Signametrics SMX2040, SMX2042, SMX2044 Operator's Manual

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Operator's Manual

Model SMX2040 6½ Digit Digital Multimeter Model SMX2042 6½ Digit Multi-Function Digital Multimeter Model SMX2044 6½ Digit LCR Sourcing Digital Multimeter

Signametrics Corporation

December, 2004

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CAUTION

In no event shall Signametrics or its Representatives be 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 Signametric's 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.

reproduced in any form without the permission of Signametrics Corporation.

Signametrics 2

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TABLE OF CONTENTS

1.0 INTRODUCTION.................................................................................................................................................7

1.1 S

AFETY CONSIDERATIONS

1.2 M

INIMUM REQUIREMENTS

1.3 F

EATURE SET

2.0 SPECIFICATIONS...............................................................................................................................................9

2.1 DC V

2.2 DC C

2.3 AC V

2.4 AC C

2.5 R

2.6 L

2.7 RTD T

2.8 A

2.9 T

2.10 T

2.11 S

2.12 A

2.13 O

OLTAGE MEASUREMENT URRENT MEASUREMENT OLTAGE MEASUREMENTS

2.3.1 AC Voltage True RMS Measurement.......................................................................................9

2.3.2 AC Peak-to-Peak Measurement (SMX2044)..........................................................................10

2.3.3 AC Crest Factor Measurement (SMX2044)...........................................................................10

2.3.4 AC Median Value Measurement (SMX2044).........................................................................11

URRENT MEASUREMENT, TRUE

ESISTANCE MEASUREMENTS

2.5.1 2-wire and 4-wire...................................................................................................................12

2.5.2 6-wire Guarded Resistance Measurement (SMX2044)..........................................................12

EAKAGE MEASUREMENT

DDITIONAL COMPONENT MEASUREMENTS

2.8.1 Diode Characterization .........................................................................................................13

2.8.2 Capacitance Measurement (SMX2042, 44)...........................................................................13

2.8.3 Inductance Measurement (SMX2044)....................................................................................13

2.8.4 In Circuit AC-Based Capacitance Measurements (SM2044) ................................................13

IMING MEASUREMENTS

2.9.1 Threshold DAC ......................................................................................................................14

2.9.2 Frequency and Period Measurement.....................................................................................14

2.9.3 Duty Cycle Measurement.......................................................................................................14

2.9.4 Pulse Width............................................................................................................................14

2.9.5 Totalizer.................................................................................................................................15

RIGGER FUNCTIONS

2.10.1 External Hardware Trigger (at DIN-7 connector) ..............................................................15

2.10.2 PXI Bus Hardware Trigger Inputs (at PXI J2)....................................................................15

2.10.3 PXI Bus Hardware Trigger Output (to PXI J2)...................................................................15

2.10.4 Analog Threshold Trigger....................................................................................................15

OURCE FUNCTIONS

2.11.1 DC Voltage Source ..............................................................................................................16

2.11.2 AC Voltage Source...............................................................................................................16

2.11.3 DC Current Source..............................................................................................................16

CCURACY NOTES THER SPECIFICATIONS

.............................................................................................................................................8

EMPERATURE MEASUREMENT

..........................................................................................................................7

.........................................................................................................................8

...................................................................................................................9

....................................................................................................................9

..................................................................................................................9

RMS..............................................................................................11

..................................................................................................................12

(SMX2044)....................................................................................................12

(SMX2044)...................................................................................12

............................................................................................13

(SMX2042, 44) ................................................................................................14

..............................................................................................................................15

(SMX2044)...........................................................................................................16

................................................................................................................................. 17

.........................................................................................................................18

3.0 GETTING STARTED.........................................................................................................................................19

3.1 S

ETTING THE

3.2 I

NSTALLING THE

3.3 I

NSTALLING THE

3.4 DMM I

3.5 S

TARTING THE CONTROL PANEL

3.6 U

SING THE CONTROL PANEL

4.0 DMM OPERATIONS AND MEASUREMENTS.............................................................................................24

4.1 V

OLTAGE MEASUREMENT

4.1.1 DC Voltage Measurements ....................................................................................................24

4.1.2 True RMS AC Voltage Measurements ...................................................................................25

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DMM..................................................................................................................................19

DMM M DMM

NPUT CONNECTORS

ODULE

.............................................................................................................19

SOFTWARE PACKAGE

......................................................................................................................19

..............................................................................................................21

....................................................................................................................22

