... 3-8

Calibration.......................................................................................................... 3-10

Calibration Equipment Requirements.................................................... 3-10

Offset Null Adjust.................................................................................. 3-11

Analog Output Circuitry ........................................................................ 3-12

Scanning Modes............................................................................................................. 3-13

Single-Module Parallel Scanning....................................................................... 3-14

Multiplexed Scanning ........................................................................................ 3-14

Single-Module Multiplexed Scanning ................................................... 3-14

Multiple-Module Multiplexed Scanning................................................ 3-15

Multiple-Chassis Scanning .................................................................... 3-16

Timing Signal............................................................................. 2-28

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

Single-Module Multiplexed Scanning (Direct).......................... 3-14

Single-Module Multiplexed Scanning (Indirect) ....................... 3-15

Chapter 4 Register Descriptions

Register Description....................................................................................................... 4-1

SCXI-1120 Registers ......................................................................................... 4-1

Module ID Register................................................................................ 4-2

Configuration Register........................................................................... 4-3

Slot 0 Register Descriptions............................................................................... 4-5

Slot-Select Register................................................................................ 4-6

Hardscan Control Register (HSCR)....................................................... 4-7

FIFO Register......................................................................................... 4-8

Chapter 5 Programming

Programming Considerations......................................................................................... 5-1

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

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

Initialization ........................................................................................... 5-3

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

SCXI-1120 User Manual vi © National Instruments Corporation

Contents

Single-Channel Measurements .......................................................................... 5-3

Direct Measurements ............................................................................. 5-3

Parallel Output ........................................................................... 5-3

Multiplexed Output.................................................................... 5-4

Indirect Measurements........................................................................... 5-4

Measurements from Other Modules .......................................... 5-4

Measurements from the SCXI-1120 via Another Module......... 5-4

Scanning Measurements .................................................................................... 5-5

1. Data Acquisition Board Setup Programming.................................... 5-6

Counter 1 and SCANDIV .......................................................... 5-8

2. Module Programming ....................................................................... 5-8

Single-Module Parallel Scanning............................................... 5-8

Single-Module Multiplexed Scanning (Direct).......................... 5-9

Single-Module Multiplexed Scanning (Indirect) ....................... 5-9

Channel Scanning from Other Modules......................... 5-9

Channel Scanning From the SCXI-1120 via Another

Module ........................................................................... 5-9

Multiple-Module Multiplexed Scanning.................................... 5-9

Multiple-Chassis Scanning ........................................................ 5-10

3. Programming the Slot 0 Hardscan Circuitry..................................... 5-10

4. Acquisition Enable, Triggering, and Servicing................................. 5-12

Scanning Examples........................................................................................................ 5-12

Example 1 .......................................................................................................... 5-12

Example 2 .......................................................................................................... 5-13

Example 3 .......................................................................................................... 5-14

Appendix A Specifications

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

Cold-Junction Sensor ..................................................................................................... A-2

Physical .......................................................................................................................... A-3

Operating Environment.................................................................................................. A-3

Storage Environment...................................................................................................... A-3

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

Appendix B Rear Signal Connector

Rear Signal Connector Signal Descriptions....................................................... B-2

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

Appendix C SCXIbus Connector

SCXIbus Connector Signal Descriptions........................................................... C-3

........................................................................................................... C-1

Appendix D SCXI-1120 Front Connector

Front Connector Signal Descriptions............................................................................. D-2

........................................................................................... D-1

Contents

Appendix E SCXI-1120 Cabling

SCXI-1340 Cable Assembly.......................................................................................... E-1

SCXI-1340 Installation ...................................................................................... E-2

SCXI-1341 Lab-NB, Lab-PC, or Lab-PC+ and SCXI-1344 Lab-LC Cable

Assembly........................................................................................................................ E-3

SCXI-1341 and SCXI-1344 Installation............................................................ E-4

SCXI-1342 PC-LPM-16 Cable Assembly ..................................................................... E-5

SCXI-1342 Installation ...................................................................................... E-6

SCXI-1180 Feedthrough Panel ...................................................................................... E-6

SCXI-1180 Installation ...................................................................................... E-6

SCXI-1302 50-Pin Terminal Block ............................................................................... E-8

SCXI-1302 Wiring Procedure............................................................................ E-8

SCXI-1302 Installation ...................................................................................... E-9

SCXI-1351 One-Slot Cable Extender............................................................................ E-9

SCXI-1351 Installation ...................................................................................... E-10

SCXI-1350 Multichassis Adapter .................................................................................. E-10

SCXI-1350 Installation ...................................................................................... E-10

SCXI-1343 Rear Screw Terminal Adapter .................................................................... E-11

SCXI-1343 Installation ...................................................................................... E-11

............................................................................................................. E-1

Appendix F Revision A and B Photo and Parts Locator Diagrams

.......................................... F-1

Appendix G Customer Communication

.......................................................................................... G-1

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

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

SCXI-1120 User Manual viii © National Instruments Corporation

Contents

Figures

Figure 2-1. SCXI-1120 General Parts Locator Diagram ...................................................... 2-2

Figure 2-2. Detailed Parts Locator Diagram......................................................................... 2-3

Figure 2-3. SCXI-1120 Front Connector Pin Assignment ................................................... 2-12

Figure 2-4. Ground-Referenced Signal Connection with High Common-Mode Voltage.... 2-14

Figure 2-5. Floating Signal Connection Referenced to Chassis Ground for Better

Signal-to-Noise Ratio......................................................................................... 2-14

Figure 2-6. Floating AC-Coupled Signal Connection .......................................................... 2-14

Figure 2-7. AC-Coupled Signal Connection with High Common-Mode Voltage ............... 2-15

Figure 2-8. Assembling and Mounting the SCXI-1330 Connector-and-Shell Assembly .... 2-17

Figure 2-9. SCXI-1320 Parts Locator Diagram.................................................................... 2-21

Figure 2-10. SCXI-1328 Parts Locator Diagram.................................................................... 2-22

Figure 2-11. SCXI-1120 Rear Signal Connector Pin Assignment ......................................... 2-24

Figure 2-12. SCANCLK Timing Requirements..................................................................... 2-28

Figure 2-13. Slot-Select Timing Diagram .............................................................................. 2-29

Figure 2-14. Serial Data Timing Diagram.............................................................................. 2-30

Figure 2-15. Configuration Register Write Timing Diagram................................................. 2-31

Figure 2-16. SCXI-1120 Module ID Register Timing Diagram ............................................ 2-31

Figure 3-1. SCXI-1120 Block Diagram................................................................................ 3-1

Figure 3-2. SCXIbus Connector Pin Assignment................................................................. 3-3

Figure 3-3. Digital Interface Circuitry Block Diagram ........................................................ 3-6

Figure 3-4. SCXI-1120 Digital Control................................................................................ 3-7

Figure 3-5. Analog Input Block Diagram............................................................................. 3-9

Figure 3-6. Analog Output Circuitry .................................................................................... 3-12

Figure 3-7. Single-Module Parallel Scanning....................................................................... 3-14

Figure 3-8. Single-Module Multiplexed Scanning (Direct).................................................. 3-15

Figure 3-9. Single-Module Multiplexed Scanning (Indirect) ............................................... 3-15

Figure 3-10. Multiple-Module Multiplexed Scanning............................................................ 3-16

Figure 3-11. Multiple-Chassis Scanning ................................................................................ 3-16

Figure B-1. SCXI-1120 Rear Signal Connector Pin Assignment ......................................... B-1

Figure C-1. SCXIbus Connector Pin Assignment................................................................. C-2

Figure D-1. SCXI-1120 Front Connector Pin Assignment ................................................... D-1

Figure E-1. SCXI-1340 Installation ...................................................................................... E-3

Figure E-2. SCXI-1180 Rear Connections............................................................................ E-7

Figure E-3. SCXI-1180 Front Panel Installation................................................................... E-8

Figure E-4. Cover Removal .................................................................................................. E-9

Figure F-1. Revision A and B SCXI-1120 Signal Conditioning Module ............................. F-1

Figure F-2. Revision A and B SCXI-1120 General Parts Locator Diagram......................... F-2

Figure F-3. Revision A and B SCXI-1120 Detailed Parts Locator Diagram........................ F-3

Contents

Tables

Table 2-1. Digital Signal Connections, Jumper Settings..................................................... 2-6

Table 2-2. Jumper W46 Settings ......................................................................................... 2-8

Table 2-3. Jumper W41 Settings ......................................................................................... 2-9

Table 2-4. Gain Jumper Allocation ..................................................................................... 2-9

Table 2-5. Gain Jumper Positions ....................................................................................... 2-10

Table 2-6. Filter Jumper Allocation .................................................................................... 2-10

Table 2-7. Jumper Settings on the SCXI-1320 Terminal Block ......................................... 2-19

Table 2-8. Jumper Settings on the SCXI-1328 Terminal Block ......................................... 2-20

Table 2-9. SCXIbus to SCXI-1120 Rear Signal Connector to Data Acquisition

Board Pin Equivalences ..................................................................................... 2-27

Table 3-1. SCXIbus Equivalents for the Rear Signal Connector........................................ 3-5

Table 3-2. Calibration Potentiometers Reference Designators ........................................... 3-12

Table 5-1. SCXI-1120 Rear Signal Connector Pin Equivalences....................................... 5-2

Table E-1. SCXI-1120 and MIO-16 Board Pinout Equivalences........................................ E-2

Table E-2. SCXI-1341 and SCXI-1344 Pin Translations.................................................... E-4

Table E-3. SCXI-1342 Pin Translations .............................................................................. E-5

Table E-4. SCXI-1343 Pin Connections.............................................................................. E-12

SCXI-1120 User Manual x © National Instruments Corporation

About This Manual

This manual describes the electrical and mechanical aspects of the SCXI-1120 and contains information concerning its operation and programming. The SCXI-1120 is a class I module that operates as eight isolated input channels. Refer to your chassis manual for a description of the different module classes. Each channel is isolated and independently configurable via jumpers. Refer to your chassis manual for a description of the different module classes. The SCXI-1120 is a member of the National Instruments Signal Conditioning eXtensions for Instrumentation (SCXI) Series for the National Instruments data acquisition plug-in boards. This board is designed for low-cost signal conditioning of thermocouples, volt sources, millivolt sources, and 4 to 20 mA sources or 0 to 20 mA process-current sources where high common-mode voltages exist.

This manual describes the installation, theory of operation, and basic programming considerations for the SCXI-1120.

Organization of This Manual

The SCXI-1120 User Manual is organized as follows:

• Chapter 1, Introduction, describes the SCXI-1120; lists the contents of your SCXI-1120 kit; describes the optional software, optional equipment, and custom cables; and explains how to unpack the SCXI-1120 kit.

• Chapter 2, Configuration and Installation, describes the SCXI-1120 jumper configurations, installation of the SCXI-1120 into the SCXI chassis, signal connections to the SCXI-1120, and cable wiring.

• Chapter 3, Theory of Operation, contains a functional overview of the SCXI-1120 module and explains the operation of each functional unit making up the SCXI-1120.

• Chapter 4, Register Descriptions, describes in detail the SCXI-1120 Module ID Register, the Configuration Register, the Slot 0 registers, and multiplexer addressing.

• Chapter 5, Programming, contains a functional programming description of the SCXI-1120 and Slot 0.

• Appendix A, Specifications, lists the specifications for the SCXI-1120.

• Appendix B, Rear Signal Connector, describes the pinout and signal names for the SCXI-1120 50-pin rear signal connector, including a description of each connection.

• Appendix C, SCXIbus Connector, describes the pinout and signal names for the SCXI-1120 96-pin SCXIbus connector, including a description of each connection.

About This Manual

• Appendix D, SCXI-1120 Front Connector, describes the pinout and signal names for the SCXI-1120 front connector, including a description of each connection.

• Appendix E, SCXI-1120 Cabling, describes how to use and install the hardware accessories for the SCXI-1120.

• Appendix F, Revision A and B Photo and Parts Locator Diagrams, contains a photograph of the Revision A and B SCXI-1120 signal conditioning module and the general and detailed parts locator diagrams.

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

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

• 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-LC, Lab-NB, Lab-PC, and Lab-PC+ boards,

unless otherwise noted. MC MC refers to the Micro Channel series computers. MIO board MIO board refers to the AT-MIO-16, AT-MIO-16D, AT-MIO-16F-5,

AT-MIO-16X, AT-MIO-64F-5, MC-MIO-16, NB-MIO-16, and

NB-MIO-16X series of multichannel I/O data acquisition boards. 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. NB NB refers to the NuBus series computers. PC PC refers to the IBM PC/XT, the IBM PC AT, and compatible computers. SCXIbus SCXIbus refers to the backplane in the chassis. A signal on the backplane

is referred to as the SCXIbus <signal name> line (or signal). The

SCXI-1120 User Manual xii © National Instruments Corporation

About This Manual

SCXIbus descriptor may be omitted when the meaning is clear.

Descriptions of all SCXIbus signals are given in Appendix C, SCXIbus

Connector. Slot 0 Slot 0 refers to the power supply and control circuitry in the SCXI chassis. Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in the

Glossary.

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 G, Customer

Communication, at the end of this manual.

Chapter 1 Introduction

This chapter describes the SCXI-1120; lists the contents of your SCXI-1120 kit; describes the optional software, optional equipment, and custom cables; and explains how to unpack the SCXI-1120 kit.

The SCXI-1120 is a class I module consisting of eight isolated input channels. The SCXI-1120 is a module for signal conditioning of thermocouples, volt sources, millivolt sources, 4 to 20 mA current sources, and 0 to 20 mA process-current sources. Refer to your chassis manual for a description of the different module classes. If external excitation is provided, thermistors, RTDs, and strain gauges can also be measured. The SCXI-1120 can operate in two output modes–in the Parallel-Output mode with all eight input channels connected in parallel to eight data acquisition board channels, or in the Multiplexed-Output mode with all eight channels multiplexed into a single data acquisition board channel.

The SCXI-1120 operates with full functionality with the National Instruments MIO-16 boards. You can use the Lab-NB, the Lab-PC, the Lab-PC+, the Lab-LC, and the PC-LPM-16 boards with the SCXI-1120, but these boards cannot scan the module when it is configured in the Multiplexed-Output mode. These boards can perform only single-channel reads in this mode. You can also use the SCXI-1120 with other systems that comply with the specifications given in Chapter 2, Configuration and Installation. You can multiplex several SCXI-1120s into a single channel, thus greatly increasing the number of analog input signals that can be digitized.

The addition of a shielded terminal block provides screw terminals for easy signal attachment to the SCXI-1120. In addition, a temperature sensor for cold-junction compensation of thermocouples is included on the terminal block. This cold-junction reference (CJR) is either multiplexed along with the eight channels or connected by jumpers to a different channel of the data acquisition board.

With the SCXI-1120, the SCXI chassis can serve as a fast-scanning signal conditioner for laboratory testing, production testing, and industrial process monitoring.

Introduction Chapter 1

What Your Kit Should Contain

The contents of the SCXI-1120 kit (part number 776572-20) are listed as follows.

Kit Component Part Number

SCXI-1120 module 181695-01 SCXI-1120 User Manual 320425-01

If your kit is missing any of the components, contact National Instruments.

Optional Software

This manual contains complete instructions for directly programming the SCXI-1120. You can order separate software packages for controlling the SCXI-1120 from National Instruments.

When you combine the PC, AT, and MC data acquisition boards with the SCXI-1120, you can use LabVIEW for Windows or LabWindows for DOS. LabVIEW and LabWindows are innovative program development software packages for data acquisition and control applications. LabVIEW uses graphical programming, whereas LabWindows enhances Microsoft C and QuickBASIC. Both packages include extensive libraries for data acquisition, instrument control, data analysis, and graphical data presentation.

Your National Instruments data acquisition board is shipped with the NI-DAQ software. NI-DAQ has a library of functions that can be called 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, SCXI, RTSI, and self-calibration. NI-DAQ maintains a consistent software interface among its different versions so you can switch between platforms with minimal modifications to your code.

You can also use the SCXI-1120, together with the PC, AT, and MC data acquisition boards, with NI-DAQ software for DOS/Windows/LabWindows. NI-DAQ software for DOS/Windows/LabWindows 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. NI-DAQ software for DOS/Windows/LabWindows is on high-density 5.25 in. and 3.5 in. diskettes.

You can use the SCXI-1120, together with the NB Series data acquisition boards, with LabVIEW, a software system that 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 boards, is included with LabVIEW. The LabVIEW Data Acquisition VI Library is functionally equivalent to the NI-DAQ software for Macintosh.

SCXI-1120 User Manual 1-2 © National Instruments Corporation

Chapter 1 Introduction

You can also use the SCXI-1120, combined with the NB Series data acquisition boards, with NI-DAQ software for Macintosh. NI-DAQ software for Macintosh, which is shipped with all National Instruments Macintosh data acquisition boards, 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.

Optional Equipment

Equipment Part Number

SCXI-1320 front terminal block 776573-20 SCXI-1328 high-accuracy isothermal terminal block 776573-28 SCXI-1330 32-pin connector-and-shell assembly 776573-30 SCXI-1340 cable assembly 776574-40 SCXI-1341 Lab-NB/Lab-PC/Lab-PC+ cable assembly 776574-41 SCXI-1342 PC-LPM-16 cable assembly 776574-42 SCXI-1343 rear screw terminal adapter 776574-43 SCXI-1344 Lab-LC cable assembly 776574-44 SCXI-1346 shielded multichassis cable adapter 776574-46 SCXI-1347 SCXI shielded cable assembly

with 1 m cable with 2 m cable with 5 m cable with 10 m cable

SCXI-1349 SCXI shielded cable assembly

with 1 m cable with 2 m cable with 5 m cable

with 10 m cable SCXI-1350 multichassis adapter 776575-50 SCXI process-current resistor kit 776582-01 Standard ribbon cable 0.5 m

1.0 m

NB6 cable

0.5 m

1.0 m

776574-471 776574-472 776574-475 776574-470

776574-491 776574-492 776574-495 776574-490

180524-05 180524-10

181305-01 181305-10

Refer to the Signal Connections section in Chapter 2, Configuration and Installation, and to Appendix E, SCXI-1120 Cabling, for additional information on cabling, connectors, and adapters.

