National Instruments 1143, 1141, 1142 User Manual
TM
SCXI
SCXI-1141/1142/1143 User Manual
SCXI-1141/1142/1143 User Manual
May 2007
371748E-01
Support
Worldwide Technical Support and Product Information
ni.com
National Instruments Corporate Headquarters
11500 North Mopac Expressway Austin, Texas 78759-3504 USA Tel: 512 683 0100
Worldwide Offices
Australia 1800 300 800, Austria 43 662 457990-0, Belgium 32 (0) 2 757 0020, Brazil 55 11 3262 3599,
Canada 800 433 3488, China 86 21 5050 9800, Czech Republic 420 224 235 774, Denmark 45 45 76 26 00,
Finland 385 (0) 9 725 72511, France 33 (0) 1 48 14 24 24, Germany 49 89 7413130, India 91 80 41190000,
Israel 972 3 6393737, Italy 39 02 413091, Japan 81 3 5472 2970, Korea 82 02 3451 3400,
Lebanon 961 (0) 1 33 28 28, Malaysia 1800 887710, Mexico 01 800 010 0793, Netherlands 31 (0) 348 433 466,
New Zealand 0800 553 322, Norway 47 (0) 66 90 76 60, Poland 48 22 3390150, Portugal 351 210 311 210,
Russia 7 495 783 6851, Singapore 1800 226 5886, Slovenia 386 3 425 42 00, South Africa 27 0 11 805 8197,
Spain 34 91 640 0085, Sweden 46 (0) 8 587 895 00, Switzerland 41 56 2005151, Taiwan 886 02 2377 2222,
Thailand 662 278 6777, Turkey 90 212 279 3031, United Kingdom 44 (0) 1635 523545
For further support information, refer to the Technical Support Information document. To comment on National
Instruments documentation, refer to the National Instruments Web site at
feedback.
ni.com/info and enter the info code
© 1994–2007 National Instruments Corporation. All rights reserved.
Important Information
Warranty
The SCXI-1141, SCXI-1142, and SCXI-1143 modules are warranted against defects in materials and workmanship for a period of one year
from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment
that proves to be defective during the warranty period. This warranty includes parts and labor.
The media on which you receive National Instruments software are warranted not to fail to execute programming instructions, due to defects in
materials and workmanship, for a period of 90 days from date of shipment, as evidenced by receipts or other documentation. National Instruments
will, at its option, repair or replace software media that do not execute programming instruc tions if National Instruments receives notice of such defects
during the warranty period. National Instruments does not warrant that the operation of the software shall be uninterrupted or error free.
A Return Material Authorization (RMA) number must be obtained from the factory and clearly marked on the outside of the package before any
equipment will be accepted for warranty work. National Instruments will pay the shipping costs of returning to the owner parts which are covered by
warranty.
National Instruments believes that the information in this document 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.
E
XCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL
I
NSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER. 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. This limitation of
the liability of National Instruments will apply regardless of the form of action, whether in contract or tort, including negligence. Any action against
National Instruments must be brought within one year after the cause of action accrues. National Instruments shall not be liable for any delay in
performance due to causes beyond its reasonable control. The warranty provided herein does not cover damages, defects, malfunctions, or service
failures caused by owner’s failure to follow the National Instruments installation, operation, or maintenance instructions; owner’s modification of the
product; owner’s abuse, misuse, or negligent acts; and power failure or surges, fire, flood, accident, actions of third parties, or other events outside
reasonable control.
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.
National Instruments respects the intellectual property of others, and we ask our users to do the same. NI software is protected by copyright and other
intellectual property laws. Where NI software may be used to reproduce software or other materials belonging to others, you may use NI software only
to reproduce materials that you may reproduce in accordance with the terms of any applicable license or other legal restriction.
Trademarks
National Instruments, NI, ni.com, and LabVIEW are trademarks of National Instruments Corporation. Refer to the Terms of Use section
on
ni.com/legal for more information about National Instruments trademarks.
Other product and company names mentioned herein are trademarks or trade names of their respective companies.
Patents
For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txt file
on your CD, or
ni.com/patents.
WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS
(1) NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF
RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN
ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT
INJURY TO A HUMAN.
(2) IN ANY APPLICATION, INCLUDING THE ABOVE, RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE
IMPAIRED BY ADVERSE FACTORS, INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY,
COMPUTER HARDWARE MALFUNCTIONS, COMPUTER OPERATING SYSTEM SOFTWARE FITNESS, FITNESS OF COMPILERS
AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION, INSTALLATION ERRORS, SOFTWARE AND HARDWARE
COMPATIBILITY PROBLEMS, MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES,
TRANSIENT FAILURES OF ELECTRONIC SYSTEMS (HARDWARE AND/OR SOFTWARE), UNANTICIPATED USES OR MISUSES, OR
ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER (ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER
COLLECTIVELY TERMED “SYSTEM FAILURES”). ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF
HARM TO PROPERTY OR PERSONS (INCLUDING THE RISK OF BODILY INJURY AND DEATH) SHOULD NOT BE RELIANT SOLELY
UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE. TO AVOID DAMAGE, INJURY, OR DEATH,
THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES,
INCLUDING BUT NOT LIMITED TO BACK-UP OR SHUT DOWN MECHANISMS. BECAUSE EACH END-USER SYSTEM IS
CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS' TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION
DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT
EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS, THE USER OR APPLICATION DESIGNER IS ULTIMATELY
RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER
NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION, INCLUDING, WITHOUT
LIMITATION, THE APPROPRIATE DESIGN, PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION.
