Signametrics SMX2055 User manual

Operator's Manual
Model SMX2055 5-½ Digit Digital PXI Multimeter
January 2010 Driver compatibility: Rev 1.60

Signametrics 2
CAUTION
In no event shall Signametrics or its Representatives are liable for any consequential damages whatsoever
(including, without limitation, damages for loss of business profits, business interruption, loss of business
information, or other loss) arising out of the use of or inability to use Signametrics products, even if Signametrics
has been advised of the possibility of such damages. Because some states do not allow the exclusion or limitation of
liability for consequential damages, the above limitations may not apply to you.
2005 Signametrics Corp. Printed in the USA. All rights reserved. Contents of this publication must not be
reproduced in any form without the permission of Signametrics Corporation.

3 Signametrics
TABLE OF CONTENTS
1.0 INTRODUCTION.................................................................................................................................................5
1.1 SAFETY CONSIDERATIONS..........................................................................................................................5
1.2 MINIMUM REQUIREMENTS .........................................................................................................................5
1.3 FEATURE SET .............................................................................................................................................5
2.0 SPECIFICATIONS...............................................................................................................................................6
2.1 DC VOLTAGE MEASUREMENT ...................................................................................................................6
2.2 DC CURRENT MEASUREMENT....................................................................................................................7
2.3 RESISTANCE MEASUREMENTS....................................................................................................................7
2.3.1 2-wire.......................................................................................................................................7
2.3.2 4-wire.......................................................................................................................................7
2.4 AC VOLTAGE MEASUREMENTS..................................................................................................................7
2.4.1 AC Voltage True RMS Measurement.......................................................................................8
2.4.2 Additional Errors Due To Signal Frequency...........................................................................8
2.5 AC CURRENT MEASUREMENT,TRUE RMS................................................................................................8
2.5.1 AC Current True RMS Measurement.......................................................................................8
2.5.2 Additional Errors Due To Current Frequency ........................................................................9
2.6 DIODE TEST FUNCTION ..............................................................................................................................9
2.7 MEASUREMENT RATES AND POWER LINE REJECTION..................................................................................9
2.8 ACCURACY NOTES ...................................................................................................................................10
2.9 OTHER SPECIFICATIONS ...........................................................................................................................10
3.0 GETTING STARTED.........................................................................................................................................12
3.1 SETTING THE DMM..................................................................................................................................12
3.2 INSTALLING THE DMM MODULE .............................................................................................................12
3.3 INSTALLING THE SOFTWARE.....................................................................................................................12
3.4 DMM INPUT CONNECTORS ......................................................................................................................13
3.5 STARTING THE CONTROL PANEL ..............................................................................................................13
3.5 USING THE CONTROL PANEL....................................................................................................................14
4.0 DMM OPERATION AND MEASUREMENT TUTORIAL...........................................................................16
4.1 VOLTAGE MEASUREMENT........................................................................................................................16
4.1.1 DC Voltage Measurements ....................................................................................................16
4.1.2 True RMS AC Voltage Measurements ...................................................................................16
4.2 CURRENT MEASUREMENTS ......................................................................................................................17
4.2.2 Improving DC Current Measurements ..................................................................................18
4.3 RESISTANCE MEASUREMENTS..................................................................................................................18
4.3.1 2-Wire Ohm Measurements ...................................................................................................18
4.3.2 4-Wire Ohm Measurements ...................................................................................................19
4.3.6 Effects of Thermo-Voltaic Offset............................................................................................19
4.8 DIODE CHARACTERIZATION .....................................................................................................................20
5.0 WINDOWS INTERFACE..................................................................................................................................20
5.1 DISTRIBUTION FILES ................................................................................................................................21
5.2 USING THE SM2060 DRIVER SET WITH C++ OR SIMILAR SOFTWARE......................................................23
5.2.1 Multiple Card Operations under Windows............................................................................23
5.3 VISUAL BASIC FRONT PANEL APPLICATION.............................................................................................24
5.3.1 Visual Basic Simple Application............................................................................................25
5.4 WINDOWS DLL DEFAULT MODES AND PARAMETERS..............................................................................25
5.5 USING THE SM2060 DLL WITH LABWINDOWS/CVI............................................................................26
5.6 WINDOWS COMMAND LANGUAGE ...........................................................................................................26
DMMCalibrate................................................................................................................................27
DMMCleanRelay ............................................................................................................................27
DMMClearMinMax ........................................................................................................................28