Introduction Chapter 1

Custom Cables

The SCXI-1120 rear signal connector is a 50-pin male ribbon-cable header. The manufacturer part number used by National Instruments for this header is as follows:

• AMP Inc. (part number 1-103310-0) The mating connector for the SCXI-1120 rear signal connector is a 50-position polarized

ribbon-socket connector with strain relief. National Instruments uses a polarized or keyed connector to prevent inadvertent upside-down connection to the SCXI-1120. Recommended manufacturer part numbers for this mating connector are as follows:

• Electronic Products Division/3M (part number 3425-7650)

• T&B/Ansley Corporation (part number 609-5041CE) Standard 50-conductor, 28 AWG, stranded ribbon cables that can be used with these connectors

are as follows:

• Electronic Products Division/3M (part number 3365/50)

• T&B/Ansley Corporation (part number 171-50) The SCXI-1120 front connector is a 32-pin DIN C male connector with columns A and C even

pins only. The manufacturer part number used by National Instruments for this connector is as follows:

• Panduit Corporation (part number 100-932-023) The mating connector for the SCXI-1120 front connector is a 32-pin DIN C female connector.

National Instruments uses a polarized connector to prevent inadvertent upside-down connection to the SCXI-1120. Recommended manufacturer part numbers for this mating connector are as follows:

• Panduit Corporation (part number 100-932-434; straight-solder eyelet pins)

• Panduit Corporation (part number 100-932-633; right-angle pins) These connectors were selected to meet UL 1950 and UL 1244 for 1,500 Vrms isolation.

Unpacking

Your SCXI-1120 module is shipped in an antistatic package to prevent electrostatic damage to the module. Several components on the module can be damaged by electrostatic discharge. To avoid such damage in handling the module, take the following precautions:

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

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

SCXI-1120 User Manual 1-4 © National Instruments Corporation

Chapter 2 Configuration and Installation

This chapter describes the SCXI-1120 jumper configurations, installation of the SCXI-1120 into the SCXI chassis, signal connections to the SCXI-1120, and cable wiring.

Module Configuration

The SCXI-1120 includes 46 jumpers that are shown in the parts locator diagrams in Figures 2-1 and 2-2.

Configuration and Installation Chapter 2

Figure 2-1. SCXI-1120 General Parts Locator Diagram

SCXI-1120 User Manual 2-2 © National Instruments Corporation

Chapter 2 Configuration and Installation

Figure 2-2 shows a detailed parts locator diagram of the SCXI-1120.

Figure 2-2. Detailed Parts Locator Diagram

Configuration and Installation Chapter 2

The jumpers are used as follows:

• Fixed jumpers

- On Revision A and B modules, jumper W42 is unused and should not be connected.

- Jumper W45 is reserved and should not be reconfigured.

- On Revision A and B modules, jumper W44 carries the SLOT0SEL* signal from the rear

signal connector, after buffering, to the SCXIbus INTR* line and should be left in the factory-default position (position 1). On Revision C and later modules, jumper W44 does not exist.

• User-configurable jumpers

- Jumper W43 carries the SCXIbus MISO line, after buffering, to the SERDATOUT signal

on the rear signal connector.

- On Revision C and later modules, jumper 42 connects a pullup resistor to the

SERDATOUT signal on the rear signal connector.

- Jumper W46 configures the guard, the analog output ground, and enables the

Pseudodifferential Reference mode.

- Jumpers W1 through W8 configure the first-stage gain of channels 0 through 7,

respectively.

- Jumpers W9 through W16 configure the second-stage gain of channels 0 through 7,

respectively.

- Jumpers W17 through W24 configure the first-stage filtering of input channels 0 through

7, respectively.

- Jumpers W25 through W40 configure the second-stage filtering of input channels 0

through 7, respectively.

- Jumper W41 directly connects the temperature sensor to the rear signal connector. To do

so, set jumper W46 in the AB-R2 or AB-R0 position first.

Further configuration of the board is software controlled and will be discussed later in this chapter.

Digital Signal Connections

The four digital signal connection jumpers have position 1 marked on the board. Position 3 is not explicitly marked on the board.

The SCXI-1120 has three jumpers dedicated for communication between the data acquisition board and the SCXIbus. These jumpers are W42, W43, and W44.

SCXI-1120 User Manual 2-4 © National Instruments Corporation

Chapter 2 Configuration and Installation

Jumper W44

On Revision A and B modules, position 1 connects, after buffering, SLOT0SEL* to the SCXIbus INTR* line. This is the factory-default setting and should not be changed. In this setting, the data acquisition board controls the SCXIbus INTR* line. See the Timing Requirements and Communication Protocol section later in this chapter, and Chapter 5, Programming, for information on the use of the INTR* line. See Appendix E, SCXI-1120 Cabling, for the pin equivalences of the SCXI-1120 rear signal connector and the data acquisition board I/O connector.

Position 3 is reserved and should not be used. On Revision C and later modules, jumper W44 is not loaded. SLOT0SEL* is always buffered to

the INTR* line.

Jumper W43

Position 1 connects, after buffering, the SCXIbus MISO line to the SERDATOUT pin of the rear signal connector. In this setting, along with the proper setting of jumper W42, the data acquisition board can read the Module ID Register of the SCXI-1120. This is the factory-default setting. See the Timing Requirements and Communication Protocol section later in this chapter, and Chapter 4, Register Descriptions, for information on reading the Module ID Register. See Appendix E, SCXI-1120 Cabling, for the pin equivalences of the SCXI-1120 rear signal connector and the data acquisition board I/O connector.

Position 3 disconnects SERDATOUT from the SCXIbus MISO line.

Jumper W42

On Revision A and B modules, jumper W42 should not be connected. On Revision C and later modules, position 1 connects a 2.2 kΩ pullup resistor to the SERDATOUT line. Position 3 does not connect the pullup resistor to the SERDATOUT line.

Using Jumpers W42 and W43

If the SCXI-1120 is not cabled to a data acquisition board, the positions of these jumpers do not matter, so leave them in their factory-default positions (both in position 1).

If the SCXI-1120 is cabled to a data acquisition board, and the SCXI chassis that the SCXI-1120 is in, is the only SCXI chassis cabled to that data acquisition board, leave the jumpers in their factory-default positions (both in position 1).

If the SCXI-1120 is cabled to a data acquisition board, and there are multiple SCXI chassis cabled to that data acquisition board with shielded cables (you are using SCXI-1346 shielded cable multichassis adapters), leave the jumpers in their factory-default positions (both in position 1).

If the SCXI-1120 is cabled to a data acquisition board, and there are multiple SCXI chassis cabled to that data acquisition board with ribbon cables (you are using SCXI-1350 multichassis adapters), leave jumper W43 in its factory-default position (position 1). On all but one of the SCXI-1120s that are cabled to the data acquisition board, move jumper W42 to position 3. It does not matter which of the SCXI-1120 modules that are cabled to the data acquisition board has jumper W42 set to position 1. If you have different types of modules cabled to the data

Configuration and Installation Chapter 2

acquisition board, those different modules will have jumpers similar to W43 and W42 of the SCXI-1120. Set those jumpers on the different modules using the same method described here for the SCXI-1120.

On Revision A and B SCXI-1120s, jumper W42 is not used. You set jumper W43 as explained in the cases above, except in the case of a multichassis ribbon cable system. In a multichassis ribbon cable system with Revision A and B SCXI-1120s cabled to the data acquisition board, you can access the MISO line in only one chassis. Pick one of the chassis that has the SCXI-1120 cabled to the DAQ board. Set jumper W43 on the SCXI-1120 to position 1. On the SCXI-1120s that are in the other chassis and cabled to the data acquisition board, set jumper W43 to position 3. Notice that you will only be able to access digital information from the chassis that has the SCXI-1120 with jumper W43 set to position 1.

On Revision C and later modules, the SERDATOUT line is driven with an open-collector driver (a driver that actively drives low or goes to a high-impedance state, relying on a pullup resistor to make the signal line go high). When using a single chassis, leave W42 and W43 in position 1, the factory default, on the SCXI-1120 that is connected to the data acquisition board. In this setting, the module drives MISO to SERDATOUT and connects the necessary pullup resistor to the SERDATOUT line. When using multiple chassis, leave jumper W43 in position 1 on all of the SCXI-1120s that are cabled to the data acquisition board. Only one of the SCXI-1120s that are cabled to the data acquisition board should have jumper W42 in position 1. It does not matter which of the SCXI-1120s that are cabled to the data acquisition board has the pullup connected. All of the other SCXI-1120 modules that are cabled to the data acquisition board should have jumper W42 in position 3. The reason for this is that if too many pullup resistors are attached to the SERDATOUT line, the drivers cannot drive the line low. See Table 2-1 for the description and configuration of the jumper settings.

Table 2-1. Digital Signal Connections, Jumper Settings

Jumper Description Configuration

W42

W43

Connects pullup to SERDATOUT (Revision C and later) factorydefault setting.

Parking position (not connected on Revision A and B)

Connects MISO to SERDATOUT Factory-default setting.

Parking position

•

(continues)

SCXI-1120 User Manual 2-6 © National Instruments Corporation

Chapter 2 Configuration and Installation

Table 2-1. Digital Signal Connections, Jumper Settings (Continued)

Jumper Description Configuration

W45

W44

Factory default

Factory default (Revision A and B modules only)

•

Analog Configuration

The SCXI-1120 has 42 analog configuration jumpers. Before starting, notice that the jumper configurations for each channel are similar; only the

jumper reference designator number changes. When you learn how to configure one channel, you can configure the other channels as well.

Grounding, Shielding, and Reference-Mode Selection

Jumper W46 Position B-R0R1 is the parked position and the factory-default setting. Position AB-R0 connects the analog reference to the analog output ground (pins 1 and 2 on the

rear signal connector). Select this configuration when using an RSE data acquisition board. You should not use differential input data acquisition boards when jumper W46 is in the AB-R0 position.

Position AB-R1 connects the analog reference to the SCXIbus guard. Position AB-R2 enables the Pseudodifferential Reference mode and connects the analog

reference to the OUTREF pin on the rear signal connector. Select this mode when the SCXI-1120 has to operate with data acquisition boards that have a nonreferenced single-ended input (NRSE). Do not use differential-input data acquisition boards when jumper W46 is in the AB-R2 position.

Note: The SCXI-1120 will drive pins 4, 6, 8, 10, 12, 14, 16, and 18 on the rear signal connector,

although the SCXI-1120 is in pseudodifferential mode.

Configuration and Installation Chapter 2

Table 2-2. Jumper W46 Settings

Jumper Description Configuration

W46 Factory setting in parking position

W46 Connects the analog reference to

AOGND (pins 1 and 2 of the rear signal connector). Use this connection with RSE data acquisition boards.

W46 Connects SCXIbus guard to the analog

reference

W46 Enables the Pseudodifferential

Reference mode (pin 19 of the rear signal connector is connected to the analog reference)

•••••

2 R1 R0

•••••

2 R1 R0

•••••

2 R1 R0

•••••

2 R1 R0

•

Direct Temperature Connection

Jumper W41 When your SCXI-1120 is operating with a data acquisition board configured in a differential

mode, such as the MIO board, you can access the temperature sensor only in the MultiplexedOutput mode. Direct temperature connection is not permissible to the data acquisition board. This is the factory setting and is position 1 of the jumper block. Position 3 is not explicitly marked.

If the temperature sensor needs to be accessed in parallel with the other eight outputs, or scanned–without software interference–along with the other channels, you need to place W41 in position 3 (this position is not explicitly marked on the module) and to configure your reference to pseudodifferential or single-ended operation (jumper W46) with your data acquisition board configured for the same reference scheme. In this position, the direct temperature sensor connection is made on pin 18 of the rear signal connector and corresponds to ACH15 of the MIO boards or the PC-LPM-16.

SCXI-1120 User Manual 2-8 © National Instruments Corporation

Chapter 2 Configuration and Installation

Table 2-3. Jumper W41 Settings

Jumper Description Configuration

W41 Temperature sensor

•

accessed in MTS mode (Factory setting)

W41 Temperature sensor

3 2 1

•

accessed in DTS mode, data acquisition board

3 2 1

configured for NRSE or RSE

Gain Jumpers

Each input channel has two gain stages. The first gain stage provides gains of 1, 10, 50, and 100, and the second stage provides gains of 1, 2, 5, 10, and 20. Tables 2-4 and 2-5 show how to set up the gain for each channel.

Table 2-4. Gain Jumper Allocation

Input Channel Number First Gain Jumper Second Gain Jumper

0W1W9 1 W2 W10 2 W3 W11 3 W4 W12 4 W5 W13 5 W6 W14 6 W7 W15 7 W8 W16

The board is shipped with the first-stage gain set to 100 (position A), and a second-stage gain set to 10 (position D). To change the gain of your module, move the appropriate jumper on your module to the position indicated in Tables 2-3 and 2-4. Refer to Figure 2-1, SCXI-1120 General Parts Locator Diagram, and Figure 2-2, Detailed Parts Locator Diagram, for jumper locations on your module.

To determine the overall gain of a given channel use the following formula:

Overall gain = First-stage gain x second-stage gain.

Configuration and Installation Chapter 2

Table 2-5. Gain Jumper Positions

Gain Setting Jumper Position

D C B A (Factory setting)

A B C D (Factory setting) E

First-stage

Second-stage

1 10 50

100

5 10 20

Filter Jumpers

Two-stage filtering is also available on your SCXI-1120 module. The first stage is located in the isolated section of the input channel, whereas the second stage is located in the nonisolated section of your input channel. Two-stage filtering eliminates the noise generated by the isolation amplifier, producing a higher signal-to-noise ratio. Furthermore, two filter bandwidths are available, 10 kHz and 4 Hz.

Table 2-6. Filter Jumper Allocation

Input Channel First Filter Jumper Second Filter Jumper

Number 4 Hz

(Factory

Setting)

10 kHz 4 Hz

(Factory

Setting)

10 kHz

0 W17-A W17-B W25 W26 1 W18-A W18-B W27 W28 2 W19-A W19-B W29 W30 3 W20-A W20-B W31 W32 4 W21-A W21-B W33 W34 5 W22-A W22-B W35 W36 6 W23-A W23-B W37 W38 7 W24-A W24-B W39 W40

Your SCXI-1120 is shipped in the 4 Hz position. Remember to make sure that both stages are set to the same bandwidth to ensure that the required bandwidth is achieved. Notice that one jumper block is available for each filter stage.

SCXI-1120 User Manual 2-10 © National Instruments Corporation

Chapter 2 Configuration and Installation

Hardware Installation

You can install the SCXI-1120 in any available SCXI chassis. After you have made any necessary changes and have verified and recorded the jumper settings on the form in Appendix G, Customer Communication, you are ready to install the SCXI-1120. The following are general installation instructions, but consult the user manual or technical reference manual of your SCXI chassis for specific instructions and warnings.

1. Turn off the computer that contains the data acquisition board or disconnect it from your SCXI chassis.

2. Turn off the SCXI chassis. Do not insert the SCXI-1120 into a chassis that is turned on.

3. Insert the SCXI-1120 into the module guides. Gently guide the module into the back of the slot until the connectors make good contact. If a cable assembly has already been installed in the rear of the chassis, the module and cable assembly must be firmly engaged; however, do not force the module into place.

4. Screw the front mounting panel of the SCXI-1120 to the top and bottom threaded strips of your SCXI chassis.

5. If this module is to be connected to an MIO-16 data acquisition board, attach the connector at the metal end of the SCXI-1340 cable assembly to the rear signal connector on the SCXI-1120 module. Screw the rear panel to the rear threaded strip. Attach the loose end of the cable to the MIO-16 board.

Note: For installation procedures with other SCXI accessories and data acquisition boards,

consult Appendix E, SCXI-1120 Cabling.

6. Check the installation.

7. Turn on the SCXI chassis.

8. Turn on the computer or reconnect it to your chassis.

The SCXI-1120 board is installed and ready for operation.

Signal Connections

This section describes the input and output signal connections to the SCXI-1120 board via the SCXI-1120 front connector and rear signal connector, and includes specifications and connection instructions for the signals given on the SCXI-1120 connectors.

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

the SCXI-1120 can result in damage to the SCXI-1120 board and to the SCXIbus. Maximum input ratings for each signal are given in this chapter under the discussion of that signal. National Instruments is not liable for any damages resulting from such signal connections.

Configuration and Installation Chapter 2

Front Connector

Figure 2-3 shows the pin assignments for the SCXI-1120 front connector.

Number

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12

9 8 7 6 5 4 3 2 1

Signal

Name

CH0+

CH1+

CH2+

CH3+

CH4+

CH5+

CH6+

CH7+

RSVD

+5 V

CHSGND

Column

A B C

Signal

Name

CH0-

CH1-

CH2-

CH3-

CH4-

CH5-

CH6-

CH7-

RSVD

MTEMP

DTEMP

Figure 2-3. SCXI-1120 Front Connector Pin Assignment

SCXI-1120 User Manual 2-12 © National Instruments Corporation

Chapter 2 Configuration and Installation

Front Connector Signal Descriptions

Pin Signal Name Description

A2 CHSGND Chassis Ground – Tied to the SCXI chassis. C2 DTEMP Direct Temperature Sensor – Connects the

temperature sensor to pin 18 of the rear signal connector MCH7- when the terminal block is configured for direct temperature connection and jumper W41 is in position 3.

A4 +5 V +5 VDC Source – Used to power the temperature

sensor on the terminal block. 0.2 mA of source not protected.