Conventions
The following conventions are used in this manual:
<> Angle brackets that contain numbers separated by an ellipsis represent
a range of values associated with a bit or signal name—for example,
AO <3. .0>.
» The » symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.
This icon denotes a note, which alerts you to important information.
This icon denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash. When this symbol is marked on a
product, refer to the Read Me First: Safety and Radio-Frequency
Interference document for information about precautions to take.
When symbol is marked on a product, it denotes a warning advising you to
take precautions to avoid electrical shock.
When symbol is marked on a product, it denotes a component that may be
hot. Touching this component may result in bodily injury.
bold Bold text denotes items that you must select or click in the software, such
as menu items and dialog box options. Bold text also denotes parameter
names.
italic Italic text denotes variables, emphasis, a cross-reference, or an introduction
to a key concept. Italic text also denotes text that is a placeholder for a word
or value that you must supply.
monospace Text in this font denotes text or characters that you should enter 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, operations,
variables, filenames, and extensions.
Contents
Chapter 1
About the SCXI-1141/1142/1143
What You Need to Get Started ......................................................................................1-2
National Instruments Documentation ............................................................................1-3
Installing Application Software, NI-DAQmx, and the DAQ Device ............................1-4
Installing the SCXI-1141/1142/1143 into an SCXI Chassis or
a PXI/SCXI Combination Chassis................................................................1-4
Installing the Terminal Block ........................................................................................1-4
Verifying the SCXI-1141/1142/1143 Installation in Software ......................................1-5
Installing SCXI Chassis and Modules in Software .........................................1-5
Troubleshooting the Self-Test Verification ...................................................................1-5
Troubleshooting in NI-DAQmx ......................................................................1-5
Chapter 2
Connecting Signals
Front Connector .............................................................................................................2-1
Front Connector Signal Descriptions ..............................................................2-3
Analog Input Channels......................................................................2-3
Digital Input and Output ...................................................................2-6
Rear Signal Connector ...................................................................................................2-7
Analog Output Signal Connections.................................................................2-11
Digital I/O Signal Connections .......................................................................2-11
Chapter 3
Configuring and Testing
SCXI-1141/1142/1143 Software-Configurable Settings ...............................................3-1
Common Software-Configurable Settings ......................................................3-1
Gain/Input Range ..............................................................................3-1
Input Selection ..................................................................................3-2
Auto-Zero..........................................................................................3-2
Configurable Settings in MAX ......................................................................................3-2
NI-DAQmx......................................................................................................3-3
Creating a Global Channel or Task...................................................3-3
Verifying the Signal.......................................................................................................3-4
Verifying the Signal in NI-DAQmx Using a Task or Global Channel ...........3-4
© National Instruments Corporation v SCXI-1141/1142/1143 User Manual
Contents
Chapter 4
Theory of Operation
Power-Up State.............................................................................................................. 4-1
Digital Control Circuitry ............................................................................................... 4-3
Input Amplifiers ............................................................................................................4-3
Correcting Gain and Offset Errors .................................................................. 4-4
Lowpass Filters.............................................................................................................. 4-5
Filter Theory ................................................................................................... 4-5
Performance of the SCXI-1141/1142/1143 Module Filters............................ 4-6
Using the SCXI-1141/1142/1143 Module as an Antialiasing Filter ............... 4-12
Using the External Clock Input....................................................................... 4-14
DC-Correction Circuitry and Overload Recovery ..........................................4-15
Filter Bypass Mode ......................................................................................... 4-16
Rear Connector Analog Outputs ................................................................................... 4-16
Multiplexed Mode (Recommended) ............................................................... 4-16
Parallel Mode ..................................................................................................4-17
Chapter 5
Magnitude Response......................................................................... 4-6
Phase Response................................................................................. 4-8
Setting the Cutoff Frequency............................................................4-11
