National Instruments NI 4050 User manual

Brand: National Instruments

Model: NI 4050

Category: Multimeters

Type: User manual

Computer-Based

Instruments

NI 4050 User Manual

Digital Multimeter Card for PCMCIA

NI 4050 User Manual

March 2000 Edition

Part Number 321427C-01

Worldwide Technical Support and Product Information

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Important Information

Warranty

The NI 4050 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as

evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to

be defective during the warranty period. This warranty includes parts and labor.

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 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.

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Compliance

FCC/Canada Radio Frequency Interference Compliance*

Determining FCC Class

The Federal Communications Commission (FCC) has rules to protect wireless communications from interference.

The FCC places digital electronics into two classes. These classes are known as Class A (for use in industrial-

commercial locations only) or Class B (for use in residential or commercial locations). Depending on where it is

operated, this product could be subject to restrictions in the FCC rules. (In Canada, the Department of

Communications (DOC), of Industry Canada, regulates wireless interference in much the same way.)

Digital electronics emit weak signals during normal operation that can affect radio, television, or other wireless

products. By examining the product you purchased, you can determine the FCC Class and therefore which of the two

FCC/DOC Warnings apply in the following sections. (Some products may not be labeled at all for FCC; if so, the

reader should then assume these are Class A devices.)

FCC Class A products only display a simple warning statement of one paragraph in length regarding interference and

undesired operation. Most of our products are FCC Class A. The FCC rules have restrictions regarding the locations

where FCC Class A products can be operated.

FCC Class B products display either a FCC ID code, starting with the letters EXN,

or the FCC Class B compliance mark that appears as shown here on the right.

Consult the FCC web site

http://www.fcc.gov for more information.

FCC/DOC Warnings

This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance with the

instructions in this manual and the CE Mark Declaration of Conformity**, 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).

Changes or modifications not expressly approved by National Instruments could void the user’s authority to operate

the equipment under the FCC Rules.

Class A

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.

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.

Class B

Federal Communications Commission

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15

of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a

residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed

and used in accordance with the instructions, may cause harmful interference to radio communications. However,

there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful

interference to radio or television reception, which can be determined by turning the equipment off and on, the user

is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment and receiver.

• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.

• Consult the dealer or an experienced radio/TV technician for help.

Canadian Department of Communications

This Class B digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.

Cet appareil numérique de la classe B respecte toutes les exigences du Règlement sur le matériel brouilleur du

Canada.

European Union - Compliance to EEC Directives

Readers in the EU/EEC/EEA must refer to the Manufacturer's Declaration of Conformity (DoC) for information**

pertaining to the CE Mark compliance scheme. The Manufacturer includes a DoC for most every hardware product

except for those bought for OEMs, if also available from an original manufacturer that also markets in the EU, or

where compliance is not required as for electrically benign apparatus or cables.

* Certain exemptions may apply in the USA, see FCC Rules §15.103 Exempted devices, and §15.105(c).

Also available in sections of CFR 47.

** The CE Mark Declaration of Conformity will contain important supplementary information and instructions

for the user or installer.

Conventions

The following conventions are used in this manual:

» 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.

bold Bold text denotes items that you must select or click on 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. This font 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, and code excerpts.

Contents

Chapter 1

Taking Measurements with the NI 4050

Cable and Probes ...........................................................................................................1-1

Introduction to the VirtualBench-DMM Soft Front Panel.............................................1-3

Use the Soft Front Panel................................................................................................1-5

Measure DC and AC Voltage..........................................................................1-5

Measure 2-Wire Resistance.............................................................................1-6

Measure the Voltage Drop Across a Diode.....................................................1-7

Measure Current..............................................................................................1-8

Measure Temperature......................................................................................1-9

Chapter 2

NI 4050 Operation

Safety Instructions .........................................................................................................2-1

Measurement Fundamentals ..........................................................................................2-2

Warm Up.........................................................................................................2-2

Selecting the Resolution..................................................................................2-2

Grounding........................................................................................................2-2

Voltage Measurements ..................................................................................................2-2

DC Voltage......................................................................................................2-2

Input Ranges .....................................................................................2-3

Measurement Considerations............................................................2-3