C4 MTEMP Multiplexed Temperature Sensor – Connects the

temperature sensor to the output multiplexer.

A6, C6, C8 RSVD Reserved – Reserved for future use. Do not connect

any signals to these pins. TTL/CMOS output. They are not protected.

A8, A10, C10, No Connect Do not connect any signals to these pins. A16, C16,A22, C22, A28, C28

A12, A14, A18, CH7+ through CH0+ Positive Input Channels – The positive inputs to A26, A20, A24, channels 7 through 0, respectively. A30, A32

C12, C14, C18, CH7- through CH0- Negative Input Channels – The negative inputs to C20, C24, C26, channels 7 through 0, respectively. C30, C32

The signals on the front connector are all analog with the exceptions of pins A6, C6, and C8. The analog signals can be divided into two groups–the analog input channels, and the temperature sensor.

Analog Input Channels

The positive input channels are located in column A. Their corresponding negative input channels are located in column C. Each input corresponds to a separate amplifier and is fully isolated from the other channels and from earth ground. The inputs are designed in a floating single-ended configuration, thus the measured signal can be referenced to a ground level with common-mode voltage up to 250 Vrms. For better noise immunity, connect the negative input channel to the signal reference. If the measured signals are floating, connect the negative input channel to chassis ground on the terminal block. Figure 2-4 shows how to connect a groundreferenced signal. Figure 2-5 shows how to connect a floating signal. Figures 2-6 and 2-7 show how to connect AC-coupled signals.

Configuration and Installation Chapter 2

out

High CMV

Module

Figure 2-4. Ground-Referenced Signal Connection with High Common-Mode Voltage

Module

out

Figure 2-5. Floating Signal Connection Referenced to Chassis Ground for Better

Signal-to-Noise Ratio

bias

Module

out

Figure 2-6. Floating AC-Coupled Signal Connection

SCXI-1120 User Manual 2-14 © National Instruments Corporation

Chapter 2 Configuration and Installation

High CMV

bias

Module

out

Figure 2-7. AC-Coupled Signal Connection with High Common-Mode Voltage

For AC-coupled signals, an external resistor from the positive input channel to the signal reference should be connected. This is needed to provide the DC path for the positive input bias current. Typical resistor values range from 100 kΩ to 1 MΩ. This solution, although necessary in this case, lowers the input impedance of the input channel amplifier and introduces an additional offset voltage proportional to the input bias current and to the resistor value used. The typical input bias current of the amplifier consists of ±80 pA and a negligible offset drift current. When a 100 kΩ resistor is used, this will result into ±8 µV of offset, which is insignificant in most applications. However, if larger valued bias resistors are used, significant input offset may result. To determine the maximum offset introduced by the biasing resistor, use the following equation:

The input signal range of an SCXI-1120 input channel is ±5 V/ G input, where G

ofsbias

= I

x R

bias

total

bias

referenced to its negative

total

is equal to the product of the first-stage and second-stage gains. In addition,

the input channels are overvoltage protected to 240 Vrms with power on or off at a maximum of

4.5 mArms sink or source.

Warning: Exceeding the input signal range and the common-mode input range results in

distorted signals. Exceeding the maximum input voltage rating (250 Vrms between terminals, and between any terminal and ground) can result in damage to the SCXI-1120, the SCXIbus, and the data acquisition board. National Instruments is not liable for any damages resulting from such signal connections.

Temperature Sensor Connection

Pins C2 and C4 are dedicated for connecting the temperature sensor to the SCXI-1120. The temperature sensor is not isolated and is referenced to the chassis ground. The connection is overvoltage protected to ±25 VDC with power on and ±15 VDC with power off.

Warning: Exceeding the overvoltage protection on the temperature connections can result in

damage to the SCXI-1120, the SCXIbus, and the data acquisition board. National Instruments is not liable for any damages resulting from such signal connections.

Configuration and Installation Chapter 2

Connector-and-Shell Assembly

Two types of signal connectors are available to connect the signals to the SCXI-1120 inputs. The first, the SCXI-1330 32-pin DIN C female connector-and-shell assembly, is available in a kit listed in the Optional Equipment section in Chapter 1, Introduction. The connector has eyelet ends for easy hook-and-solder wire connection. With this kit, you can build your own signal cable to connect to the SCXI-1120 inputs. After you have built the cable, the shell covers and protects the connector. Perform the following steps to assemble and mount the connector-andshell assembly to your SCXI module:

1. Refer to Figure 2-8, Assembling and Mounting the SCXI-1330 Connector-and-Shell Assembly, and the diagram included with your SCXI-1330 kit to build the connector-andshell assembly.

2. Turn off the computer that contains your data acquisition board or disconnect the board from your SCXI chassis.

3. Turn off your SCXI chassis.

4. Slide the selected module out of the SCXI chassis.

5. Remove the module cover.

6. Place one jack screw as indicated in Figure 2-8.

7. While holding the jack screw in place, insert the lock washer and then the nut. Notice that you might need long-nose pliers to insert the washer and nut.

8. Tighten the nut by holding it firmly and rotating the jack screw.

9. Repeat steps 6 through 8 for the second jack screw.

10. Replace the module cover and tighten the grounding screw.

11. Slide the module back in place.

12. Connect the SCXI-1330 to your module connector and secure it by tightening both mounting screws.

SCXI-1120 User Manual 2-16 © National Instruments Corporation

Chapter 2 Configuration and Installation

Shell Assembly

Mounting Screw

Connector

Mounting Screw

Jack

Screws

Shell Assembly

Lock Washers

Nut

SCXI-1120 Module

Nut

Figure 2-8. Assembling and Mounting the SCXI-1330 Connector-and-Shell Assembly

SCXI-1320 and SCXI-1328 Terminal Blocks

Grounding Screw

The second type of connector available to connect the signals to the SCXI-1120 inputs is a terminal block with an onboard temperature sensor and screw terminals for easy connection. One terminal block, the SCXI-1328 isothermal terminal block, has a high-accuracy onboard temperature sensor. The terminal block kits are listed in the Optional Equipment section in Chapter 1, Introduction.

The SCXI-1320 terminal block and SCXI-1328 high-accuracy isothermal terminal block consist of a shielded board with supports for connection to the SCXI-1120 input connector. The terminal blocks have 18 screw terminals for easy connection. Eight pairs of screw terminals are for signal connection to the eight inputs of the SCXI-1120, and one pair of screw terminals connects to the chassis ground.

Configuration and Installation Chapter 2

The following warnings contain important safety information concerning hazardous voltages and terminal blocks.

Warnings: When using the terminal block with high common-mode voltages, you must

insulate your signal wires appropriately. National Instruments is not liable for any damages or injuries resulting from inadequate signal wire insulation.

If high voltages (≥42 Vrms) are present, you must connect the safety earth ground to the strain-relief tab. This complies with UL 1244 and protects against electric shock when the terminal block is not connected to the chassis. To connect the safety earth ground to the strain-relief tab, run an earth ground wire in the cable from the signal source to the terminal block. National Instruments is not liable for any damages or injuries resulting from inadequate safety earth ground connections.

When connecting your signals to the SCXI-1320 terminal block for use with the SCXI-1120, follow the labeling on the SCXI-1320 indicated under the module type column for the SCXI-1120 as indicated in Figure 2-9.

When connecting your signals to the SCXI-1328 high-accuracy isothermal terminal block for use with the SCXI-1120, follow the labeling on the SCXI-1328 indicated along the module type row for the SCXI-1120 as indicated in Figure 2-10.

Terminal Block Temperature Sensor To accommodate thermocouples with the SCXI-1120, the terminal block has a temperature

sensor for cold-junction compensation. You can connect the temperature sensor in two ways:

• You can connect the temperature sensor to the MTEMP pin (C4) on the module front connector and multiplex the sensor at the output multiplexer along with amplifier outputs. This is the Multiplexed Temperature Sensor (MTS) mode. Refer to the Configuration Register section in Chapter 4, Register Descriptions, for further details.

• You can connect the temperature sensor to a separate data acquisition channel via pin 18 on the module rear signal connector when you set SCXI-1120 jumper W41 to position 3. This is the Direct Temperature Sensor (DTS) mode.

Note: Use an average of a large number of samples to obtain the most accurate reading.

Noisy environments require more samples for greater accuracy.

The SCXI-1320 temperature sensor outputs 10 mV/°C and has an accuracy of ±1° C over the 0° to 55° C temperature range. To determine the temperature, use the following formulas:

T (°C) = 100(V

T (° C)

T (°F) =

[]

TEMPOUT

)

+32

where V

TEMPOUT

is the temperature sensor output and T (°F) and T (°C) are the temperature

readings in degrees Fahrenheit and degrees Celsius, respectively. The SCXI-1328 temperature sensor outputs 0.62 to 0.07 V from 0° to 55° C and has an accuracy

of ±0.35° C over the 15° to 35° C range and ±0.65° C over the 0° to 15° and 35° to 55° C ranges.

SCXI-1120 User Manual 2-18 © National Instruments Corporation

Chapter 2 Configuration and Installation

To determine the temperature, use the following formulas:

T (°C) = T = T

where T

TK=

a = 1.288 x 10 b = 2.356 x 10 c = 9.556 x 10

is the temperature in kelvin

a + b lnR

[]

- 273.15

-3

-4

-8

+c lnR

()

RT = resistance of the thermistor in Ω

= 50,000

TEMPOUT

T (°F) =



TEMPOUT



2.5− V



TEMPOUT

= output voltage of the temperature sensor

T (° C)

[]

+32

 



where T (°F) and T (°C) are the temperature readings in degrees Fahrenheit and degrees Celsius, respectively.

Terminal Block Jumper Configuration In addition to the screw terminals, the terminal block has one jumper for configuring the onboard

temperature sensor. When you set jumper W1 on the terminal block to the MTEMP position, the jumper connects the temperature sensor to the SCXI-1120 output multiplexer. This is the factory setting. The DTEMP position connects the temperature sensor to SCXI-1120 jumper W41.

In both MTS and DTS modes, the reference to the temperature sensor signal is the SCXI-1120 analog ground that is connected to MCHO- in the MTS mode, or to OUTREF or AOGND (with SCXI-1120 jumper W46 set in positions AB-R2 and AB-R0, respectively) in the DTS mode.

One jumper block comprises both positions; thus, you can use only one type of configuration at a time. The parking position for the jumper block is the MTEMP position (the temperature sensor is disabled until the RTEMP bit in the Configuration Register selects the sensor).

Tables 2-7 and 2-8 show the jumper settings on the SCXI-1320 and SCXI-1328 terminal blocks.

Table 2-7. Jumper Settings on the SCXI-1320 Terminal Block

Jumper Position Description

•

MTEMP

•

DTEMP

•

MTEMP

•

DTEMP

MTS mode selected; factory setting; parking position

DTS mode selected

Configuration and Installation Chapter 2

Table 2-8. Jumper Settings on the SCXI-1328 Terminal Block

Jumper Position Description

DTEMP MTEMP

•••

•

•••

DTEMP MTEMP

•

MTS mode selected; factory setting; parking position

DTS mode selected

Terminal Block Signal Connection Warnings: The chassis GND terminals on your terminal block are for grounding high

impedance sources such as a floating source (1 mA maximum). Do not use these terminals as safety earth grounds.

Shock Hazard: This unit should only be opened by qualified personnel aware of

the dangers involved. Disconnect all power before removing cover. Always install grounding screw.

To connect the signal to the terminal block, use the following procedure:

1. Remove the grounding screw of the top cover.

2. Snap out the top cover of the shield by placing a screwdriver in the groove at the bottom of the terminal block.

3. Slide the signal wires, one at a time, through the front panel strain-relief opening. You can add insulation or padding if necessary.

4. Connect the wires to the screw terminals by wrapping the wires around the screws and tightening the screws without letting the wires slip out.

5. Tighten the larger strain-relief screws.

6. Snap the top cover back in place.

7. Reinsert the grounding screw to ensure proper shielding.

8. Connect the terminal block to the SCXI-1120 front connector as explained in the Terminal Block Installation section later in this chapter.

Figure 2-9 shows a parts locator diagram for the SCXI-1320 terminal block. Figure 2-10 shows

a parts locator diagram for the SCXI-1328 terminal block.

SCXI-1120 User Manual 2-20 © National Instruments Corporation

Chapter 2 Configuration and Installation

Figure 2-9. SCXI-1320 Parts Locator Diagram

Configuration and Installation Chapter 2

Figure 2-10. SCXI-1328 Parts Locator Diagram

SCXI-1120 User Manual 2-22 © National Instruments Corporation

Chapter 2 Configuration and Installation

Terminal Block Installation To connect the terminal block to the SCXI-1120 front connector, perform the following steps:

1. Connect the SCXI-1120 front connector to its mating connector on the terminal block.

2. Make sure that the SCXI-1120 top and bottom thumbscrews do not obstruct the rear panel of the terminal block.

3. Tighten the top and bottom screws on the back of the terminal block to hold it securely in place.

Rear Signal Connector

Note: If you will be using the SCXI-1120 with a National Instruments data acquisition board

and cable assembly, you do not need to read the remainder of this chapter. If you will also be using the SCXI-1180 feedthrough panel, the SCXI-1343 rear screw terminal adapter, or the SCXI-1351 one-slot cable extender with the SCXI-1120, you should read this section.

Figure 2-11 shows the pin assignments for the SCXI-1120 rear signal connector.

Configuration and Installation Chapter 2

AOGND

MCH0+ MCH1+ MCH2+ MCH3+ MCH4+ MCH5+ MCH6+ MCH7+

OUTREF

SERDATIN

DAQD*/A

SLOT0SEL*

DIG GND

1 2 3 4

5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

AOGND MCH0MCH1-

MCH2MCH3MCH4MCH5MCH6MCH7-

DIG GND SERDATOUT

SERCLK

RSVD

35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

SCANCLK

Figure 2-11. SCXI-1120 Rear Signal Connector Pin Assignment

SCXI-1120 User Manual 2-24 © National Instruments Corporation

Chapter 2 Configuration and Installation

Rear Signal Connector Signal Descriptions

Pin Signal Name Description

1-2 AOGND Analog Output Ground – Connected to the analog

reference when jumper W46 is in position AB-R0.

3-18 MCH0± through MCH7± Analog Output Channels 0 through 7 – Connects to

the data acquisition board differential analog input channels.

19 OUTREF Output Reference – Serves as the reference node for

the analog output channels and the temperature sensor–in the DTS mode–in the Pseudodifferential Reference mode. It should be connected to the analog input sense of the NRSE data acquisition board.

24, 33 DIG GND Digital Ground – Supply the reference for data

acquisition board digital signals and are tied to the module digital ground.

25 SERDATIN Serial Data In – Taps into the SCXIbus MOSI line

to provide serial input data to a module or Slot 0.

26 SERDATOUT Serial Data Out – Taps into the SCXIbus MISO line

to accept serial output data from a module.

27 DAQD*/A Data Acquisition Board Data/Address Line – Taps

into the SCXIbus D*/A line to indicate to the module whether the incoming serial stream is data or address information.

29 SLOT0SEL* Slot 0 Select – Taps into the SCXIbus INTR* line

to indicate whether the information on MOSI is being sent to a module or Slot 0.

36 SCANCLK Scan Clock – Indicates to the SCXI-1120 that a

sample has been taken by the data acquisition board and causes the SCXI-1120 to change channels.

37 SERCLK Serial Clock – This signal taps into the SCXIbus

SPICLK line to clock the data on the MOSI and

MISO lines. 43 RSVD Reserved. All other pins are not connected. See the Timing Requirements and Communication Protocol section later in this chapter for more

detailed information on timing.

Configuration and Installation Chapter 2

The signals on the rear signal connector can be classified as analog output signals, digital I/O signals, or timing I/O signals. Signal connection guidelines for each of these groups are given in the following section.

Analog Output Signal Connections

Pins 1 through 19 of the rear signal connector are analog output signal pins. Pins 1 and 2 are AOGND signal pins. AOGND is an analog output common signal that is routed through jumper W46 to the analog reference on the SCXI-1120. You can use these pins for a general analog power ground tie point to the SCXI-1120 if necessary. In particular, when using differential input data acquisition boards, such as the MIO-16 board, it is preferable to leave jumper W46 in its factory setting or in position AB-R1 to avoid ground loops. With data acquisition boards that are configured for referenced single-ended (RSE) measurements, jumper W46 should be in position AB-R0 to connect the SCXI-1120 analog ground reference to the data acquisition analog ground. Pin 19 is the OUTREF pin, and is connected internally to the analog reference when jumper W46 is in position AB-R2. Pins 3 through 18 are the analog output channels of the SCXI-1120. Pins 3 and 4, or MCH0±, are a multiplexed output of all eight channels and the temperature sensor output. Pins 5 through 18, or MCH1± through MCH7±, are a parallel connection of channels 1 through 7 to the rear signal connector. Pin 18 is a direct connection to the temperature sensor when jumper W41 is in position 3. Notice that the temperature sensor is located on the terminal block. For further details on configuring the temperature sensor output, refer to the SCXI-1320 and SCXI-1328 Terminal Blocks section earlier in this chapter.

Warning: The SCXI-1120 analog outputs are not overvoltage protected. Applying external

voltage to these outputs can result in damage to the SCXI-1120. National Instruments is not liable for any damages resulting from such signal connections.

Note: The SCXI-1120 analog outputs are short-circuit protected. Digital I/O Signal Connections

Pins 24 through 27, 29, 33, 36, 37, and 43 constitute the digital I/O lines of the rear signal connector. They are divided into three categories–the digital input signals, the digital output signals, and the digital timing signals.

The digital input signals are pins 24, 25, 27, 29, 33, and 37. The data acquisition board uses these pins to configure the SCXI module that is under data acquisition board control. Each digital line emulates the SCXIbus communication signals as follows:

• Pin 25 is SERDATIN and is equivalent to the SCXIbus MOSI serial data input line.