Signametrics 4
DMMClosePCI ...............................................................................................................................28
DMMDelay .....................................................................................................................................29
DMMErrString................................................................................................................................29
DMMGetBusInfo.............................................................................................................................30
DMMGetCalDate............................................................................................................................30
DMMGetdB.....................................................................................................................................31
DMMGetdBStr................................................................................................................................31
DMMGetDeviation .........................................................................................................................32
DMMGetDeviatStr..........................................................................................................................33
DMMGetDiffMnMxStr....................................................................................................................33
DMMGetFunction...........................................................................................................................34
DMMGetGrdVer.............................................................................................................................34
DMMGetHwVer..............................................................................................................................35
DMMGetID.....................................................................................................................................35
DMMGetManDate..........................................................................................................................36
DMMGetMax..................................................................................................................................36
DMMGetMaxStr .............................................................................................................................37
DMMGetMin...................................................................................................................................37
DMMGetMinStr..............................................................................................................................38
DMMGetRange...............................................................................................................................38
DMMGetRate..................................................................................................................................39
DMMGetType .................................................................................................................................39
DMMGetVer ...................................................................................................................................40
DMMInit .........................................................................................................................................41
DMMIsAutoRange ..........................................................................................................................41
DMMIsInitialized............................................................................................................................42
DMMIsRelative...............................................................................................................................42
DMMOpenPCI................................................................................................................................43
DMMRead.......................................................................................................................................43
DMMReadNorm..............................................................................................................................44
DMMReadStr..................................................................................................................................45
DMMSetAutoRange ........................................................................................................................45
DMMSetFunction............................................................................................................................46
DMMSetRange................................................................................................................................46
DMMSetRate...................................................................................................................................47
DMMSetRelative.............................................................................................................................48
DMMTerminate...............................................................................................................................48
5.7 CALIBRATION SERVICE COMMANDS.........................................................................................................49
AC_zero ..........................................................................................................................................49
DMMLoadCalFile...........................................................................................................................49
GetGain...........................................................................................................................................50
GetOffset.........................................................................................................................................50
SetFcomp ........................................................................................................................................51
SetOffset..........................................................................................................................................52
Linearize_AD..................................................................................................................................52
Read_ADcounts ..............................................................................................................................53
5.8 MAINTANANCE COMMANDS.....................................................................................................................54
GrdXingTest....................................................................................................................................54
5.9 ERROR CODES ..........................................................................................................................................54
5.10 WARNING CODES ...................................................................................................................................55
5.11 PARAMETER LIST ...................................................................................................................................55
5.11.1 Measurement and Source Functions....................................................................................55
5.11.2 Range Values .......................................................................................................................55
5.11.3 Measurement Rate parameters ............................................................................................56
6 CALIBRATION .....................................................................................................................................................57
7.0 WARRANTY AND SERVICE...........................................................................................................................59
8.0 ACCESSORIES...................................................................................................................................................59

1.0 Introduction
Congratulations! You have purchased a PXI/CompactPCI Plug-in Digital Multimeter. The SMX2055 Digital
Multimeters (DMM’s) are easy to setup and use, have sophisticated analog and digital circuitry to provide very
repeatable measurements, and are protected to handle any unexpected situations your measurement environment
may encounter. To get years of reliable service from these DMM’s, please take a few moments and review this
manual before installing and using this precision instrument.
This manual describes the SMX2055 PXI/cPCI module.
1.1 Safety Considerations
Safety Considerations
The SMX2055 DMM is capable of measuring up to 240 VDC or 240 VAC across the Volt HI and LO
terminals, and can also measure common mode signals that "float" the DMM above EARTH ground by up
to 300 VDC or 250 VAC. When making common mode measurements, the majority of the circuits inside
the DMM are at the common mode voltage. These voltages can be lethal and can KILL! During and
after installing your DMM, check to see that there are no wires or ribbon cables from your PC
trapped inside the DMM.
The DMM comes installed with four shields (bottom, top and two edge strips) that must not be removed
for performance as well as safety reasons. Removal of these shields and/or improper assembly of the
shields can result in lethal voltages occurring within your PC. Be sure to check your installation before
closing the cover on your personal computer.
Warning
Check to see that no loose wires or ribbon cables infringe upon any of the internal circuits of the
DMM, as this may apply measurement voltages to your computer, causing electrocution and/or
damage to your computer!
To avoid shock hazard, install the DMM only into a computer that has its power connector
connected to a power receptacle with an earth safety ground.
When making any measurements above 50 VDC or 40 VAC, only use Safety Test Leads. Examples
of these are the Signametrics Basic Test Leads and Deluxe Test Leads, offered as an accessory with the
Signametrics DMM’s.
1.2 Minimum Requirements
The SMX2055 DMM’s are precision plug-in modules that are compatible with IBM type personal computers (PCs),
PXI and cPCI chassis. It requires as a minimum a Pentiums computer. They require a half-length expansion slot on
the PCI bus or 3U PXI slot. A mouse must be installed when controlling the DMM from the Windows Control
Panel. The SMX2055 comes with a Windows' DLL, for operation with Windows' Version 95/98/Me/2000/XP and
NT4.0.
1.3 Feature Set
The SMX2055 is a traditional 5-1/2 digit DMM and it can be used as a general purpose DMM. The High Workload
Multi Function SM2064 adds timing, capacitance, inductance, sourcing and a lot more speed. With its specialized
measurements, it can replace some costly instruments, shrinking the size and cost of a test system.
5 Signametrics

