Important Information
Warranty
The NI 2501 and NI 2503 are warranted against defects in materials and workmanship for a period of one year from the
date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or
replace equipment that proves to be defective during the warranty period. This warranty includes parts and labor.
The media on which you receive National Instruments software are warranted not to fail to execute programming
instructions, due to defects in materials and workmanship, for a period of 90 days from date of shipment, as evidenced
by receipts or other documentation. National Instruments will, at its option, repair or replace software media that do not
execute programming instructions if National Instruments receives notice of such defects during the warranty period.
National Instruments does not warrant that the operation of the software shall be uninterrupted or error free.
A Return Material Authorization (RMA) number must be obtained from the factory and clearly marked on the outside
of the package before any equipment will be accepted for warranty work. National Instruments will pay the shipping costs
of returning to the owner parts which are covered by warranty.
National Instruments believes that the information in this manual is accurate. The document has been carefully reviewed
for technical accuracy. In the event that technical or typographical errors exist, National Instruments reserves the right to
make changes to subsequent editions of this document without prior notice to holders of this edition. The reader should
consult National Instruments if errors are suspected. In no event shall National Instruments be liable for any damages
arising out of or related to this document or the information contained in it.
EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS
ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED
BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS 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.
Trademarks
CVI™, LabVIEW™, NI-SWITCH™, and PXI™ 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.
Compliance
FCC/DOC Radio Frequency Interference
Class A Compliance
This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance
with the instructions in this manual, may cause interference to radio and television reception. Classification
requirements are the same for the Federal Communications Commission (FCC) and the Canadian
Department of Communications (DOC). This equipment has been tested and found to comply with the
following two regulatory agencies:
Federal Communications Commission
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant
to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference when the equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction
manual, may cause harmful interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmful interference in which case the user will be required to correct the
interference at his own expense.
Notices to User: Changes or modifications not expressly approved by National Instruments could void
the user’s authority to operate the equipment under the FCC Rules.
This device complies with the FCC rules only if used with shielded interface cables
of suitable quality and construction. National Instruments used such cables to test
this device and provides them for sale to the user. The use of inferior or nonshielded
interface cables could void the user’s authority to operate the equipment under the
FCC rules.
If necessary, consult National Instruments or an experienced radio/television technician for additional
suggestions. The following booklet prepared by the FCC may also be helpful: Interference to Home
Electronic Entertainment Equipment Handbook. This booklet is available from the U.S. Government
Printing Office, Washington, DC 20402.
Canadian Department of Communications
This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment
Regulations.
Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur
du Canada.
Conventions
The following conventions are used in this manual.
<>
Angle brackets containing numbers separated by an ellipsis represent a
range of values associated with a port, bit, or signal name (for example,
CH<0..7> stands for the signals CH0 through CH7).
This icon to the left of bold italicized text denotes a note, which alerts
you to important information.
This icon to the left of bold italicized text denotes a caution, which
advises you of precautions to take to avoid injury, data loss, or a
system crash.
!
This icon to the left of bold italicized text denotes a warning, which advises
you of precautions to take to avoid being electrically shocked.
bold italic
Bold italic text denotes a note, caution, or warning.
italic
Italic text denotes variables, emphasis, a cross reference, or an introduction
to a key concept. This font also denotes text from which you supply the
appropriate word or value, as in CHx.
Chapter 1
Routing Signals with Your NI 2501/2503
About the NI 2501/2503 ................................................................................................1-1
Analog Bus......................................................................................................1-2
Triggers............................................................................................................1-2
Cold-Junction Sensor Channel ........................................................................1-3
NI 2501 Amplifier...........................................................................................1-3
Connecting Signals ........................................................................................................1-4
Contact Protection..........................................................................................................1-10
Terminal Blocks.............................................................................................................1-10
NI-SWITCH Driver Software .........................................................................1-10
National Instruments Application Software....................................................1-11
Third Party Software .......................................................................................1-11
Chapter 2
NI 2501/2503 Operation
Functional Overview......................................................................................................2-1
Multiplexer.....................................................................................................................2-4
Two-Wire Mode..............................................................................................2-4
Four-Wire Mode..............................................................................................2-5
Matrix Mode....................................................................................................2-5
Switch Control Circuitry................................................................................................2-5
Random Scanning..........................................................................................................2-5
Triggers............................................................................................................2-6
External Trigger Input.......................................................................2-6
Modes................................................................................................2-7
Initiating Scanning...........................................................................................2-8
Multicard Triggering .......................................................................................2-8
Appendix A
Specifications
© National Instruments Corporation
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NI 2501/2503 User Manual
Contents
Appendix B
Accessories
Appendix C
Customizing Your Card
Appendix D
Architecture Drawings
Appendix E
Customer Communication
Glossary
Index
Figures
Figure 1-2.
Figure 1-4.
Front Connector Pinout Assignments for One-Wire Mode .................. 1-6
Front Connector Pinout Assignments to Create a 6 x 4 Matrix............ 1-8
Figure 2-2.
NI 2503 Module Block Diagram .......................................................... 2-3
Figure D-1. NI 2501 Switch Architecture ................................................................ D-2
Figure D-2. NI 2503 Switch Architecture ................................................................ D-3
Tables
NI 2501/2503 User Manual
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© National Instruments Corporation
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Routing Signals with Your
NI 2501/2503
This manual describes the electrical and mechanical aspects of the
NI 2501 FET multiplexer and the NI 2503 mechanical relay multiplexer
and contains information concerning their installation and operation.
This manual uses the term NI 2501/2503 whenever information applies
to both instruments.
About the NI 2501/2503
This section summarizes the features and operation of the NI 2501/2503
switch card. Refer to Chapter 2, NI 2501/2503 Operation, for more
complete details. In addition, refer to Appendix A, Specifications,
for detailed specifications of the two switch cards.
The NI 2501 is a FET switch card, and the NI 2503 is an armature
relay switch card. Each consists of a 24 x 1 two-wire multiplexer in
PXI/Compact PCI format. You can take advantage of the switch card’s
flexibility to handle a wide variety of test systems through the use of
various accessories and software configurations. You can use the National
Instruments NI-SWITCH software included with your kit to configure and
operate the NI 2501/2503 switch card.
The NI 2501/2503 can also operate as two 12 x 1 or four 6 x 1 two-wire
multiplexers. You can use software-configurable switches to configure
the switch card as a 48 x 1 one-wire multiplexer for making large numbers
operate as a 12 x 1 four-wire multiplexer to handle resistive measurements,
such as thermistors or RTDs. Finally, you can use a National Instruments
TB-2606 terminal block to further configure the NI 2501/2503 as a 6 x 4
two-wire matrix.
on one-wire, two-wire, four-wire, and matrix configurations, and includes
diagrams of the pinout connections to make.
© National Instruments Corporation
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NI 2501/2503 User Manual
Chapter 1
Routing Signals with Your NI 2501/2503
Refer to Appendix B, Accessories, for more information on terminal blocks
you can order from National Instruments.
of the multiplexer or matrix. For example, you can connect two cards to
create a 48 x 1 two-wire multiplexer or a 12 x 4 two-wire matrix.
Caution
The maximum voltage is different for the NI 2501 and NI 2503 switch cards.
If you intend to use more than one type of card, be sure you do not exceed the
maximum voltage of any card in your system. Refer to Appendix A, Specifications,
for information.
!
Analog Bus
The NI 2501/2503 works with a four-wire analog bus. You connect the
analog bus to the switch card through its main front-panel connector.
You can use the analog bus to simplify connecting multiple cards to an
instrument such as a digital multimeter (DMM). This bus makes it possible
to create large systems using multiple switch cards.
For example, if you have two NI 2501/2503 cards—or one of each—in two
adjacent slots, you can connect them through the analog bus and create a
48 x 1 two-wire multiplexer. With this flexibility, you keep the wiring of
the modules to a minimum while you create large switching solutions. In
such cases, the scanning architecture uses some of the PXI trigger lines for
synchronization and delivers full access to all of the scanning features for
the cards. The National Instruments software you receive with the
NI 2501/2503 handles the complexity of programming the cards.
Triggers
Two triggers are used to handshake the NI 2501/2503 switch with PXI
instruments or other external instruments. The Scanner Advanced trigger
indicates when the card has closed all the necessary switches for the next
scan and the switches have settled, or debounced. This trigger is typically
wired to a measurement device, such as a DMM, which is configured to
take a reading when it receives the trigger.