• Pin 27 is DAQD*/A and is equivalent to the SCXIbus D*/A line. It indicates to the module

whether the incoming serial stream on SERDATIN is data (DAQD*/A = 0) or address (DAQD*/A = 1) information.

• Pin 29 is SLOT0SEL* and is equivalent to the SCXIbus INTR* line. It indicates whether the

data on the SERDATIN line is being sent to Slot 0 (SLOT0SEL* = 0) or to a module (SLOT0SEL* = 1).

• Pins 24 and 33 are the digital ground references for the data acquisition board digital signals

and are tied to the module digital ground.

• Pin 37 is SERCLK and is equivalent to the SCXIbus SPICLK line and is used to clock the

serial data on the SERDATIN line into the module registers.

SCXI-1120 User Manual 2-26 © National Instruments Corporation

Chapter 2 Configuration and Installation

The digital output signal is pin 26:

• Pin 26 is SERDATOUT and is equivalent to SCXIbus MISO when jumper W43 is in

position 1.

The digital I/O signals of the SCXI-1120 match the digital I/O lines of the MIO-16 board. When used with an SCXI-1341, SCXI-1342, or SCXI-1344 cable assembly, the SCXI-1120 signals match the digital lines of the Lab-NB/Lab-PC+/Lab-LC boards and the PC-LPM-16 board, respectively. Table 2-9 lists the equivalences. For more information, consult Appendix E, SCXI-1120 Cabling.

Table 2-9. SCXIbus to SCXI-1120 Rear Signal Connector to

Data Acquisition Board Pin Equivalences

SCXIbus Line SCXI-1120

Rear Signal

MIO-16 Board Lab-NB/Lab-PC/

Lab-PC+/Lab-LC

PC-LPM-16

Connector

MOSI SERDATIN ADIO0 PB4 DOUT4 D*/A DAQD*/A ADIO1 PB5 DOUT5 INTR* SLOT0SEL* ADIO2 PB6 DOUT6 SPICLK SERCLK EXTSTROBE* PB7 DOUT7 MISO SERDATOUT BDIO0 PC1 DIN6

The digital timing signals are pins 36 and 43:

• Pin 36 is used as a clock by the SCXI-1120 to increment the MUXCOUNTER after each

conversion by the data acquisition board during scanning. This signal is referred to as SCANCLK. See Chapter 3, Theory of Operation, for a description of MUXCOUNTER.

• Pin 43 is a reserved digital input. The following specifications and ratings apply to the digital I/O lines.

Absolute maximum voltage

input rating 5.5 V with respect to DIG GND

Digital input specifications (referenced to DIG GND):

input logic high voltage 2 V minimum

input logic low voltage 0.8 V maximum

input current leakage ±1 µA maximum

Digital output specifications (referenced to DIG GND):

output logic high voltage 3.7 V minimum at 4 mA maximum

output logic low voltage 0.4 V maximum at 4 mA maximum

Configuration and Installation Chapter 2

Timing Requirements and Communication Protocol

Timing Signal The data acquisition timing signal is SCANCLK. SCANCLK is used to increment MUXCOUNTER on its rising edge. Figure 2-12 shows the

timing requirements of the SCANCLK signal. These requirements will ensure that SCANCLK is properly transmitted over TRIG0.

high

SCANCLK

low

T T

low high

Time low before rising edge 400 nsec minimum Time high before falling edge 250 nsec minimum

Figure 2-12. SCANCLK Timing Requirements

For output selection time specifications, refer to Appendix A, Specifications.

Communication Signals

This section describes the methods for communicating on the Serial Peripheral Interface (SPI) bus and their timing requirements. The communication signals are SERDATIN, DAQD*/A, SLOT0SEL*, SERDATOUT, and SERCLK. Furthermore, SS* is produced by Slot 0 according to data acquisition board programming, and SS* timing relationships will also be discussed. For information on the Slot 0 Slot-Select Register, consult Chapter 4, Register Descriptions.

The data acquisition board determines to which slot it will talk by writing a slot-select number to Slot 0. In the case of an SCXI-1001 chassis, this write also determines to which chassis the data acquisition board will talk. Writing a slot-select number is also used in programming the Slot 0 hardscan circuitry. See Chapter 5, Programming, for information on programming the Slot 0 hardscan circuitry.

The following sections detail the procedure for selecting a slot in a particular chassis. Figure 2-13 illustrates the timing of this procedure with the example case of selecting Slot 11 in Chassis 9. Notice that the factory-default chassis address for the SCXI-1000 is address 0. For information on changing the address of your chassis, consult the SCXI-1000/1001 User Manual. An SCXI-1000 chassis will respond to any chassis number.

SCXI-1120 User Manual 2-28 © National Instruments Corporation

Chapter 2 Configuration and Installation

SLOT0SEL*

SS*X

Chassis Y

SS*1 1

Chassis 9 SERCLK

SERDATIN

ss_dis

clk_wait

slot0sel*_wait

0100 110 11

Chassis ID = 9 Slot 11

ss_en

ss _ dis

_ wait

clk

slot0sel* _ wait

ss _ en

SLOT0SEL* low to SS* disabled 200 nsec maximum SLOT0SEL* low to first rising edge on SERCLK 75 nsec minimum

Last rising edge on SERCLK to SLOT0SEL* high 250 nsec minimum SLOT0SEL* high to SS* enabled 350 nsec maximum

Figure 2-13. Slot-Select Timing Diagram

To write the 16-bit slot-select number to Slot 0, follow these steps:

1. Initial conditions:

SERDATIN = don't care. DAQD*/A = don't care. SLOT0SEL* = 1. SERCLK = 1.

2. Clear SLOT0SEL* to 0. This will deassert all SS* lines to all modules in all chassis.

3. For each bit, starting with the MSB, perform the following action:

a. SERDATIN = bit to be sent. These bits are the data that are being written to the

Slot-Select Register. b. SERCLK = 0. c. SERCLK = 1. This rising edge clocks the data.

4. Set SLOT0SEL* to 1. This will assert the SS* line of the module whose slot number was written to Slot 0. If multiple chassis are being used, only the appropriate slot in the chassis whose address corresponds to the written chassis number will be selected. When no communication is taking place between the data acquisition board and any modules, you should write zero to the Slot-Select Register to ensure that no accidental writes occur.

Figure 2-14 shows the timing requirements on the SERCLK and SERDATIN signals. You must observe these timing requirements for all communications. T

is a specification of the

delay

SCXI-1120.

Configuration and Installation Chapter 2

high

SERCLK

low

SERDATIN

SERDATOUT

low

high

setup

hold

delay

setup

delay

Minimum low time 65 nsec minimum Minimum high time 400 nsec minimum SERDATIN setup time 200 nsec minimum SERDATIN hold time 200 nsec minimum SERDATOUT delay 350 nsec maximum

hold

Figure 2-14. Serial Data Timing Diagram

After the Slot-Select line to an SCXI-1120 has been asserted, you can write to its Configuration Register and read from its Module ID Register using the following protocols. The contents of the Module ID Register are reinitialized by deasserting Slot-Select. After the 32 bits of data are read from the Module ID Register, further data will be zeros until reinitialization occurs.

To write to the Configuration Register, follow these steps:

1. Initial conditions:

SS* asserted low. SERDATIN = don't care. DAQD*/A = 0 (indicates data will be written to Configuration Register). SLOT0SEL* = 1. SERCLK = 1 (and has not transitioned since SS* went low).

2. For each bit to be written:

Establish the desired SERDATIN level corresponding to this bit. SERCLK = 0. SERCLK = 1. Clock the data.

3. Pull SLOT0SEL* low to deassert the SS* line and establish conditions for writing a new slot-select number to the Slot 0 Slot-Select Register.

4. If you are not selecting another slot, you should write zero to the Slot 0 Slot-Select Register.

Figure 2-15 illustrates a write to the SCXI-1120 Configuration Register of the binary pattern:

10000011 00001111

SCXI-1120 User Manual 2-30 © National Instruments Corporation

Chapter 2 Configuration and Installation

SLOT0SEL*

SS*

SERCLK

SERDATIN

01 00001100001111

Figure 2-15. Configuration Register Write Timing Diagram

To read from the Module ID Register, follow these steps:

1. Initial conditions:

SS* asserted low. SERDATIN = don't care. DAQD*/A = 1. Make sure DAQD*/A does not go low or erroneous data will be written to the Configuration Register. SLOT0SEL* = 1. SERCLK = 1 (and has not changed since SS* went low).

2. For each bit to be read:

SERCLK = 0. SERCLK = 1. Clock the data. Read the level of the SERDATOUT line.

3. Pull SLOT0SEL* low to deassert the SS* line and establish conditions for writing a new slot-select number to the Slot 0 Slot-Select Register.

4. If you are not selecting another slot, you should write zero to the Slot 0 Slot-Select Register.

Figure 2-16 illustrates a read of the SCXI-1120 Module ID Register.

SLOT0SEL*

SS*

SERCLK

SERDATOUT

delay

010000 00000000000000000000000000

byte 0 = 4 byte 3 = 0byte 2 = 0byte 1 = 0

SS* high to SERDATOUT high 350 nsec maximum

delay

Figure 2-16. SCXI-1120 Module ID Register Timing Diagram

For further details on programming these signals, refer to Chapter 5, Programming.

Chapter 3 Theory of Operation

This chapter contains a functional overview of the SCXI-1120 module and explains the operation of each functional unit making up the SCXI-1120.

Functional Overview

The block diagram in Figure 3-1 illustrates the key functional components of the SCXI-1120.

Isolated Section

Front Connector

•

Nonisolated

Section

Input Channel 0

Input Channel 1

Input Channel 6

Input Channel 7

Temperature Sensor

SCXIbus

Digital

Interface

and

Control

•

Timing

and

Analog

Output

Stage

Rear Signal Connector

Figure 3-1. SCXI-1120 Block Diagram

Theory of Operation Chapter 3

The major components of the SCXI-1120 are as follows:

• SCXIbus connector

• Digital interface

• Digital control circuitry

• Timing and analog circuitry

The SCXI-1120 consists of eight isolated amplifier channels with gains of 1, 2, 5, 10, 20, 50, 100, 200, 500, 1,000, and 2,000. The SCXI-1120 also has a digital section for automatic control of channel scanning, temperature selection, and MUXCOUNTER clock selection.

The theory of operation of each of these components is explained in the rest of this chapter.

SCXIbus Connector

Figure 3-2 shows the pinout of the SCXIbus connector.

SCXI-1120 User Manual 3-2 © National Instruments Corporation

Chapter 3 Theory of Operation

GUARD GUARD GUARD

AB0+ GUARD GUARD GUARD

GUARD GUARD GUARD

RESET*

MISO

V-

VCHSGND CHSGND

V+ V+

+5 V

SPICLK

TRIG0

SS*

A1 B1 A2 B2 A3 B3 A4 B4 A5 B5 A6 B6 A7 B7 A8 B8 A9 B9 A10 B10 A11 B11 A12 B12 A13 B13 A14 B14 A15 B15 A16 B16 A17 B17 A18 B18 A19 B19 A20 B20 A21 B21 A22 B22 A23 B23 A24 B24

D1 C1 D2 C2 D3 C3 D4 C4 D5 C5 D6 C6 D7 C7 D8 C8 D9 C9 D10 C10 D11 C11 D12 C12 D13 C13 D14 C14 D15 C15 D16 C16 D17 C17 D18 C18 D19 C19 D20 C20 D21 C21 D22 C22 D23 C23 D24 C24

GUARD GUARD GUARD

AB0GUARD GUARD GUARD

GUARD GUARD GUARD

CHSGND

RSVD

INTR*

D*/A

V-

VCHSGND CHSGND

V+ V+

+5 V

MOSI

SCANCON

Figure 3-2. SCXIbus Connector Pin Assignment

Theory of Operation Chapter 3

SCXIbus Connector Signal Descriptions

Pin Signal Name Description

A1, B1, C1, D1, GUARD Guard – Shields and guards the analog bus lines A2, D2, A3, B3, from noise. C3, D3, A4, D4, A5, B5, C5, D5, A6, D6

B2 AB0+ Analog Bus 0+ – Positive analog bus 0 line. Used

to multiplex several modules to one analog signal.

C2 AB0- Analog Bus 0- – Negative analog bus 0 line. Used

to multiplex several modules to one analog signal.

C13-C17, A21, CHSGND Chassis Ground – Digital and analog ground B21, C21, D21 reference.

C18 RSVD Reserved. A19 RESET* Reset – When pulled low, reinitializes the module to

its power-up state. Totem pole. Input.

B19 MISO Master-In-Slave-Out – Transmits data from the

module to the SCXIbus. Open collector. I/O.

C19 D*/A Data/Address – Indicates to the module whether

address information or data information is being sent to the module on MOSI. Open collector. I/O.

D19 INTR* Interrupt – Active low. Causes data that is on

MOSI to be written to the Slot-Select Register Slot 0. Open collector. Output.

A20, B20, C20, V- Negative Analog Supply – -18.5 V to -25 V. D20

A22, B22, C22, V+ Positive Analog Supply – +18.5 V to +25 V. D22

A23, D23 +5 V +5 VDC Source – Digital power supply. B23 SPICLK Serial Peripheral Interface (SPI) Clock – Clocks the

serial data on the MOSI and MISO lines. Open collector. I/O.

C23 MOSI Master-Out-Slave-In – Transmits data from the

SCXIbus to the module. Open collector. I/O.

SCXI-1120 User Manual 3-4 © National Instruments Corporation

Chapter 3 Theory of Operation

Pin Signal Name Description (continued)

A24 TRIG0 TRIG0 – General-purpose trigger line used by the

SCXI-1120 to send SCANCLK to other modules or receive SCANCLK from other modules. Open collector. I/O.

B24 SS* Slot Select – When low, enables module

communications over the SCXIbus. Totem pole. Input.

C24 SCANCON Scanning Control – Combination output enable and

reload signal for scanning operations. Totem pole.

Input. All other pins are not connected. MOSI, MISO, SPICLK, and SS* form a synchronous communication link that conforms with

SPI using an idle-high clock and second-edge data latching. D*/A, INTR*, and RESET* are additional control signals.

When the module is being used in an SCXI-1000 or SCXI-1001 chassis, the data acquisition board, via the module rear signal connector, must tap into the open-collector backplane signal lines as a master to write to the module. The signal connections from the rear signal connector to the backplane are shown in Table 3-1.

Table 3-1. SCXIbus Equivalents for the Rear Signal Connector

Rear Signal Connector

SCXIbus Equivalent

Signal

SERDATIN MOSI DAQD*/A D*/A SLOT0SEL* INTR* Jumper W44 must be set to position 1

(Revision A and B modules only) SERCLK SPICLK SERDATOUT MISO Jumper 43 must be set to position 1

The SCXI-1120 module converts the data acquisition board signals to open-collector signals on the backplane of the SCXI chassis. In order for the data acquisition board to talk to a slot, the board must first assert the SS* for that slot. This is done by asserting INTR* low, writing a 16-bit number over MOSI corresponding to the desired slot (and chassis if an SCXI-1001 chassis is being used), and then releasing INTR* high. At this point, the SS* of the desired slot is asserted low and the data acquisition board can communicate with the module in that slot according to the SPI protocol.

Theory of Operation Chapter 3

Digital Interface

Figure 3-3 shows a diagram of the SCXI-1120 and SCXIbus digital interface circuitry.

SCXIbus

SS*

MOSI

D*/A

MISO

INTR*

SPICLK

SERDATIN

Buffered Serial Data

Digital

Interface

Buffered Digital Signal Controls

DAQD*/A

SLOT0SEL*

SERCLK

SERDATOUT

Rear Signal Connector

Figure 3-3. Digital Interface Circuitry Block Diagram

The digital interface circuitry is divided into a data acquisition section and an SCXIbus section. The SCXI-1120 connects to the SCXIbus via a 4x24 metral receptacle and to the data acquisition board via a 50-pin ribbon-cable header. The digital interface circuitry buffers the digital signals from the data acquisition board and the SCXIbus and sends signals back and forth between the data acquisition board and the SCXIbus.

SCXI-1120 User Manual 3-6 © National Instruments Corporation

Chapter 3 Theory of Operation

Digital Control Circuitry

Figure 3-4 diagrams the SCXI-1120 digital control.

Serial Data Out

Input Channel Select

Module ID Register

Configuration

Output

Stage

Control

Hardware

Control

SCANCLK

Path

Control

Scan

Figure 3-4. SCXI-1120 Digital Control

Buffered Serial Data In

Buffered Digital Control Signals

The digital control section consists of the Configuration Register and the Module ID Register. The Configuration Register is a two-byte, serial-in, parallel-out shift register. Data is received on

the MOSI line from either Slot 0 or the data acquisition board when SS* is enabled and D*/A indicates data transfer (D*/A low). The Configuration Register provides channel selection and configures the SCXI-1120 for scanning options. All the control bits are fed into a latch before being routed to the rest of the module. The channel-select bits are taken directly from the shift register. Complete descriptions of the register bits are given in Chapter 4, Register Descriptions. Writes to the Configuration Register require the following steps:

1. SS* goes low, enabling communication with the board.

2. D*/A goes low, indicating that the information sent on the MOSI line is data.

3. The serial data is available on MOSI and SPICLK clocks it into the register.

4. SS* goes high and D*/A goes high, indicating an end of communication. This action latches the Configuration Register bits.

When the SCXIbus is reset, all bits in the Configuration Register are cleared.

Theory of Operation Chapter 3

The Module ID Register connects to MISO on the SCXIbus. The Module ID Register is an 8-bit, parallel/serial-in, serial-out shift register and an SPI communication adapter. The contents of the Module ID Register are written onto MISO during the first four bytes of transfer after SS* has been asserted low. Zeros are written to MISO thereafter until SS* is released and reasserted. The SCXI-1120 module ID is hex 00000004.