Signametrics 6
SMX2055 basic features:
Volts DC; for ranges, 240mV to 240V
Volts AC; Tru RMS; four ranges, 240mV to 240V
2-Wire Ohms, six ranges 240 to 24 M
4-Wire Ohms, five ranges 240 to 2.4 M
DC current, four ranges 2.4 mA to 2.4 A
AC current, four ranges 2.4 mA to 2.4 A
Diode V/I characteristics at 100 A to 1mA
Auto range, Relative, Min, Max, dB, %deviation operations
High Dynamic range; ±240,000 counts (240.000V)
Selectable measurement rate: 1 to 100 readings/sec
2.0 Specifications
The following specifications are based on both, verification of large number of units as well as
mathematical evaluation. They should be considered under the environment specified.
It is important to note that a DMM specified range is expressed as a numeric value indicating the highest
absolute measurement that can be displayed using the range. The lowest value that can be detected is
expressed by the corresponding resolution for the range.
2.1 DC Voltage Measurement
Input Characteristics
Input Resistance 240 mV, 2.4 V Ranges: >10 G, with typical leakage of 50pA
Input Resistance 24 V, 240 V Ranges: 10.00 M
Accuracy ± (% of reading + Volts) [1]
Range Full Scale
5-½ Digits Resolution One Year 23C 10C
240 mV 240.000 mV 1 V 0.015 + 7 V
2.4 V 2.40000 V 10 V 0.014 + 30 V
24 V 24.0000 V 100 V 0.02 + 750 V
240 V 240.000 V 1 mV 0.02 + 3 mV
[1] With measurement rate set to 2rps or lower rate, within one hour from Zero (Relative control).
For resolution at higher measurement rates, see the following table. Use this table for DC Volts, DC
current and Resistance measurements.
Maximum reading rate
Resolution
2 / second 5-1/2 digits 19 bits
8 / second 5 digits 18 bits
50 / second 4-1/2 digits 17 bits
100 / second 4 digits 16 bits
DCV Noise Rejection Normal Mode Rejection, at 50, 60, or 400 Hz ± 0.5%, is better than 95 dB
for Rates of 6rps and lower. Common Mode Rejection (with 1 klead imbalance) is better than 120
dB for these conditions.

7 Signametrics
2.2 DC Current Measurement
Input Characteristics
Number of built-in shunts Two
Currents greater than 2.4A require external shunt
Protected with 2.5A Fast blow fuse
Accuracy ± (% of reading + Amps) [1]
Range Full Scale
5-½ Digits Resolution Max Burden Voltage One Year 23C 10C
2.4 mA 2.40000 mA 10 A 25mV 0.07 + 7 A
24 mA 24.0000 mA 100 A 250mV 0.08 + 9 A
240 mA 240.000 mA 1 A 55mV 0.07 + 60 A
2.4 A 2.40000 A 10 A 520mV 0.2 + 160 A
[1] With measurement rate set to 2rps or lower rate, within one hour from Zero (Relative control).
2.3 Resistance Measurements
2.3.1 2-wire
Accuracy ± (% of reading + ) [1]
Range [2] Full Scale
5-½ Digits Resolution Test current One Year
23C 10C
240 240.000 1 m1 mA 0.02 + 100 m
2.4 k2.40000 k10 m1 mA 0.02 + 200 m
24 k24.0000 k100 m100 A 0.02 + 1 
240 k240.000 k1 10 A 0.06 + 20 
2.4 M2.40000 M10 1 A 0.06 + 200 
24 M24.0000 M100 100 nA 0.2 + 25 k
[1] With measurement rate set to 2rps or lower rate, within one hour from Zero (Relative control).
[2] Test voltages are 2.4V max with the exception of the 240 ranges 240 mV.
2.3.2 4-wire
Accuracy ± (% of reading + ) [1]
Range [2] Full Scale
5-½ Digits Resolution Source current One Year
23C 10C
240 240.000 1 m1 mA 0.02 + 50 m
2.4 k2.40000 k10 m1 mA 0.02 + 100 m
24 k24.0000 k100 m100 A 0.02 + 500 m
240 k240.000 k1 10 A 0.06 + 10 
2.4 M2.40000 M10 1 A 0.06 + 200 
[1] With measurement rate set to 2rps or lower rate, within one hour from Zero (Relative control).
[2] Test voltages are 2.4V max with the exception of the 240 ranges 240 mV.
2.4 AC Voltage Measurements
Input Characteristics
Input Resistance 1 M, shunted by < 300 pF, all ranges
Max. Crest Factor 4 at Full Scale, increasing to 7 at Lowest Specified Voltage
AC coupled Specified range: 10 Hz to 100 kHz
Typical Settling time < 0.5 sec to within 0.1% of final value
Typical Settling time Fast RMS < 0.05 sec to within 0.1% of final value