The External Trigger Input trigger is sourced by another instrument, such
as the DMM, and causes the NI 2501/2503 to advance to the next entry
in the scan list. The triggers can be routed to the front connector of the
NI 2501/2503, to any of the PXI TTL triggers, or to the PXI star trigger. If
no external trigger input is available, you can have the software trigger the
NI 2501/2503 to advance to the next entry in the scan list.
NI 2501/2503 User Manual
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© National Instruments Corporation
Chapter 1
Routing Signals with Your NI 2501/2503
Refer to Chapter 2, NI 2501/2503 Operation, for more information on
triggers.
Cold-Junction Sensor Channel
For low-voltage measurements, such as those provided by thermocouples,
the NI 2503 has very low thermal offset—less than 2 µV—to ensure
accurate measurements. For cold-junction compensation when switching
thermocouples, the NI 2501/2503 has a dedicated channel for a
temperature sensor. The National Instruments TB-2605 and TBX-68S
terminal blocks both have onboard temperature sensors that connect to the
dedicated cold-junction sensor channel.
NI 2501 Amplifier
The NI 2501 has an amplifier with a gain of 1. This amplifier can be
switched in-line before the COM0 signal and the AB0 signal. The amplifier
helps to decrease the settling time of the FET switch. The amplifier’s
high impedance isolates the FET from the resistance, capacitance,
and inductance in the external wiring. This isolation decreases the
resistance/capacitance time constant seen by the FET, which improves
settling time.
The amplifier has an offset that should be calibrated for more accurate
measurements. The calibration data can be stored into and retrieved from
the EEPROM on the board. The software you received with your switch
card includes API function calls to retrieve and store calibration data.
When the amplifier is used, the switch card becomes directional, where
CHx is for signal inputs and COM0 or AB0 are for signal outputs.
The NI 2501 also has an amplifier in the CJS0+ to COM0+ signal path.
This amplifier in the cold-junction sensor signal path is used to improve
settling time performance. It prevents the impedance of the cold-junction
sensor from increasing the settling time when switching the CJS channel.
As a result, when scanning thermocouples, the settling time for the
cold-junction sensor channel should be about the same as for the channels
with the thermocouples.
© National Instruments Corporation
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NI 2501/2503 User Manual
Chapter 1
Routing Signals with Your NI 2501/2503
Connecting Signals
This section describes the signal connections to the NI 2501/2503 module
via the module front connector. This section also includes specifications
and connection instructions for the signals on the NI 2501/2503 module
connectors.
Caution
Static electricity is a major cause of component failure. To prevent damage to the
electrical components in the module, observe antistatic precautions whenever
removing a module from the chassis or whenever working on a module.
!
Front Connector
depending on the wiring mode you use. The following four diagrams show
the pin assignments for two-wire mode, one-wire mode, four-wire mode,
and matrix mode, respectively. Two-wire mode is shown first because it is
the most common configuration. Table 1-1, following the diagrams,
describes the connector signals. For more information on the wiring modes,
Warning Any connections that exceed the maximum settings for the NI 2501/2503 can
result in an electrical shock hazard and damage to the NI 2501/2503 module and
any or all of the boards connected to the PXI backplane. National Instruments
is NOT liable for any damages or injuries resulting from exceeding maximum
voltage ratings. Refer to Appendix A, Specifications, for information.
NI 2501/2503 User Manual
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© National Instruments Corporation
Chapter 1
Routing Signals with Your NI 2501/2503
34 68
CH0– 33 67
CJS0–
CJS0+
CH0+
CH1+
CH2+
CH3+
CH4+
CH5+
COM0+
COM1+
32 66
31 65
30 64
29 63
28 62
CH1–
CH2–
CH3–
CH4–
CH5–
COM0– 27 61
COM1– 26 60
CH6–
CH7– 24 58
25 59 CH6+
CH7+
CH8–
23 57 CH8+
1_WIRE_LO_REF1
22 56
21 55
GND
CH9–
CH9+
CH10– 20 54
CH10+
CH11+
AB0+
19 53
18 52
17 51
16 50
15 49
CH11–
AB0–
AB1–
AB1+
CH12–
CH13–
CH12+
CH13+
CH14+
CH15+
CH16+
CH17+
COM2+
COM3+
SCAN_ADV
CH14– 14 48
CH15– 13 47
CH16– 12 46
CH17–
COM2–
COM3–
+5 V
11 45
10 44
9
8
7
6
5
4
3
2
1
43
42
41
40
39
38
37
36
35
GND
CH18–
CH19–
CH20–
CH21–
CH22–
CH23–
EXT_TRIG_IN
CH18+
CH19+
CH20+
CH21+
CH22+
CH23+
1not used in two-wire mode
Figure 1-1. Front Connector Pinout Assignments for Two-Wire Mode
© National Instruments Corporation
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NI 2501/2503 User Manual
Chapter 1
Routing Signals with Your NI 2501/2503
CJS–1
CJS+1
34 68
CH24 33 67
CH0
32 66
31 65
30 64
29 63
28 62
CH25
CH26
CH27
CH28
CH29
CH1
CH2
CH3
CH4
CH5
COM0– 27 61
COM1– (CH30–CH35)1 26 60
CH30
CH31 24 58
COM0+
COM1+ (CH6–CH11)1
25 59 CH6
CH7
CH32
23 57 CH8
22 56
21 55
1_WIRE_LO_REF
CH33
GND
CH9
CH34 20 54
CH10
19 53
18 52
17 51
16 50
15 49
CH35
AB0–
AB1–1
CH36
CH37
CH11
AB0+
AB1+1
CH12
CH13
CH38 14 48
CH39 13 47
CH40 12 46
CH14
CH15
CH16
CH41
COM2– (CH36–CH41)1
COM3– (CH42–CH48)1
+5 V
11 45
10 44
CH17
COM2+ (CH12–CH17)1
COM3+ (CH18–CH23)1
SCAN_ADV
9
8
7
6
5
4
3
2
1
43
42
41
40
39
38
37
36
35
GND
CH42
CH43
CH44
CH45
CH46
CH47
EXT_TRIG_IN
CH18
CH19
CH20
CH21
CH22
CH23
1not used in one-wire mode
Figure 1-2. Front Connector Pinout Assignments for One-Wire Mode
NI 2501/2503 User Manual
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© National Instruments Corporation
Chapter 1
Routing Signals with Your NI 2501/2503
CJS–1
CJS+1
34 68
CH0A– 33 67
CH0A+
CH1A+
CH2A+
CH3A+
CH4A+
CH5A+
COM0A+
COM1A+
32 66
31 65
30 64
29 63
28 62
CH1A–
CH2A–
CH3A–
CH4A–
CH5A–
COM0A– 27 61
COM1A– 26 60
CH6A–
CH7A– 24 58
25 59 CH6A+
CH7A+
CH8A–
23 57 CH8A+
1_WIRE_LO_REF1
22 56
21 55
GND
CH9A–
CH9A+
CH10A+
CH11A+
AB0A+
CH10A– 20 54
19 53
18 52
17 51
16 50
15 49
CH11A–
AB0A–
AB0B–
CH0B–
CH1B–
AB0B+
CH0B+
CH1B+
CH2B+
CH3B+
CH4B+
CH5B+
COM0B+
COM1B+
SCAN_ADV
CH2B– 14 48
CH3B– 13 47
CH4B– 12 46
CH5B–
COM0B–
COM1B–
+5 V
11 45
10 44
9
8
7
6
5
4
3
2
1
43
42
41
40
39
38
37
36
35
GND
CH6B–
CH7B–
CH8B–
CH9B–
CH10B–
CH11B–
EXT_TRIG_IN
CH6B+
CH7B+
CH8B+
CH9B+
CH10B+
CH11B+
1not used in four-wire mode
Figure 1-3. Front Connector Pinout Assignments for Four-Wire Mode
© National Instruments Corporation
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NI 2501/2503 User Manual
Chapter 1
Routing Signals with Your NI 2501/2503
CJS–1
CJS+1
COL0+
34 68
COL0– 33 67
32 66
31 65
30 64
29 63
28 62
COL1–
COL2–
COL3–
COL4–
COL5–
COL1+
COL2+
COL3+
COL4+
COL5+
ROW0– 27 61
ROW1– 26 60
ROW0+
ROW1+
COL0–
25 59 COL0+
COL1– 24 58
COL1+
COL2–
23 57 COL2+
1_WIRE_LO_REF1
22 56
GND
21 55
COL3+
COL3–
COL4– 20 54
COL4+
19 53
18 52
17 51
16 50
15 49
COL5–
AB0– (ROW0–)
AB1– (ROW2–)
COL0–
COL5+
AB0+ (ROW0+)
AB1+ (ROW2+)
COL0+
COL1–
COL1+
COL2– 14 48
COL3– 13 47
COL4– 12 46
COL2+
COL3+
COL4+
COL5–
ROW2–
ROW3–
+5 V
11 45
10 44
COL5+
ROW2+
9
8
7
6
5
4
3
2
1
43
42
41
40
39
38
37
36
35
ROW3+
SCAN_ADV
GND
COL0–
COL1–
COL2–
COL3–
COL4–
COL5–
EXT_TRIG_IN
COL0+
COL1+
COL2+
COL3+
COL4+
COL5+
1not used in matrix mode
Figure 1-4. Front Connector Pinout Assignments to Create a 6 x 4 Matrix
For matrix mode, connect all pins with the same name together external to
the switch card. The National Instruments TB-2606 terminal block
connects the necessary pins to create the 6 x 4 matrix.
