National Instruments Computer Hardware NI 4050 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  
 
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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Trademarks  
CVI, ComponentWorks, LabVIEW, National Instruments, ni.com, NI-DAQ, SCXI, and VirtualBenchare trademarks  
of National Instruments Corporation.  
Product and company names mentioned herein are trademarks or trade names of their respective companies.  
WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS  
(1) NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL  
OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL  
COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE  
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(2) IN ANY APPLICATION, INCLUDING THE ABOVE, RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS  
CAN BE IMPAIRED BY ADVERSE FACTORS, INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL  
POWER SUPPLY, COMPUTER HARDWARE MALFUNCTIONS, COMPUTER OPERATING SYSTEM SOFTWARE  
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SYSTEMS (HARDWARE AND/OR SOFTWARE), UNANTICIPATED USES OR MISUSES, OR ERRORS ON THE PART OF  
THE USER OR APPLICATIONS DESIGNER (ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER  
COLLECTIVELY TERMED “SYSTEM FAILURES”). ANY APPLICATION WHERE A SYSTEM FAILURE WOULD  
CREATE A RISK OF HARM TO PROPERTY OR PERSONS (INCLUDING THE RISK OF BODILY INJURY AND DEATH)  
SHOULD NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM  
FAILURE. TO AVOID DAMAGE, INJURY, OR DEATH, THE USER OR APPLICATION DESIGNER MUST TAKE  
REASONABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES, INCLUDING BUT NOT LIMITED TO  
BACK-UP OR SHUT DOWN MECHANISMS. BECAUSE EACH END-USER SYSTEM IS CUSTOMIZED AND DIFFERS  
FROM NATIONAL INSTRUMENTS' TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER  
MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT  
EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS, THE USER OR APPLICATION DESIGNER IS  
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SYSTEM OR APPLICATION, INCLUDING, WITHOUT LIMITATION, THE APPROPRIATE DESIGN, PROCESS AND  
SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION.  
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.  
Chapter 1  
Use the Soft Front Panel ................................................................................................1-5  
Measure 2-Wire Resistance.............................................................................1-6  
Measure the Voltage Drop Across a Diode.....................................................1-7  
Chapter 2  
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  
© National Instruments Corporation  
vii  
NI 4050 User Manual  
Contents  
Appendix A  
Technical Support Resources  
Glossary  
Index  
Figures  
Figure 1-3.  
Figure 1-8.  
Digits of Precision................................................................................. 1-5  
Figure 2-1.  
Figure 2-2.  
Figure 2-3.  
Figure 2-4.  
Figure 2-5.  
Effect of Input Impedance on Signal Measurements............................ 2-3  
Normal Mode Measurement Effects..................................................... 2-5  
Common Mode Measurement Effects .................................................. 2-6  
Circuit for 2-Wire Resistance Measurements....................................... 2-8  
Circuit for Diode Measurements........................................................... 2-9  
NI 4050 User Manual  
viii  
1
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.  
© National Instruments Corporation  
1-1  
NI 4050 User Manual  
     
Chapter 1  
Taking Measurements with the NI 4050  
Portable  
Computer  
PCMCIA Slot  
NI 4050  
Accessory Cable  
Probes  
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 Vrms or 42 Vpk-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 Vrms  
.
NI 4050 User Manual  
1-2  
   
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, ,  
k, M, 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.  
© National Instruments Corporation  
1-3  
NI 4050 User Manual  
     
Chapter 1  
Taking Measurements with the NI 4050  
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.  
NI 4050 User Manual  
1-4  
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.  
© National Instruments Corporation  
1-5  
NI 4050 User Manual  
       
Chapter 1  
Taking Measurements with the NI 4050  
The NI 4050 is protected against damage from voltages within  
±250 VDC or 250 Vrms in all ranges. You should never apply voltages  
above these levels to the inputs.  
HI  
HI  
DC Voltage  
Source  
AC Voltage  
Source  
250 V  
MAX.  
250 V  
MAX.  
+
LO  
LO  
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 mVrms, 200 mVrms, 2 Vrms, 25 Vrms, and 250 Vrms  
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.  
NI 4050 User Manual  
1-6  
     
Chapter 1  
Taking Measurements with the NI 4050  
HI  
250 V  
MAX.  
Resistor  
LO  
Figure 1-5. Connections for Resistance Measurement  
3. Select the range for your measurement—200 , 2 k, 20 k, 200 k,  
2 M, 200 M, 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.  
100 µA  
HI  
+
250 V  
Diode  
MAX.  
LO  
Figure 1-6. Connecting Signals for Diode Test  
© National Instruments Corporation  
1-7  
NI 4050 User Manual  
       
Chapter 1  
Taking Measurements with the NI 4050  
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.  
HI  
Current  
Source  
250 V  
MAX.  
LO  
Current Shunt  
Accessory  
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.  
NI 4050 User Manual  
1-8  
     
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.  
HI  
250 V  
MAX.  
Resistor  
LO  
Figure 1-8. Connecting Signals for RTDs and Thermistors  
© National Instruments Corporation  
1-9  
NI 4050 User Manual  
     
2
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 Vrms  
.
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.  
© National Instruments Corporation  
2-1  
NI 4050 User Manual  
         
Chapter 2  
NI 4050 Operation  
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.  
NI 4050 User Manual  
2-2  
           
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 Minput impedance; the 2 V, 200 mV, and  
20 mV ranges have an input impedance greater than 1 G. 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 Rin is large, at least 1 M, it will require a large  
source impedance, Rs, to cause a large change in the measured voltage, Vm.  
External Source  
Impedance Rs  
Measured  
Voltage  
Vm  
HI  
+
Input  
Impedance  
Rin  
Source  
Voltage Vs  
Input  
VΩ  
+
LO  
Vs Rin  
= ----------------------  
Rs + Rin  
Vm  
Figure 2-1. Effect of Input Impedance on Signal Measurements  
© National Instruments Corporation  
2-3  
NI 4050 User Manual  
         