Using the SCXI-1141/1142/1143 Module
Developing Your Application in NI-DAQmx............................................................... 5-1
Typical Program Flowchart ............................................................................ 5-1
General Discussion of Typical Flowchart....................................................... 5-3
Creating a Task Using DAQ Assistant or Programmatically ........... 5-3
Adjusting Timing and Triggering..................................................... 5-3
Configuring Channel Properties ....................................................... 5-4
Acquiring, Analyzing, and Presenting.............................................. 5-7
Completing the Application.............................................................. 5-7
Developing an Application Using LabVIEW ................................................. 5-7
Using a NI-DAQmx Channel Property Node in LabVIEW ............. 5-9
Specifying Channel Strings in NI-DAQmx .................................................... 5-10
Text Based ADEs ............................................................................. 5-10
Programmable NI-DAQmx Properties ............................................. 5-12
Calibration .....................................................................................................................5-13
External Calibration ........................................................................................ 5-13
Appendix A
Specifications
SCXI-1141/1142/1143 User Manual vi ni.com
Appendix B
Removing the SCXI-1141/1142/1143 Module
Appendix C
Common Questions
Glossary
Index
Figures
Figure 2-1. Ground-Referenced Signal Connection.................................................2-4
Figure 2-2. Floating Signal Connection ...................................................................2-5
Figure 2-3. Ground-Referenced AC-Coupled Signal Connection ...........................2-5
Figure 2-4. Ground Offset AC-Coupled Signal Connection....................................2-6
Figure 2-5. Floating AC-Coupled Signal Connection..............................................2-6
Figure 4-1. SCXI-1141/1142/1143 Module Block Diagram ...................................4-2
Figure 4-2. Ideal and Real Lowpass Filter Transfer Function Characteristics ........4-5
Figure 4-3. Real and Ideal Filter Responses to a Step Input Signal.........................4-6
Figure 4-4. Typical Magnitude Response of the SCXI-1141/1142/1143
Module Filters .......................................................................................4-7
Figure 4-5. Typical Passband Responses of the SCXI-1141/1142/1143 Module.... 4-8
Figure 4-6. Phase Response Characteristics of the SCXI-1141/1142/1143
Module Filters .......................................................................................4-9
Figure 4-7. Phase Error of the SCXI-1141/1142/1143 Module ............................... 4-10
Figure 4-8. Unit Step Response of the SCXI-1141/1142/1143 Module ..................4-11
Figure 4-9. Aliasing of an Input Signal with a Frequency 0.8 Times
the Sample Rate.....................................................................................4-12
Contents
Figure 5-1. Typical Program Flowchart for Voltage Measurement Channels ......... 5-2
Figure A-1. SCXI-1141/1142/1143 Dimensions ......................................................A-5
Figure B-1. Removing the SCXI-1141/1142/1143 Module .....................................B-2
© National Instruments Corporation vii SCXI-1141/1142/1143 User Manual
Contents
Tables
Table 1-1. Accessories Available for the SCXI-1141/1142/1143.......................... 1-4
Table 2-1. Front Signal Pin Assignments............................................................... 2-2
Table 2-2. Rear Signal Pin Assignments................................................................ 2-8
Table 2-3. SCXI-1141/1142/1143 Rear Communication Signals .......................... 2-9
Table 2-4. SCXIbus to SCXI-1141/1142/1143 Module Rear Signal Connector
to DAQ Device Pin Equivalencies........................................................ 2-12
Table 4-1. Cutoff Frequency Ranges for the SCXI-1141/1142/1143 Module
Prefilters and Postfilters........................................................................ 4-15
Table 5-1. NI-DAQmx Voltage Measurement Properties ..................................... 5-4
Table 5-2. NI-DAQmx Thermocouple Measurement Properties ........................... 5-5
Table 5-3. NI-DAQmx RTD Measurement Properties .......................................... 5-6
Table 5-4. NI-DAQmx Thermistor Measurement Properties ................................ 5-6
Table 5-5. NI-DAQmx Current Measurement Properties ...................................... 5-6
Table 5-6. Programming a Task in LabVIEW ...................................................... 5-8
Table A-1. Settling Time with Respect to Cutoff Frequency ................................. A-3
Table C-1. Digital SIgnals on the SCXI-1141/1142/1143 ...................................... C-2
SCXI-1141/1142/1143 User Manual viii ni.com
About the SCXI-1141/1142/1143
This chapter describes the SCXI-1141/1142/1143 module, and explains
how to install and remove the hardware and software.
The SCXI-1141/1142/1143 module has eight lowpass filters and
eight differential-input amplifiers. The SCXI-1141 has elliptic filters;
the SCXI-1142, Bessel filters; and the SCXI-1143, Butterworth filters.
You can use the SCXI-1141/1142/1143 module for lowpass filtering and
antialiasing applications as well as for general-purpose signal amplification
and filtering. The SCXI-1141/1142/1143 module works with National
Instruments E/M Series DAQ devices. You can use one DAQ device to
control several SCXI-1141/1142/1143 modules, in combination with other
SCXI modules in a chassis. Each SCXI-1141/1142/1143 module can
multiplex its channels into a single channel of the DAQ device, although
separate outputs are also available. You can multiplex the output of several
SCXI-1141/1142/1143 modules into a single channel, thus greatly
increasing the number of analog input signals that the DAQ device can
digitize.