NI 2501/2503 User Manual
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© National Instruments Corporation
Chapter 1
Routing Signals with Your NI 2501/2503
Table 1-1. Front Connector Signal Description
Signal Name
Type
Output
Description
+5 V
+5 VDC Source—Powers the temperature sensor
on the terminal block. 0.2 mA of source protected
by a resettable poly fuse.
GND
Output
Input
Ground
CJS±
Cold-junction Temperature Sensor Input—
Connects to the temperature sensor of the
terminal block.
1_WIRE_LO_REF
EXT_TRIG_IN
Input
Input
The common reference signal used in one-wire
mode.
External Trigger Input—Trigger from an
instrument to advance the switch card to the
next scan entry.
SCAN_ADV
Output
Scanner Advanced—Trigger to an instrument
that indicated the switch card has advanced to
the next scan and relays are debounced.
CH<0..47> (one wire)
CH<0..23>± (two wire)
CH<0..11>A± (four wire)
CH<0..11>B± (four wire)
Input/Output
Channels—Where signals are connected to the
switch card. CHx+ and CHx– are switched
together.
COM0± (one wire)
Input/Output
Input/Output
Common—The common for each bank.
COM<0..3>± (two wire)
COM<0..1>A± (four wire)
COM<0..1>B± (four wire)
AB0± (one wire)
Analog Bus—Used to wire multiple switch cards
to an instrument such as a DMM.
AB<0..1>± (two wire)
AB0A± (four wire)
AB0B± (four wire)
COL<0..5>±
Input/Output
Input/Output
Columns—Where signals are connected to the
switch card. The card behaves as a matrix when
proper external wiring is added.
ROW<0..3>±
Rows—Where signals are connected to the
switch card. In matrix configuration any row
can be connected to any column.
© National Instruments Corporation
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NI 2501/2503 User Manual
Chapter 1
Routing Signals with Your NI 2501/2503
Contact Protection
Caution
When inductive loads are connected to the relays, a large counter electromotive
!
force may occur at relay switching time due to the energy stored in the inductive
load. These flyback voltages can severely damage the relay contacts and greatly
shorten the life of the relay.
It is best to limit flyback voltages at your inductive load by installing a flyback
diode for DC loads or a movistor for AC loads.
Terminal Blocks
Several terminal blocks with screw terminals are available for easy signal
connection to the NI 2501/2503 inputs. Refer to Appendix B, Accessories.
Software Choices
You have several options to choose from when programming your National
Instruments switch card. You can use the NI-SWITCH driver software, or
National Instruments application software.
NI-SWITCH Driver Software
The NI-SWITCH instrument driver is an Intelligent Virtual Instrument
(IVI) compliant instrument driver that is bundled with NI-SWITCH cards
at no cost.
NI-SWITCH features a set of operations and attributes that exercise all
the functionality of the switching hardware, including configuration,
opening/closing, and scanning. In addition, NI-SWITCH comes with
an interactive soft front panel and online documentation.
NI-SWITCH eliminates the need to understand complex register
programming and interrupt handling in the Microsoft operating systems,
and frees you to focus on creating your test system.
NI 2501/2503 User Manual
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© National Instruments Corporation
Chapter 1
Routing Signals with Your NI 2501/2503
National Instruments Application Software
LabVIEW and LabWindows/CVI are innovative program development
software packages for data acquisition and control applications. LabVIEW
uses graphical programming, whereas LabWindows/CVI enhances
traditional programming languages. Both packages include extensive
libraries for data acquisition, instrument control, data analysis, and
graphical data presentation. Using LabVIEW or LabWindows/CVI can
significantly reduce the development time for your data acquisition and
control application.
LabVIEW features interactive graphics, a state-of-the-art user interface,
and a powerful graphical programming language. The LabVIEW
NI-SWITCH VI Library, a series of virtual instruments (VIs) for using
LabVIEW with National Instruments switch hardware, is included with
the NI-SWITCH driver.
LabWindows/CVI features interactive graphics, a state-of-the-art user
interface, and uses the ANSI standard C programming language. The
LabWindows/CVI NI-SWITCH Library, a series of functions for using
LabWindows/CVI with National Instruments switch hardware, is included
with the NI-SWITCH driver.
Third Party Software
The NI-SWITCH instrument driver also includes support files for
Microsoft Visual C++ and Microsoft Visual Basic. Please see the
NI-SWITCH readme file for version support information.
© National Instruments Corporation
1-11
NI 2501/2503 User Manual
2
NI 2501/2503 Operation
This chapter contains a functional overview of the NI 2501/2503
module and explains the operation of each functional unit making up
the NI 2501/2503 module.
Functional Overview
The block diagrams on the following pages illustrate the key functional
components of the switch card modules. Figure 2-1 shows the NI 2501 and
Figure 2-2 shows the NI 2503.
The major components of the NI 2501/2503 modules are as follows:
•
•
•
•
•
Multiplexer
Relay/FET switch control circuitry
Random scanning
PXIbus interface
Triggers
© National Instruments Corporation
2-1
NI 2501/2503 User Manual
Chapter 2
NI 2501/2503 Operation
Analog Bus0
Com0
CH0
One Wire /
Two Wire
Select
Unity Gain
Amplifier
Select
CH5
AISENSE
Cold Junction Sensor
Com1
CH6
CH11
Analog Bus1
Com2
CH12
CH17
Com3
CH18
CH23
Figure 2-1. NI 2501 Module Block Diagram
NI 2501/2503 User Manual
2-2
© National Instruments Corporation
Chapter 2
NI 2501/2503 Operation
Multiplexer
The relay multiplexer consists of four banks of six channels. The switches
for the six channels in each bank connect the channels to a common output
for each bank.
•
•
•
Bank 0 consists of Channels 0–5 and Common 0.
Bank 1 consists of Channels 6–11 and Common 1.
Bank 2 consists of Channels 12–17 and Common 2.
Bank 3 consists of Channels 18–23 and Common 3.
Each channel connects to the corresponding bank common by closing its
relay/FET switch. You can have multiple channels connected to the bank
common at the same time. Bank connection relay/FET switches can
combine the commons of the four banks. See Appendix D, Architecture
Drawings, for illustrations of the NI 2501 and NI 2503 architecture.
The NI 2503 relays are single-side stable. When power is removed from the
relay coil, the relay returns to its de-energized state. The de-energized state
opens all the relays, disconnecting the device from external inputs and
outputs.
See Figures 1-1 through 1-4 in Chapter 1, Routing Signals with Your
NI 2501/2503, for the pin names used for the different modes of operation.
Different names are used for the pin assignments in the different modes to
better reflect the operation in the different modes and to simplify the task
of wiring.
Two-Wire Mode
One-Wire Mode
Two-wire mode is the default and most common configuration for the
NI 2501/2503 switch cards. The CHx+ and CHx– channels are switched
together to the COMx+ and COMx– signals for the corresponding bank.