Input Impedance .................................................................2-3

Thermal EMF .....................................................................2-4

Noise Rejection...................................................................2-4

AC Voltage......................................................................................................2-6

Input Ranges .....................................................................................2-7

Measurement Considerations............................................................2-7

AC Offset Voltage..............................................................2-7

Frequency Response...........................................................2-7

Resistance Measurements..............................................................................................2-8

2-Wire Resistance Measurements ...................................................................2-8

Input Ranges .....................................................................................2-8

Continuity Measurements................................................................................2-9

Diode Measurements .....................................................................................................2-9

Contents

NI 4050 User Manual viii www.ni.com

Appendix A

Specifications

Appendix B

Technical Support Resources

Glossary

Index

Figures

Figure 1-1. Installing the NI 4050 and Cables.........................................................1-2

Figure 1-2. NI-DMM Soft Front Panel....................................................................1-3

Figure 1-3. Digits of Precision.................................................................................1-5

Figure 1-4. Connecting Probes for Voltage Measurement......................................1-6

Figure 1-5. Connections for Resistance Measurement............................................1-7

Figure 1-6. Connecting Signals for Diode Test.......................................................1-7

Figure 1-7. Connections for Current Measurement.................................................1-8

Figure 1-8. Connecting Signals for RTDs and Thermistors....................................1-9

Figure 2-1. Effect of Input Impedance on Signal Measurements............................2-3

Figure 2-2. Normal Mode Measurement Effects.....................................................2-5

Figure 2-3. Common Mode Measurement Effects ..................................................2-6

Figure 2-4. Circuit for 2-Wire Resistance Measurements.......................................2-8

Figure 2-5. Circuit for Diode Measurements...........................................................2-9

Taking Measurements with

the NI 4050

Thank you for buying a National Instruments 4050 digital multimeter card.

A system based on the NI 4050 offers the flexibility, performance, and

size that makes it ideal for service, repair, and manufacturing as well as

for use in industrial and laboratory environments. The NI 4050, used in

conjunction with your computer, is a versatile, cost-effective platform for

high-resolution measurements.

For the most current versions of manuals and example programs, visit

www.ni.com/instruments for free downloads.

Detailed specifications for the NI 4050 are in Appendix A, Specifications.

Note

Before using any measurement equipment, it is important that you thoroughly

understand the safety instructions for that product. The beginning of Chapter 2, NI 4050

Operation, covers the safety guidelines for your NI 4050.

Cable and Probes

The NI 4050 instrument kit contains the NI 4050 accessory cable that

connects the NI 4050 to a pair of test probes with shrouded banana plugs,

which are also included in the kit. Both the NI 4050 accessory cable and the

test probes meet international safety requirements including UL 3111 and

IEC 1010-1 for the full ranges of applications supported by the NI 4050.

Before using any probes or accessories not supplied by National

Instruments, ensure that they meet applicable safety requirements for the

signal levels you may encounter.

To use the NI 4050 accessory cable and probes with the NI 4050, first

connect the cable to the card as shown in Figure 1-1. The accessory cable

connector is polarized so that it cannot be plugged in incorrectly.

Chapter 1 Taking Measurements with the NI 4050

NI 4050 User Manual 1-2 www.ni.com

Figure 1-1. Installing the NI 4050 and Cables

The test probes connect to the NI 4050 accessory cable via shrouded

banana jacks. The shrouds around the banana jacks prevent you from

contacting potentially hazardous voltages connected to the test probes.

You can also connect the cable to standard, unshrouded banana jack probes

or accessories; however, use unshrouded probes or accessories only when

the voltages are less than 30 V

rms

or 42 V

pk-to-pk

Caution To prevent possible safety hazards, the maximum voltage between either of the

inputs and the ground of the computer should never exceed ±250 VDC or 250 V

rms

PCMCIA Slot

Portable

Computer

NI 4050

Probes

Accessory Cable

Chapter 1 Taking Measurements with the NI 4050

Introduction to the VirtualBench-DMM Soft Front Panel

The following sections explain how to make connections to your NI 4050

and take simple measurements using the VirtualBench-DMM, as shown in

Figure 1-2. To launch the soft front panel, select Start»Programs»

National Instruments DMM»Soft Front Panel.