1
The SCXI-1304 shielded terminal block has screw terminals for easily
connecting signals to the SCXI-1141/1142/1143 module and is the terminal
block recommended for use with this module.
Refer to Appendix A, Specifications, for detailed SCXI-1141/1142/1143
module specifications.
© National Instruments Corporation 1-1 SCXI-1141/1142/1143 User Manual
Chapter 1 About the SCXI-1141/1142/1143
What You Need to Get Started
To set up and use the SCXI-1141/1142/1143 module, you need the
following:
❑ Hardware
– SCXI-1141/1142/1143 module
– One of the following terminal blocks:
• SCXI-1304
• SCXI-1305
– An SCXI chassis or PXI/SCXI combination chassis
– One of the following:
• E/M Series DAQ device
• SCXI-1600
– A computer if using an SCXI chassis
– Cabling, cable adapter, and sensors as required for your
application
❑ Software
–NI-DAQ
– One of the following software packages:
•LabVIEW
• Measurement Studio
™
• LabWindows
/CVI
™
❑ Documentation
– Read Me First: Safety and Radio-Frequency Interference
– DAQ Getting Started Guide
– SCXI Quick Start Guide
– SCXI-1141/1142/1143 User Manual
– Terminal block installation guide for your application
– Documentation for your software
You can download NI documents from
the latest version of NI-DAQmx visit
Updates. In the Product Line drop-down menu locate Multifunction
ni.com/manuals. To download
ni.com and click Drivers and
SCXI-1141/1142/1143 User Manual 1-2 ni.com
Chapter 1 About the SCXI-1141/1142/1143
DAQ. Select the appropriate information for your application in the
remaining drop-down menus and click Go.
National Instruments Documentation
The SCXI-1141/1142/1143 User Manual is one piece of the documentation
set for data acquisition (DAQ) systems. You could have any of several
types of manuals depending on the hardware and software in the system.
Use the manuals you have as follows:
• SCXI chassis or PXI/SCXI combination chassis manual—Read this
manual for maintenance information on the chassis and for installation
instructions.
• The DAQ Getting Started Guide—This document has information on
installing NI-DAQ and the E/M Series DAQ device. Install these
before you install the SCXI module.
• The SCXI Quick Start Guide—This document contains a quick
overview for setting up an SCXI chassis, installing SCXI modules and
terminal blocks, and attaching sensors. It also describes setting up the
SCXI system in MAX.
• The SCXI hardware user manuals—Read these manuals next
for detailed information about signal connections and module
configuration. They also explain, in greater detail, how the module
works and contain application hints.
• Accessory installation guides or manuals—Read the terminal block
and cable assembly installation guides. They explain how to physically
connect the relevant pieces of the system. Consult these guides when
you are making the connections.
• The E/M Series DAQ device documentation—This documentation has
detailed information about the E/M Series DAQ device that plugs into
or is connected to the computer. Use this documentation for hardware
installation and configuration instructions, specification information
about the E/M Series DAQ device, and application hints.
• Software documentation—You may have both application software
and NI-DAQ software documentation. NI application software
includes LabVIEW, LabWindows/CVI, and Measurement Studio.
After you set up the hardware system, use either your application
software documentation or the NI-DAQ documentation to help you
write your application. If you have a large, complex system, it is
worthwhile to look through the software documentation before you
configure the hardware.
© National Instruments Corporation 1-3 SCXI-1141/1142/1143 User Manual
Chapter 1 About the SCXI-1141/1142/1143
• The following help file for software information:
– Start»Programs»National Instruments»NI-DAQ»
NI-DAQmx Help
Installing Application Software, NI-DAQmx, and the DAQ Device
Refer to the DAQ Getting Started Guide packaged with the NI-DAQmx
software to install your application software, NI-DAQmx driver software,
and the E/M Series DAQ device to which you will connect the
SCXI-1141/1142/1143. NI-DAQ 8.3 or later is recommended to configure
and program the SCXI-1141/1142/1143 module.
Note Refer to the Read Me First: Radio-Frequency Interference document before
removing equipment covers or connecting or disconnecting any signal wires.
Installing the SCXI-1141/1142/1143 into an SCXI Chassis or a PXI/SCXI Combination Chassis
Refer to the SCXI Quick Start Guide to install the SCXI-1141/1142/1143
module.
Installing the Terminal Block
Table 1-1 shows the supported SCXI-1141/1142/1143 terminal blocks.
Refer to the SCXI Quick Start Guide and the terminal block installation
guide for more information about the terminal block.
Table 1-1. Accessories Available for the SCXI-1141/1142/1143
Accessory Description
SCXI-1304 Screw terminal block—Mounts on the front of the SCXI-1141/1142/1143 module.
It includes AC coupling circuitry and ground referencing through a 100 KΩ bias
resistor on each channel.
SCXI-1305 BNC terminal block—Mounts on the front of the SCXI-1141/1142/1143 module.