One-wire mode doubles the channel count of what is available in two-wire
mode. However, the signals connected to the switch card need a common
reference. For one-wire measurements, Bank 0 includes extra relays
between the multiplexed channel relays and COM0. The 1WIRE relay
switch connects COM0– to the 1-Wire Lo Ref signal. The HLSELECT
relay connects COM0+ to either CHx+ or CHx–. The de-energized states
for these relays configure the device for two-wire measurements.
NI 2501/2503 User Manual
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© National Instruments Corporation
Chapter 2
NI 2501/2503 Operation
Four-Wire Mode
Matrix Mode
Four-wire mode is typically used for resistance measurements. In this
COMxA+, COMxA–, COMxB+, and COMxB–.
By adding some external wiring, you can configure the switch card as
a two-wire 6 x 4 crosspoint matrix. (See Figure 1-4 in Chapter 1.) The
TB-2606 terminal block simplifies your wiring task by connecting the
necessary pins on the switch card’s front connector to create the 6 x 4
matrix.
In the matrix configuration, you can connect any ROWx signal to any COLx
signal.
Switch Control Circuitry
The switch control circuitry (SCC) is responsible for opening and closing
FET switches on the NI 2501 or relays on the NI 2503. You can load
commands for the SCC into memory storage using the driver software
you received with your kit. Consult the online help or your software
documentation for specific information on the appropriate commands.
There are two reasons for storing the commands in memory before the
SCC can process them:
•
The operate/release time for the NI 2503 is 3 to 5 ms. Using memory
storage, the software can send multiple commands to the SCC without
having to wait for a relay action to complete.
•
The memory is used to store a scan list necessary for hardware random
scanning.
Random Scanning
The NI 2501/2503 can perform random scanning. In random scanning,
the switch card can scan the channels in any order.
The scan list is downloaded to onboard memory. Commands in the scan
list can:
•
•
Open or close relays
Wait for an external trigger
© National Instruments Corporation
2-5
NI 2501/2503 User Manual
Chapter 2
NI 2501/2503 Operation
•
•
Generate a scanner advanced trigger
Generate a breakpoint interrupt
You can use the driver software to configure the switch card for continuous
or one-time scanning. In continuous scanning, the switch card cycles
through the scan list until you disable scanning. For one-time scanning, the
switch card cycles through the scan list only once.
You can also use software commands to clear the scan list or reset it to the
beginning at any time.
The onboard control logic for the NI 2501/2503 switch card gives you
direct access to open and close the relays, and also the capability to
download up to 1024 random scanning instructions. The software included
with the card automatically configures the NI 2501/2503 and downloads
the scan list to hardware for you. The scan list itself downloads directly into
the memory of the card to deliver the fastest scan possible with no
controller intervention. You can configure the switch card to process the
scan list once or to continuously loop through the scan list.
When configured to operate as a single switch card with multiple
multiplexers—such as four 6 x 1 two-wire multiplexers—the scan
architecture makes it possible for each multiplexer to have its own parallel
scan list (which must be triggered together). Also, if the switch card is
configured as a matrix, the scanning architecture scans the matrix through
a series of user-definable states.
PXI Interface
The NI 2501/2503 switch card has a PXI interface through which you
can use your driver software to configure and control the card. The
NI 2501/2503 takes advantage of PXI features. It uses the PXI TTL triggers
to synchronize scanning with a measurement device such as a National
Instruments NI-4060 PXI digital multimeter (DMM).
Triggers
External Trigger Input
The NI 2501/2503 can use an external trigger input to advance between
scan setups in a scan list. Using the driver software, you can configure the
switch card to route the external trigger from any of the PXI TTL trigger
lines, the PXI star trigger, or the EXT TRIG IN pin on the front connector.
Alternatively, you can use a software command to trigger the switch card.
NI 2501/2503 User Manual
2-6
© National Instruments Corporation
Chapter 2
NI 2501/2503 Operation
Routing the external trigger from the front connector to the PXI trigger
lines gives you the capability to trigger multiple switch cards with only one
board connected to the external trigger from the measurement device.
All external trigger lines are compatible with TTL voltage levels and are
edge sensitive.
The external trigger from the front connector requires a minimum pulse
width of 500 ns. The line has a low pass filter to prevent false triggering.
The minimum pulse width from the PXI TTL triggers and PXI star trigger
is 70 ns.
Scanner Advanced
The NI 2501/2503 can generate a scanner advanced trigger to indicate
when the switch card is set up and ready to take measurements. Using the
driver software, you can configure the switch card to route the scanner
advanced (SCANADV) trigger to any PXI TTL trigger line, the PXI star
trigger, or the SCAN_ADV pin on the front connector. You can configure
the switch card to generate the SCANADV trigger when a relay has settled
(or debounced).
All SCANADV trigger lines are compatible with TTL voltage levels.
Because the NI 2501/2503 has open collector drives on the PXI TTL trigger
lines, you can have multiple switch cards using the same trigger line in the
multicard SCANADV mode.
Modes
SCANADV has two modes of operation. In its default mode, the
SCANADV trigger asserts for 1 µs after the relay has debounced. You
can also configure the switch card for handshaking mode, in which the
SCANADV trigger goes high after a relay settles, and the SCANADV
trigger goes low after the external trigger input asserts. Use this
handshaking mode for multicard scanning.
Note
The NI 2501/2503 ignores external triggers when it is not in a wait-for-trigger
state while scanning.
© National Instruments Corporation
2-7
NI 2501/2503 User Manual
Chapter 2
NI 2501/2503 Operation
Initiating Scanning
When you use the NI 2501/2503 to initiate a scan, make sure the
measurement device is armed (waiting for trigger) before enabling
scanning on the switch card. Enabling scanning causes the first switch(es)
in the scan list to close and generates a scanner advanced trigger after the
relay/FET switches have settled or debounced.
When you use the measurement device to initiate a scan, make sure
scanning is enabled on the NI 2501/2503 before the measurement device
starts to take measurements. This ensures that the switch card has the
correct signal routed and that the switch card is waiting for an external
trigger from the measurement device.
Always configure the triggers in a system before configuring the
measurement device or the NI 2501/2503 for scanning. When triggers are
configured, a state change or pulse could occur on the trigger line. This is
also possible when you reset the switch card.
Multicard Triggering
You can use multiple NI 2501/2503 switch cards together in conjunction
with an instrument such as a DMM. In multiple switch-card systems,
be sure to identify one switch card as the master switch card.
All other switch cards for the system are identified as slave switch cards.
The master switch card can route an external trigger from the front
connector to a PXI backplane trigger. In addition, the master switch card
can route the SCANADV trigger from the PXI backplane to the front
connector. This functionality makes it possible to wire external triggers
from/to only one switch card in the system, which simplifies the wiring
scheme.
For more information, refer to the NI-SWITCH Software User Manual.
NI 2501/2503 User Manual
2-8
© National Instruments Corporation
A
Specifications
This appendix lists the specifications for the NI 2501 and NI 2503
switch cards. These specifications are typical at 25° C unless otherwise
noted.
NI 2501
Input Characteristics
Number of Channels .............................. 24
Maximum Working Voltage .................. ± 10 VDC from chassis ground
Overvoltage Protection
Signals CH<0..23>, COM<0..3>
Powered on or off .................... ± 25 VDC
Signals AB<0..1>
Powered on .............................. ± 25 VDC
Powered off.............................. ± 15 VDC
FET Switch On Resistance
Typical ............................................ 50 Ω
Max @ 25° C.................................. 85 Ω
Max @ 85° C.................................. 100 Ω
Total Signal Path Resistance (Channel x to Analog Bus x)
Typical ............................................ 1650 Ω
Maximum........................................ 1900 Ω
Total Signal Path Resistance (Channel x to Common x)
Typical ............................................ 1900 Ω
Maximum........................................ 2150 Ω
© National Instruments Corporation
A-1
NI 2501/2503 User Manual
Appendix A
Specifications for NI 2501
Transfer Characteristics
Channel Amplifier (Unity Gain)
Offset Voltage (Differential) ..................1.2 mV max
Cold-Junction Sensor Channel Amplifier (Unity Gain)
Offset Voltage
Maximum ........................................60 µV
Frequency Bandwidth (50 Ω source, 1 MΩ 25 pF load)
–3 dB ...............................................400 KHz
–10 dB .............................................1 MHz
Channel to Channel
Crosstalk/Isolation..................................50 dB
Dynamic Characteristics
Operating Speed
Typical.............................................25,000 cycles/s
Maximum ........................................250,000 cycles/s
Settling Time (+5 V to –5 V Step) 6 in. AB connector to PXI-MIO
0.012% Accuracy
With output buffer selected......8.5 µs
Without output buffer...............9.0 µs
0.006% Accuracy
With output buffer selected......10 µs
Without output buffer...............11.5 µs
0.0015% Accuracy
With output buffer selected......16 µs
Without output buffer...............18 µs
Settling Time (+5 V to –5 V Step) 3 m cable to PXI-MIO
0.012% Accuracy
With output buffer selected......21 µs
Without output buffer...............45 µs
NI 2501/2503 User Manual
A-2
© National Instruments Corporation
Appendix A
Specifications for NI 2501
0.006% Accuracy
With output buffer selected ..... 30 µs
Without output buffer .............. 60 µs
0.0015% Accuracy
With output buffer selected ..... 80 µs
Without output buffer .............. 160 µs
Note
Settling time is greatly affected by the external wiring to the switch card. You can
improve the settling time by minimizing the wiring from the analog bus connection
to the measurement device.