Figure 1-2.

NI-DMM Soft Front Panel

The following text describes the options available on the soft front panel.

Refer to Help»Online Reference located on the soft front panel for

information on front panel menus.

The range selector determines the range of measurements

VirtualBench-DMM makes. The range differs for each measurement mode.

If the measurement exceeds the range, +OVER or –OVER appears in the

measurement display. Auto selects the range that best matches the input

signal.

The value indicator displays the value measured by your NI 4060

(The value shown is an example only.).

The unit indicator displays the measurement units of the value you are

measuring. The units are expressed as VAC, VDC, mVAC, mVDC, Ω,

kΩ,MΩ, mA, AC, or mA DC. The indicator also displays the digits of

resolution. By clicking on the indicator, you can change the DMM’s

resolution.

Chapter 1 Taking Measurements with the NI 4050

NI 4050 User Manual 1-4 www.ni.com

The Function selector allows you select a measurement mode. Select

Edit»Settings and click on the tabs for Current and Resistance or

Temperature to control the data type acquired by VirtualBench-DMM.

DC volts measures the DC component of a voltage signal.

AC volts measures the AC component of a voltage signal.

DC current measures the DC component of a current source.

AC current measures the AC component of a current source.

2-wire measures resistance using the 2-wire method.

4-wire measures resistance using the 4-wire method.

Diode measures the voltage drop across a diode. The maximum voltage

VirtualBench-DMM measures is 2 V.

Temperature measures temperature.

The run button starts and stops continuous DMM measurements.

The single button performs a single measurement.

The math buttons allow you to manipulate readings mathematically.

Null starts relative mode. VirtualBench-DMM makes all subsequent

measurements relative to the measurement it makes when you click

on Null.

Max/Min displays the maximum and minimum values that occur after you

start Relative mode.

mX+B enables the mX+B calculation on all readings.

dB compresses a large range of measurements into a much smaller range

by expressing DC or AC voltage in decibels.

dBm shows decibels above or below a 1 mW reference.

Chapter 1 Taking Measurements with the NI 4050

% selects the percentage calculation. VirtualBench-DMM expresses the

displayed reading as a percent deviation from the reference value entered

in the Math Settings. Refer to Help»Online Reference, Math Settings topic

for more information about dB, dBm, mX+B, and percentage calculations.

The log button enables data logging. To configure the datalog file and log

interval, select Edit»Settings. Refer to Help»Online Reference, Logging

Measurements to Disk topic for more details.

Digits of Precision—A pop-up ring control in the DMM front panel display

allows you to set measurement accuracy to 3 1/2, 4 1/2, or 5 1/2. A larger

value gives greater precision but slower measurement performance. Refer

to Figure 1-3.

Figure 1-3. Digits of Precision

Use the Soft Front Panel

The following sections describe procedures for measuring DC and AC

voltage, resistance, diode, and temperature, using the soft front panel.

Measure DC and AC Voltage

Use the following procedure to measure DC and AC voltage using the soft

front panel:

1. Connect the test probes to voltage signals as shown in Figure 1-4. For

DC voltages, the HI (red) terminal is the positive terminal, and the

LO (black) terminal is negative. For AC voltages, positive and negative

terms are irrelevant.

Chapter 1 Taking Measurements with the NI 4050

NI 4050 User Manual 1-6 www.ni.com

The NI 4050 is protected against damage from voltages within

±250 VDC or 250 V

rms

in all ranges. You should never apply voltages

above these levels to the inputs.

Figure 1-4. Connecting Probes for Voltage Measurement

2. Select the mode you will measure:

•DC Volts

•AC Volts

3. Select the range for your measurement or autoranging:

• DC Volts—± 20 mV, ± 200 mV, ± 2 V, ± 25 V, and ± 250 V

• AC Volts—20 mV

rms

, 200 mV

rms

, 2 V

rms

, 25 V

rms

, and 250 V

rms

The value indicator displays the voltage measured.