Signametrics 8
2.4.1 AC Voltage True RMS Measurement
Accuracy ± (% of reading + Volts) [1]
Range Full Scale
5-½ Digits [3] Resolution Lowest specified Input Voltage One Year [2]
23C 10C
240 mV 240.000 mV 1 V 5 mV 0.15 + 150V
2.4 V 2.40000 V 10 V 20 mV 0.25 + 10mV
24 V 24.0000 V 100 V 200 mV 0.15 + 100mV
240 V 240.000 V 1 mV 2 V 0.25 + 400mV
[1] With measurement rate set to 2rps or lower rate
[2] Input frequency 47Hz to 10kHz. For other frequencies add error in tabel below
[3] Signal is limited to 8x106Volt Hz Product
2.4.2 Additional Errors Due To Signal Frequency
Add the following error to the above values for signal frequencies lower than 47Hz or greater than 10kHz
Range Signal Frequency % of reading + Volts [1]
20 Hz - 47 Hz 0.8 + 50V 240 mV
10 kHz - 50 kHz 0.48 + 80V
20 Hz - 47 Hz 0.75 + 1mV2.4 V
10 kHz - 50 kHz 0.45 + 2mV
20 Hz - 47 Hz 0.85 + 20mV24V
10 kHz - 50 kHz 0.2 + 15mV
20 Hz - 47 Hz 0.85 + 200mV240V
10 kHz - 50 kHz 0.15 + 100mV
[1] Select measurement rates that are lower than 1/10th of the signal frequency.
ACV Noise Rejection Common Mode rejection, for 50 Hz or 60 Hz with 1 kimbalance in either lead, is better
than 80 dB.
2.5 AC Current Measurement, True RMS
Input Characteristics
Crest Factor 4 at Full Scale
Number of built-in shunts Two
Currents greater 2.4A require external shunt
Protected with 2.5A Fast blow fuse
2.5.1 AC Current True RMS Measurement
Accuracy ± (% of reading + Amps) [1]
Range Full Scale
5-½ Digits Resolution Lowest Specified Current Max Burden Voltage One Year 23C 
10C [2]
2.4 mA 2.40000 mA 10 A 60 A 25mV 0.3 + 20 A
24 mA 24.0000 mA 100 A 300 A 250mV 0.2 + 100 A
240 mA 240.000 mA 1 A 3 mA 55mV 0.17 + 1 mA
2.4 A 2.40000 A 10 A 30 mA 520mV 0.31 + 10 mA
[1] With measurement rate set to 2rps or lower rate
[2] Input frequency 47Hz to 1kHz. For other frequencies, see tabel below

9 Signametrics
2.5.2 Additional Errors Due To Current Frequency
Range Signal Frequency [1] % of reading
20 Hz - 47 Hz 0.882.4 mA
1 kHz - 10 kHz 0.12
20 Hz - 47 Hz 0.8424 mA
1 kHz - 10 kHz 0.24
20 Hz - 47 Hz 0.8240 mA
1 kHz - 10 kHz 0.2
20 Hz - 47 Hz 0.552.4 A
1 kHz - 10 kHz 0.2
[1] All AC Current ranges have typical measurement capability of at least 20 kHz
2.6 Diode Test Function
Test Currents Five
Current sources voltage compliance 4 V
Accuracy ± (% of reading + Volts) [1]
Range Full Scale
5-½ Digits Resolution One Year 23C 10C
0.1 A 0.022 + 15 V
1 A 0.018 + 12 V
10 A 0.015 + 10 V
100 A 0.014 + 8 V
1 mA
2.40000 V 10 V
0.014 + 8 V
[1] With measurement rate set to 2rps or lower rate
2.7 Measurement Rates and power line rejection
Use DMMSetRate() using the following codes.
Power line RejectionRate
(Readings/sec) Symbol Code
50Hz 60Hz 400Hz
1 RATE_1 1