Analog and Timing Circuitry

The SCXIbus provides analog power (±18.5 VDC) that is regulated on the SCXI-1120 to ±15 VDC, a guard, an analog bus (AB0±), and a chassis ground (CHSGND). AB0± buses the

SCXI-1120 output to other modules or receives outputs from other modules via the SCXIbus. The guard guards the analog bus and can be connected via jumper W46 to the analog ground reference or can be left floating (a connection can be made by another board).

The data acquisition board analog input and timing is the interface between the SCXI-1120 output and the data acquisition board. This is described in the following section.

Analog Input Channels

Figure 3-5 is a diagram of the analog input block.

SCXI-1120 User Manual 3-8 © National Instruments Corporation

Chapter 3 Theory of Operation

Input Channel 0

LPF

To Output

Stage

Input Channel 1

LPF

To Output

Stage

Input Channel 2

LPF

To Output

Stage

Input Channel 3

LPF

To Output

Stage

Input Channel 4

Front Connector

LPF

Input Channel 5

Input Channel 6

Input Channel 7

MTEMP DTEMP

LPF

To Output

Stage

Figure 3-5. Analog Input Block Diagram

Theory of Operation Chapter 3

The analog input consists of eight isolated single-ended noninverting amplifiers. In addition, lowpass filtering is available at the inputs. You can jumper select one of two bandwidths, 10 kHz or 4 Hz. The amplifier gain is divided into two stages, a first stage providing gains of 1, 10, 50, and 100, and a second stage providing gains of 1, 2, 5, 10, and 20. Each channel is configurable to a different bandwidth and gain.

Use the following formula to determine the overall gain of a given amplifier input channel:

total

= G

1st

x G

2nd

where G

is the overall gain and G

total

and G

1st

are the first- and second-stage gains. Here it is

2nd

important to note that the choice of gain in each stage will affect the amplifier bandwidth. To determine the bandwidth of a given gain stage use the following formula:

BW = GBWP/G

where BW is a given amplifier stage bandwidth, GBWP is the gain bandwidth product (typically 800 kHz), and G is the gain at this stage. This BW might be of concern at high first-stage gains such as 50 and 100. In this case, the first-stage amplifier has a BW equal to 16 kHz and 8 kHz, respectively. Due to this decrease in the amplifier bandwidth, you will notice a decrease in the channel overall bandwidth, but a better noise immunity. If this bandwidth limitation is unacceptable, you should spread the gains over both stages, thus increasing the BW of each amplifier stage. This will introduce, in most cases, a negligible effect on the channel bandwidth. For example, to achieve a gain of 100, use G G

= 50 and G

1st

2nd

= 20.

= 10 and G

1st

= 10; for a gain of 1,000, use

2nd

All the amplifier input channels are overvoltage protected to 240 Vrms with power on or off. The isolated amplifiers fulfill two purposes on the SCXI-1120 module. They convert a small

signal riding on a high common-mode voltage into a single-ended signal with respect to the SCXI-1120 chassis ground. With this conversion, the input analog signal can be extracted from a high common-mode voltage or noise before being sampled and converted by the data acquisition board. The isolated amplifier also amplifies and conditions an input signal, which results in an increase in measurement resolution and accuracy.

After isolation, further filtering is available to increase the noise immunity of the amplifier channel. It is important to note that the overall amplifier bandwidth is determined by both filtering stages, so to achieve the required bandwidth, both filtering sections should be set the same, as indicated in Chapter 2, Configuration and Installation.

Calibration

Calibration Equipment Requirements

For best measurement results, calibrate the SCXI-1120 so that its offset is adjusted to 0 ± 3 mV RTO and 0 ± 6 µV RTI. No special equipment is needed other than a regular voltmeter with the following specifications.

• Range: ± 30 mV to ±300 mV

• Resolution: 3 1/2 digits or greater

SCXI-1120 User Manual 3-10 © National Instruments Corporation

Chapter 3 Theory of Operation

A multiranging 3 1/2-digit digital multimeter can provide you with the necessary function as described previously. We will refer to the measuring instrument as a digital multimeter (DMM).

Each channel on the SCXI-1120 has two potentiometers dedicated for calibration. One potentiometer is used to null the output offset; the other is used to null the input offset.

Offset Null Adjust

To null the offset of the amplifier channels, complete the following steps:

1. Set the DMM range to the smallest range that can measure ±3 mV.

2. Short the inputs of the DMM together and then to chassis ground.

3. Record the measurement indicated by the DMM display. This is the DMM inherent offset and it should be subtracted from subsequent measurements.

4. Short the desired channel inputs together and then to chassis ground.

5. Set the amplifier gain to 1.

6. Connect the amplifier output to the DMM. Make sure that the DMM can achieve the accuracy and resolution you need.

7. Adjust the output potentiometer of the desired channel until the output is 0 ± 3 mV.

8. Set the DMM range to the smallest range that can measure ±6 mV.

9. Set the amplifier gain to 1,000.

10. Adjust the input potentiometer of the desired channel until the output is 0 ± 6 mV.

11. Go to the next channel. To avoid erroneous results when nulling the amplifier, follow these steps in the order indicated. You may seal the potentiometers after calibration with antisabotage lacquer to avoid tampering

with the calibration. Table 3-2 lists the potentiometer reference designators that correspond to each channel.

Theory of Operation Chapter 3

Table 3-2. Calibration Potentiometers Reference Designators

Input Channel Amplifier Channel

Number Input Null Output

Null

0 R8 R24 1 R10 R25 2 R12 R26 3 R14 R27 4 R16 R28 5 R18 R29 6 R20 R30 7 R21 R31

Analog Output Circuitry

Figure 3-6 shows the SCXI-1120 analog output circuitry.

Channel 0

•

Channel 7

MTEMP

Output Stage and

Hardware Scan

Control

Analog

Reference

Output

Mux

SCXIbus

DTEMP

AB0

Switch

Channel 1

From

Channel 6

From

Channel 7

Buffer

MCH1+From

•

MCH6+

MCH7+

W41

•

Output

Stage

Control

MCH1-

MCH6-

•

MCH0+

MCH0-

Rear Signal Connector

MCH7-

Figure 3-6. Analog Output Circuitry

SCXI-1120 User Manual 3-12 © National Instruments Corporation

Chapter 3 Theory of Operation

The SCXI-1120 output circuitry consists of a buffered-output multiplexer and channel-select hardware. The channel-select hardware consists of a three-bit counter, MUXCOUNTER. This counter is needed when the board is operating in the Multiplexed-Output mode. The counter output is sent to the output multiplexer address pins to determine which of the eight channels is to be connected to MCH0. In the Single-Channel Read mode, the MUXCOUNTER is loaded with the desired channel number. In the Scanning mode, the counter is loaded with the first channel to be read. During the scan, the counter is clocked by SCANCLK from the data acquisition board, or TRIG0 from the SCXIbus, depending on the state of the CLKSELECT bit in the Configuration Register. During scanning operations, the MUXCOUNTER is reloaded with the channel value stored in the Configuration Register when SCANCON is high (inactive), and will count upwards on each rising clock edge when SCANCON is low (active). In the Parallel-Output mode, the MUXCOUNTER is disabled and its output indicates binary 00; thus, amplifier Channel 0 is selected at the output multiplexer and is connected to MCH0. The seven other channels are hardwired to MCH1 through MCH7 on the rear signal connector.

The output multiplexer multiplexes all eight amplifier outputs and the temperature-sensor reading provided on the MTEMP line. To read the temperature sensor when it is multiplexed with the other input channels, the RTEMP bit of the Configuration Register must be set high. This measurement is only software controlled. For hardware control of the temperature sensor reading, connect the temperature sensor to pin 18 on the rear signal connector as described in Chapter 2, Configuration and Installation. The multiplexer output connects to the MCH0± and is connected to the data acquisition board analog channel input. In the case of the MIO data acquisition boards, MCH0± on the rear signal connector corresponds to ACH0 and ACH8.

Furthermore, the multiplexed output of the SCXI-1120 can be bused, via switches to AB0± on the SCXIbus, to other modules. When you use multiple modules, it is possible to bus the module output via AB0 to the module that connects to the data acquisition board. In this case, the AB0 switches of all the modules are closed, whereas the output multiplexer of all the modules, except the one being read, are disabled. Refer to chapters 2 and 5 for further details on how to configure and program multiple modules.

In addition to the Multiplexed-Output mode described in the previous paragraph, it is possible to operate the SCXI-1120 in the Parallel-Output mode. In this mode, you need no software–other than the software used with your data acquisition board–to control the scanning of the eight channels or to perform a single read. To access the temperature sensor in this mode, configure the temperature sensor in the DTS mode. At power up or reset, amplifier Channel 0 is selected on the output multiplexer, and thus connects to MCH0. The other seven amplifier channels are hardwired to the rear signal connector. Notice that when the Multiplexed-Output mode is selected, pins 5 through 18 on the rear signal connector are still driven by the SCXI-1120. The SCXI-1120 outputs on the rear signal connector are short-circuit protected.

Refer to the following Scanning Modes section for further details on how to scan the SCXI-1120 channels.

Scanning Modes

The SCXI-1120 has four basic types of scanning modes–single-module parallel scanning, single-module multiplexed scanning, multiple-module multiplexed scanning, and multiple-chassis scanning, which is possible only with the SCXI-1001 chassis. For additional information, consult Chapter 2, Configuration and Installation, Chapter 5, Programming, your

Theory of Operation Chapter 3

data acquisition board user manual, or your SCXI chassis user manual. If you need more information, contact National Instruments.

Single-Module Parallel Scanning

Single-module parallel scanning is the simplest scanning mode. Directly cable the SCXI-1120 to the data acquisition board as shown in Figure 3-7. In this configuration, each analog signal has its own channel. Timing signals are not necessary for this type of scanning because the module provides all channels to the data acquisition board at all times. You can implement single-module parallel scanning with any data acquisition board that is appropriately cabled to the SCXI-1120.

Eight Isolated

Floating

Single-Ended

Inputs

CH0 CH1 CH2 CH3 CH4 CH5 CH6 CH7

SCXI-1120

Cable Assembly

MCH0 MCH1 MCH2 MCH3 MCH4 MCH5 MCH6 MCH7

Data Acquisition Board

Analog Input 0 Analog Input 1 Analog Input 2 Analog Input 3 Analog Input 4 Analog Input 5 Analog Input 6 Analog Input 7

Figure 3-7. Single-Module Parallel Scanning

Multiplexed Scanning

Only the MIO-16 data acquisition boards support multiplexed scanning on the SCXI-1120. During multiplexed scanning, a module sends the SCANCLK signal to Slot 0 over the TRIG0 backplane line, and Slot 0 sends SCANCON signals to each module. Each module uses its SCANCON signal to reload MUXCOUNTER and to determine when the SCXI-1120 output is enabled. Slot 0 contains a module scan list first-in-first-out (FIFO) memory chip, similar to the Channel/Gain FIFO on an MIO-16 board, except that instead of having a channel number and gain setting for each entry, the Slot 0 FIFO contains a slot number and a sample count for each entry. The list in Slot 0 will determine which module is being accessed and for how many samples. It is important that you make sure that the lists on the data acquisition board and Slot 0 are compatible so that the samples are acquired as intended. See your SCXI chassis manual for more information.

Single-Module Multiplexed Scanning

Single-Module Multiplexed Scanning (Direct) This is the simplest multiplexed-scanning mode. Directly cable the SCXI-1120 to the data

acquisition board as shown in Figure 3-8. The module sends SCANCLK onto TRIG0, and Slot 0 sends SCANCON back to the module. SCANCON will be low at all times during the scan

SCXI-1120 User Manual 3-14 © National Instruments Corporation

Chapter 3 Theory of Operation

except during changes from one Slot 0 scan list entry to the next, when SCANCON pulses high to make the MUXCOUNTER reload its starting channel. Notice that although you are using only a single module, you can put many entries with different counts in the Slot 0 FIFO, so that some channels are read more often than others. You cannot change the start channel in the module Configuration Register during a scan.

SCXI-1000 or SCXI-1001 Chassis

SLOT 0

SCANCON X

TRIG0

Eight Isolated

Floating

Single-Ended

Inputs

SLOT X

SCXI-1120

SCANCLK

MCH0

Data Acquisition Board

Cable

Assembly

Timing Output

Analog Input

Figure 3-8. Single-Module Multiplexed Scanning (Direct)

Single-Module Multiplexed Scanning (Indirect) In this mode, the SCXI-1120 is not directly cabled to the data acquisition board. Instead, you

connect another module to the data acquisition board, and the analog output of the SCXI-1120 is sent over Analog Bus 0, through the intermediate module, and then to the data acquisition board. The SCXI-1120 receives its MUXCOUNTER clock from TRIG0, which is sent by the intermediate module, as shown in Figure 3-9. Slot 0 operation is the same for direct connection scanning.

SCXI-1000 or SCXI-1001 Chassis

SCANCON X

TRIG0

Data Acquisition Board

Cable

Assembly

Timing Output Analog Input

SLOT 0

SCXI-1120

SLOT X

SCANCLK

MCH0

Other

Module

Analog Bus 0

Figure 3-9. Single-Module Multiplexed Scanning (Indirect)

Multiple-Module Multiplexed Scanning

In this mode, all the modules tie into Analog Bus 0 and SCANCON enables the output of their amplifiers. The module that is directly cabled to the data acquisition board sends SCANCLK

Theory of Operation Chapter 3

onto TRIG0 for the other modules and Slot 0, as shown in Figure 3-10. The scan list in Slot 0 is programmed with the sequence of modules and the number of samples per entry.

SCXI-1000 or SCXI-1001 Chassis

SCANCON X

Data Acquisition Board

Timing

Output

Analog

Input

Cable Assembly

SCANCON A

SLOT 0

SCANCON B

SLOT A

TRIG0

SCXI Module

SLOT B

SCANCLK MCH0

SCXI ModuleSCXI Module

SLOT X

Analog Bus 0

Figure 3-10. Multiple-Module Multiplexed Scanning

Multiple-Chassis Scanning

In this mode, you attach each SCXI-1001 chassis to a daisy chain of cable assemblies and multichassis adapter boards, as shown in Figure 3-11. You program each chassis separately, and each chassis occupies a dedicated channel of the data acquisition board. Within each chassis, scanning operations act as if the other chassis are not being used, with one exception–you must program the Slot 0 scan list in each chassis with dummy entries of Slot 13 to fill the samples when the data acquisition board will be sampling another chassis or data acquisition board channel. This will keep the chassis synchronized. Notice that you can only perform multiple-chassis scanning with the SCXI-1001 chassis and MIO-16 data acquisition boards. See Chapter 5, Programming, for more information on multiple-chassis scanning. See Appendix E, SCXI-1120 Cabling, for more information on the necessary cable accessories for multichassis scanning.

Data Acquisition Board

Input Ch. N

Input Ch. 1 Input Ch. 0

Timing Output

Cable

Assembly

Multichassis

Adapter

Cable

Assembly

Multichassis

Adapter

Cable

Assemblies

Multichassis

Adapter

Chassis 2Chassis 1

Chassis 2 Chassis

Chassis N

Figure 3-11. Multiple-Chassis Scanning

SCXI-1120 User Manual 3-16 © National Instruments Corporation

Chapter 4 Register Descriptions

This chapter describes in detail the SCXI-1120 Module ID Register, the Configuration Register, the Slot 0 registers, and multiplexer addressing.

Note: If you plan to use a programming software package such as NI-DAQ, LabWindows, or

LabVIEW with your SCXI-1120 board, you do not need to read this chapter.

Register Description

Register Description Format

This register description chapter discusses each of the SCXI-1120 registers and the Slot 0 registers. A detailed bit description of each register is given. The individual register description gives the type, word size, and bit map of the register, followed by a description of each bit.

The register bit map shows a diagram of the register with the MSB shown on the left (bit 15 for a 16-bit register, bit 7 for an 8-bit register), and the LSB shown on the right (bit 0). A rectangle is used to represent each bit. Each bit is labeled with a name inside its rectangle. An asterisk (*) after the bit name indicates that the bit is inverted (negative logic). The Module ID register has a unique format and is described in the Module ID Register section.

In many of the registers, several bits are labeled with an X, indicating don't care bits. When you write to a register, you may set or clear these bits without effect.

SCXI-1120 Registers

The SCXI-1120 has two registers. The Module ID Register is a four-byte, read-only register that contains the Module ID number of the SCXI-1120. The Configuration Register is a 16-bit, write-only register that controls the functions and characteristics of the SCXI-1120.

Module ID Register

The Module ID Register contains the 4-byte module ID code for the SCXI-1120. This code number will be read as the first four bytes on the MISO line whenever the module is accessed. The bytes will appear least significant byte first. Within each byte, data is sent out MSB first. Additional data transfers will result in all zeros being sent on the MISO line. The Module ID Register is reinitialized to its original value each time the SCXI-1120 is deselected by the SS* signal on the backplane.

Type: Read-only Word Size: 4-byte Bit Map:

Byte 0

76543210

00000100

Byte 1

76543210

00000000

Byte 2

76543210

00000000

Byte 3

76543210

00000000

SCXI-1120 User Manual 4-2 © National Instruments Corporation

Chapter 4 Register Descriptions

Configuration Register

The Configuration Register contains 16 bits that control the functions of the SCXI-1120. When SS* is asserted (low) and D*/A indicates data (low), the register will shift in the data present on the MOSI line, bit 15 first, and then latch it when the SCXI-1120 is deselected by the SS* signal on the backplane. The Configuration Register initializes to all zeros when the SCXI chassis is reset or first turned on.