Chapter 2  
NI 4050 Operation  
Thermal EMF  
Thermal EMFs, or thermoelectric potentials, are voltages generated at the  
junctions of dissimilar metals and are functions of temperature. Thermal  
EMFs in a circuit under test can cause higher than expected offsets that  
change with temperature.  
Noise Rejection  
The NI 4050 filters out AC voltages in the DC voltage measurement  
ranges. However, if the amplitudes of the AC voltages are large compared  
to the DC voltages, or if the peak value (AC + DC) of the measured voltage  
is outside the overrange limits, the NI 4050 may exhibit additional errors.  
To minimize these errors, keep the NI 4050 away from strong AC magnetic  
sources and minimize the area of the loop formed by the test leads.  
Choosing the 5 1/2 digit resolution will also help minimize noise from  
AC sources. If the peak value of the measured voltage is likely to exceed  
the selected input range, select the next highest input range.  
Normal Mode Rejection  
Normal mode rejection (NMR) is the ability of the NI 4050 to reject a  
normally (differentially) applied signal. The ability is quantified in the  
normal mode rejection ratio (NMRR) specification, which indicates the  
capability of the NI 4050 to reject 50 or 60 Hz and is valid only at the  
specified frequency and useful only when taking DC measurements. The  
NMRR is specified at the powerline frequency because this is typically  
where most measurement noise occurs.  
Figure 2-2 shows a 60 Hz signal connected differentially to the NI 4050 in  
DC Volts mode. Vm is the voltage that will be measured after the signal is  
rejected. NMR is very useful when trying to measure DC voltages in the  
presence of large powerline interference.  
NI 4050 User Manual  
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Chapter 2  
NI 4050 Operation  
HI  
+
Measured  
Voltage  
Vm  
Source  
Voltage  
Vs at 60 Hz  
Input  
VΩ  
LO  
20  
V
m = Vs × 10  
Figure 2-2. Normal Mode Measurement Effects  
If you are measuring signals in the presence of large normal mode voltages,  
consult Appendix A, Specifications, to calculate the additional error to your  
system. Use the equation in Figure 2-2 to calculate the voltage error due to  
normal mode voltage.  
Common Mode Rejection  
Common mode rejection (CMR) is the ability of the NI 4050 to reject  
signals that are common to both input terminals. The ability is quantified in  
the common mode rejection ratio (CMRR) specification. Theoretically, the  
floating measurement circuitry of the NI 4050 should have an infinite  
CMRR. Parasitic resistances and capacitances to earth ground limit the  
CMR of the NI 4050. This effect is most noticeable when measuring small  
signals in the presence of a large common mode voltage, as shown in  
Figure 2-3.  
© National Instruments Corporation  
2-5  
NI 4050 User Manual  
   
Chapter 2  
NI 4050 Operation  
HI  
+
Measured  
Voltage  
Vm  
Source  
Voltage  
Vs  
Input  
VΩ  
+
LO  
Common  
Voltage  
Vc  
+
–CMRR  
--------------------  
V
20  
s
Verror  
=
----- + V × 10  
c
2
Vm = Vs + Verror  
Figure 2-3. Common Mode Measurement Effects  
Using the equation in Figure 2-3, you can calculate the voltage error due to  
the common mode voltage. If you are measuring signals in the presence of  
large common mode voltages, consult Appendix A, Specifications, to  
calculate the additional error to your system.  
Effective Common Mode Rejection  
Effective common mode rejection is the sum of the CMRR and the NMRR  
at a given frequency. It is the effective rejection on a given noise signal that  
is applied to both input leads as it gets rejected first by the CMR capability  
of the instrument then again by its NMR capability. This specification is  
most useful at the powerline frequency where most of the noise resides and  
is only valid for DC measurements.  
AC Voltage  
In the AC voltage ranges, the NI 4050 measures the AC-coupled RMS  
value of a signal. The RMS value of a signal is a fundamental measurement  
of the magnitude of an AC signal. The RMS value of an AC signal can be  
defined mathematically as the square root of the average of the square of  
the signal.  
In practical terms, the RMS value of an AC signal is the DC value required  
to produce an equivalent amount of heat in the same resistive load. The  
NI 4050 first AC-couples the measured signal to remove any DC  
NI 4050 User Manual  
2-6  
     
Chapter 2  
NI 4050 Operation  
components and then measures the RMS value of the AC component. This  
method lets you measure a small AC signal in the presence of a large DC  
offset.  
Input Ranges  
The NI 4050 has five input ranges available for measuring AC voltages.  
These ranges are 20 mVrms, 200 mVrms, 2.0 Vrms, 25 Vrms, and 250 Vrms  
.
The impedance in each of these ranges is a 0.068 µF capacitor followed by  
1 M. When the NI 4050 is powered off, the 250 V, 25 V, and 2 V input  
ranges have a 0.068 µF capacitor, followed by a 1 Minput impedance.  
The 200 mV and 20 mV ranges have a 0.068 µF capacitor, followed by  
an approximate 100 kinput impedance.  
The NI 4050 can measure AC voltages to its specified accuracy as long as  
the voltage is at least 10% and no more than 100% of the selected input  
range. The DC component in any of these ranges can be as high as  
250 VDC. Each range, except for the 250 V range, has a 10% overrange.  
The AC voltage measurement accuracy depends on many factors, including  
the signal amplitude, frequency, and waveform shape.  
Measurement Considerations  
AC Offset Voltage  
The AC measurements of the NI 4050 are specified over the range of 10%  
to 100% of the full-scale input range. Below 10% of the input range, errors  
due to the AC voltage offset become significant. This offset, unlike DC  
voltage offsets, cannot simply be subtracted from the readings or zeroed out  
because the offset gets converted in the RMS conversion. To minimize the  
errors due to the AC offset voltage, choose an input range that keeps the  
measured voltage between 10% and 100% of full scale.  
Frequency Response  
The accuracy of the NI 4050’s AC voltage measurements is a function of  
the input signal frequency. Your NI 4050 is calibrated at the factory using  
a 1 kHz sine wave. Your frequency-dependent error will be minimal around  
this frequency. The error will then increase as you approach the upper and  
lower bandwidth limits. This additional error is added to the accuracy  
errors in computing the absolute error.  
© National Instruments Corporation  
2-7  
NI 4050 User Manual  
       