2 RATE_2 2

3 RATE_3 3

7 RATE_7 7

14 RATE_14 14

27 RATE_27 27

55 RATE_55 55

100 RATE_100 100


Signametrics 10
2.8 Accuracy Notes
Important: all accuracy specifications for DCV, Resistance, DCI, ACV, and ACI apply for the time periods shown
in the respective specification tables. To meet these specifications, Self Calibration must be performed once a day or
as indicated in the specification table. This is a simple software operation that takes a few seconds. It can be
performed by calling Windows command DMMCal(), or selecting S-Cal in the control panel.
These products are capable of continuous measurement as well as data transfer rates of up to 100 readings per
second (rps). In general, to achieve 5-1/2 Digits of resolution, the rate should be set to 2rps or lower.
2.9 Other Specifications
Temperature Coefficient over 0C to 50C Range
Less than 0.1 x accuracy specification per C At 23C 10C
Hardware Interface Single PXI/cPCI 3U slot
Overload Protection (voltage inputs) 300 VDC, 250 VAC
Isolation 300 VDC, 250 VAC from Earth Ground
Maximum Input (Volt x Hertz) 8x106Volt x Hz normal mode input (across Voltage HI &
LO).
1x106Volt x Hz Common Mode input (from Voltage HI or
LO relative to Earth Ground).
Safety Designed to IEC 1010-1, Installation Category II.
Calibration Calibrations are performed by Signametrics in a computer at
23C internal temperature rise. All calibration constants are
stored in a text file.
Temperature Range Operating -10C to 65C
Temperature Range Storage -40C to 85C
Size Single 3U PXI or CompactPCI slot
Power +5 volts, 200 mA maximum
Note: Signametrics reserves the right to make changes in materials, specifications, product functionality, or
accessories without notice.
Accessories
Several accessories are available for the SM2060 series DMM’s, which can be purchased directly from
Signametrics, or one of its approved distributors or representatives. These are some of the accessories available:
DMM probes SM-PRB ($15.70)
DMM probe kit SM-PRK ($38.50)
Deluxe probe kit SM-PRD ($95.00).
Shielded SMT Tweezers Probes SM-PRSMT ($24.90).
Multi Stacking Double Banana shielded cable 36” SM-CBL36 ($39.00).

11 Signametrics
Multi Stacking Double Banana shielded cable 48” SM-CBL48 ($43.00).
Mini DIN Trigger, 6-Wire Ohms connector SM2060-CON7 ($14.00).
Lab View VI’s library SM204x.llb (free).
Extended 3 Year warrantee (does not include calibration) $120.00 for SM2055.

Signametrics 12
3.0 Getting Started
After unpacking the DMM, please inspect for any shipping damage that may have occurred, and report any claims
to your transportation carrier.
The DMM is shipped with the Digital Multimeter module; Installation CD and a floppy disk that contain the
calibration and verification files. Also included is the Certificate of Calibration.
3.1 Setting the DMM
The DMM is provided with plug-and-play installation software, and does not require any switch settings, or other
adjustments prior to installation.
The SM60CAL.DAT file supplied with your DMM has a unique calibration record for that DMM (See
"Calibration" at the end of this manual.) When using multiple DMM’s in the same chassis, the SM60CAL.DAT
file must have a calibration record for each DMM. Append the unique calibration records of each DMM into one
SM60CAL.DAT file using a text editor such as Notepad. The default location for the SM60CAL.DAT file is at
the root directory C:\.
3.2 Installing the DMM Module Warning
To avoid shock hazard, install the DMM only into a personal computer that has its power line connector
connected to an AC receptacle with an Earth Safety ground.
After installation, check to see that no loose wires or ribbon cables infringe upon any of the internal circuits
of the DMM, as this may apply measurement voltages to your computer, causing personal injury and/or
damage to your computer!
Caution: Only install the DMM module with the power turned OFF to the PC!
Use extreme care when plugging the DMM module(s) into a PCI bus slot. If possible, choose an empty slot away
from any high-speed boards (e.g. video cards) or the power supply. Please be patient during the installation
process! The DMM comes with 4 safety-input jacks. Because of their necessary size, they are a tight fit in many
PC chassis. Insert the bracket end of the DMM into your PC first, watching for any interference between the safety
input jacks and your PC chassis. “Sliding” the bracket end of the DMM into the chassis may be helpful. Be
patient! You should only have to install it once!
3.3 Installing the Software
It is recommended that you first plug in the DMM into the PC chassis, than turn on the computer power. The first
time you power up your computer with the DMM installed, your computer will detect it as new hardware and
prompt you for a driver. The driver your computer requires is located on the installation CD (SM2060.INF).
Following the above driver installation, run the ‘SETUP’ program provided on the CD. This takes care of all
installation and registration requirements of the software. If you are installing the DMM on a computer that had an
SM2060 series install in it, you should first uninstall the old software. Also make sure you backup and remove the
old calibration record (SM60CAL.DAT). For a clean reinstallation remove all INF files containing reference to the
Signametrics DMM. Depending on operating system, these files will be located at Windows\inf, Windows\inf\other
or WINNT\inf. The files will be named Oemx.INF where x is 0,1,2,… and/or SIGNAMETRICS.INF or
SM2060.INF. If present, these files will prevent “Found New Hardware” wizard from detecting the new DMM.