........................................................................................................................24

...........................................................................................19

3 Signametrics

4.1.3 AC Peak-to-Peak and Crest Factor Measurement (SMX2044).............................................25

4.1.4 AC Median Value Measurement (SMX2044).........................................................................26

4.2 C

URRENT MEASUREMENTS

4.2.1 Improving Current Measurements.........................................................................................26

4.2.2 Low Level DC Current Measurements...................................................................................27

4.2.3 Extended DC Current Measurements (SM2044) ...................................................................27

4.3 R

ESISTANCE MEASUREMENTS

4.3.1 2-wire Ohm Measurements....................................................................................................27

4.3.2 4-wire Ohm Measurements....................................................................................................27

4.3.3 Using Offset Ohms function...................................................................................................28

4.3.4 6-wire Guarded Resistance Measurement (SMX2044)..........................................................28

4.3.5 Leakage Measurements (SMX2044) ......................................................................................29

4.3.6 Extended Resistance Measurements (SMX2044)...................................................................30

4.3.7 Effects of Thermo-Voltaic Offset ............................................................................................31

4.3.8 Guarding High Value Resistance Measurements (SMX2044)...............................................32

4.4 RTD T

4.5 I

4.6 D

4.7 C

4.8 IN-C

4.9 I

4.10 C

4.11 T

4.12 F

4.13 S

4.14 S

4.15 I

5.1 D

5.2 U

5.3 V

5.4 W

5.5 U

5.6 W

EMPERATURE MEASUREMENT

NTERNAL TEMPERATURE

IODE CHARACTERIZATION APACITANCE MEASUREMENT

IRCUIT CAPACITANCE MEASUREMENT

NDUCTANCE MEASUREMENT

HARACTERISTIC IMPEDANCE MEASUREMENT RIGGER OPERATION

4.11.1 External Hardware Trigger.................................................................................................34

4.11.2 Analog Threshold Trigger....................................................................................................35

4.11.3 Software Issued Triggered Operations................................................................................35

4.11.4 Using the PXI bus Trigger Facilities...................................................................................35

REQUENCY AND TIMING MEASUREMENTS

4.12.1 Threshold DAC ....................................................................................................................36

4.12.2 Frequency and Period Measurements .................................................................................37

4.12.3 Duty Cycle Measurement.....................................................................................................38

4.12.4 Pulse Width..........................................................................................................................38

4.12.5 Totalizer Event Counter.......................................................................................................38

OURCING FUNCTIONS

4.13.1 DC Voltage Source ..............................................................................................................39

4.13.2 AC Voltage Source...............................................................................................................40

4.13.3 DC Current Source..............................................................................................................40

4.13.4 Source Current - Measure Voltage......................................................................................40

YNTHESIZING RESISTANCE

NTERFACING TO THE

4.15.1 Triggering the SMX2040 DMMs .........................................................................................42

4.15.2 Multiplexing with the SMX2040 DMMs...............................................................................43

4.15.3 Interface Commands and Timing .........................................................................................43

ISTRIBUTION FILES

5.1.1 The SM40CAL.DAT file........................................................................................................46

SING THE

ISUAL BASIC FRONT PANEL APPLICATION

INDOWS

SING THE

INDOWS COMMAND LANGUAGE

SMX2040 D

Multiple Card Operations Under Windows....................................................................................47

5.3.1 Visual Basic Simple Application............................................................................................49

DLL D

EFAULT MODES AND PARAMETERS

SMX2040 DLL

DMMArmAnalogTrigger ................................................................................................................51

DMMArmTrigger............................................................................................................................52

DMMBurstBuffRead .......................................................................................................................53

DMMBurstRead..............................................................................................................................54

DMMCalibrate................................................................................................................................55

DMMCleanRelay ............................................................................................................................55

DMMClearMinMax ........................................................................................................................56

DMMClosePCI ...............................................................................................................................56

......................................................................................................................26

..................................................................................................................27

(SMX2044)...................................................................................32

(SMX2044) ....................................................................................................32

.....................................................................................................................33

(SMX2044).............................................................................................33

(SMX2044) ..............................................................................................34

.............................................................................................................................34

(SMX2044).......................................................................................................39

(SMX2044)...............................................................................................41

SMX4032

................................................................................................................................45

RIVER WITH

SERIES RELAY SCANNERS

C++

WITH LABWINDOWS

...........................................................................................................51