Chapter 2  
NI 4050 Operation  
These additional errors are shown in Appendix A, Specifications. While the  
NI 4050 is characterized and specified over the 20 Hz to 25 kHz frequency  
range, measurements outside of this range can still be made with decreased  
accuracy.  
Resistance Measurements  
2-Wire Resistance Measurements  
The NI 4050 measures 2-wire resistance by passing a current through the  
device under test and reading the resulting voltage drop through the same  
connections, as illustrated in Figure 2-4. The resistance value is then  
computed using Ohm’s Law (R=V/I). To accurately measure the value of  
a resistor, make sure the resistor is not connected to any other circuits.  
Erroneous or misleading readings can 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.  
Iex  
HI  
+
Input  
VΩ  
Vsense  
Iex  
Runknown  
LO  
Iex  
Vsense  
Runknown  
=
Iex  
Iex = 100 µA (200 , 2 k, 20 kranges)  
1 µA (200 k, 2 M, 200 Mranges)  
Figure 2-4. Circuit for 2-Wire Resistance Measurements  
Input Ranges  
The NI 4050 has five basic input ranges for 2-wire resistance as well as an  
extended range. The basic ranges are 200 , 2.0 k, 20 k, 200 k, and  
2 M. With the extended range, measurements up to at least 200 Mare  
possible.  
NI 4050 User Manual  
2-8  
           
Chapter 2  
NI 4050 Operation  
In the extended ohms range, the NI 4050 adds a 1 Mresistor in parallel  
with the test resistor, and then calculates the value of the resistor being  
tested. The test current for the 200 , 2.0 k, and 20 kranges is 100 µA.  
The test current for the 200 k, 2 M, and 200 Mranges is 1 µA.  
Continuity Measurements  
Many traditional multimeters can take continuity measurements, which test  
for the presence or absence of continuity between the two test probes.  
These measurements are simply resistance measurements, where the  
resistance between the two probes is measured and compared to a set value.  
You can perform continuity measurements on a circuit by setting the  
NI 4050 to the 200 range and comparing the measured value to some low  
resistance value, typically 10 . If the measured value is less than 10 ,  
there is continuity between the test probes.  
Diode Measurements  
To properly 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, as  
illustrated in Figure 2-5. Diode measurements are made with a fixed range  
of 2.0 V.  
Note Different multimeters use different currents to excite the diode. This may result in  
different readings for the same diode.  
Iex  
HI  
+
+
Input  
VΩ  
Vsense  
Vdiode  
Iex  
LO  
Iex  
Vsense = Vdiode  
Figure 2-5. Circuit for Diode Measurements  
© National Instruments Corporation  
2-9  
NI 4050 User Manual  
         
A
Specifications  
This appendix lists the specifications of the NI 4050. These specifications  
are guaranteed between 15 and 35 °C unless otherwise specified.  
DC Voltage  
Accuracy (% of reading ± µV)  
24 Hour  
90 Day  
1 Year  
Temperature Coefficient  
Range  
(25 °C ± 1 °C)  
(25 °C ± 10 °C)  
(25° C ± 10 °C)  
(% of Reading/ °C ± µV/ °C)  
250.000 V  
25.0000 V  
2.00000 V  
200.000 mV  
20.0000 mV  
0.0032% ± 4.9 mV  
0.0032% ± 4.9 mV  
0.0029% ± 37 µV  
0.0029% ± 27 µV  
0.0029% ± 27 µV  
0.021% ± 49 mV  
0.021% ± 49 mV  
0.014% ± 260 µV  
0.014% ± 250 µV  
0.014% ± 250 µV  
0.024% ± 49 mV  
0.024% ± 49 mV  
0.017% ± 260 µV  
0.017% ± 250 µV  
0.017% ± 250 µV  
0.0017% ± 4800 µV  
0.0017% ± 4800 µV  
0.0009% ± 25 µV  
0.0009% ± 25 µV  
0.0009% ± 25 µV  
Accuracy numbers are for 5 1/2 digits and include the effects of full-scale and zero-scale errors, temperature variation,  
linearity, and noise.  
Noise Rejection  
NMRR (10 Hz reading rate, 50/60 Hz  
powerline frequency ±1%)..................... 80 dB  
DC ECMRR ........................................... 140 dB (with a 1 kimbalance  
in LO lead)  
AC ECMR (RDC to 60 Hz) ................... 150 dB (with a 1 kimbalance  
in LO lead)  
Input Characteristics  
Input bias current ................................... 1 nA max  
Input resistance ...................................... > 1 G(2 V, 200 mV,  
20 mV ranges);  
1 M(250 V, 25 V)  
© National Instruments Corporation  
A-1  
NI 4050 User Manual  
       