3.4 DMM Input Connectors
Before using the DMM, please take a few moments and review this section to understand where the voltage,
current, or resistance and other inputs and outputs should be applied. This section contains important
information concerning voltage and current limits. Do not exceed these limits, as personal injury or damage
to the instrument, your computer or application may result.
Figure 3-1. The DMM input connectors.
V, + This is the positive terminal for all Volts, 2Wand diode test. It is also the Source high for 4W
measurements. The maximum input across V, + and V, - is 300 VDC or 250 VAC when in the measuring
mode. When in the 2-Wire or 4-Wire resistance mode, the maximum input allowed before damage occurs is
100 volts.
V, - This is the negative terminal for all Volts, 2Wand diode test. It is also the Source low for 4W
measurements. Do not float this terminal or any other DMM terminal more than 300 VDC or 250 VAC above
Earth Ground.
I + This is the positive terminal for all Current measurements. It is also the Sense high for 4Wmeasurements.
The maximum input across I, 4W+ and I, 4W- is 2.5 A. Do not apply more than 5 V peak across the I+ and I-
terminals.
I – This is the negative terminal for all Current measurements. In the Current modes, it is protected with a 2.5 A,
250 V Fast Blow fuse (5 x 20 mm). It is also the Sense low for 4Wmeasurements. V, - and I, 4W- should
never have more than 5 V peak across them.
3.5 Starting the Control Panel
13 Signametrics

You can verify the installation and gain familiarity with the DMM by exercising its measurement functions using
the Windows based Control Panel. To run the control panel, double click the “SM2064.EXE” icon. If you do not
hear the relays click, it is most likely due to an installation error. Another possible source for an error is that the
SM60CAL.DAT file does not correspond to the installed DMM.
When the DMM is started the first time, using the provided control panel (SM2064.EXE), it takes a few extra
seconds to extract its calibration data from the on-board store, and write it to a file C:\SM60CAL.DAT
The Control Panel is operated with a mouse. All functions are accessed using the left mouse button. When the
DMM is operated at very slow reading rates, you may have to hold down the left mouse button longer than usual for
the program to acknowledge the mouse click.
Note: The SM2060 front panel powers up in DCV, 8 readings per second (rps) and 240 V range. If the DMM is
operated in Autorange, with an open input, it will switch between the 2.4V and 24V ranges every few seconds, as a
range change occurs. This is perfectly normal with ultra high impedance DMM’s such as the SM2055. This
phenomenon is caused by the virtually infinite input impedance of the 2.4V DC range. On these ranges, an open
input will read whatever charge is associated with the signal conditioning of the DMM. As this electrical charge
changes, the SM2055 will change ranges, causing the range switching. This is normal.
3.5 Using the Control Panel
Figure 3-2. The Control Panel. The three main groups include Measure, Source and Range buttons. The
Range buttons are context sensitive such that only “240m, 2.4, 24 and 240 appear when in AC Voltage
Function is selected, and 2.4m, 24m, 240m and 2.4 appear when AC Current functions is selected, etc.
Note: All of the controls described below correspond to their respective software function, which can be invoked
within your control software or as objects in a visual programming environment. The software command language
provides a powerful set of capabilities. Some of the functions are not included in the control panel, but are in the
software.
DC/AC This function switches between DC and AC. This is applicable for the following DMM functions:
Voltage, Current, and Voltage-Source. If Voltage-Source is the function presently in use, the Source control under
the Tools menu can be used to set frequency and amplitude in ACV, and amplitude only in DCV and DCI.
Relative This is the Relative function. When activated, the last reading is stored and subtracted from all
subsequent readings. This is a very important function when making low-level DCV measurements, or in 2W.
For example, when using 2W, you can null out lead resistance by shorting the leads together and clicking on
Relative. When making low level DC voltage measurements (e.g., in the V region), first apply a copper short to
the V,+ & -input terminals, allow the reading to stabilize for a few seconds, and click on Relative. This will
correct for any internal offsets. The Relative button can also be used in the Percent and dB deviation displays
(shown below), which are activated using the Tools in the top menu.
Signametrics 14

The Min/Max box can be used to analyze variations in terms of Min, Max,
Percent and dBV. This display can be activated by selecting the
Min/Max/Deviation from the Tools menue. For instance, testing a circuit
bandwidth with an input of 1V RMS, activate the Relative function with the
frequency set to 100Hz, than sweep gradually the frequency, and monitor the
percent deviation as well as the dBV error and capture any response anomalies
with the Min/Max display. The left display indicates peaking of 2.468% (0.21
dBV) and maximum peaking in the response of +56.24mV and a notch of –
10.79mV from the reference at 100Hz.
Rate Box: Controls the DMM Measurement rate. As rate decreases, the measurement noise decreases. Also
consider the power line frequency (50/60 Hz) of operation when setting it, as certain rates have better noise
rejection at either 50 or 60 Hz. (See “Specifications” for details.). When measuring RMS values, there is no point
setting the Rate to a value greater than 2rps.
Range: Can be set to Autorange or manual by clicking on the appropriate range in the lower part of the Windows
panel. Autoranging is best used for bench top application and is not recommended for an automated test
application due to the uncertainty of the DMM range, as well as the extra time for range changes. Locking a range
is highly recommended when operating in an automated test system, especially to speed up measurements. Another
reason to lock a range is to control the input impedance in DCV. The 240 mV and 2.4 V ranges have virtually
infinite input impedance, while the 24 V and 240 V ranges have 10 Minput impedance.
S_Cal: This function is the System Calibration that corrects for internal gain, scale factor and zero errors. The
DMM does this by alternatively selecting its local DC reference and a zero input. It is required at least once every
day to meet the accuracy specifications. It is recommended that you also perform this function whenever the
external environment changes (e.g. the temperature in your work environment changes by more than 5C. This
function takes a few seconds to perform. Disconnect all leads to the DMM before doing this operation. Keep in
mind that this is not a substitute for periodic calibration, which must be performed with external standards.
15 Signametrics