It is functionally equivalent to the SCXI-1304 terminal block.
SCXI-1141/1142/1143 User Manual 1-4 ni.com
Chapter 1 About the SCXI-1141/1142/1143
Verifying the SCXI-1141/1142/1143 Installation in Software
Refer to the SCXI Quick Start Guide for information on verifying the SCXI
installation.
Installing SCXI Chassis and Modules in Software
Refer to the SCXI Quick Start Guide for information on installing chassis
and modules using NI-DAQmx in software.
Troubleshooting the Self-Test Verification
If the self-test verification did not verify the chassis configuration,
complete the steps in this section to troubleshoot the SCXI configuration.
Troubleshooting in NI-DAQmx
• If you get a Verify SCXI Chassis message box showing the SCXI
chassis model number, Chassis ID: x, and one or more messages
stating Slot Number: x Configuration has module: SCXI-XXXX
or 1141/1142/1143, hardware in chassis is: Empty, take the
following troubleshooting actions:
– Make sure the SCXI chassis is powered on.
– Make sure all SCXI modules are properly installed in the chassis.
Refer to the SCXI Quick Start Guide for proper installation
instructions.
– Make sure the cable between the SCXI chassis and E/M Series
DAQ device is properly connected.
– Inspect the cable connectors for bent pins.
– Make sure you are using the correct NI cable assembly.
– Test the E/M Series DAQ device to verify it is working properly.
Refer to the E/M Series DAQ device help file for more
information.
© National Instruments Corporation 1-5 SCXI-1141/1142/1143 User Manual
Chapter 1 About the SCXI-1141/1142/1143
• If you get a Verify SCXI Chassis message box showing the SCXI
chassis model number, Chassis ID: x, and the message Slot
Number: x Configuration has module: SCXI-XXXX or
1141/1142/1143, hardware in chassis is: SCXI-YYYY,
1141/1142/1143, or Empty, complete the following troubleshooting
steps to correct the error.
1. Expand NI-DAQmx Devices.
2. Right-click the SCXI chassis and click Properties to load the
3. Under the Modules tab, ensure that the cabled module is listed in
4. If the cabled module is not listed in the correct slot, complete the
• If you have more than one kind of SCXI module in the SCXI chassis,
ensure that you have the highest priority SCXI module cabled to the
E/M Series DAQ device. Refer to the SCXI Quick Start Guide to find
out which SCXI module in the chassis should be cabled to the
E/M Series DAQ device.
• After checking the preceding items, return to the Troubleshooting the
Self-Test Verification section and retest the SCXI chassis.
chassis configurator.
the correct slot.
following troubleshooting steps:
a. If the cabled module is not listed in the correct slot and the
slot is empty, click the drop-down listbox next to the correct
slot and select the cabled module. Configure the cabled
module following the steps listed in the SCXI Quick Start
Guide. Click OK.
b. If another module is displayed where the cabled module
should be, click the drop-down listbox next to the correct slot
and select the cabled module. A message box opens asking
you to confirm the module replacement. Click OK. Configure
the cabled module following the steps listed in the SCXI
Quick Start Guide. Click OK.
If these measures do not successfully configure the SCXI system, contact
NI. Refer to the Technical Support Information document for contact
information.
SCXI-1141/1142/1143 User Manual 1-6 ni.com
Connecting Signals
This chapter describes input and output signal connections to the
SCXI-1141/1142/1143 module through the front and rear signal
connectors.
Caution Connections that exceed any of the maximum ratings of input or output signals
on the SCXI-1141/1142/1143 module can damage the SCXI-1141/1142/1143 module, the
SCXIbus, any connected DAQ device, and the computer with which the DAQ device is
used. NI is not liable for any damage resulting from such signal connections.
Front Connector
Table 2-1 shows the pin assignments for the SCXI-1141/1142/1143
module front connector.
2
© National Instruments Corporation 2-1 SCXI-1141/1142/1143 User Manual
Chapter 2 Connecting Signals
Table 2-1. Front Signal Pin Assignments
Front Connector Diagram Pin Number Column A Column B Column C
32 AI 0 + NC AI 0 –
Column
A B C
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
NC means no connection.
RSVD means reserved.
31 NC NC NC
30 AI 1 + NC AI 1 –
29 NC NC NC
28 A GND NC A GND
27 NC NC NC
26 AI 2 + NC AI 2 –
25 NC NC NC
24 AI 3 + NC AI 3 –
23 NC NC NC
22 A GND NC A GND
21 NC NC NC
20 AI 4 + NC AI 4 –
19 NC NC NC
18 AI 5 + NC AI 5 –
17 NC NC NC
16 A GND NC A GND
15 NC NC NC
14 AI 6 + NC AI 6 –
13 NC NC NC
12 AI 7 + NC AI 7 –
11 NC NC NC
10 NC NC NC
9 NC NC NC
8 RSVD NC RSVD
7 NC NC NC
6 RSVD NC RSVD
5 NC NC NC
4 RSVD NC EXT CLK
3 NC NC NC
2 D GND NC OUT CLK
1 NC NC NC
SCXI-1141/1142/1143 User Manual 2-2 ni.com
Front Connector Signal Descriptions
Pins Signal Names Description
Chapter 2 Connecting Signals
A32, A30, A26, A24,
A20, A18, A14, A12
C32, C30, C26, C24,
C20, C18, C14, C12
A28, A22, A16, C28,
C22, C16
A2, C8 D GND Digital ground—these pins connect to the module
A8, A6, A4, C8 RSVD Reserved—do not connect any signals to these pins.