Appendix A  
Specifications  
DC Current  
Accuracy (% of reading ± µA)  
DC current measurements require the use of the CSM current shunt  
modules.  
24 Hour  
90 Day  
1 Year  
Temperature Coefficient  
Range  
(25 °C ± 1 °C)  
(25 °C ± 10 °C)  
(25 °C ± 10 °C)  
(% of Reading/°C ± µA/°C)  
200.000 mA*  
20.0000 mA*  
10.0000 A**  
0.1% ± 27 µA  
0.1% ± 27 µA  
0.02% ± 4 mA  
0.14% ± 250 µA  
0.14% ± 250 µA  
0.035% ± 26 mA  
0.15% ± 250 µA  
0.15% ± 250 µA  
0.035% ± 26 mA  
0.0035% ± 25 µA  
0.0035% ± 25 µA  
0.007% ± 2.5 mA  
Accuracy numbers are for 5 1/2 digits and include the effects of full-scale and zero-scale errors, temperature variation,  
linerarity, and noise.  
* Requires 200 mA shunt, CSM-200mA.  
** Requires 10 A shunt, CSM-10A.  
Input Characteristics  
200 mA shunt  
Input protection ...............................Fuse F1 500 mA/250 V fast  
fusing  
Shunt resistor...................................1 Ω  
Burden voltage.................................< 400 mV at 200 mA  
10 A shunt  
Input protection ...............................Fuse F1 12.5 A/250 V fast fusing  
Shunt resistor...................................10 mΩ  
Burden voltage.................................< 300 mV at 10 A  
NI 4050 User Manual  
A-2  
Appendix A  
Specifications  
AC Voltage  
Accuracy (% of reading ± mV)  
24 Hour  
90 Day  
1 Year  
Temperature Coefficient  
Range  
(25 °C ± 1 °C)  
0.6% ± 500 mV  
0.3% ± 30 mV  
0.4% ± 3 mV  
(25 °C ± 10 °C)  
(25 °C ± 10 °C)  
(% of Reading/°C ± mV/°C)  
250.000 V  
25.0000 V  
2.00000 V  
200.000 mV  
20.0000 mV  
0.62% ± 680 mV  
0.32% ± 210 mV  
0.42% ± 21 mV  
0.32% ± 1.20 mV  
0.42% ± 170 µV  
0.62% ± 680 mV  
0.32% ± 210 mV  
0.42% ± 21 mV  
0.32% ± 1.20 mV  
0.42% ± 170 µV  
0.007% ± 20 mV  
0.007% ± 20 mV  
0.019% ± 2 mV  
0.3% ± 0.22 mV  
0.4% ± 100 µV  
0.007% ± 0.110 mV  
0.019% ± 12 µV  
Accuracy numbers are for 5 1/2 digits and include the effects of full-scale and zero-scale errors, temperature variation,  
linerarity, and noise, applies for sine waves 10% of input range. Accuracy may be affected by source impedance, cable  
capacitances dielectric absorption, or slew rate.  
Noise Rejection  
AC CMRR (DC to 60 Hz)...................... > 80 dB (with a 1 kimbalance  
in LO lead)  
Input Characteristics  
Input resistance ...................................... 1 Mall ranges  
Bandwidth .............................................. 20 Hz–25 kHz  
Additional AC Errors  
Frequency-dependent errors  
Input Frequency  
20–50 Hz  
Additional Error (% of Reading)  
2.5%  
1%  
50–100 Hz  
100 Hz–5 kHz  
5–10 kHz  
0%  
1%  
10–25 kHz  
2.5%  
© National Instruments Corporation  
A-3  
NI 4050 User Manual  
Appendix A  
Specifications  
AC Current  
Accuracy (% of reading ± mA)  
AC current measurements require the use of the CSM current shunt  
module.  
24 Hour  
90 Day  
1 Year  
Temperature Coefficient  
Range  
(25 °C ± 1 °C)  
(25 °C ± 10 °C)  
(25 °C ± 10 °C)  
(% of Reading/°C ± mA/°C)  
200.000 mA*  
20.0000 mA*  
10.0000 A**  
0.45% ± 0.22 mA  
0.35% ± 110 µA  
0.3% ± 22 mA  
0.47% ± 1.2 mA  
0.37% ± 170 µA  
0.32% ± 120 mA  
0.47% ± 1.2 mA  
0.37% ± 170 µA  
0.32% ± 120 mA  
0.007% ± 0.110 mA  
0.019% ± 0.120 mA  
0.026% ± 11 mA  
Accuracy numbers are for 5 1/2 digits and include the effects of full-scale and zero-scale errors, temperature variation,  
linerarity, and noise.  
* Requires 200 mA shunt, CSM-200mA.  
** Requires 10 A shunt, CSM-10A.  
Input Characteristics  
200 mA shunt  
Input protection ...............................Fuse F1 500 mA/250 V fast  
fusing  
Shunt resistor...................................1 Ω  
Burden voltage.................................< 400 mV at 200 mA  
10 A shunt  
Input protection ...............................Fuse F1 12.5 A/250 V fast fusing  
Shunt resistor...................................10 mΩ  
Burden voltage.................................< 300 mV at 10 A  
NI 4050 User Manual  
A-4  
Appendix A  
Specifications  
Resistance  
Accuracy (% of reading ± Ω)  
24 Hour  
90 Day  
1 Year  
Temperature Coefficient  
Range  
(25 °C ± 1 °C)  
(25 °C ± 10 °C)  
(25 °C ± 10 °C)  
(% of Reading/°C ± /°C)  
Extended Ohm  
(> 2 MΩ)  
0.1% ± 6 kΩ  
0.1% ± 60 kΩ  
0.1% ± 60 kΩ  
0.0072% ± 6 kΩ  
2.00000 MΩ  
200.000 kΩ  
20.0000 kΩ  
2.00000 kΩ  
200.000 Ω  
0.012% ± 55 Ω  
0.012% ± 37 Ω  
0.006% ± 0.5 Ω  
0.006% ± 0.4 Ω  
0.006% ± 0.4 Ω  
0.077% ± 370 Ω  
0.077% ± 350 Ω  
0.024% ± 4 Ω  
0.024% ± 4 Ω  
0.024% ± 4 Ω  
0.080% ± 20 Ω  
0.080% ± 2 Ω  
0.027% ± 4 Ω  
0.027% ± 4 Ω  
0.027% ± 4 Ω  
0.0072% ± 35 Ω  
0.0072% ± 35 Ω  
0.0020% ± 0.40 Ω  
0.0020% ± 0.40 Ω  
0.0020% ± 0.40 Ω  
Accuracy numbers are for 5 1/2 digits and include the effects of full-scale and zero-scale errors, temperature variation,  
linearity, and noise.  
Measurement mode................................ 2-wire Ohms  
Test current ............................................ 100 µA for 200 Ω, 2 kΩ,  
20 kranges  
1 µA for 2 MΩ, 200 kranges  
1 µA and 1 Min parallel for  
extended Ohms mode  
Diode Testing  
Accuracy (% of reading ± µV)  
24 Hour  
90 Day  
1 Year  
Temperature Coefficient  
Range  
(25 °C ± 1 °C)  
(25 °C ± 10 °C)  
(25 °C ± 10 °C)  
(% of Reading/°C ± µV/°C)  
2 V  
0.006% ± 60 µV  
0.024% ± 400 µV  
0.027% ± 400 µV  
0.002% ± 40 µV  
Accuracy numbers are for 5 1/2 digits and include the effects of full-scale and zero-scale errors, temperature variation,  
linearity, and noise.  
Test current ............................................ 100 µA  
© National Instruments Corporation  
A-5  
NI 4050 User Manual  
Appendix A  
Specifications  
General Specifications  
Settling time............................................Affected by source impedance  
and input signal changes  
Warm-up time.........................................30 minutes for measurements  
accurate within specifications  
Bus type ..................................................PCMCIA, slave  
Altitude ...................................................Up to 2,000 m; at higher altitudes  
the installation category must be  
derated  
Working voltage .....................................250 V maximum between either  
input terminal and earth ground  
Power requirement..................................+5 VDC, 45 mA in operational  
mode  
Safety......................................................Designed in accordance with  
IEC 1010-1 and UL 3111 for  
electrical measuring and testing  
equipment,  
Installation Category II,  
Pollution Degree 2,  
Double Insulated,  
Indoor use,  
UL 3111 listed  
Physical  
Dimensions .............................................Type II PC Card  
Environment  
Operating temperature ............................0 to 55 °C  
Storage temperature................................–20 to 70 °C  
Relative humidity ...................................10% to 90% noncondensing  
NI 4050 User Manual  
A-6  
B
Technical Support Resources  
This appendix describes the comprehensive resources available to you in  
the Technical Support section of the National Instruments Web site and  
provides technical support telephone numbers for you to use if you have  
trouble connecting to our Web site or if you do not have internet access.  
NI Web Support  
To provide you with immediate answers and solutions 24 hours a day,  
365 days a year, National Instruments maintains extensive online technical  
support resources. They are available to you at no cost, are updated daily,  
and can be found in the Technical Support section of our Web site at  
Online Problem-Solving and Diagnostic Resources  
KnowledgeBase—A searchable database containing thousands of  
frequently asked questions (FAQs) and their corresponding answers or  
solutions, including special sections devoted to our newest products.  
The database is updated daily in response to new customer experiences  
and feedback.  
Troubleshooting Wizards—Step-by-step guides lead you through  
common problems and answer questions about our entire product line.  
Wizards include screen shots that illustrate the steps being described  
and provide detailed information ranging from simple getting started  
instructions to advanced topics.  
Product Manuals—A comprehensive, searchable library of the latest  
editions of National Instruments hardware and software product  
manuals.  
Hardware Reference Database—A searchable database containing  
brief hardware descriptions, mechanical drawings, and helpful images  
of jumper settings and connector pinouts.  
Application Notes—A library with more than 100 short papers  
addressing specific topics such as creating and calling DLLs,  
developing your own instrument driver software, and porting  
applications between platforms and operating systems.  
© National Instruments Corporation  
B-1  
NI 4050 User Manual  
     