Signametrics 4

(SMX2044)..........................................................................34

(SMX2044)..................................................................34

(SMX2042, 44)..................................................................36

...................................................................42

OR SIMILAR SOFTWARE

.............................................................................................48

..............................................................................49

/CVI®.........................................................................50

..........................................................47

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DMMDelay .....................................................................................................................................57

DMMDisableTrimDAC...................................................................................................................57

DMMDisArmTrigger ......................................................................................................................58

DMMDutyCycleStr .........................................................................................................................58

DMMErrString................................................................................................................................59

DMMFrequencyStr.........................................................................................................................59

DMMGetACCapsR .........................................................................................................................61

DMMGetBusInfo.............................................................................................................................61

DMMGetCalDate............................................................................................................................62

DMMGetdB.....................................................................................................................................62

DMMGetdBStr................................................................................................................................63

DMMGetCJTemp............................................................................................................................63

DMMGetDeviation .........................................................................................................................64

DMMGetDeviatStr..........................................................................................................................65

DMMGetFuncRange.......................................................................................................................65

DMMGetFunction...........................................................................................................................66

DMMGetGrdVer.............................................................................................................................66

DMMGetHwVer..............................................................................................................................67

DMMGetID.....................................................................................................................................67

DMMGetManDate..........................................................................................................................68

DMMGetMax..................................................................................................................................68

DMMGetMaxStr .............................................................................................................................69

DMMGetMin...................................................................................................................................69

DMMGetMinStr..............................................................................................................................70

DMMGetRange...............................................................................................................................70

DMMGetRate..................................................................................................................................71

DMMGetSourceFreq ......................................................................................................................71

DMMGetTCType.............................................................................................................................72

DMMGetType .................................................................................................................................72

DMMGetVer ...................................................................................................................................73

DMMInit .........................................................................................................................................73

DMMIsAutoRange ..........................................................................................................................74

DMMIsInitialized............................................................................................................................75

DMMIsRelative...............................................................................................................................75

DMMLoadCalFile...........................................................................................................................76

DMMOpenPCI................................................................................................................................77

DMMOpenCalACCaps...................................................................................................................77

DMMOpenTerminalCal..................................................................................................................78

DMMPeriodStr ...............................................................................................................................78

DMMPolledRead ............................................................................................................................80

DMMPolledReadCmd .....................................................................................................................80

DMMPolledReadStr........................................................................................................................81

DMMRead.......................................................................................................................................81

DMMReadBuffer.............................................................................................................................82

DMMReadBufferStr........................................................................................................................83

DMMReadCJTemp .........................................................................................................................83

DMMReadCrestFactor ...................................................................................................................84

DMMReadDutyCycle......................................................................................................................85

DMMReadFrequency......................................................................................................................85

DMMReadFrequencyStr.................................................................................................................86

DMMReadInductorQ......................................................................................................................87

DMMReadMeasurement.................................................................................................................87

DMMReadMedian........................................................................................................................... 88

DMMReadNorm..............................................................................................................................88

DMMReadPeakToPeak...................................................................................................................89

DMMReadPeriod............................................................................................................................89

DMMReadStr..................................................................................................................................90

DMMReadTotalizer ........................................................................................................................91

DMMReadWidth.............................................................................................................................92

DMMReady.....................................................................................................................................92

5 Signametrics

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DMMSetACCapsDelay ...................................................................................................................93

DMMSetACCapsLevel....................................................................................................................93

DMMSetACVSource .......................................................................................................................94

DMMSetAutoRange ........................................................................................................................95

DMMSetBuffTrigRead ....................................................................................................................95

DMMSetCapsAveSamp...................................................................................................................96

DMMSetCJTemp.............................................................................................................................97

DMMSetCompThreshold ................................................................................................................98

DMMSetCounterRng.......................................................................................................................98

DMMSetDCISource........................................................................................................................99

DMMSetDCVSource.......................................................................................................................99

DMMSetExternalShunt.................................................................................................................100

DMMSetFuncRange......................................................................................................................101

DMMSetFunction..........................................................................................................................101

DMMSetInductFreq......................................................................................................................102

DMMSetOffsetOhms.....................................................................................................................102

DMMSetRange..............................................................................................................................103

DMMSetRate.................................................................................................................................103

DMMSetRelative...........................................................................................................................104

DMMSetResistance.......................................................................................................................106

DMMSetRTD ................................................................................................................................106

DMMSetSensoreParams...............................................................................................................107

DMMSetSourceMode....................................................................................................................107