PXI Bus Interface
PXI Trigger Bus
Slave
Trigger Lines.......................................... 8
Star Trigger ............................................ 1
Power Requirement
+5 V
Typical ............................................ 300 mA
+12 V
Typical ............................................ 30 mA
–12 V
Typical ............................................ 30 mA
Physical
Dimensions............................................. 10 by 16 cm (3.9 by 6.3 in.)
Weight.................................................... 0.254 kg (0.56 lb.)
I/O Connector......................................... 68-pin male SCSI
© National Instruments Corporation
A-3
NI 2501/2503 User Manual
Appendix A
Specifications for NI 2501
Environment
Operating Temperature ........................ 0° to 50° C
Storage Temperature............................ –55° to 150° C
Relative Humidity...................................5% to 90% non-condensing
Shock and Vibration
Functional Shock
MIL-T-28800E Class 3 (30 g half-sine shock pulse)
Also meets IEC 60068-2-27
Random Vibration
MIL-T-28800E, MIL-STD-810E Category 1
Operational...............................5 to 500 Hz, 0.3 grms
Non-operational........................5 to 500 Hz, 2.4 grms
Certifications and Compliances
CE Mark Compliance
This product meets applicable EU directives as follows:
Safety Isolation................................low-voltage safety,
EN 61010-1:1993
EMC Directive
Immunity..................................EN 50082-1:1992
Emissions .................................EN 55011:1991,
Group 1 Class A at 10 m
NI 2501/2503 User Manual
A-4
© National Instruments Corporation
Appendix A
Specifications for NI 2503
NI 2503
Input Characteristics
Number of Relays Available
as Channels ............................................ 24
Common Mode Voltage
Channel to Channel......................... 30 Vrms/60 VDC
Channel to Earth ............................. 30 Vrms/60 VDC
Maximum Allowed Voltage—Differential Mode or Single ended
AC................................................... 30 Vrms
DC................................................... 60 VDC
Maximum Switching Capacity—Differential Mode or Single ended
DC................................................... 1 A @ 30 VDC
Maximum Switching Power per
Differential Channel or Single ended..... 60 VA, 30 W
Contact on Resistance (Initial)............... 100 mΩ
Contact Material..................................... Gold-clad Silver Alloy
Transfer Characteristics
Thermal E.M.F. (Differential)................ <2 µV
Maximum Frequency Bandwidth 50 Ω Termination
Worst case channel ......................... 35 MHz
© National Instruments Corporation
A-5
NI 2501/2503 User Manual
Appendix A
Specifications for NI 2503
Channel to Channel Crosstalk/Isolation
Differential..............................................50 Ω termination
Frequency
10 KHz
Crosstalk
< –100 dB
< –80 dB
< –55 dB
< –30 dB
< –25 dB
100 KHz
1 MHz
10 MHz
35 MHz
Dynamic Characteristics
Maximum Operating Speed....................200 cycles/s
Relay Operate Time (@ 20° C)..............3 ms typical, 5 ms max
Relay Release Time (@ 20° C)..............1.5 ms typical, 5 ms max
Expected Life
Mechanical (@ 180 cpm) ................5 × 107 operations
Electrical at Maximum Load...........2 × 106 operations
PXI Bus Interface
PXI Trigger Bus
Slave
Trigger Lines ..........................................8
Star Trigger.............................................1
Power Requirement
+5 V
Typical.............................................370 mA
Maximum ........................................700 mA
NI 2501/2503 User Manual
A-6
© National Instruments Corporation
Appendix A
Specifications for NI 2503
Physical
Dimensions............................................. 10 by 16 cm (3.9 by 6.3 in.)
Weight.................................................... 0.118 kg (0.4 lb.)
I/O Connector......................................... 68-pin male SCSI
Environment
Operating Temperature.........................0° to 50° C
Storage Temperature ............................–55° to 150° C
Relative Humidity.................................. 5% to 85% non-condensing
Shock and Vibration
Functional Shock
MIL-T-28800E Class 3 (30 g half sine shock pulse)
Also meets IEC 60068-2-27
Random Vibration
MIL-T-28800E, MIL-STD-810E Category 1
Operational .............................. 5 to 500 Hz, 0.3 grams
Non-operational....................... 5 to 500 Hz, 2.4 grams
Certifications and Compliances
CE Mark Compliance
This product meets applicable EU directives as follows:
Safety Isolation ............................... low-voltage safety,
EN 61010-1:1993
EMC Directive
Immunity ................................. EN 50082-1:1992
Emissions................................. EN 55011:1991,
Group 1 Class A at 10 m
© National Instruments Corporation
A-7
NI 2501/2503 User Manual
B
Accessories
This appendix lists various National Instruments products you can use with
your NI 2501/2503 module.
•
The TB-2605 terminal block has screw terminal connections for all
channels, bank commons, analog bus, and trigger signals. You can use
this card for multiplexer switching applications. The terminal block
has a temperature sensor that is used for thermocouple cold-junction
compensation.
•
The TB-2606 terminal block converts the switch card to a 6 x 4
two-wire matrix configuration. This terminal block creates the matrix
configuration by connecting channels (0, 6, 12, 18) (1, 7, 13, 19) …
(5, 11, 17, 23).
•
•
Analog bus connectors plug into TB-2605 and TB-2606 terminal
blocks. These analog bus plugs connect the analog bus of two cards
and terminate in banana plugs.
The TBX-68S I/O connector block is a DIN rail-mounted terminal
block with screw terminal connections you can use for all channels,
bank outputs, analog bus, and trigger signals. You can use this card
for multiplexer switching applications. The terminal block has a
temperature sensor that is used for thermocouple cold-junction
compensation. This is connected to the switch card through the
SH68-68S cable.
•
•
•
SH68-68S shielded 68-conductor cable connects the NI 2501/2503 to
the TBX-68S, TBX-68LP, or TBX-68LPR.
The TBX-68LP and TBX-68LPR are low-cost termination accessories
with 68 screw terminals.
CA-1000 is a configurable signal conditioning enclosure. It uses the
TBX-68LPR terminal block.
Contact National Instruments for more specific information about these
products.
© National Instruments Corporation
B-1
NI 2501/2503 User Manual
C
Customizing Your Card
This appendix describes options for customizing your NI 2501/2503 card.
Current-Loop Receivers
The NI 2501/2503 modules have sockets for transforming individual
channels to current-to-voltage converters. National Instruments offers
a process-current pack of four 249 Ω, 0.1%, 5 ppm, 0.25 W resistors.
The reference designator format for the current-loop resistors is such that
for input channel x, the resistor is RCLx. For example, the resistor for
channel 14 is RCL14.
Caution
Before installing the resistors in your module, make sure that no signals are
connected to your module front connector.
!
Before installing your module in the PXI chassis, you must install the
resistors by performing the following steps:
1. Ground yourself via a grounding strap or a ground connected to
your PXI chassis. Properly grounding yourself prevents damage to
your PXI module from electrostatic discharge.
2. Bend and trim the resistor lead as shown in Figure C-1. Be sure that
the resistor does not extend more than 0.5 in. above the surface of the
circuit board.