C4 EXT CLK External clock—you can use this signal to set the
C2 OUT CLK Output clock—this signal has a frequency that is
Note: All other pins are not connected.
AI+<0..7+> Positive input channels—these pins connect to the
noninverting inputs of the instrumentation amplifier
of each channel.
AI–<0..7–> Negative input channels—these pins connect to the
inverting inputs of the instrumentation amplifier of
each channel.
A GND Analog ground—these pins connect to the module
analog ground.
digital ground.
filter cutoff frequency.
proportional to the cutoff frequency. You can use this
signal to externally control the cutoff frequency.
Analog Input Channels
The SCXI-1141/1142/1143 module instrumentation amplifiers can reject
any common-mode voltage within their common-mode input range caused
by ground-potential differences between the signal source and the module.
In addition, the amplifiers can reject common-mode noise pickup in the
leads connecting the signal sources to the SCXI-1141/1142/1143 module.
However, you should take care to minimize noise pickup. The
common-mode rejection of the instrumentation amplifiers decreases
significantly at high frequencies. The amplifiers do not reject
normal-mode noise.
The maximum differential input voltage range of the
SCXI-1141/1142/1143 module instrumentation amplifiers is a function of
the gain of the amplifiers, G, and is equal to 5 V/G. The common-mode
input range of the SCXI-1141/1142/1143 module, however, is not a
function of gain—the differential input amplifier rejects common-mode
signals as long as the signal at both inputs is within ±5 V of the module
© National Instruments Corporation 2-3 SCXI-1141/1142/1143 User Manual
Chapter 2 Connecting Signals
Caution Exceeding the differential or common-mode input voltage limits distorts input
signals. Exceeding the maximum common-mode input voltage rating can damage the
SCXI-1141/1142/1143 module, the SCXIbus, and the DAQ device. NI is not liable for any
damage resulting from such signal connections.
Note The recommended SCXI-1304 or SCXI-1305 terminal block has all necessary
circuitry for AC or DC coupling and for floating or ground-referenced signals. The
SCXI-1304 AC/DC Coupling Terminal Block Installation Guide and SCXI-1305 AC/DC
Coupling BNC Terminal Block Installation Guide have instructions for signal connection.
Figures 2-2 through 2-5 provide supplemental information on connecting signals to the
SCXI-1141/1142/1143 module.
analog ground. The inputs are protected against maximum input voltages
of up to ±15 V powered off and ±30 V powered on.
All eight channels have fully differential inputs, so you can
ground-reference the signals you measure. If the signals connected to the
differential amplified inputs are not ground referenced, connect a 100 kΩ
resistor from the negative input to ground to provide a DC path for the input
bias currents. If you do not do this, the bias currents of the instrumentation
amplifiers of the nonreferenced channels charge up stray capacitances,
resulting in uncontrollable drift and possible saturation.
Figure 2-1 illustrates how to connect a ground-referenced signal source to
an SCXI-1141/1142/1143 module channel.
IN+
IN–
SCXI-1141/1142/1143
Figure 2-1. Ground-Referenced Signal Connection
SCXI-1141/1142/1143 User Manual 2-4 ni.com
Chapter 2 Connecting Signals
Figure 2-2 illustrates how to connect a non-referenced (floating) signal
source to an SCXI channel.
IN+
IN–
100 kΩ
SCXI-1141/1142/1143
A GND
A
Figure 2-2. Floating Signal Connection
For AC-coupled signals, connect an external resistor from the AC-coupled
input channel to ground. This provides a DC path for the amplifier input
bias current. Typical resistor values range from 100 kΩ to 10 MΩ . This
solution, although necessary, lowers the input impedance of the channel
and introduces an additional DC offset voltage proportional to the product
of the input bias current and the resistor value used. Using a 1 MΩ resistor
results in ±200 µV of offset, which is insignificant in most applications.
However, if you use larger-valued bias resistors, significant input offset can
result. Lower-valued bias resistors increase loading of the source, which
can result in gain error.
Figures 2-3 through 2-5 illustrate how to connect AC-coupled signals.