Signametrics 16
4.0 DMM Operation and Measurement Tutorial
Most of the measurement functions are accessible from the Windows Control Panel (Figure above). All of the
functions are included in the Windows DLL driver library. To gain familiarity with the DMM, run the Windows
‘SETUP.EXE’ to install the software, then run the DMM, as described in the previous section. This section
describes in detail the DMM’s operation and measurement practices for best performance.
4.1 Voltage Measurement
Measures from 0.1 V to 240 VDC or VAC. Use the V, + and V, - terminals, being certain to always leave the
I+, I- and DIN-7 terminals disconnected. Use the AC/DC button on the Control Panel to switch between AC and
DC.
Making Voltage Measurements is straightforward. The following tips will allow you to make the most accurate
voltage measurements.
4.1.1 DC Voltage Measurements
When making very low-level DCV measurements (<1 mV), you should first place a copper wire shorting plug
across the V, + and V, - terminals and perform Relative function to eliminate zero errors before making your
measurements. A common source of error can come from your test leads, which can introduce several Volts of
error due to thermal voltages. To minimize thermal voltaic effects, after handling the test leads; you should wait a
few seconds before making measurements. Signametrics offers several high quality probes that are optimal for low-
level measurements.
Note: The front panel powers up in 8rps, DCV, 240 V range. If the DMM is operated in Autorange, with an open
input, The DMM will keep changing ranges. This is perfectly normal with ultra high impedance DMM’. The
virtually infinite input impedance of the 240 mV and 2.4 V DCV ranges causes this phenomenon. On these ranges,
an open input will read whatever charge is associated with the signal conditioning of the DMM. As this electrical
charge accumulates, the DMM will change ranges.
4.1.2 True RMS AC Voltage Measurements
ACV is specified for signals greater than 1mV, from 10 Hz to 50 kHz. The ACV function is AC coupled, and
measures the true RMS value of the waveform.
ACV measurements, if possible, should have the NEUTRAL or GROUND attached to the V,- terminal. See
Figure 4-1, below. This prevents any “Common Mode” problems from occurring (Common Mode refers to floating
the SM2060 V,LO above Earth Ground.) Common Mode problems can result in noisy readings, or even cause
the PC to hang-up under high V X Hz input conditions. In many systems, grounding the source to be measured at
Earth Ground (being certain to avoid any ground loops) can give better results.
The settling time and low end bandwidth of the RMS function are effected by the status of the Fast RMS control
circuit. When fast RMS is selected, the RMS settling time is about 10 times faster, but the low end frequency is
significantly increased.

Figure 4-1.Make Voltage ACV measurements with the source ground attached to the V,- to minimize
“Common Mode” measurement problems.
4.2 Current Measurements
The DMM measures AC and DC currents between 100 A and 2.5 A. Use the +I, 4Wterminals, being certain to
always leave the V,+ & -terminals disconnected. Use the AC/DC button to switch between AC and DC. The AC
current is an AC coupled True RMS measurement function. See figure 4-2 for connection.
The Current functions are protected with a 2.5 A, 250 V fuse. The 2.4mA and 24mA ranges utilize a 10shunt,
while the 240mA and 2.4A ranges use a 0.1shunt. In addition to the shunt resistors, there is some additional
parasitic resistance in the current measurement path associated with the fuse and the internal wiring. The result is a
low burden voltage.
Warning! Applying voltages greater than 35 V to the I+, I- terminals can cause personal injury and/or
damage to your DMM and computer! Think before applying any inputs to these terminals!
17 Signametrics