3. Insert the resistor into the appropriate socket, labeled RCLx.
© National Instruments Corporation
C-1
NI 2501/2503 User Manual
D
Architecture Drawings
This appendix contains architecture drawings for the NI 2501 and NI 2503
switch cards. The drawings show the signal names that are used when the
boards are in two-wire mode. To make these drawings relevant for
one-wire mode, four-wire mode, or 6 x 4 matrix mode, use the signal names
shown in Figures 1-2 through 1-4, respectively, in Chapter 1, Routing
Signals with Your NI 2501/2503.
Relay or switch names are based on the signal names where applicable. For
example, the switch that connects CH9+ to COM1 and CH9– to COM1– is
named CH9.
For the other configuration relays, the names are as follows:
•
•
•
•
For the relays that connect banks, the switch name is BCx-y, where
x and y are the bank numbers that are being connected.
For the relay that switches 1-Wire Lo Ref to COM0–, the name is
1WIRE.
For the relay that switches CHx+ or CHx– to COM0+, the name is
HLSELECT.
For the Amp Select switches (NI 2501 only), the names are AMP0 and
AMP1.
© National Instruments Corporation
D-1
NI 2501/2503 User Manual
Appendix D
Architecture Drawings
CH11+
CH11–
CH10+
CH10–
CH9+
CH9–
Bank1
CH8+
CH8–
CH7+
CH7–
COM1+
COM1–
CH6+
CH6–
BC01
CH5+
CH5–
CH4+
CH4–
AB0
CH3+
CH3–
AB0+
AB0–
Bank0
CH2+
CH2–
HLSELECT
AMP1
AMP0
COM0+
COM0–
CH1+
CH1–
1WIRE
CH0+
CH0–
1-Wire Lo Ref
CJS+
CJS–
AB1
AB1+
AB1–
BC02
CH12+
CH12–
COM2+
COM2–
CH13+
CH13–
CH14+
CH14–
Bank2
CH15+
CH15–
CH16+
CH16–
CH17+
CH17–
BC23
CH18+
CH18–
COM3+
COM3–
CH19+
CH19–
CH20+
CH20–
Bank3
CH21+
CH21–
CH22+
CH22–
CH23+
CH23–
Figure D-1. NI 2501 Switch Architecture
NI 2501/2503 User Manual
D-2
© National Instruments Corporation
Appendix D
Architecture Drawings
CH11+
CH11–
CH10+
CH10–
CH9+
CH9–
Bank1
CH8+
CH8–
CH7+
CH7–
COM1+
COM1–
CH6+
CH6–
BC01
CH5+
CH5–
CH4+
CH4–
CH3+
CH3–
Bank0
CH2+
CH2–
AB0
AB1
HLSELECT
AB0+
AB0–
CH1+
CH1–
1WIRE
COM0+
COM0–
CH0+
CH0–
1-Wire Lo Ref
CJS+
CJS–
AB1+
AB1–
BC02
CH12+
CH12–
COM2+
COM2–
CH13+
CH13–
CH14+
CH14–
Bank2
CH15+
CH15–
CH16+
CH16–
CH17+
CH17–
BC23
CH18+
CH18–
COM3+
COM3–
CH19+
CH19–
CH20+
CH20–
Bank3
CH21+
CH21–
CH22+
CH22–
CH23+
CH23–
Figure D-2. NI 2503 Switch Architecture
© National Instruments Corporation
D-3
NI 2501/2503 User Manual
E
Common Questions
This appendix addresses common questions you may have while using
your NI 2501 or NI 2503 switch card.
How fast can I scan with the NI 2501 switch card?
The NI 2501 can be scanned as fast as 250 Kscans/s. However, at faster
scan rates, the accuracy of the card declines due to the settling time of the
card. National Instruments recommends you set the scan rate to allow for
enough settling time to ensure the desired accuracy.
How fast can I scan with the NI 2503 switch card?
The NI 2503 uses relays that have typical operate and release times of 3 ms.
In addition to the operate and release times, the NI 2503 also requires from
0.5 to 1.0 ms for the relay contacts to stop bouncing. The combination of
these two times are known as debounce time. The default debounce time for
the NI 2503 switch card is set to just under 5 ms. This setting allows the
card to be scanned at 200 scans/s. However, if the software implements
break-before-make, this would reduce the scan rate to 100 scans/s.
Typically, when using a DMM to make accurate measurements, the DMM
requires hundreds of ms. Consequently, the DMM becomes the limiting
factor in determining the scan rate.
What should I do if the software detects the board but the switches do
not switch?
•
Verify that the switches do not switch. Close your application program
and then launch the soft front panel as described in the Setup and Test
document you received with your kit. The soft front panel shows the
state of each relay or FET switch on the board. Try closing and opening
the switches.
•
Also be sure to check the return codes of the NI-SWITCH operation to
ensure that there are no errors (negative value) or warnings (positive
value). You can also use the NI-Spy utility to check for error codes.
© National Instruments Corporation
E-1
NI 2501/2503 User Manual
Appendix E
Common Questions
•
Finally, verify that your code is correct. For reference, see the
examples described in the NI-SWITCH Software User Manual. The
NI-SWITCH driver also ships with several examples in source code.
Compare your algorithm to the ones in the examples.
What should I do if scanning does not work?
•
First, ensure that you have configured the switch card and the
instrument to match trigger lines. The output trigger of the instrument
should connect to the trigger input of the switch card. In addition, the
scanner advanced trigger of the switch card should be connected to the
input trigger of the instrument.
•
If the switch card is used to initiate the scan, make sure the DMM is
waiting for a trigger before enabling scanning on the switch card. This
is the recommended method for hardware scanning.
•
•
If the DMM is used to initiate the scan, enable scanning on the switch
card before configuring the DMM to start taking measurements.
Also be sure to check the return codes of the NI-SWITCH operation to
ensure that there are no errors (negative value) or warnings (positive
value). You can also use the NI-Spy utility to check for error codes.
•
Finally, verify that your code is correct. For reference, see the
examples described in the NI-SWITCH Software User Manual. The
NI-SWITCH driver also ships with several examples in source code.
Compare your algorithm to the ones in the examples.
Do I need to program the switch card myself?
The NI 2501/2503 comes with the NI-SWITCH driver software, which
exports the full functionality of the card. NI-SWITCH handles the complex
issues of direct memory access, interrupts, and operating system
interfacing.
NI 2501/2503 User Manual
E-2
© National Instruments Corporation
F
Customer Communication
For your convenience, this appendix contains forms to help you gather the information necessary
to help us solve your technical problems and a form you can use to comment on the product
documentation. When you contact us, we need the information on the Technical Support Form and
the configuration form, if your manual contains one, about your system configuration to answer your
questions as quickly as possible.
National Instruments has technical assistance through electronic, fax, and telephone systems to quickly
provide the information you need. Our electronic services include a bulletin board service, an FTP site,
a fax-on-demand system, and e-mail support. If you have a hardware or software problem, first try
the electronic support systems. If the information available on these systems does not answer your
questions, we offer fax and telephone support through our technical support centers, which are staffed
by applications engineers.
Electronic Services
Bulletin Board Support
National Instruments has BBS and FTP sites dedicated for 24-hour support with a collection of files
and documents to answer most common customer questions. From these sites, you can also download
the latest instrument drivers, updates, and example programs. For recorded instructions on how to use
the bulletin board and FTP services and for BBS automated information, call 512 795 6990. You can
access these services at:
United States: 512 794 5422
Up to 14,400 baud, 8 data bits, 1 stop bit, no parity
United Kingdom: 01635 551422
Up to 9,600 baud, 8 data bits, 1 stop bit, no parity
France: 01 48 65 15 59
Up to 9,600 baud, 8 data bits, 1 stop bit, no parity
FTP Support
To access our FTP site, log on to our Internet host, ftp.natinst.com, as anonymous and use
documents are located in the /support directories.
© National Instruments Corporation
F-1
NI 2501/2503 User Manual
Fax-on-Demand Support
Fax-on-Demand is a 24-hour information retrieval system containing a library of documents on a wide
range of technical information. You can access Fax-on-Demand from a touch-tone telephone at
512 418 1111.
E-Mail Support (Currently USA Only)
You can submit technical support questions to the applications engineering team through e-mail at the
Internet address listed below. Remember to include your name, address, and phone number so we can
contact you with solutions and suggestions.