Type: Write-only Word Size: 16-bit Bit Map:

15 14 13 12 11 10 9 8

CLKOUTEN CLKSELECT X X X CHAN2 CHAN1 CHAN0

76543210

X X RTEMP RSVD SCANCLKEN SCANCONEN AB0EN FOUTEN*

Bit Name Description

15 CLKOUTEN Scan Clock Output Enable – This bit determines whether

the SCANCLK signal from the rear signal connector is sent out, in inverted form, to the TRIG0 backplane signal. If CLKOUTEN is set to 1, SCANCLK* is transmitted on TRIG0. If CLKOUTEN is cleared to 0, SCANCLK* is not transmitted on TRIG0.

14 CLKSELECT Scan Clock Select – This bit determines whether the

SCXI-1120 uses SCANCLK or the inverted form of TRIG0 to clock the MUXCOUNTER for the purposes of scanning through the analog channels. If CLKSELECT is cleared to 0, SCANCLK is used to clock MUXCOUNTER. If CLKSELECT is set to 1, TRIG0* is used as the source to

clock MUXCOUNTER. 13-11, 7-6 X Don't care bits – Unused. 10-8 CHAN<2..0> Channel Select – These bits determine the channel number

(zero to seven) that is loaded into the MUXCOUNTER to

determine the analog channel to be read during a single

read, or the starting channel on the module for a scanned

data acquisition. CHAN2 is the MSB.

Bit Name Description (continued)

5 RTEMP Read Temperature – This bit determines whether the

selected channel output or the MTEMP signal is driven

onto the MCH0± pins of the rear signal connector. If

RTEMP is cleared to 0, the selected channel output is used

as the module output. If RTEMP is set to 1, the MTEMP

signal is used as the module output. The module output

will only be driven when FOUTEN* is cleared to 0, or

SCANCON is active (low) while SCANCONEN* is

cleared. 4 RSVD Reserved – This bit should always be written to 0. 3 SCANCLKEN Scan Clock Enable – This bit determines whether

MUXCOUNTER will increment on each clock signal (the

clock source is determined by CLKSELECT), or keep its

loaded value. If SCANCLKEN is set to 1,

MUXCOUNTER will be clocked during scans. If

SCANCLKEN is cleared to 0, MUXCOUNTER will not be

clocked. 2 SCANCONEN Scan Control Enable – This bit, when set to 1, enables the

SCANCON signal. 1 AB0EN Analog Bus 0 Enable – This bit determines whether Analog

Bus 0 on the SCXIbus drives MCH0 on the rear signal

connector. If AB0EN is cleared to 0, Analog Bus 0 doesnot

drive MCH0. If AB0EN is set to 1, Analog Bus 0 + drives

MCH0+ through a buffer and a Analog Bus 0 - is connected

to MCH0-. 0 FOUTEN* Forced Output Enable – This bit determines whether the

module will drive the MCH0± pins on the rear signal

connector with either the selected channel output or the

MTEMP signal, depending on the state of RTEMP. If

FOUTEN* is cleared to 0, the MCH0± pins will be driven

through a buffer by the selected channel output or the

MTEMP line. If FOUTEN* is set to 1, the MCH0± pins

will not be driven by the selected channel output or

MTEMP, unless SCANCON is active (low) and the

SCANCONEN bit is cleared. If the selected channel output

or MTEMP is driving the output buffer, it will drive Analog

Bus 0 if AB0EN is set. If nothing is driving the output

buffer, the SCXI-1120 output will saturate.

SCXI-1120 User Manual 4-4 © National Instruments Corporation

Chapter 4 Register Descriptions

Slot 0 Register Descriptions

Slot 0 has three registers. The Slot-Select Register is a 16-bit, write-only register that determines with which slot the data acquisition board will speak when SLOT0SEL* is released high. In the case of the SCXI-1001 chassis, the Slot-Select Register also determines in which chassis the desired slot is. The FIFO Register is a 16-bit, write-only register used for storing the Slot 0 scan list that determines the chassis scan sequence. The Hardscan Control Register (HSCR) is an 8-bit, write-only register used for setting up the timing circuitry in Slot 0. The Slot-Select Register is written to by using the SLOT0SEL* line. The HSCR and the FIFO Register are written to as if they were registers located on modules in Slots 13 and 14. You should maintain software copies of the Slot-Select Register, HSCRs, and all the Slot 0 scan lists that correspond to the writes to FIFO Registers.

If you are using multiple chassis, it is important to understand the architectural differences of the Slot-Select Register as compared to the HSCR and the FIFO Register. Although each chassis has its own physical Slot-Select Register, all are written to at the same time. The jumper settings in Slot 0 of a chassis determine with which chassis number Slot 0 is identified. From the software perspective, only one Slot-Select Register exists in a system composed of multiple chassis. The HSCR and FIFO Register, on the other hand, are unique to each chassis and you must program them separately.

Slot-Select Register

The Slot-Select Register contains 16 bits that determine which module in which chassis will be enabled for communication when the SLOT0SEL* line is high. An SCXI-1000 chassis will select the appropriate module in its chassis, regardless of the chassis number written. The Slot-Select Register will shift in the data present on the MOSI line, bit 16 first, when SLOT0SEL* is low.

Type: Write-only Word Size: 16-bit Bit Map:

15 14 13 12 11 10 9 8

X X X X X X X CHS4

76543210

CHS3 CHS2 CHS1 CHS0 SL3 SL2 SL1 SL0

Bit Name Description

15-9 X Don't care bits – Unused. 8-4 CHS<4..0> Chassis Bit 4 through 0 – These bits determine

which chassis is selected. On the SCXI-1000

chassis, these are don't care bits. 3-0 SL<3..0> Slot Bit 3 through 0 – These bits determine which

slot in the selected chassis is selected.

Chapter 4 Register Descriptions

Hardscan Control Register (HSCR)

The HSCR contains eight bits that control the setup and operation of the hardscan timing circuitry of Slot 0. To write to the HSCR, follow the procedure given in the Register Writes section in Chapter 5, Programming, using 13 as the slot number and writing eight bits to the HSCR. The register will shift in the data present on the MOSI line, bit 7 first, when Slot 13 is selected by the Slot-Select Register.

Type: Write-only Word Size: 8-bit Bit Map:

76543210

RSVD FRT RD ONCE HSRS* LOAD* SCANCONEN CLKEN

Bit Name Description

7 RSVD Reserved. 6 FRT Forced Retransmit – This bit, when clear, causes the scan

list in the FIFO to be reinitialized to the first entry, thus

allowing the scan list to be reprogrammed in two steps

instead of having to rewrite the entire list. When this bit is

set, it has no effect. 5 RD Read – This bit, when clear, prevents the FIFO from being

read. When set, the FIFO is being read except at the end

of a scan list entry during scanning, when reading is briefly

disabled to advance to the next scan list entry. 4 ONCE Once – When set, this bit will cause the Hardscan circuitry

to shut down at the end of the scan list circuitry during a

data acquisition. When clear, the circuitry will wrap

around and continue seamlessly with the first scan list entry

after the entry is finished. 3 HSRS* Hardscan Reset – When clear, this bit causes all the

hardware scanning circuitry, including the FIFO, to be reset

to the power up state. When set, this bit has no effect. 2 LOAD* Load – This bit, when clear, forces a loading of the Slot 0

sample counter with the output of the FIFO. When set,

this bit has no effect. 1 SCANCONEN Scan Control Enable – When set, this bit enables the

SCANCON lines. When clear, all SCANCON lines are

disabled (high). 0 CLKEN Clock Enable – When set, this bit enables TRIG0 as a

clock for the hardscan circuitry. When clear, TRIG0 is

disabled.

FIFO Register

The FIFO Register is used to add entries to the Slot 0 FIFO. The FIFO contains the Slot 0 scan list. Each entry contains a slot number to be accessed, and a count number to determine the number of samples to be taken from that slot. To write to the FIFO Register, follow the procedure given in the Register Writes section in Chapter 5, Programming, using 14 as the slot number, and writing 16 bits to the FIFO Register. The register will shift in the data present on the MOSI line, bit 7 first, when Slot 14 is selected by the Slot-Select Register. The Slot 0 scan list is created by consecutive writes to the FIFO Register. Each write creates a new entry at the end of the scan list. The maximum number of entries is 256. To clear the FIFO of all entries, clear the HSRS* bit in the HSCR.

Type: Write-only Word Size: 16-bit Bit Map:

15 14 13 12 11 10 9 8

X X X X X MOD3 MOD2 MOD1

76543210

MOD0 CNT6 CNT5 CNT4 CNT3 CNT2 CNT1 CNT0

Bit Name Description

15-11 X Don't care bits – Unused. 10-7 MOD<3..0> Module Number – The value of these bits plus one

determines the number of the slot to be accessed for this scan entry. For example, to access Slot 6, MOD<3..0> would be 0101.

6-0 CNT<6..0> Count – The value of these bits plus one determines

how many samples will be taken before the next scan list entry becomes active. A value of zero corresponds to one sample and a value of 127 corresponds to 128 samples.

Chapter 5 Programming

This chapter contains a functional programming description of the SCXI-1120 and Slot 0. Note: If you plan to use a programming software package such as NI-DAQ, LabWindows, or

LabVIEW with your SCXI-1120 board, you do not need to read this chapter.

Programming Considerations

Programming the SCXI-1120 involves writing to the Configuration Register. Programming Slot 0 involves writing to the HSCR and FIFO Register. Programming the data acquisition boards involves writes to their registers. See your data acquisition board user manual for more information. The programming instructions list the sequence of steps to take. The instructions are language independent; that is, they instruct you to write a value to a given register without presenting the actual code.

Notation

For the bit patterns to be written, the following symbols are used:

0 binary zero 1 binary one X don't care; either zero or one may be written C one of three bits used to specify the channel to be loaded into the MUXCOUNTER. This

value will either be the channel to be read for single reads, or a starting channel for scanned measurements.

The 16-bit patterns are presented MSB first, left to right.

Register Writes

This section describes how to write to the Configuration Register, HSCR, and FIFO Register, including the procedure for writing to the Slot-Select Register to select the appropriate slot. For timing specifics, refer to the Timing Requirements and Communication Protocol section in Chapter 2, Configuration and Installation. The rear signal connector pin equivalences to the different National Instruments data acquisition boards are given in Table 5-1. Also see Appendix E, SCXI-1120 Cabling. The Configuration Register, the HSCR, and the FIFO Register are write-only registers.

The different bits in these registers often control independent pieces of circuitry. There are times when you may want to set or clear a specific bit or bits without affecting the remaining bits. However, a write to one of these registers will affect all bits simultaneously. You cannot read the registers to determine which bits have been set or cleared in the past; therefore, you should maintain a software copy of these registers. You can then read the software copy to determine the status of the register. To change the state of a single bit without disturbing the remaining bits, set or clear the bit in the software copy and write the software copy to the register.

Programming Chapter 5

Table 5-1. SCXI-1120 Rear Signal Connector Pin Equivalences

SCXIbus Line SCXI-1120 Rear

Signal Connector

MIO-16 Board Lab-NB/Lab-PC/

Lab-PC+/Lab-LC

PC-LPM-16

MOSI SERDATIN ADIO0 PB4 DOUT4 D*/A DAQD*/A ADIO1 PB5 DOUT5 INTR* SLOT0SEL* ADIO2 PB6 DOUT6 SPICLK SERCLK EXTSTROBE* PB7 DOUT7 MISO SERDATOUT BDIO0 PC1 DIN6

Register Selection and Write Procedure

1. Select the slot of the module to be written to (or Slot 13 or 14). Initial conditions:

SERDATIN = X. DAQD*/A = X. SLOT0SEL* = 1. SERCLK = 1.

2. Clear SLOT0SEL* to 0. This will deassert all SS* lines to all modules in all chassis.

3. For each bit, starting with the MSB (bit 15):

a. SERDATIN = bit to be sent. These bits are the data that is being written to the

Slot-Select Register. b. Clear SERCLK to 0. c. Set SERCLK to 1. This rising edge clocks the data. (If you are using an MIO-16 board,

writing to the EXTSTROBE* register will pulse EXTSTROBE* low and then high,

accomplishing steps 3b and 3c.)

4. Set SLOT0SEL* to 1. This will assert the SS* line of the module whose slot number was written to Slot 0. If you are using multiple chassis, only the appropriate slot in the chassis whose address corresponds to the written chassis number will be selected automatically. When no communications are taking place between the data acquisition board and any modules, write zero to the Slot-Select Register to ensure that no accidental writes occur.

5. If you are writing to a Configuration Register, clear DAQD*/A to 0 (this indicates data will be written to Configuration Register). If you are writing to the HSCR or FIFO Register, leave DAQD*/A high.

6. For each bit to be written to the Configuration Register: a. Establish desired SERDATIN level corresponding to this bit. b. Clear SERCLK to 0. c. Set SERCLK to 1 (clock the data). (If you are using an MIO-16 board, writing to the

EXTSTROBE* register will pulse EXTSTROBE* low and then high, accomplishing steps 6b and 6c.)

Chapter 5 Programming

7. Pull SLOT0SEL* low to deassert the SS* line, latch the data into the Configuration Register and establish conditions for writing a new slot-select number to the Slot 0 Slot-Select Register.

8. If you are not selecting another slot, write zero to the Slot 0 Slot-Select Register. If you are selecting another slot, start at step 3.

For a timing illustration of a Configuration Register write, see Figure 2-15, Configuration Register Write Timing Diagram, which shows the proper write to configure an SCXI-1120 that is directly cabled to an MIO-16 board for multiple-module multiplexed scanning with a start channel of 3.

Initialization

The SCXI-1120 powers up with its Configuration register cleared to all zeros. You can force this state by sending an active low signal on the RESET* pin of the SCXIbus connector. In the reset state, CH0 through CH3 are routed to MCH0 through MCH3 on the rear signal connector. The module is disconnected from Analog Bus 0 and disabled from scanning.

Single-Channel Measurements

This section describes how to program the SCXI-1120, either alone or in conjunction with other modules, to make single-channel, or nonscanned, measurements.

Direct Measurements

Parallel Output To perform a parallel output measurement, you must cable the SCXI-1120 rear signal connector

to a data acquisition board with each output connected to a different data acquisition board channel. See Chapter 2, Configuration and Installation, for more information. For information on how to make the voltage measurement with your data acquisition board, consult your data acquisition board user manual. Remember to account for the gains of both the SCXI-1120 and the data acquisition board when calculating the actual voltage present at the input of the SCXI-1120.

To measure one of the eight differential input channels to the SCXI-1120, or the DTEMP line if the module has been configured appropriately, perform the following steps:

1. Write the binary pattern 00XXX000 XX000000 to the SCXI-1120 Configuration Register. Notice that this can be the RESET state.

2. Measure the voltage with the data acquisition board.

Programming Chapter 5

Multiplexed Output To perform a direct multiplexed output measurement, you must cable the SCXI-1120 rear signal

connector to a data acquisition board. See Chapter 2, Configuration and Installation, for more information. For information on how to make the voltage measurement with your data acquisition board, consult your data acquisition board user manual. Remember to account for the gains of both the SCXI-1120 and the data acquisition board when calculating the actual voltage present at the input of the SCXI-1120.

To measure one of the eight differential input channels to the SCXI-1120, perform the following steps:

1. Write the binary pattern 00XXXXCC XX000000 to the SCXI-1120 Configuration Register.

2. Measure the voltage with the data acquisition board.

To measure the voltage on the MTEMP line, perform the following steps:

1. Write the binary pattern 00XXXXXX XX100000 to the SCXI-1120 Configuration Register.

2. Measure the voltage with the data acquisition board.

Indirect Measurements

Indirect measurements involve one module sending a signal to Analog Bus 0, where it is picked up by another module and transmitted to the data acquisition board.

Measurements from Other Modules To perform measurements from other modules, you must cable the SCXI-1120 rear signal

connector to a data acquisition board. See Chapter 2, Configuration and Installation, for more information. To make a measurement from another module, perform the following steps:

1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0. For an SCXI-1120, clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0.

2. Write the binary pattern 00XXXXXX XX100011 to the SCXI-1120 Configuration Register. This step disables the SCXI-1120 from driving Analog Bus 0 and allows Analog Bus 0 to drive MCH0 through the output buffer.

3. Program the other module to drive Analog Bus 0 with the signal to be measured.

4. Measure the voltage with the data acquisition board.

Measurements from the SCXI-1120 via Another Module To perform measurements via another module, you must cable the other module rear signal

connector to a data acquisition board. The other module must be able to transfer Analog Bus 0 to the data acquisition board. See Chapter 2, Configuration and Installation, for more information.

Chapter 5 Programming

To measure one of the eight differential input channels to the SCXI-1120, perform the following steps:

1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0. For an SCXI-1120, clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0.

2. Program the other module not to drive Analog Bus 0, but to send Analog Bus 0 to the data acquisition board.

3. Write the binary pattern 00XXXCCC XX000010 to the SCXI-1120 Configuration Register.

4. Measure the voltage with the data acquisition board.

To measure the voltage on the MTEMP line, perform the following steps:

1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0. For an SCXI-1120, clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0.

2. Program the other module not to drive Analog Bus 0, but to send Analog Bus 0 to the data acquisition board.

3. Write the binary pattern 00XXXXXX XX100010 to the SCXI-1120 Configuration Register.

4. Measure the voltage with the data acquisition board.

Scanning Measurements

Programming for scanned data acquisition involves programming your data acquisition board, modules, and Slot 0. In general, the steps to be taken are as follows:

1. Perform all data acquisition board programming to the point of enabling the data acquisition.

2. Perform all module programming.

3. Program the Slot 0 hardscan circuitry.

4. Enable the data acquisition, trigger it either through software or hardware, and service the data acquisition.

The MIO boards can do all types of scanning. Lab-NB, Lab-PC, Lab-PC+, Lab-LC, and PC-LPM-16 boards support only single-module parallel scanning, and do not support any of the multiplexed scanning modes. Notice that single-module parallel scanning is typically done without any module or Slot 0 programming; only programming the data acquisition board is necessary.