Measure 2-Wire Resistance

Use the following procedure to measure 2-wire resistance using the soft

front panel:

1. Connect the test probes to a resistor as shown in Figure 1-5. To

accurately measure the value of a resistor, make sure the resistor is not

connected to any other circuits. Erroneous or misleading readings may

result if the resistor you are measuring is connected to external circuits

that supply voltages or currents or to external circuits that change the

effective resistance of that resistor.

AC Voltage

Source

DC Voltage

Source

–

250 V

MAX.

250 V

MAX.

Chapter 1 Taking Measurements with the NI 4050

Figure 1-5. Connections for Resistance Measurement

2. Select 2-wire resistance mode.

3. Select the range for your measurement—200 Ω, 2 kΩ, 20 kΩ, 200 kΩ,

2 MΩ, 200 MΩ, or autorange.

The value indicator indicates the resistance measured. See the 2-Wire

Resistance Measurements section of Chapter 2, NI 4050 Operation, for

more information on 2-wire resistance measurements.

Measuring the Voltage Drop Across a Diode

The NI 4050 can excite a device under test and read the resulting voltage

drop. Diode mode is useful for testing diodes. Use the following procedure

to measure the forward drop across a diode. Voltage up to 2 V can be

measured in this mode.

1. Connect the test probes to a diode as shown in Figure 1-6. To

accurately measure the forward voltage of a diode, make sure that the

diode is not connected to any other circuits. The NI 4050 biases the

diode with a current of 100 µA and measures the resulting voltage

drop. Diode measurements are made with a fixed range of 2.0 V.

Figure 1-6. Connecting Signals for Diode Test

Resistor

250 V

MAX.

Diode

–

100 µA

250 V

MAX.

Chapter 1 Taking Measurements with the NI 4050

NI 4050 User Manual 1-8 www.ni.com

2. Select diode mode.

3. Select the range for your measurement. Only the 2 V range is available

for diode measurement.

The value indicator will indicate the voltage drop measured. If the display

indicates 2.200 VDC, the diode is either reverse biased or defective. See the

Diode Measurements section of Chapter 2, NI 4050 Operation, for more

information on diode measurements.

Measure Current

You can use the NI 4050 to measure current with an optional National

Instruments CSM series current shunt module. These accessories are

connected between the NI 4050 cable and the test probes as shown in

Figure 1-7.

Connections for Current Measurement

Current shunt accessories contain a precision resistor that converts the

current through the shunt into a voltage that the NI 4050 can measure in

voltage mode. While the soft front panel cannot measure current directly

with the NI 4050, you can calculate the value of the current flowing through

the shunt by dividing the voltage measured by the value of the precision

resistor.

Current

Source

Current Shunt

Accessory

250 V

MAX.

Chapter 1 Taking Measurements with the NI 4050

Measure Temperature

You can measure temperature using common temperature transducers such

as resistive temperature devices (RTD) and thermistors. You can measure

transducers in the 2-wire resistance mode, as shown in Figure 1-8.

Although the soft front panel does not support temperature measurements,

you can convert and scale the transducer value to temperature

programmatically through software.

Note

The NI 4050 for PCMCIA does not support 4-wire resistance measurements. To

avoid measurement errors due to resistance offset, before doing resistance measurements,

measure the resistance to your loads.

Figure 1-8.

Connecting Signals for RTDs and Thermistors

Resistor

250 V

MAX.

NI 4050 Operation

This chapter contains safety instructions, measurement fundamentals and

concerns, and scanning information.

Safety Instructions

Cautions

To avoid personal injury or damage to electronic equipment, observe the

following:

Do not operate this instrument in an explosive atmosphere or where there may be

flammable gases or fumes.

Equipment described in this document must be used in an Installation Category II

environment per IEC 664. This category requires local level supply mains-connected

installation.

The NI 4050 must be used in a UL-listed laptop or personal computer.

To prevent safety hazards, the maximum voltage between either of the inputs and the

ground of the computer should never exceed ±250 VDC or 250 V

rms

Do not operate damaged equipment. The safety protection features built into this

instrument can become impaired if the instrument becomes damaged in any way. If the

instrument is damaged, do not use it until service-trained personnel can check its safety.

If necessary, return the instrument to National Instruments for service and repair to ensure

that its safety is not compromised.

Do not operate this instrument in a manner that contradicts the information specified in this

document. Misuse of this instrument could result in a shock hazard.