Telephone and Fax Support
National Instruments has branch offices all over the world. Use the list below to find the technical
support number for your country. If there is no National Instruments office in your country, contact
the source from which you purchased your software to obtain support.
Country
Telephone
Fax
Australia
Austria
Belgium
Brazil
Canada (Ontario)
Canada (Québec)
Denmark
Finland
03 9879 5166
0662 45 79 90 0
02 757 00 20
011 288 3336
905 785 0085
514 694 8521
45 76 26 00
09 725 725 11
01 48 14 24 24
089 741 31 30
2645 3186
03 6120092
02 413091
03 5472 2970
02 596 7456
5 520 2635
03 9879 6277
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NI 2501/2503 User Manual
F-2
© National Instruments Corporation
Technical Support Form
Photocopy this form and update it each time you make changes to your software or hardware, and use
the completed copy of this form as a reference for your current configuration. Completing this form
accurately before contacting National Instruments for technical support helps our applications
engineers answer your questions more efficiently.
If you are using any National Instruments hardware or software products related to this problem,
include the configuration forms from their user manuals. Include additional pages if necessary.
Name __________________________________________________________________________
Company _______________________________________________________________________
Address ________________________________________________________________________
_______________________________________________________________________________
Fax ( ___ ) ________________Phone ( ___ ) __________________________________________
Computer brand____________ Model ___________________Processor_____________________
Operating system (include version number) ____________________________________________
Clock speed ______MHz RAM _____MB
Display adapter __________________________
Mouse ___yes ___no Other adapters installed_______________________________________
Hard disk capacity _____MB Brand_________________________________________________
Instruments used _________________________________________________________________
_______________________________________________________________________________
National Instruments hardware product model _____________ Revision ____________________
Configuration ___________________________________________________________________
National Instruments software product ___________________ Version _____________________
Configuration ___________________________________________________________________
The problem is: __________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
List any error messages: ___________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
The following steps reproduce the problem: ___________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
NI 2501/2503 Hardware and Software
Configuration Form
Record the settings and revisions of your hardware and software on the line to the right of each item.
Complete a new copy of this form each time you revise your software or hardware configuration, and
use this form as a reference for your current configuration. Completing this form accurately before
contacting National Instruments for technical support helps our applications engineers answer your
questions more efficiently.
National Instruments Products
Using NI 2501 or NI 2503?_________________________________________________________
Hardware revision ________________________________________________________________
Switching mode__________________________________________________________________
List National Instruments Software Installed and Version
NI-SWITCH version ______________________________________________________________
LabVIEW version ________________________________________________________________
LabWindows/CVI version __________________________________________________________
Other National Instruments software version ____________________________________________
________________________________________________________________________________
Programming choice _______________________________________________________________
Other Products
PXI Chassis make and model _______________________________________________________
Microprocessor __________________________________________________________________
Clock frequency or speed __________________________________________________________
Type of video board installed _______________________________________________________
Operating system version __________________________________________________________
Operating system mode____________________________________________________________
Programming language ____________________________________________________________
Programming language version______________________________________________________
Switch accessories________________________________________________________________
_______________________________________________________________________________
Instruments connected to switch _____________________________________________________
_______________________________________________________________________________
List All Boards in PXI Mainframe
PXI Slot
Manufacturer, Description, and Function
1
2
3
4
5
6
7
8
Documentation Comment Form
National Instruments encourages you to comment on the documentation supplied with our products.
This information helps us provide quality products to meet your needs.
Title:
NI 2501/2503 User Manual
Edition Date: July 1998
Part Number: 321906B-01
Please comment on the completeness, clarity, and organization of the manual.
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Glossary
Prefix
n-
Meanings
nano-
Value
10–9
10– 6
10–3
103
µ-
micro-
milli-
m-
k-
kilo-
M-
G-
mega-
giga-
106
109
Symbols
°
degrees
Ω
%
±
ohms
percent
plus or minus
A
A
amperes
AC
ANSI
alternating current
American National Standards Institute
B
breakpoint
a specified point in program code where the program pauses to perform
some action; a breakpoint interrupt can be added to a scan list for
debugging or other special needs.
© National Instruments Corporation
G-1
NI 2501/2503 User Manual
Glossary
bus
the group of conductors that interconnect individual circuitry in a computer.
Typically, a bus is the expansion vehicle to which I/O or other devices are
connected. Examples of PC buses are the ISA and PCI bus.
C
C
Celsius
channel
pin or wire lead on the multiplexer to which you apply or from which you
read the analog or digital signal. Signals can be single-ended or differential.
cold-junction
compensation
a method of compensating for inaccuracies in thermocouple circuits
contact bounce
the intermittent switching that occurs when the movable metal parts of a
relay make or break contact
D
DC
direct current
debounced
device
indicates when the contact bounce has ended. See contact bounce.
a plug-in board, card, or pad that can contain multiple channels and
conversion devices. Some examples of devices are computers,
multimeters, multiplexers, oscillators, operator interfaces, and
counters.
digital multimeter
a multifunction meter used to make measurements such as voltage, current,
resistance frequency, temperature, and so on
DIN
Deutsche Industrie Norme
DMA
direct memory access—a method by which data can be transferred to/from
computer memory from/to a device or memory on the bus while the
processor does something else. DMA is the fastest method of transferring
data to/from computer memory.
DMM
See digital multimeter.
drivers/driver software
software that controls a specific hardware device such as a switch card
NI 2501/2503 User Manual
G-2
© National Instruments Corporation
Glossary
E
external trigger
a voltage pulse from an external source that triggers an event such as
A/D conversion
F
FET
Field Effect Transistor
H
handshaking
the use of two trigger lines between two instruments, such as a switch and
a DMM, to synchronize their actions
Hz
hertz—the number of scans read or updates written per second
I
in.
inches
I/O
input/output—the transfer of data to/from a computer system involving
communications channels, operator interface devices, and/or data
acquisition and control interfaces
Intelligent Virtual
Instrument
an advanced architecture for instrument drivers that includes features such
as simulation and state caching
ISA
IVI
Industry Standard Architecture
See Intelligent Virtual Instrument.
M
MB
megabytes of memory
matrix
superset of multiplexer; consists of connected rows and columns that
allows for a direct connection from any row to any column
movistor
transient suppression device
© National Instruments Corporation
G-3
NI 2501/2503 User Manual
Glossary
multiplexer
a switching device with multiple inputs that sequentially connects each
of its inputs to its output, typically at high speeds, in order to measure
several signals with a single analog input channel
mux
See multiplexer.
N
NI-SWITCH
an IVI-based instrument driver that supports the National Instruments line
of switch cards
P
PXI
PCI with extensions for instrumentation
R
random scanning
scanning the channels in a mux in any order
relay
a switch that connects or disconnects the signal to a common through the
physical movement of a metal arm
RMA
rms
Return Material Authorization
root mean square—the square root of the average value of the square of the
instantaneous signal amplitude; a measure of signal amplitude
RTD
resistance temperature detector—a metallic probe that measures
temperature based upon its coefficient of resistivity
S
s
seconds
scan
the data acquisition of signals connected to multiple channels of a
multiplexer. Typically, the measurement device uses a trigger to
advance the multiplexer to the next channel in the scan.
scan list
a list of channels supplied to NI-SWITCH that indicates the order in which
channels will be scanned
NI 2501/2503 User Manual
G-4
© National Instruments Corporation
Glossary
scanner advanced
trigger
the trigger generated by the switch card when scanning. The trigger occurs
after the switch card has closed a switch and the switch has settled.
sensor
a device that responds to a physical stimulus (heat, light, sound,
pressure, motion, flow, and so on), and produces a corresponding
electrical signal
settling time
the amount of time required for a voltage to reach its final value within
specified limits
soft front panel
a graphical program included with NI-SWITCH that you can use to
interactively control the switch
T
TBX
Terminal Block Extension
terminal block
thermistor
an accessory containing wire connection points, typically screw terminals
a semiconductor sensor that exhibits a repeatable change in electrical
resistance as a function of temperature. Most thermistors exhibit a
negative temperature coefficient.
thermocouple
a temperature sensor created by joining two dissimilar metals. The
junction produces a small voltage as a function of the temperature.