Programming Chapter 5

1. Data Acquisition Board Setup Programming

The programming steps for your data acquisition board are given in your data acquisition board user manual. You should follow the instructions in the following sections:

• AT-MIO-16 User Manual

- Multiple A/D Conversions with Continuous Channel Scanning (Round Robin)

- Multiple A/D Conversions with Interval Channel Scanning (Pseudosimultaneous)

• AT-MIO-16D User Manual

- Multiple A/D Conversions with Continuous Channel Scanning (Round Robin)

- Multiple A/D Conversions with Interval Channel Scanning (Pseudosimultaneous)

• AT-MIO-16F-5 User Manual

- Posttrigger Data Acquisition with Continuous Channel Scanning

- Posttrigger Data Acquisition with Interval Channel Scanning

• AT-MIO-16X User Manual

- Continuous Channel Scanning Data Acquisition

- Interval Channel Scanning Data Acquisition

• AT-MIO-64F-5 User Manual

- Continuous Channel Scanning Data Acquisition

- Interval Channel Scanning Data Acquisition

• Lab-LC User Manual

- Programming Multiple A/D Conversions with Channel Scanning

• Lab-NB User Manual

- Programming Multiple A/D Conversions with Channel Scanning

• Lab-PC User Manual

- Programming Multiple A/D Conversions with Channel Scanning

• Lab-PC+ User Manual

- Programming Multiple A/D Conversions with Channel Scanning

- Programming Multiple A/D Conversions with Interval Scanning

- Programming Multiple A/D Conversions in Single-Channel Interval Acquisition Mode

Chapter 5 Programming

• MC-MIO-16 User Manual

- Multiple A/D Conversions with Continuous Channel Scanning (Round Robin)

- Multiple A/D Conversions with Interval Channel Scanning (Pseudosimultaneous)

• NB-MIO-16 User Manual

- Programming Multiple A/D Conversions with Channel Scanning

• NB-MIO-16X User Manual

- Multiple A/D Conversions with Continuous Channel Scanning (Round Robin)

- Multiple A/D Conversions with Interval Channel Scanning (Pseudosimultaneous)

• PC-LPM-16 User Manual

- Programming Multiple A/D Conversions with Channel Scanning

Follow the instructions in these sections through the part labeled as follows:

• Clear the A/D Circuitry and Reset the Mux Counter in the MIO board user manual (except for

the AT-MIO-16X and AT-MIO-64F-5). Do not continue to the part called Enable the Scanning Data Acquisition Operation. You will do this after you have programmed the modules and Slot 0.

• Program the Sample Counter (if you are doing continuous channel scanning) or Program the

Scan-Interval Counter (if you are doing interval channel scanning) in the AT-MIO-16X and AT-MIO-64F-5 user manuals. Do not continue to the part labeled Enable a Scanning Data Acquisition Operation or Enable an Interval Scanning Data Acquisition Operation. You will do this after you have programmed the modules and Slot 0.

Note: For multiplexed scanning with an MIO board, it is important that you follow the

instructions in the channel scanning sections, not the single-channel sections. Although you may be using only one MIO board channel, the channel scanning programming will ensure that the MIO board outputs SCANCLK, which is needed by the SCXI-1120 and Slot 0.

• Clear the A/D Circuitry in the Lab-LC User Manual. Do not continue to the part called

Program the Sample-Interval Counter. You will do this after you have programmed the modules and Slot 0.

• Clear the A/D Circuitry in the Lab-PC User Manual, the Lab PC+ User Manual, and the

PC-LPM-16 User Manual. Do not continue to the part called Start and Service the Data Acquisition Operation. You will do this after you have programmed the modules and Slot 0.

• Clear the A/D Circuitry in the Lab-NB User Manual. Do not continue to the part called

Program the Sample-Interval Counter (Counter A0). You will do this after you have

programmed the modules and Slot 0.

Programming Chapter 5

Counter 1 and SCANDIV All MIO boards can operate their data acquisition board scan lists in two ways–they can acquire

one sample per data acquisition board scan list entry; or they can acquire N samples per data acquisition board scan list entry, where N is a number from 2 to 65,535 that is programmed in Counter 1. This second method of operation is especially useful when the data acquisition board scan list length is limited to 16 entries, as it is on all MIO boards except the AT-MIO-16F-5, which can have up to 512 entries. Because you can multiplex many SCXI-1120s in one chassis to one MIO board channel, often the simplest way to program the MIO board is to use only one data acquisition board scan list entry, and make N the total number of samples to be taken on all modules in one scan. Check your MIO board user manual for limitations in the data acquisition board scan list format.

To program the MIO board to take N samples per data acquisition board scan list entry, perform the following additional programming steps at the end of the Enable the Scanning Data Acquisition Operation section in the appropriate data acquisition board user manual:

1. Write FF01 to the Am9513 Command Register to select Counter 1 Mode Register.

2. Write 0325 (hex) to the Am9513 Data Register to store Counter 1 Mode Value for most MIO boards. For the AT-MIO-16F-5, and the AT-MIO-16X, and the AT-MIO-64F-5, write 1325 (hex).

3. Write FF09 to the Am9513 Command Register to select Counter 1 Load Register.

4. Write the number of samples to be taken per scan list entry (2 to 65,535) to the Am9513 Data Register to load Counter 1.

5. Write FF41 to the Am9513 Command Register to load Counter 1.

6. Write FFF1 to the Am9513 Command Register to step Counter 1.

7. Write FF21 to the Am9513 Command Register to arm Counter 1.

8. Set the SCANDIV bit in Command Register 1.

2. Module Programming

This section describes the programming steps for various scanning possibilities.

Single-Module Parallel Scanning To perform single-module parallel scanning, you must cable the SCXI-1120 rear signal

connector to a data acquisition board with each output connected to a different data acquisition board channel. See Chapter 2, Configuration and Installation, for more information.

To program the SCXI-1120 for single-module parallel scanning, write the binary pattern 00XXXX00 XX000000 to the SCXI-1120 Configuration Register. Notice that this can be the RESET state.

Chapter 5 Programming

Single-Module Multiplexed Scanning (Direct) To perform simple channel scanning, you must cable the SCXI-1120 to a data acquisition board.

See Chapter 2, Configuration and Installation, for more information. To program the module for scanned-channel measurements, write the binary pattern 10XXXCCC

XX001101 to the SCXI-1120 Configuration Register. CCC represents the starting channel number.

Single-Module Multiplexed Scanning (Indirect) To indirectly scan a module, send the output of the scanned module onto Analog Bus 0, where it

is picked up by another module and transmitted to the data acquisition board.

Channel Scanning from Other Modules. To scan measurements from other modules, you must cable the SCXI-1120 to a data acquisition board. See Chapter 2, Configuration and Installation, for more information. The module programming steps are as follows:

1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0. For an SCXI-1120, clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0.

2. Write the binary pattern 10XXXXXX XX100011 to the SCXI-1120 Configuration Register. This step disables the SCXI-1120 from driving Analog Bus 0 and allows Analog Bus 0 to drive MCH0 through the output buffer.

3. Program the other module to be scanned.

Channel Scanning from the SCXI-1120 via Another Module. To scan the SCXI-1120 via other modules, you must cable the other module to a data acquisition board, and the other module must be able to transfer Analog Bus 0 to the data acquisition board. The other module must also be able to send a SCANCLK*-compatible signal on TRIG0. See Chapter 2, Configuration and Installation, for more information. The module programming steps are as follows:

1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0. For an SCXI-1120, clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0.

2. Program the other module not to drive Analog Bus 0, but to send Analog Bus 0 to the data acquisition board. Also program the other module to send a SCANCLK*-compatible signal to TRIG0.

3. Write the binary pattern 01XXXCCC XX001111 to the SCXI-1120 Configuration Register, where CCC is the starting channel number.

Multiple-Module Multiplexed Scanning To scan multiple modules, you must connect one module to the data acquisition board, and the

module must be able to transfer Analog Bus 0 to the data acquisition board. This module must

Programming Chapter 5

also be able to send a SCANCLK*-compatible signal on TRIG0. See Chapter 2, Configuration and Installation, for more information. The module programming steps are as follows:

1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0. For an SCXI-1120, clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0.

2. Program the module that is connected to the data acquisition board to connect Analog Bus 0 to the data acquisition board but not drive Analog Bus 0 unless it is receiving an active low signal on SCANCON. Also program the module to send a SCANCLK*-compatible signal onto TRIG0. If this module is an SCXI-1120, this programming is accomplished by writing the binary pattern 10XXXCCC XX001111 to its Configuration Register.

Note: If this module is an SCXI-1120 and is not going to be scanned (it is just being used as

an interface), write a 0 to bit 2 (SCANCONEN) in the Configuration Register. The start channel bits become don't care bits.

3. Program the other modules to be used in the scan to connect their outputs to Analog Bus 0 but not drive Analog Bus 0 unless receiving an active low signal on SCANCON. Also program the modules to use TRIG0 as their clock source. For SCXI-1120 modules, this programming is accomplished by writing the binary pattern 01XXXCCC XX001111 to their Configuration Registers.

Multiple-Chassis Scanning To scan modules on multiple chassis, you must use the SCXI-1001 chassis. The cable from the

data acquisition board must bus the digital lines to one module on each chassis. Additionally, the cable must provide each chassis with its own analog channel. The data acquisition board must be able to take several readings at a time on a given channel before accessing a new channel. See the Counter 1 and SCANDIV subsection of the 1. Data Acquisition Board Setup Programming section earlier in this chapter. You can use the MIO-16 boards, in conjunction with the SCXI-1350 multichassis adapter, for multichassis scanning.

For each chassis, program the modules according to the appropriate mode of operation, disregarding the fact that other chassis will be involved.

For example, you want to scan thirteen modules. Twelve modules are in one chassis, and the thirteenth is in the second chassis and is to be scanned through a fourteenth module that is cabled to the data acquisition board but is not involved in the scan. Program the twelve modules in the first chassis according to the steps in the previous Multiple-Module Multiplexed Scanning section, and program the thirteenth and fourteenth modules according to Channel Scanning from the SCXI-1120 via Another Module earlier in this chapter.

3. Programming the Slot 0 Hardscan Circuitry

The following section describes how to program the Slot 0 circuitry for scanning operations. For a more detailed description of the Slot 0 scanning circuitry, consult the SCXI-1000/1001 User Manual. Descriptions of the Slot 0 registers are in the Slot 0 Register Descriptions section of Chapter 4, Register Descriptions. It is not necessary to read this section if you are performing single-module parallel scanning.

Chapter 5 Programming

To program the hardscan circuitry, perform the following steps:

1. Write binary 0000 0000 to the HSCR.

2. Write binary 0000 1000 to the HSCR.

3. Write the Slot 0 scan list to the FIFO.

4. Write binary 0010 1100 to the HSCR.

5. Write binary 101S 1100 to the HSCR.

6. Write binary 101S 1110 to the HSCR.

7. Write binary 101S 1111 to the HSCR.

To program the hardscan circuitry to use the current scan list, perform the following steps:

1. Write binary 0000 1000 to the HSCR.

2. Write binary 0100 1000 to the HSCR.

3. Write binary 0000 1000 to the HSCR.

4. Write binary 0010 1100 to the HSCR.

5. Write binary 101S 1100 to the HSCR.

6. Write binary 101S 1110 to the HSCR.

7. Write binary 101S 1111 to the HSCR.

In the preceding steps:

S = 0 if you want the scanning to repeat when the end of the list is reached. S = 1 if you want the circuitry to shut down after a single scan.

When you are writing multiple entries to the same register, for example, repetitive writes to the HSCR or several FIFO entries, it is important that SS*13 or SS*14 go inactive (high) between each entry. Select another slot or toggle the SLOT0SEL* line to temporarily deassert the appropriate SS* line.

If consecutive scan list entries access an SCXI-1120, the module will reload the MUXCOUNTER with the starting channel after each entry. Thus, two entries with counts of four for one module will yield different behavior than one entry with a count of eight.

For multiple-chassis scanning, program each Slot 0 with dummy entries to fill the sample counts when the data acquisition board is accessing other chassis. Use Slot 13 as the dummy entry slot.

See Example 3 at the end of this chapter.

Programming Chapter 5

4. Acquisition Enable, Triggering, and Servicing

At this point, you should now continue from where you left off in the 1. Data Acquisition Board Setup Programming section of this chapter. Perform the following steps given in your data

acquisition board user manual.

• MIO board user manual

- Enable the scanning data acquisition operation.

- Apply a trigger.

- Service the data acquisition operation.

• Lab-PC User Manual, Lab-PC+ User Manual, and PC-LPM-16 User Manual

- Start and service the data acquisition operation.

• Lab-LC User Manual

- Program the sample-interval counter.

- Service the data acquisition operation.

• Lab-NB User Manual

- Program the sample-interval counter (Counter A0).

- Service the data acquisition operation.

Scanning Examples

The following examples are intended to aid your understanding of module and Slot 0 programming. It will be helpful to refer to the bit descriptions for the Configuration Register and the FIFO Register in Chapter 4, Register Descriptions.

Example 1

You want to scan, in Multiplexed mode, channels 1 through 4 on an SCXI-1120 in Slot 1 of an SCXI-1000 chassis. The SCXI-1120 is directly cabled to a data acquisition board.

The programming steps are as follows:

1. Program your data acquisition board as described in the 1. Data Acquisition Board Setup Programming section of this chapter.

2. Following the procedure given in the Register Writes section, write 10000100 00001101 to the Configuration Register of the SCXI-1120 in Slot 1.

Chapter 5 Programming

3. Follow the steps outlined in the section earlier in this chapter, 3. Programming the Slot 0 Hardscan Circuitry, where step 3, Write the Slot 0 scan list to the FIFO, consists of the

following:

Write 00000000 00000011 to the FIFO Register. This corresponds to Slot 1 for four samples.

4. Follow the procedure given in the 4. Acquisition Enable, Triggering, and Servicing section earlier in this chapter.

Example 2

An SCXI-1000 chassis has four SCXI-1120 modules in Slots 1, 2, 3, and 4. The SCXI-1120 in Slot 4 is cabled to the data acquisition board. You want to scan channels 3 through 7 on the SCXI-1120 in Slot 1, channels 0 through 6 on the SCXI-1120 in Slot 4, and channels 7 through 3 on the SCXI-1120 in Slot 3.

The programming steps are as follows:

1. Program your data acquisition board as described in the 1. Data Acquisition Board Setup Programming section.

2. Following the procedure given in the Register Writes section, write 00000000 00000000 to the Configuration Register of the SCXI-1120 in Slot 2. This step resets the module, including the clearing of the AB0EN bit (bit 0). Notice that a complete reset of this module is not necessary, but is used for simplicity.

3. Following the procedure given in the Register Writes section, write 10XXX000 00001111 to the Configuration Register of the SCXI-1120 in Slot 4.

4. Following the procedure given in the Register Writes section, write 01XXX011 00001111 to the Configuration Register of the SCXI-1120 in Slot 1.

5. Following the procedure given in the Register Writes section, write 01XXX111 00001111 to the Configuration Register of the SCXI-1120 in Slot 3. Notice that after Channel 7, the SCXI-1120 will wrap around to Channel 0.

6. Follow the steps given in the section earlier in this chapter, 3. Programming the Slot 0 Hardscan Circuitry, where step 3, Write the Slot 0 scan list to the FIFO, consists of the following:

a. Write 00000000 00000100 to the FIFO Register. This corresponds to Slot 1 for five

samples.

b. Write 00000001 10000110 to the FIFO Register. This corresponds to Slot 4 for

seven samples.

c. Write 00000001 00000100 to the FIFO Register. This corresponds to Slot 3 for five

samples.

Make sure to toggle SLOT0SEL* or reselect the FIFO Register from scratch between steps 6a, 6b, and 6c.

Programming Chapter 5

7. Follow the procedure given in the 4. Acquisition Enable, Triggering, and Servicing section earlier in this chapter.

Example 3

You want to scan five channels on an SCXI-1120 in Slot 4 of Chassis 1, then seven channels of an SCXI-1120 in Slot 11 of Chassis 2, three channels of an SCXI-1120 in Slot 3 in Chassis 3, and one channel of an SCXI-1120 in Slot 8 of Chassis 3.

Assuming that the modules are correctly cabled and programmed, the Slot 0 scan lists should be as follows:

Chassis 1 Chassis 2 Chassis 3

Entry Slot

Number

Count Entry Slot

Number

Count Entry Slot

Number

Count

1 4 51135 11312 213112117 2 3 3

3134 3 8 1

Other solutions are possible. In the section earlier in this chapter, 3. Programming the Slot 0 Hardscan Circuitry, step 3, Write

the Slot 0 scan list to the FIFO, consists of the following steps:

1. Select Slot 14 in Chassis 1.

2. Write XXXXX001 10000100 over MOSI.

3. Toggle SLOT0SEL*.

4. Write XXXXX110 00001010 over MOSI.

5. Select Slot 14 in Chassis 2.

6. Write XXXXX110 00000100 over MOSI.

7. Toggle SLOT0SEL*.

8. Write XXXXX101 00000110 over MOSI.

9. Toggle SLOT0SEL*.

10. Write XXXXX110 00000011 over MOSI.

11. Select Slot 14 in Chassis 3.

12. Write XXXXX110 00001011 over MOSI.

Chapter 5 Programming

13. Toggle SLOT0SEL*.

14. Write XXXXX001 00000010 over MOSI.

15. Toggle SLOT0SEL*.

16. Write XXXXX011 10000000 over MOSI.

17. Select Slot 0 in Chassis 0.

Appendix A Specifications

This appendix lists the specifications for the SCXI-1120. These are typical at 25° C unless otherwise stated. The operating temperature range is 0° to 50° C.