Appendix B  
Technical Support Resources  
Software-Related Resources  
Instrument Driver Network—A library with hundreds of instrument  
drivers for control of standalone instruments via GPIB, VXI, or serial  
interfaces. You also can submit a request for a particular instrument  
driver if it does not already appear in the library.  
Example Programs Database—A database with numerous,  
non-shipping example programs for National Instruments  
programming environments. You can use them to complement the  
example programs that are already included with National Instruments  
products.  
Software Library—A library with updates and patches to application  
software, links to the latest versions of driver software for National  
Instruments hardware products, and utility routines.  
Worldwide Support  
National Instruments has offices located around the globe. Many branch  
offices maintain a Web site to provide information on local services. You  
can access these Web sites from www.ni.com/worldwide  
If you have trouble connecting to our Web site, please contact your local  
National Instruments office or the source from which you purchased your  
National Instruments product(s) to obtain support.  
For telephone support in the United States, dial 512 795 8248. For  
telephone support outside the United States, contact your local branch  
office:  
Australia 03 9879 5166, Austria 0662 45 79 90 0, Belgium 02 757 00 20,  
Brazil 011 284 5011, Canada (Calgary) 403 274 9391,  
Canada (Ontario) 905 785 0085, Canada (Québec) 514 694 8521,  
China 0755 3904939, Denmark 45 76 26 00, Finland 09 725 725 11,  
France 01 48 14 24 24, Germany 089 741 31 30, Greece 30 1 42 96 427,  
Hong Kong 2645 3186, India 91805275406, Israel 03 6120092,  
Italy 02 413091, Japan 03 5472 2970, Korea 02 596 7456,  
Mexico (D.F.) 5 280 7625, Mexico (Monterrey) 8 357 7695,  
Netherlands 0348 433466, New Zealand 09 914 0488,  
Norway 32 27 73 00, Poland 0 22 528 94 06, Portugal 351 1 726 9011,  
Singapore 2265886, Spain 91 640 0085, Sweden 08 587 895 00,  
Switzerland 056 200 51 51, Taiwan 02 2528 7227,  
United Kingdom 01635 523545  
NI 4050 User Manual  
B-2  
Glossary  
Prefix  
p-  
Meanings  
pico-  
Value  
10–12  
10–9  
10– 6  
10–3  
103  
n-  
nano-  
micro-  
milli-  
µ-  
m-  
k-  
kilo-  
M-  
G-  
mega-  
giga-  
106  
109  
Numbers/Symbols  
%
+
percent  
positive of, or plus  
negative of, or minus  
per  
/
°
degree  
±
plus or minus  
ohm  
A
A
amperes  
AC  
alternating current  
AC coupled  
the passing of a signal through a filter network that removes the  
DC component of the signal  
A/D  
analog-to-digital  
© National Instruments Corporation  
G-1  
NI 4050 User Manual  
 