Do not substitute parts or modify equipment. Because of the danger of introducing

additional hazards, do not install unauthorized parts or modify the instrument. Return the

instrument to National Instruments for service and repair to ensure that its safety is not

compromised.

Connections that exceed any of the maximum signal ratings on the NI 4050 can create a

shock or fire hazard or can damage any or all of the devices connected to the NI 4050.

National Instruments is not liable for any damages or injuries resulting from incorrect

signal connections.

Clean the instrument and accessories by brushing off light dust with a soft, nonmetallic

brush. Remove other contaminants with a stiff nonmetallic brush. The unit must be

completely dry and free from contaminants before returning to service.

Chapter 2 NI 4050 Operation

NI 4050 User Manual 2-2 www.ni.com

Measurement Fundamentals

Warm Up

The required warm-up time for the NI 4050 is 30 minutes. This warm-up

time is important because measurements made with the NI 4050

multimeter can change with temperature. This change is called a thermal

drift and affects your accuracy. To minimize the effects of thermal drift and

ensure the specified accuracies, take all measurements after the NI 4050

has had a chance to fully warm up. Depending on your environment, the

NI 4050 can operate significantly above ambient temperature. Therefore,

measurements made immediately after powering up the system can differ

significantly from measurements made after the system has fully warmed

up. The NI 4050 temperature specifications are listed in the Accuracy

sections in Appendix A, Specifications.

Selecting the Resolution

The resolution on the NI 4050 multimeter is programmable. You can select

from three different resolutions: 5 1/2 digits, 4 1/2 digits, or 3 1/2 digits.

These settings allow you to trade off speed for resolution. The 5 1/2 digit

setting has the highest resolution and slowest reading rate, while the

3 1/2 digit setting gives you the least resolution and fastest reading rate.

Measurement mode and range affect the reading rate by requiring different

conversion times to obtain a given resolution for the different modes and

ranges.

Grounding

When measuring ground-referenced signals, connect the

ground-referenced side of your signal to the IN HI + terminal for best

performance.

Voltage Measurements

DC Voltage

Your NI 4050 multimeter uses a high-resolution delta sigma, A/D

converter (ADC) to sample signals and convert them into a digital form.

The ADC is preceded by a series of gain and attenuation circuitry that allow

both small and large signals to be measured using the same converter. The

NI 4050 uses a digital filter, which heavily rejects powerline frequencies

(50–60 Hz) and their harmonics, as well as high-frequency noise.

Chapter 2 NI 4050 Operation

Input Ranges

The NI 4050 has five input ranges available for measuring DC voltages.

These ranges are ±20 mV, ±200 mV, ±2.0 V, ±25V, and ±250 V. Each

range has a 10% overrange, except for the 250 V range. The 250 V and

25 V input ranges have a 1 MΩ input impedance; the 2 V, 200 mV, and

20 mV ranges have an input impedance greater than 1 GΩ. Take these

values into consideration when measuring high-impedance sources. When

the NI 4050 is powered off, the 250 V and 25 V input range have a 1 MΩ

input impedance and the 2 V, 200 mV, and 20 mV ranges have an input

impedance of 100 kΩ.

If you are taking measurements that require a high degree of accuracy, you

should consider problems associated with input impedance, noise effects,

and thermal electromotive forces (thermal EMFs). These effects are

discussed in the Measurement Considerations section.

Measurement Considerations

Input Impedance

Figure 2-1 illustrates the input impedance of an NI 4050 and its effect on

the measurement of a circuit under test. If you know the source impedance

of the circuit being tested, you can correct for the attenuation caused by the

NI 4050 in software. Since R

is large, at least 1 MΩ, it will require a large

source impedance, R

, to cause a large change in the measured voltage, V

Figure 2-1.

Effect of Input Impedance on Signal Measurements

Source

Voltage V

External Source

Impedance R

–

Input

Impedance

Measured

Voltage

+ R

-------------- -------------=

Input

VΩ

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National Instruments NI 4050 User manual

Brand: National Instruments

Model: NI 4050

Category: Multimeters

Type: User manual

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National Instruments NI 4050 User manual

National Instruments NI 4050 User manual

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