1µF
IN+
1MΩ
IN–
SCXI-1141/1142/1143
Figure 2-3. Ground-Referenced AC-Coupled Signal Connection
© National Instruments Corporation 2-5 SCXI-1141/1142/1143 User Manual
Chapter 2 Connecting Signals
1 µF
1 µF
1
MΩ
1 MΩ
A GND
A
IN+
IN–
SCXI-1141/1142/1143
Figure 2-4. Ground Offset AC-Coupled Signal Connection
1 µF
100 kΩ
1 MΩ
A GND
A
IN+
IN–
SCXI-1141/1142/1143
Figure 2-5. Floating AC-Coupled Signal Connection
Digital Input and Output
You can use the EXT CLK input pin on the front connector of the
SCXI-1141/1142/1143 module to control filter cutoff frequency for special
purposes. The clock should be a TTL-logic-level or CMOS-logic-level
square wave, with a frequency of less than 2.5 MHz that is 100 times the
desired cutoff frequency. The absolute maximum input voltage for the
EXT CLK pin is 5.5 V with respect to D GND; the minimum input voltage
is –0.5 V.
The OUT CLK pin on the front connector is a CMOS-logic-level output
clock, which you can configure to have a frequency that is proportional to
filter cutoff frequency.
See Chapter 4, Theory of Operation, for more details on using these
two signals.
SCXI-1141/1142/1143 User Manual 2-6 ni.com
Rear Signal Connector
Note If you use the SCXI-1141/1142/1143 module with a National Instruments DAQ
device and SCXI cable assembly, you do not need to read the remainder of this chapter.
If you also use the SCXI-1180 feedthrough panel, the SCXI-1343 rear screw-terminal
adapter, or the SCXI-1351 one-slot cable extender with the SCXI-1141/1142/1143
module, you should read this section.
Chapter 2 Connecting Signals
© National Instruments Corporation 2-7 SCXI-1141/1142/1143 User Manual
Chapter 2 Connecting Signals
Table 2-2 shows the pin assignments for the SCXI-1141/1142/1143 module
rear signal connector. Pins without signal labels are not connected.
Table 2-2. Rear Signal Pin Assignments
Rear Connector Diagram Signal Name Pin Number Pin Number Signal Name
NC 1 2 NC
AI 0 + 3 4 AI 0 –
12
34
56
78
910
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
AI 1 + 5 6 A GND
AI 2 + 7 8 A GND
AI 3 + 9 10 A GND
AI 4 + 11 12 A GND
AI 5 + 13 14 A GND
AI 6 + 15 16 A GND
AI 7 + 17 18 A GND
NC 19 20 NC
NC 21 22 NC
NC 23 24 DIG GND
SER DAT IN 25 26 SER DAT OUT
DAQ D*/A 27 28 NC
SLOT 0 SEL* 29 30 NC
NC 31 32 NC
DIG GND 33 34 NC
NC 35 36 SCAN CLK
SER CLK 37 38 NC
NC 39 40 NC
NC 41 42 NC
RSVD 43 44 NC
NC 45 46 NC
NC means no connection.
RSVD means reserved.
SCXI-1141/1142/1143 User Manual 2-8 ni.com
NC 47 48 NC
NC 49 50 NC
Pin
Table 2-3. SCXI-1141/1142/1143 Rear Communication Signals
SCXI Signal
Name
Chapter 2 Connecting Signals
In parallel output mode, channel 0 is selected at the output multiplexer and
is connected to AI 0. The seven other channels are directly connected to
AI 1 through AI 7, respectively, on the rear connector.
In multiplexed mode, the AI 0 signal pair is used for sending all eight
channels of the SCXI-1141/1142/1143, and analog signals from other
modules, to the connected E/M Series DAQ device. If the module is cabled
directly to the DAQ device, the other analog channels of the DAQ device
are unavailable for general-purpose analog input because they are
connected to the SCXI-1141/1142/1143 amplifier outputs. This means that
connecting an SCXI-1180 module to the 50-pin breakout connector of the
SCXI-1349, or other cable adapter assembly, may cause interference and
incorrect measurements when the DAQ device is cabled to the
SCXI-1141/1142/1143.
The communication signals between the DAQ device and the SCXI system
are listed in Table 2-3. If the DAQ device is connected to the
SCXI-1141/1142/1143, these digital lines are unavailable for
general-purpose digital I/O.
NI-DAQmx
Device Signal
Name
Direction Description
5, 7, 9,
11, 13,
15, 17
6, 8,
10, 12,
14, 16,
18
24,
33
AI <1..7> N/A Output Analog outputs—these pins are the
outputs of channels 1 through 7,
regardless of the scanning mode.
A GND AI GND — Analog ground—these pins connect
to the module analog ground. They
are used as the reference points for
AI 1 + through AI 7 +.
DIG GND D GND — Digital ground—these pins supply
the reference for E/M Series DAQ
device digital signals and connect to
the module digital ground.
25 SER DAT IN P0.0 Input Serial data in—this signal taps into
the SCXIbus MOSI line to send
serial input data to a module or
Slot 0.