Glossary  
ADC  
analog-to-digital converter—an electronic device, often an integrated  
circuit, that converts an analog voltage to a digital number  
ADC resolution  
the resolution of the ADC, which is measured in bits. An ADC with16 bits  
has a higher resolution, and thus a higher degree of accuracy, than a  
12-bit ADC.  
ADE  
Application Development Environment  
amplification  
a type of signal conditioning that improves accuracy in the resulting  
digitized signal and reduces noise  
amplitude flatness  
aperture time  
a measure of how close to constant the gain of a circuit remains over a range  
of frequencies  
the period of time over which a measurement is averaged; also called the  
number of powerline cycles  
attenuate  
autozero  
to reduce in magnitude  
technique of internally shorting the internal circuit while disconnecting the  
measurement to compensate for temperature effects  
B
b
bit—one binary digit, either 0 or 1  
B
byte—eight related bits of data, an eight-bit binary number. Also used to  
denote the amount of memory required to store one byte of data.  
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 PCI and ISA bus.  
burden voltage  
the voltage drop across the input section of the current mode  
C
C
Celsius  
CMRR  
common-mode rejection ratio—a measure of an instrument’s ability to  
reject interference from a common-mode signal, usually expressed in  
decibels (dB)  
NI 4050 User Manual  
G-2  
Glossary  
CompactPCI  
refers to the core specification defined by the PCI Industrial Computer  
Manufacturer’s Group (PICMG)  
conversion device  
device that transforms a signal from one form to another. For example,  
analog-to-digital converters (ADCs) for analog input, digital-to-analog  
converters (DACs) for analog output, digital input or output ports, and  
counter/timers are conversion devices.  
conversion time  
the time required, in an analog input or output system, from the moment a  
channel is interrogated (such as with a read instruction) to the moment that  
accurate data is available  
coupling  
CPU  
the manner in which a signal is connected from one location to another  
central processing unit  
crest factor  
CSM  
the ratio of the peak value of the signal to the RMS value of the signal  
current shunt module  
D
DAQ  
data acquisition—(1) collecting and measuring electrical signals from  
sensors, transducers, and test probes or fixtures and inputting them to a  
computer for processing; (2) collecting and measuring the same kinds of  
electrical signals with A/D and/or DIO boards plugged into a computer, and  
possibly generating control signals with D/A and/or DIO boards in the  
same computer  
dB  
decibel—the unit for expressing a logarithmic measure of the ratio of two  
signal levels: dB=20log10 V1/V2, for signals in volts  
DC  
direct current  
default setting  
a default parameter value recorded in the driver. In many cases, the default  
input of a control is a certain value (often 0) that means use the current  
default setting.  
device  
a plug-in data acquisition board, card, or pad that can contain multiple  
channels and conversion devices. Plug-in boards, PCMCIA cards,  
devices such as the DAQPad-1200, which connects to your computer  
parallel port, are all examples of DAQ devices.  
© National Instruments Corporation  
G-3  
NI 4050 User Manual  
Glossary  
dielectric absorption  
a parasitic phenomenon related to capacitors that can cause unexpectedly  
long settling times in circuits using capacitors with poor dielectric  
absorption specifications  
differential input  
an analog input consisting of two terminals, both of which are isolated from  
computer ground, whose difference is measured  
DMM  
DNL  
digital multimeter  
differential nonlinearity—a measure in LSB of the worst-case deviation of  
code widths from their ideal value of 1 LSB  
double insulated  
drivers  
a device that contains the necessary insulating structures to provide electric  
shock protection without the requirement of a safety ground connection  
software that controls a specific hardware instrument  
E
ECMR  
Effective Common Mode Rejection—a measure of an instrument’s ability  
to reject interference from a common-mode signal. This includes both the  
effects of normal mode rejection and common mode rejection.  
EEPROM  
electrically erasable programmable read-only memory—ROM that can be  
erased with an electrical signal and reprogrammed  
EXT TRIG IN  
external trigger input signal  
F
F
farads  
filtering  
a type of signal conditioning that allows you to filter unwanted signals from  
the signal you are trying to measure  
G
gain  
the factor by which a signal is amplified, sometimes expressed in decibels  
NI 4050 User Manual  
G-4  
Glossary  
H
harmonics  
multiples of the fundamental frequency of a signal  
half-power bandwidth  
the frequency range over which a circuit maintains a level of at least –3 dB  
with respect to the maximum level  
hardware  
Hz  
the physical components of a computer system, such as the circuit boards,  
plug-in boards, chassis, enclosures, peripherals, cables, and so on  
hertz—per second, as in cycles per second or samples per second  
I
Iex  
excitation current  
IEC  
International Electrotechnical Commission  
Institute of Electrical and Electronics Engineers  
inches  
IEEE  
in.  
inductance  
input bias current  
input impedance  
the relationship of induced voltage to current  
the current that flows into the inputs of a circuit  
the measured resistance and capacitance between the input terminals of a  
circuit  
Installation Category  
classification system for expected transients on electrical supply  
(Overvoltage Category) installations  
instrument driver  
a set of high-level software functions that controls a specific plug-in DAQ  
board. Instrument drivers are available in several forms, ranging from a  
function callable language to a virtual instrument (VI) in LabVIEW.  
interrupt  
a computer signal indicating that the CPU should suspend its current task  
to service a designated activity  
interrupt level  
I/O  
the relative priority at which a device can interrupt  
input/output—the transfer of data to/from a computer system involving  
communications channels, operator interface devices, and/or data  
acquisition and control interfaces  
© National Instruments Corporation  
G-5  
NI 4050 User Manual  
Glossary  
ISA  