trigger
TTL
any event that causes or starts some form of data capture
Transistor-Transistor Logic
V
V
volts
VDC
VI
volts, direct current
virtual instrument—(1) a combination of hardware and/or software
elements, typically used with a PC, that has the functionality of a classic
stand-alone instrument (2) a LabVIEW software module (VI), which
consists of a front panel user interface and a block diagram program
© National Instruments Corporation
G-5
NI 2501/2503 User Manual
Glossary
W
W
watts
wire
data path between nodes
NI 2501/2503 User Manual
G-6
© National Instruments Corporation
Index
COM<0..1>Α± signal (table), 1-9
COM<0..1>B± signal (table), 1-9
COM0± signal (table), 1-9
Numbers
1_WIRE_LO_REF signal (table), 1-9
+5 V signal (table), 1-9
common questions, E-1 to E-2
connecting signals. See signal connections.
contact protection (caution), 1-10
conventions used in this manual, v
current-loop receivers, C1 to C-2
customer communication, F-1 to F-2
customizing NI 2501/2503, C1 to C-2
A
AB<0..1>± signal (table), 1-9
AB0± signal (table), 1-9
AB0A± signal (table), 1-9
AB0B± signal (table), 1-9
accessories for NI 2501/2503, B-1
amplifier for NI 2501, 1-3
analog bus, 1-2
D
debounced switches, 1-2
dynamic characteristics
NI 2501, A-2 to A-3
NI 2503, A-6
analog bus connectors, for terminal blocks, B-1
architecture drawings, D-1 to D-3
B
block diagrams
E
NI 2501 module, 2-2
NI 2503 module, 2-3
bulletin board support, F-1
electrical hazards
exceeding maximum settings (warning), 1-4
static electricity (caution), 1-4
electronic support services, F-1 to F-2
e-mail support, F-2
environmental specifications
NI 2501, A-4
C
CA-1000, B-1
cable, SH68-68S, B-1
NI 2503, A-7
calibration data, storing in EEPROM, 1-3
CE Mark Compliance, A-4, A-7
CH<0..23>± signal (table), 1-9
CH<0..47> one-wire signal (table), 1-9
CH<0..11>A± signal (table), 1-9
CH<0..11>Β± signal (table), 1-9
CJS± signal (table), 1-9
COL<0..5>± signal (table), 1-9
cold-junction sensor channel, 1-3
COM<0..3>± signal (table), 1-9
external trigger input, 1-2, 2-6 to 2-7
EXT_TRIG_IN signal (table), 1-9, 2-6
F
fax and telephone support numbers, F-2
Fax-on-Demand support, F-2
flyback voltages (caution), 1-10
four-wire multiplexer, 1-7, 2-5
© National Instruments Corporation
I-1
NI 2501/2503 User Manual
Index
front connector
N
pinout assignments
National Instruments application
software, 1-11
NI 2501/2503. See also operation of
NI 2501/2503.
four-wire mode (figure), 1-7
matrix mode (figure), 1-8
one-wire mode (figure), 1-6
overview, 1-4
accessories, B-1
two-wire mode (figure), 1-5
signal descriptions (table), 1-9
FTP support, F-1
architecture drawings, D1 to D-3
block diagrams
NI 2501 module, 2-2
NI 2503 module, 2-3
common questions, E-1 to E-2
customizing, C1 to C-2
features, 1-1 to 1-2
G
GND signal (table), 1-9
functional overview, 2-1
maximum voltage (note), 1-2
overview, 1-1 to 1-2
signal connections, 1-4 to 1-9
software choices, 1-10 to 1-11
specifications
I
initiating scanning, 2-8
input characteristics
NI 2501, A-1
NI 2503, A-5
NI 2501, A-1 to A-4
NI 2503, A-5 to A-7
NI-SWITCH driver software, 1-10, E-1 to E-2
I/O connector blocks
TBX-68LP, B-1
TBX-68LPR, B-1
TBX-68S, 1-3, B-1
O
one-wire multiplexer, 1-6, 2-4
operation of NI 2501/2503, 2-1 to 2-8
block diagrams
L
LabVIEW software, 1-11
LabWindows/CVI software, 1-11
NI 2501 module, 2-2
NI 2503 module, 2-3
functional overview, 2-1
multiplexer, 2-4 to 2-5
PXI interface, 2-6 to 2-8
initiating scanning, 2-8
multicard triggering, 2-8
triggers, 2-6 to 2-7
M
matrix mode, 1-8, 2-5
maximum voltage (note), 1-2
modes of operation, 2-7
multicard triggering, 2-8
multiplexer, 2-4 to 2-5
four-wire, 2-5
random scanning, 2-5 to 2-6
switch control circuitry, 2-5
matrix mode, 2-5
one-wire, 2-4
two-wire, 2-4
NI 2501/2503 User Manual
I-2
© National Instruments Corporation
Index
P
S
physical specifications
NI 2501, A-3
SCAN_ADV signal (table), 1-9, 2-7
scanner advanced trigger, 1-2, 2-7
scanning
NI 2503, A-7
pinout assignments for front connector
four-wire mode (figure), 1-7
matrix mode, (figure), 1-8
one-wire mode (figure), 1-6
overview, 1-4
two-wire mode (figure), 1-5
power requirements
NI 2501, A-3
failure to scan, E-2
initiating, 2-8
random scanning, 2-5 to 2-6
speed of scanning, E-1
SH68-68S shielded cable, B-1
shock and vibration specifications
NI 2501, A-4
NI 2503, A-7
NI 2503, A-7
product compliance specifications
NI 2501, A-4
signal connections, 1-4 to 1-9
exceeding maximum settings
(warning), 1-4
front connector pinout assignments
four-wire mode (figure), 1-7
matrix mode (figure), 1-8
one-wire mode (figure), 1-6
overview, 1-4
NI 2503, A-7
PXI interface, 2-6 to 2-8
initiating scanning, 2-7 to 2-8
multicard triggering, 2-8
specifications
two-wire mode (figure), 1-5
signal descriptions (table), 1-9
software choices
NI 2501, A-3
NI 2503, A-6
triggers, 2-6 to 2-7
external trigger input, 2-7
modes, 2-7
National Instruments application
software, 1-11
NI-SWITCH driver software, 1-10
third-party software, 1-11
specifications
scanner advanced, 2-7
PXI trigger bus specifications
NI 2501, A-3
NI 2501, A-1 to A-4
NI 2503, A-6
CE mark compliance, A-4
dynamic characteristics, A-2 to A-3
environment, A-4
input characteristics, A-1
physical, A-3
Q
questions and answers, E-1 to E-2
power requirements, A-3
PXI bus interface, A-3
PXI trigger bus, A-3
shock and vibration, A-4
transfer characteristics, A-2
R
random scanning, 2-5 to 2-6
relay multiplexer, 2-3 to 2-5
resistors, installing, C1 to C-2
ROW<0..3>± signal (table), 1-9
© National Instruments Corporation
I-3
NI 2501/2503 User Manual
Index
NI 2503, A-5 to A-7
technical support, F-1 to F-2
telephone and fax support numbers, F-2
terminal blocks
CE mark compliance, A-7
dynamic characteristics, A-6
environment, A-7
input characteristics, A-5
physical, A-7
analog bus connectors, B-1
availability, 1-10
TB-2605, 1-3, B-1
power requirements, A-7
PXI bus interface, A-6
PXI trigger bus, A-6
TB-2606, 1-1, 1-8, 2-5, B-1
transfer characteristics
NI 2501, A-2
shock and vibration, A-7
transfer characteristics, A-6
NI 2503, A-6
triggers
static electricity, component failure due to
(caution), 1-4
external trigger input, 1-2, 2-6 to 2-7
modes, 2-7
switch control circuitry, 2-5
switch failure, E-1 to E-2
multicard triggering, 2-8
overview, 1-2
scanner advanced, 1-2, 2-7
two-wire multiplexer, 1-5, 2-4
T
TB-2605 terminal block, 1-3, B-1
V
TB-2606 terminal block, 1-1, 1-8, 2-5, B-1
TBX-68LP I/O connector block, B-1
TBX-68LPR I/O connector block, B-1
TBX-68S I/O connector block, 1-3, B-1
voltage
flyback voltages (caution), 1-10
maximum voltage (note), 1-2
NI 2501/2503 User Manual
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© National Instruments Corporation
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