Figure 4-2. AC and DC Current measurement connection.
4.2.2 Improving DC Current Measurements
When making sensitive DC current measurements disconnect all terminals not associated with the measurement.
User the Relative function while in the desired DC current range to zero out any residual error. Using the S-Cal
(DMMCalibrate ()) prior to activating Relative will improve accuracy further. Although the DMM is designed to
withstand up-to 2.4A indefinitely, be aware that excessive heat may be generated when measuring higher AC or DC
currents. If allowed to rise this heat may adversely effect subsequent measurements. In consideration with this
effect, it is recommended that whenever practical, higher current measurements be limited to short time intervals.
The lower two ranges of DC current may be effected by relay contamination.
4.3 Resistance Measurements
The key for stable and accurate Resistance measurements, with low test voltage, is in the number of current sources
used. This DMM uses six. The DMM measures resistance by forcing a current, and measuring a voltage, which the
DMM converts and displayes as a resistance value. Most measurements can be made in the 2-wire mode. The 4-
wire ohms is used to make low value resistance measurements. All resistance measurement modes are susceptible to
Thermo-Voltaic (Thermal EMF) errors. See section 4.3.5 for details.
4.3.1 2-Wire Ohm Measurements
The DMM measure using 240to 24 Mranges. Use the V,+, V,-terminals for this function. Be certain to
disconnect the I+, I- terminals in order to reduce leakage, noise and for better safety.
Most resistance measurements can be made using the simple 2-wire Ohms method. Simply connect V,+ to one
end of the resistor, and the V,- to the other end. If the resistor to be measured is less than 24 k, you should null
out any lead resistance errors by first touching the V,+and V,-test leads together and then performing a
Relative function. If making measurements above 200 k, you should use shielded or twisted leads to minimize
noise pickup. This is especially true for measurements above 1 M.
You may also want to control the Ohms current used in making resistance measurements. (See the Specifications
section, "Resistance, 2-wire and 4-wire", for a table of resistance range vs. current level.) All of the Ohms ranges of
the DMM have enough current and voltage compliance to turn on diode junctions. For characterizing
semiconductor part types, use the Diode measurement function. To avoid turning on a semiconductor junction, you
may need to select a higher range (lower current). When checking semiconductor junctions, the DMM displays a
resistance value linearly related to the voltage across the junction.
Signametrics 18

For applications requiring voltage and current controlled resistance measurements, use the SMX2064, which has
Extended Resistance Measurement function as well as active guarding.
4.3.2 4-Wire Ohm Measurements
4-wire Ohms measurements are advantageous for making measurements below 200 k, eliminating lead resistance
errors. The Voltage (V,) Input terminals serve as a current source to stimulus the resistance, and the I, 4WInput
terminals are the sense inputs. The Source + and Sense + leads are connected to one side of the resistor, and the
Source - and Sense - leads are connected to the other side. Both Sense leads should be closest to the body of the
resistor. See Figure 4-3.
4-wire Ohm makes very repeatable low ohms measurements, from 10 mto 200 k. It is not recommended to use
4Wwhen making measurements above 200 k.
Figure 4-3. The I- and I+ sense leads should be closest to the body of the resistor when making 4W
measurements.
4.3.6 Effects of Thermo-Voltaic Offset
Resistance measurements are sensitive to Thermo-Voltaic (Thermal EMF) errors. These error voltages can be
caused by poor test leads, relay contacts and other elements in the measurement path. They affect all measurement
methods, including 2-Wire and 4-Wire. To quantify this error, consider a system in which signals are routed to the
DMM via a relay multiplexing system. Many vendors of switching products do not provide Thermal EMF
specification, and it is not uncommon to find relays that have more than 50 V. With several relay contacts in the
path, the error can be significant. This error can be measured using the DMM’s 240mV DC range. To do this, close
a single relay that is not connected to any load, wait for a short time (about 2 minutes), than measure the voltage
across the shorted relay contacts. Make sure to short the DMM leads and set ‘relative’ to clear the DMM offset prior
to the measurement. To calculate worst-case error, count all relay contacts, which are in series with the
measurement (V, +, V, -terminals in 2-Wire, and I+, I- terminals in 4-Wire mode). Multiply this count by the
Thermal EMF voltage. Use Ohms law to convert this voltage to resistance error as in the following table.
Resistance Measurement Errors due to Thermo-Voltaic offsets.
Range Ohms DMM Error due to Error due to Error due to
19 Signametrics

Signametrics 20
Current Resolution 10 V EMF 100 V EMF 1mV EMF
240 1 mA 1m  10 m100 m1 
2.4 k1 mA 10 m10 m100 m1 
24 k100 uA 100 m100 m1 10 
240 k10 uA 1 1 10 100 
2.4 M1 uA 10 10 100 10 
24 M100 nA 100 100 1 k100 
4.8 Diode Characterization
The Diode measurement function is used for characterizing semiconductor part types. This function is designed to
display a semiconductor device’s forward or reverse voltage. The DMM measures diode voltage at a selected
current. The available source currents for diode I/V characterization include five DC current values, 100 A, 1 A,
10 A, 100 A and 1 mA. The SMX2064 have an additional 10 mA range. It also has a variable current source that
can be used concurrently with DCV measurement (see “Source Current / Measure Voltage”). This allows a variable
current from 10 A to 12.5 mA. The maximum diode voltage compliance is approximately4 V.
Applications include I/V characteristics of Diodes, LEDs, Low voltage Zener diodes, Band Gap devices, as well as
IC testing and polarity checking.
5.0 Windows Interface