industry standard architecture  
isolation  
a type of signal conditioning in which you isolate the transducer signals  
from the computer for safety purposes. This protects you and your  
computer from large voltage spikes and makes sure the measurements from  
the DAQ device are not affected by differences in ground potentials.  
isolation voltage  
the voltage that an isolated circuit can normally withstand, usually  
specified from input to input and/or from any input to the amplifier output,  
or to the computer bus  
M
m
meters  
MB  
megabytes of memory  
N
NI-DAQ  
National Instruments driver software for DAQ hardware.  
NMRR  
normal mode rejection ratio—a measure of an instrument’s ability to reject  
a signal applied directly to the differential inputs of the instrument  
noise  
an undesirable electrical signal—Noise comes from external sources such  
as the AC power line, motors, generators, transformers, fluorescent lights,  
soldering irons, CRT displays, computers, electrical storms, welders, radio  
transmitters, and internal sources such as semiconductors, resistors, and  
capacitors. Noise corrupts signals you are trying to send or receive.  
O
Ohm’s Law  
(R=V/I)—the relationship of voltage to current in a resistance  
overrange  
a segment of the input range of an instrument outside of the normal  
measuring range. Measurements can still be made, usually with a  
degradation in specifications.  
NI 4050 User Manual  
G-6  
Glossary  
P
PCI  
Peripheral Component Interconnect—a high-performance expansion bus  
architecture originally developed by Intel to replace ISA and EISA; it is  
achieving widespread acceptance as a standard for PCs and workstations  
and offers a theoretical maximum transfer rate of 132 Mbytes/s  
peak value  
PXI  
the absolute maximum or minimum amplitude of a signal (AC + DC)  
PCI eXtensions for Instrumentation. PXI is an open specification that  
builds off the CompactPCI specification by adding  
instrumentation-specific features.  
R
R
resistor  
RAM  
range error  
random-access memory  
an error in accuracy that is determined by the input range that is selected.  
The range error is independent of the value of the signal being measured.  
reading error  
reading rate  
an error in accuracy that is determined by the input range, as well as the  
value being measured  
the rate at which a new measurement is taken. In addition to the  
measurement speed, the selection of the reading rate affects the filtering,  
and thus the noise level, of measurements.  
resolution  
rms  
the smallest signal increment that can be detected by a measurement  
system. Resolution can be expressed in bits or in digits. The number of bits  
in a system is roughly equal to 3.3 times the number of digits.  
root mean square—a measure of signal amplitude; the square root of the  
average value of the square of the instantaneous signal amplitude  
ROM  
Rsense  
read-only memory  
the sense resistor. The voltage across this resistor is measured and  
converted to a current.  
© National Instruments Corporation  
G-7  
NI 4050 User Manual  
Glossary  
S
s
seconds  
samples  
S
sense  
in four-wire resistance the sense measures the voltage across the resistor  
being excited by the excitation current  
settling time  
S/s  
the amount of time required for a voltage to reach its final value within  
specified limits  
samples per second—used to express the rate at which an instrument  
samples an analog signal  
system noise  
a measure of the amount of noise seen by an analog circuit or an ADC when  
the analog inputs are grounded  
T
temperature  
coefficient  
the percentage that a measurement will vary according to temperature.  
See also thermal drift  
thermal drift  
measurements that change as the temperature varies  
thermoelectric  
potentials  
See thermal EMFs  
thermal EMFs  
thermal electromotive forces—voltages generated at the junctions of  
dissimilar metals that are functions of temperature. Also called  
thermoelectric potentials.  
transfer rate  
the rate, measured in bytes/s, at which data is moved from source to  
destination after software initialization and set up operations; the maximum  
rate at which the hardware can operate  
U
UL  
Underwriters Laboratory  
NI 4050 User Manual  
G-8  
Glossary  
V
V
volts  
VAC  
VDC  
Verror  
VI  
volts alternating current  
volts direct current  
voltage error  
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  
VMC  
Vrms  
voltmeter complete signal  
volts, root mean square value  
Vsense  
the voltage that is created across the device under test when excited by a  
current  
W
waveform shape  
the shape the magnitude of a signal creates over time  
working voltage  
the highest voltage that should be applied to a product in normal use,  
normally well under the breakdown voltage for safety margin  
© National Instruments Corporation  
G-9  
NI 4050 User Manual  
Index  
diode measurement  
A
circuit (figure), 2-9  
description, 2-9  
using VirtualBench-DMM Soft Front  
panel, 1-7 to 1-8  
AC current specifications, A-4  
AC voltage measurement, 2-6 to 2-8  
AC offset voltage, 2-7  
frequency response, 2-7 to 2-8  
input ranges, 2-7  
diode testing specifications, A-5  
using VirtualBench-DMM Soft Front  
panel, 1-5 to 1-6  
AC voltage specifications, A-3  
E
effective common mode rejection, 2-6  
environment specifications, A-6  
C
cables and probes, 1-1 to 1-2  
installing, 1-1 to 1-2  
F
frequency response, AC voltage  
measurement, 2-7 to 2-8  
overview, 1-1  
common mode rejection, 2-6 to 2-7  
continuity measurements, 2-9  
conventions used in manual, vi  
current measurement, 1-8  
G
grounding the NI 4050, 2-2  
D
I
DC current specifications, A-2  
DC voltage measurement, 2-2 to 2-6  
common mode rejection, 2-6 to 2-7  
effective common mode rejection, 2-6  
input impedance, 2-3  
input impedance, DC voltage measurement, 2-3  
input ranges  
AC voltage measurement, 2-7  
DC voltage measurement, 2-3  
two-wire resistance measurements,  
2-8 to 2-9  
input ranges, 2-3  
noise rejection, 2-4 to 2-6  
normal mode rejection, 2-4 to 2-5  
thermal EMF, 2-4  
using VirtualBench-DMM Soft Front panel,  
1-5 to 1-6  
M
measurement  
AC voltage, 2-6 to 2-8  
AC offset voltage, 2-7  
frequency response, 2-7 to 2-8  
input ranges, 2-7  
DC voltage specifications, A-1  
diagnostic resources, online, B-1  
© National Instruments Corporation  
I-1  
NI 4050 User Manual  
 