© National Instruments Corporation 2-9 SCXI-1141/1142/1143 User Manual
Chapter 2 Connecting Signals
Table 2-3. SCXI-1141/1142/1143 Rear Communication Signals (Continued)
NI-DAQmx
Device Signal
Name
Direction Description
Pin
SCXI Signal
Name
26 SER DAT OUT P0.4 Output Serial data out—this signal taps into
the SCXIbus MISO line to accept
serial output data from a module.
27 DAQ D*/A P0.1 Input Board data/address line—this signal
taps into the SCXIbus D*/A line to
indicate to the module whether the
incoming serial stream is data or
address information.
29 SLOT 0 SEL* P0.2 Input Slot 0 select—this signal taps into
the SCXIbus INTR* line to indicate
whether the information on MOSI is
being sent to a module or Slot 0.
36 SCAN CLK AI HOLD,
AI HOLD COMP
Input Scan clock—a rising edge indicates
to the scanned SCXI module that the
E/M Series DAQ device has taken a
sample and causes the module to
advance channels.
37 SER CLK EXT STROBE* Input Serial clock—this signal taps into
the SCXIbus SPI CLK line to clock
the data on the MOSI and MISO
lines.
43 RSVD RSVD Input Reserved.
Notes: All other pins are not connected.
An * means the signal is asserted low.
The signals on the rear signal connector are classified as analog output,
digital I/O, or timing I/O signals.
SCXI-1141/1142/1143 User Manual 2-10 ni.com
Analog Output Signal Connections
Pins 3 through 17 of the rear signal connector are analog output signal pins.
Pin 3 is the main output, and pin 4 is its reference signal. All eight channels
are multiplexed onto this output when the module is software-configured
for multiplexed scanning mode. In parallel scanning mode, the output of
pin 3 is the output of one selected channel. Channel 0 is the power-up and
reset default. When scanning multiple modules, you can also connect this
output to the SCXIbus analog bus and the analog bus will drive this output.
Pins 5, 7, 9, 11, 13, 15, and 17 are direct outputs from channels 1 through 7,
respectively. In parallel mode, all eight channels are available
simultaneously at the rear connector. Pins 6, 8, 10, 12, 14, 16, and 18 are
the reference signals for outputs 1 through 7.
Caution The SCXI-1141/1142/1143 module analog outputs are not overvoltage protected,
although they are short-circuit protected. Applying external voltage to these outputs can
result in damage to the SCXI-1141/1142/1143 module. NI is not liable for any damage
resulting from such signal connections.
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. Each of these pins is in one of three
categories—digital input signals, digital output signals, and timing signals.
Pins 24 and 33 are the digital ground reference for all of the DAQ device
digital signals and are tied to the module digital ground.
Chapter 2 Connecting Signals
The digital input signals are pins 25, 27, 29, and 37. Each digital line
emulates an SCXIbus communication signal as follows:
• Pin 25 is SER DAT IN and is equivalent to the SCXIbus MOSI serial
data input line.
• Pin 27 is DAQ D*/A and is equivalent to the SCXIbus D*/A line.
Pin 27 indicates to the module whether the incoming serial stream on
SER DAT IN is data (DAQ D*/A = 0) or address (DAQ D*/A = 1)
information.
• Pin 29 is SLOT 0 SEL* and is equivalent to the SCXIbus INTR* line.
Pin 29 indicates whether the data on the SER DAT IN line is being sent
to Slot 0 (SLOT 0 SEL* = 0) or to a module (SLOT 0 SEL* = 1).
• Pin 37 is SER CLK and is equivalent to the SCXIbus SPI CLK line.
Pin 37 is used to clock the serial data on the SER DAT IN line into the
module registers.
© National Instruments Corporation 2-11 SCXI-1141/1142/1143 User Manual
Chapter 2 Connecting Signals
The digital output signal is pin 26. Pin 26 is SER DAT OUT and is
equivalent to the SCXIbus MISO serial data output line.
The digital I/O signals of the SCXI-1141/1142/1143 module correspond
to the digital I/O lines of an E/M Series DAQ device. Table 2-4 lists the
equivalencies.
Table 2-4. SCXIbus to SCXI-1141/1142/1143 Module Rear Signal Connector
to DAQ Device Pin Equivalencies
SCXIbus Line
SCXI-1141/1142/1143
Rear Signal Connector
E/M Series
DAQ Device
MOSI SER DAT IN DIO0
D*/A DAQ D*/A DIO1
INTR* SLOT 0 SEL* DIO2
SPI CLK SER CLK EXT STROBE*
MISO SER DAT OUT DIO4
Note: An * means the signal is asserted low.
The digital timing signals are pins 36 and 43:
• Pin 36 is SCAN CLK, the signal used as a clock for the
SCXI-1141/1142/1143 module multiplexer counter. The DAQ device
pulses this signal at the end of each conversion if the module is in
multiplexed mode.
• Pin 43 is a reserved digital input.
SCXI-1141/1142/1143 User Manual 2-12 ni.com
Loading...