Analog Input

Gain (jumper-selectable) 1, 2, 5, 10, 20, 50, 100, 200, 500, 1,000, 2,000 Output range ±5 V Number of channels 8 Gain accuracy 0.15% of full scale Offset voltage

Input ±6 µV Output ±3 mV

Stability versus ambient temperature

Input offset drift ±0.2 µV/°C Output offset drift ±200 µV/°C Gain drift 20 ppm/°C

Input bias current ±80 pA Input resistance

Normal 40 MΩ Power off 50 kΩ Overload 50 kΩ

Output resistance

Multiplexed-Output mode 100 Ω Parallel-Output mode 330 Ω

Filtering (jumper selectable) 4 Hz (-10 dB) or 10 kHz (-3 dB), 3-pole RC Output selection time

(with 5 V step, all gains)

0.012% accuracy

0.006% accuracy

0.0015% accuracy

1 2

5.2 µsec typical, 7 µsec maximum 10 µsec 20 µsec

Includes the combined effects of the SCXI-1120 and the AT-MIO-16F-5

Includes the combined effects of the SCXI-1120 and the AT-MIO-16X

Specifications Appendix A

Rise time

4 Hz 0.12 sec 10 kHz 70 µsec

Slew rate 0.15 V/µsec Noise (400 kHz bandwidth)

Input (gain = 1,000)

4 Hz filter 100 nVrms 10 kHz filter 4 µVrms

Output (gain = 1)

4 Hz 150 µVrms 10 kHz 1 mVrms

Operating common-mode voltage 50 or 60 Hz

Channel to channel or Channel to earth 250 Vrms

Common-mode rejection ratio,

50 or 60 Hz 1 kΩ in input leads 160 dB minimum at 4 Hz bandwidth NMR (50 or 60 Hz) 60 dB at 4 Hz bandwidth

Input protection (continuous) 250 Vrms maximum Output protection Continuous short-to-ground Power dissipation 7.5 W maximum

Cold-Junction Sensor

SCXI-1320

Accuracy 1.0° from 0° to 55° C Output 10 mV/°C

SCXI-1328

Accuracy

0.35° from 15° to 35° C

0.65° from 0° to 15° and 35° to 55° C

Output 1.91 to 0.58 V from 0° to 55° C

Includes the combined effects of the SCXI-1120 and the AT-MIO-16F-5

Includes the combined effects of the SCXI-1120 and the AT-MIO-16X

Located on the SCXI-1320 and SCXI-1328 terminal blocks

Includes the combined effects of the temperature sensor accuracy and the temperature difference between the

temperature sensor and any screw terminal

Module tested using the UL 1244 standard to twice the working voltage + 1,000 Vrms

Appendix A Specifications

Note: You can find the temperature T (°C) as follows:

T (°C) = T

where T

a = 1.288 x 10 b = 2.356 x 10 c = 9.556 x 10

[]

- 273.15

is the temperature in kelvin

a+b lnR

()

-3

-4

-8

+c lnR

()

RT = resistance of the thermistor in Ω

=50,000

TEMPOUT



TEMPOUT



2.5−V



TEMPOUT

= output voltage of the temperature sensor

 



Physical

Dimensions 1.2 by 6.8 by 8.0 in. Connectors 50-pin male ribbon-cable rear connector

32-pin DIN C male front connector (18-screw terminal adapter available)

Operating Environment

Temperature 0° to 50° C Relative humidity 5% to 90% at 35° C

Storage Environment

Temperature -55° to 150° C

-55° to 125° C for the SCXI-1328

Relative humidity 5% to 90% noncondensing

Appendix B Rear Signal Connector

This appendix describes the pinout and signal names for the SCXI-1120 50-pin rear signal connector, including a description of each connection.

Figure B-1 shows the pin assignments for the SCXI-1120 rear signal connector.

AOGND

MCH0+ MCH1+ MCH2+ MCH3+ MCH4+ MCH5+ MCH6+ MCH7+

OUTREF

SERDATIN

DAQD*/A

SLOT0SEL*

DIG GND

1 2 3 4

5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

AOGND MCH0MCH1-

MCH2MCH3MCH4MCH5MCH6MCH7-

DIG GND SERDATOUT

SERCLK

RSVD

35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

SCANCLK

Figure B-1. SCXI-1120 Rear Signal Connector Pin Assignment

Rear Signal Connector Appendix B

Rear Signal Connector Signal Descriptions

Pin Signal Name Description

1-2 AOGND Analog Output Ground – Connected to the analog

reference when jumper W46 is in position AB-R0.

3-18 MCH0± through MCH7± Analog Output Channels 0 through 7 – Connects to

the data acquisition board differential analog inputchannels.

19 OUTREF Output Reference – Serves as the reference node for

24, 33 DIG GND Digital Ground – Supply the reference for data

acquisition board digital signals and are tied to the module digital ground.

25 SERDATIN Serial Data In – Taps into the SCXIbus MOSI line

to provide serial input data to a module or Slot 0.

26 SERDATOUT Serial Data Out – Taps into the SCXIbus MISO line

to accept serial output data from a module.

27 DAQD*/A Data Acquisition Board Data/Address Line – Taps

into the SCXIbus D*/A line to indicate to the module whether the incoming serial stream is data or address information.

29 SLOT0SEL* Slot 0 Select – Taps into the SCXIbus INTR* line

to indicate whether the information on MOSI is being sent to a module or Slot 0.

36 SCANCLK Scan Clock – Indicates to the SCXI-1120 that a

sample has been taken by the data acquisition board and causes the SCXI-1120 to change channels.

37 SERCLK Serial Clock – This signal taps into the SCXIbus

SPICLK line to clock the data on the MOSI and

MISO lines. 43 RSVD Reserved. All other pins are not connected.

Appendix B Rear Signal Connector

See the Timing Requirements and Communication Protocol section in Chapter 2, Configuration and Installation, for more detailed information on timing. Detailed signal specifications are also

included in Chapter 2.

Appendix C SCXIbus Connector

This appendix describes the pinout and signal names for the SCXI-1120 96-pin SCXIbus connector, including a description of each connection.

Figure C-1 shows the pinout of the SCXI-1120 SCXIbus connector.

SCXIbus Connector Appendix C

GUARD GUARD GUARD

AB0+ GUARD GUARD GUARD

GUARD GUARD GUARD

RESET*

MISO

V-

VCHSGND CHSGND

V+ V+

+5 V

SPICLK

TRIG0

SS*

A1 B1 A2 B2 A3 B3 A4 B4 A5 B5 A6 B6 A7 B7 A8 B8 A9 B9 A10 B10 A11 B11 A12 B12 A13 B13 A14 B14 A15 B15 A16 B16 A17 B17 A18 B18 A19 B19 A20 B20 A21 B21 A22 B22 A23 B23 A24 B24

D1 C1 D2 C2 D3 C3 D4 C4 D5 C5 D6 C6 D7 C7 D8 C8 D9 C9 D10 C10 D11 C11 D12 C12 D13 C13 D14 C14 D15 C15 D16 C16 D17 C17 D18 C18 D19 C19 D20 C20 D21 C21 D22 C22 D23 C23 D24 C24

GUARD GUARD GUARD

AB0GUARD GUARD GUARD

GUARD GUARD GUARD

CHSGND

RSVD

INTR*

D*/A

V-

VCHSGND CHSGND

V+ V+

+5 V

MOSI

SCANCON

Figure C-1. SCXIbus Connector Pin Assignment

Appendix C SCXIbus Connector

SCXIbus Connector Signal Descriptions

Pin Signal Name Description

A1, B1, C1, D1, GUARD Guard – Shields and guards the analog bus lines A2, D2, A3, B3, from noise. C3, D3, A4, D4, A5, B5, C5, D5, A6, D6

B2 AB0+ Analog Bus 0+ – Positive analog bus 0 line. Used

to multiplex several modules to one analog signal.

C2 AB0- Analog Bus 0- – Negative analog bus 0 line. Used

to multiplex several modules to one analog signal.

C13-C17, A21, CHSGND Chassis Ground – Digital and analog ground B21, C21, D21 reference.

C18 RSVD Reserved. A19 RESET* Reset – When pulled low, reinitializes the module to

its power-up state. Totem pole. Input.

B19 MISO Master-In-Slave-Out – Transmits data from the

module to the SCXIbus. Open collector. I/O.

C19 D*/A Data/Address – Indicates to the module whether

address information or data information is being sent to the module on MOSI. Open collector. I/O.

D19 INTR* Interrupt – Active low. Causes data that is on

MOSI to be written to the Slot-Select Register Slot 0. Open collector. Output.

A20, B20, C20, V- Negative Analog Supply – -18.5 V to -25 V. D20

A22, B22, C22, V+ Positive Analog Supply – +18.5 V to +25 V. D22

A23, D23 +5 V +5 VDC Source – Digital power supply. B23 SPICLK Serial Peripheral Interface (SPI) Clock – Clocks the

serial data on the MOSI and MISO lines. Open collector. I/O.

C23 MOSI Master-Out-Slave-In – Transmits data from the

SCXIbus to the module. Open collector. I/O.

SCXIbus Connector Appendix C

Pin Signal Name Description (continued)

A24 TRIG0 TRIG0 – General-purpose trigger line used by the

SCXI-1120 to send SCANCLK to other modules or receive SCANCLK from other modules. Open collector. I/O.

B24 SS* Slot Select – When low, enables module

communications over the SCXIbus. Totem pole. Input.

C24 SCANCON Scanning Control – Combination output enable and

reload signal for scanning operations. Totem pole.

Input. All other pins are not connected. Further information is given in Chapter 3, Theory of Operation.

Appendix D SCXI-1120 Front Connector

This appendix describes the pinout and signal names for the SCXI-1120 front connector, including a description of each connection.

Figure D-1 shows the pin assignments for the SCXI-1120 front connector.

Number

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12

9 8 7 6 5 4 3 2 1

Signal

Name

CH0+

CH1+

CH2+

CH3+

CH4+

CH5+

CH6+

CH7+

RSVD

+5 V

CHSGND

Column

A B C

Signal

Name

CH0-

CH1-

CH2-

CH3-

CH4-

CH5-

CH6-

CH7-

RSVD

MTEMP

DTEMP

Figure D-1. SCXI-1120 Front Connector Pin Assignment

SCXI-1120 Front Connector Appendix D

Front Connector Signal Descriptions

Pin Signal Name Description

A2 CHSGND Chassis Ground – Tied to the SCXI chassis. C2 DTEMP Direct Temperature Sensor – Connects the

temperature sensor to pin 18 of the rear signal

connector MCH7- when the terminal block is

configured for direct temperature connection and

jumper W41 is in position 3. A4 +5 V +5 VDC Source – Used to power the temperature

sensor on the terminal block. 0.2 mA of source not

protected. C4 MTEMP Multiplexed Temperature Sensor – Connects the

temperature sensor to the output multiplexer. A6, C6, C8 RSVD Reserved – Reserved for future use. Do not connect

any signals to these pins. TTL/CMOS output. They

are not protected. A8, A10, C10, No Connect Do not connect any signals to these pins.

A16, C16,A22, C22, A28, C28

A12, A14, A18, CH7+ through CH0+ Positive Input Channels – The positive inputs to A26, A20, A24, channels 7 through 0, respectively. A30, A32

C12, C14, C18, CH7- through CH0- Negative Input Channels – The negative inputs to C20, C24, C26, channels 7 through 0, respectively. C30, C32

Further information is given in Chapter 2, Configuration and Installation.

Appendix E SCXI-1120 Cabling

This appendix describes how to use and install the hardware accessories for the SCXI-1120:

• SCXI-1340 cable assembly

• SCXI-1341 Lab-NB, Lab-PC, and Lab-PC+ cable assembly

• SCXI-1342 PC-LPM-16 cable assembly

• SCXI-1344 Lab-LC cable assembly

• SCXI-1180 feedthrough panel

• SCXI-1302 50-pin terminal block

• SCXI-1351 one-slot cable extender

• SCXI-1350 multichassis adapter

• SCXI-1343 screw terminal adapter

SCXI-1340 Cable Assembly

The SCXI-1340 cable assembly connects an MIO-16 board to an SCXI-1120 module. The SCXI-1340 consists of a 50-conductor ribbon cable that has mounting bracket at one end and a 50-pin female connector at the other end. The female connector connects to the I/O connector of the MIO-16 board. Attached to the mounting bracket is a 50-pin female mounting-bracket connector that connects to the module rear signal connector. To extend the signals of the MIO-16 board to an SCXI-1180 feedthrough panel or an SCXI-1181 breadboard module, you can use the male breakout connector that is near the mounting bracket on the ribbon cable. All 50 pins from the MIO-16 board go straight through to the rear signal connector. You can use a standard 50-pin ribbon cable instead of the SCXI-1340 cable assembly. The SCXI-1340 has the following advantages over the ribbon cable:

• The SCXI-1340 has strain relief so that you cannot accidentally disconnect the cable.

• The SCXI-1340 includes a mounting bracket that mounts to the chassis so that you can

remove and reinsert the module without explicitly removing the cable from the back of the chassis. This is especially useful when the SCXI chassis is rack mounted, making rear access difficult.

• The SCXI-1340 has an extra male breakout connector for use with the SCXI-1180

feedthrough panel or additional modules or breadboards that need a direct connection to the MIO-16 board.

• The SCXI-1340 rear panel gives the module and the chassis both mechanical and electrical

shielding.

SCXI-1120 Cabling Appendix E

Table E-1 lists the pin equivalences of the MIO-16 board and the SCXI-1120.

Table E-1. SCXI-1120 and MIO-16 Board Pinout Equivalences

Pin SCXI-1120 Rear Signal Connector MIO-16 Board

Equivalent

1-2 AOGND AIGND 3 MCH0+ ACH0 4 MCH0- ACH8 5 MCH1+ ACH1 6 MCH1- ACH9 7 MCH2+ ACH2 8 MCH2- ACH10 9 MCH3+ ACH3 10 MCH3- ACH11 11 MCH4+ ACH4 12 MCH4- ACH12 13 MCH5+ ACH5 14 MCH5- ACH13 15 MCH6+ ACH6 16 MCH6- ACH14 17 MCH7+ ACH7 18 MCH7- ACH15 19 OUTREF AISENSE 24, 33 DIG GND DIG GND 25 SERDATIN ADIO0 26 SERDATOUT BDIO0 27 DAQD*/A ADIO1 29 SLOT0SEL* ADIO2 36 SCANCLK SCANCLK 37 SERCLK EXTSTROBE* 43 RSVD OUT1

No other pins are connected on the SCXI-1120.

SCXI-1340 Installation

Follow these steps to install the SCXI-1340:

1. Make sure that the computer and the SCXI chassis are turned off.

2. Install the SCXI module in the chassis.

3. Plug the mounting bracket connector onto the module rear signal connector (see Figure E-1).

Make sure the alignment tab on the bracket enters the upper module guide of the chassis.

4. Screw the mounting bracket to the threaded strips in the rear of the chassis.

National Instruments SCXI-1120 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Limited Warranty

Copyright

Trademarks

Figures

Tables

About This Manual

Organization of This Manual

Conventions Used in This Manual

Related Documentation

Customer Communication

Chapter 1 Introduction

What Your Kit Should Contain

Optional Software

Optional Equipment

Custom Cables

Unpacking

Chapter 2 Configuration and Installation

Module Configuration

Figure 2-1. SCXI-1120 General Parts Locator Diagram

Figure 2-2. Detailed Parts Locator Diagram

Digital Signal Connections

Jumper W44

Jumper W43

Jumper W42

Using Jumpers W42 and W43

Table 2-1. Digital Signal Connections, Jumper Settings

Analog Configuration

Grounding, Shielding, and Reference-Mode Selection

Table 2-2. Jumper W46 Settings

Direct Temperature Connection

Table 2-3. Jumper W41 Settings

Gain Jumpers

Table 2-4. Gain Jumper Allocation

Table 2-5. Gain Jumper Positions

Filter Jumpers

Table 2-6. Filter Jumper Allocation

Hardware Installation

Signal Connections

Front Connector

Figure 2-3. SCXI-1120 Front Connector Pin Assignment

Front Connector Signal Descriptions

Analog Input Channels

Figure 2-4. Ground-Referenced Signal Connection with High Common-Mode Voltage

Figure 2-6. Floating AC-Coupled Signal Connection

Figure 2-7. AC-Coupled Signal Connection with High Common-Mode Voltage

Temperature Sensor Connection

Connector-and-Shell Assembly

Figure 2-8. Assembling and Mounting the SCXI-1330 Connector-and-Shell Assembly

SCXI-1320 and SCXI-1328 Terminal Blocks

Table 2-7. Jumper Settings on the SCXI-1320 Terminal Block

Table 2-8. Jumper Settings on the SCXI-1328 Terminal Block

Terminal Block Signal Connection Warnings: The chassis GND terminals on your terminal block are for grounding high

Figure 2-9. SCXI-1320 Parts Locator Diagram

Figure 2-10. SCXI-1328 Parts Locator Diagram

Rear Signal Connector

Figure 2-11. SCXI-1120 Rear Signal Connector Pin Assignment

Rear Signal Connector Signal Descriptions

Analog Output Signal Connections

Note: The SCXI-1120 analog outputs are short-circuit protected. Digital I/O Signal Connections

Timing Requirements and Communication Protocol

Figure 2-12. SCANCLK Timing Requirements

Communication Signals

Figure 2-13. Slot-Select Timing Diagram

Figure 2-14. Serial Data Timing Diagram

Figure 2-15. Configuration Register Write Timing Diagram

Chapter 3 Theory of Operation

Functional Overview

Figure 3-1. SCXI-1120 Block Diagram

SCXIbus Connector

Figure 3-2. SCXIbus Connector Pin Assignment

SCXIbus Connector Signal Descriptions

Table 3-1. SCXIbus Equivalents for the Rear Signal Connector

Digital Interface

Figure 3-3. Digital Interface Circuitry Block Diagram

Digital Control Circuitry

Figure 3-4. SCXI-1120 Digital Control