Index  
using VirtualBench-DMM Soft Front  
panel, 1-5 to 1-6  
fundamentals of measurement  
grounding, 2-2  
current, 1-8  
selecting resolution, 2-2  
warm-up time, 2-2  
noise rejection  
DC voltage, 2-2 to 2-6  
common mode rejection, 2-6 to 2-7  
effective common mode  
rejection, 2-6  
AC voltage specifications, A-3  
DC voltage measurement, 2-4 to 2-6  
common mode rejection, 2-6 to 2-7  
effective common mode  
input impedance, 2-3  
input ranges, 2-3  
noise rejection, 2-4 to 2-6  
normal mode rejection, 2-4 to 2-5  
thermal EMF, 2-4  
using VirtualBench-DMM Soft Front  
panel, 1-5 to 1-6  
rejection, 2-6  
normal mode rejection, 2-4 to 2-5  
DC voltage specifications, A-1  
normal mode rejection, 2-4 to 2-5  
diode  
O
circuit (figure), 2-9  
description, 2-9  
online problem-solving and diagnostic  
resources, B-1  
operation of NI 4050. See measurement.  
using VirtualBench-DMM Soft Front  
panel, 1-7 to 1-8  
fundamentals of measurement  
grounding, 2-2  
P
selecting resolution, 2-2  
warm-up time, 2-2  
physical specifications, A-6  
probes and cables, 1-1 to 1-2  
installing, 1-1 to 1-2  
resistance, 2-8 to 2-9  
continuity, 2-9  
overview, 1-1  
problem-solving and diagnostic resources,  
online, B-1  
two-wire, 2-8 to 2-9  
circuit (figure), 2-8  
input ranges, 2-8 to 2-9  
using VirtualBench-DMM Soft  
Front panel, 1-6 to 1-7  
temperature, 1-9  
R
resistance measurement, 2-8 to 2-9  
continuity, 2-9  
N
two-wire, 2-8 to 2-9  
circuit (figure), 2-8  
National Instruments Web support, B-1 to B-2  
NI 4050. See also measurement;  
specifications.  
input ranges, 2-8 to 2-9  
using VirtualBench-DMM Soft Front  
panel, 1-6 to 1-7  
cables and probes, 1-1 to 1-2  
resistance specifications, A-5  
resolution selection, 2-2  
NI 4050 User Manual  
I-2  
© National Instruments Corporation  
Index  
S
V
safety instructions, 2-1  
soft front panel. See VirtualBench-DMM Soft  
Front panel.  
VirtualBench-DMM Soft Front  
panel, 1-3 to 1-9  
current measurement, 1-8  
DC and AC voltage measurement,  
1-5 to 1-6  
diode measurement, 1-7 to 1-8  
illustration, 1-3  
software-related resources, B-2  
specifications, A-1 to A-6  
AC current, A-4  
AC voltage, A-3  
options on front panel, 1-3 to 1-5  
two-wire resistance measurement,  
1-6 to 1-7  
DC current, A-2  
DC voltage, A-1  
diode testing, A-5  
voltage measurement. See AC voltage  
measurement; DC voltage measurement.  
environment, A-6  
general, A-6  
physical, A-6  
resistance, A-5  
W
warm-up time requirement for NI 4050, 2-2  
Web support from National Instruments,  
B-1 to B-2  
online problem-solving and diagnostic  
resources, B-1  
software-related resources, B-2  
Worldwide technical support, B-2  
T
technical support resources, B-1 to B-2  
temperature measurements, using  
VirtualBench-DMM Soft Front panel, 1-9  
thermal EMF, DC voltage measurement, 2-4  
two-wire resistance measurements, 2-8 to 2-9  
circuit (figure), 2-8  
input ranges, 2-8 to 2-9  
using VirtualBench-DMM Soft Front  
panel, 1-6 to 1-7  
© National Instruments Corporation  
I-3  
NI 4050 User Manual  

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