DMMSetSynchronized...................................................................................................................108

DMMSetTCType ...........................................................................................................................109

DMMSetTempUnits....................................................................................................................... 109

DMMSetTrigRead.........................................................................................................................110

DMMSetTrimDAC ........................................................................................................................111

DMMStartTotalizer.......................................................................................................................111

DMMStopTotalizer .......................................................................................................................113

DMMTerminate.............................................................................................................................113

DMMTrigger.................................................................................................................................114

DMMWidthStr...............................................................................................................................114

SetACCapsFreq.............................................................................................................................115

6.0 MAINTENANCE ..............................................................................................................................................116

6.1 P

ERFORMANCE TESTS

6.2 DC V

6.3 R

6.4 R

6.5 AC V

6.6 DC C

6.7 AC C

6.8 C

6.9 F

6.10 C

7.0 WARRANTY AND SERVICE.........................................................................................................................125

8.0 ACCESSORIES.................................................................................................................................................125

OLTAGE TEST ESISTANCE TEST, 2-WIRE ESISTANCE TEST, 4-WIRE

OLTAGE TEST

URRENT TEST

URRENT TEST APACITANCE TEST

REQUENCY COUNTER TEST

ALIBRATION

............................................................................................................................117

................................................................................................................................117

.....................................................................................................................118

................................................................................................................................120

................................................................................................................................121

(SMX2044

....................................................................................................................................... 124

ONLY

)..................................................................................................122

(SMX2044

ONLY

).....................................................................................123

Signametrics 6

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1.0 Introduction

Congratulations! You have purchased a PXI/CompactPCI Plug-in instrument with analog and systems performance that rivals the best, all-in-one box instruments. The SMX2040 series digital multimeters (DMMs) 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 DMMs, please take a few moments and review this manual before installing and using this precision instrument.

This manual describes the SMX2040 and SMX2044 DMMs. Each DMM delivers unmatched breakthrough performance in a PXI and CompactPCI plug-in instrument. With a rich repertoire of functions, the SMX2040 series out performs all other plug-in DMMs, including the trusted Signametrics SM-2020CT, and most brand named bench top units.

Note: In this manual, all references to the "SMX2040" and “DMM” apply to the SMX2040 and SMX2044. Features unique to the SMX2044 will be identified as such.

1.1 Safety Considerations

Safety Considerations

The SMX2040 series of DMMs is capable of measuring up to 300 VDC or 250 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 PXI/CompactPCI chassis trapped inside the DMM.

The DMM comes installed with two shields (bottom and top) 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 chassis. Also make sure the ch assis is 3 U in size.

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 PXI/CompactPCI chassis !

To avoid shock hazard, install the DMM only into a 3U PXI and CompactPCI chassis 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 optional accessory with the Signametrics DMMs. Do not use these units in a 6U chassis as an electrocution hazard will be present.

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7 Signametrics

1.2 Minimum Requirements

The SMX2040 series of system DMMs are precision plug-in modules that are compatible with 3U PXI or CompactPCI chassis. The processor type must be a Pentium or equivalent processor running MS Windows. The DMM requires a single PXI or CompactPCI slot. A mouse must be installed when controlling the DMM from the Windows Control Panel. The SMX2040 comes with a Windows' DLL, for operation with Windows' Version 95/98/Me/2000/XP and NT4.0.

1.3 Feature Set

The base unit, the SMX2040, has 6-1/2 digit performance and can be used as a general purpose DMM, giving very accurate and stable readings. The SMX2044 adds to the SMX2040 additional measurement functions not found in other DMMs such as inductance measurement and sourcing capabilities.

SMX2040, 42, 44 6½ Digit DMMs feature table:

Function SMX2040

DMM

DCV 4 ranges, >10 GΩ & 10 MΩ input resistance.

ACV 4 ranges, 1 MΩ input √ √ √ 2-Wire Ohms, six ranges 330 Ω to 33 MΩ √ plus 33 Ω,

4-Wire Ohms, four ranges 330 Ω to 330 kΩ √ plus 33 Ω plus 33 Ω range Offset Ohms DC current, four ranges 3.3 mA to 2.5 A AC current, four ranges 3.3 mA to 2.5 A

Diode V/I characteristics at 100 ηA to 1mA √ Auto range, Relative Min/Max, dB and percent deviation functions On board measurement buffer Measurement rate: 0.2 to 1,000/sec External and threshold trigger Thermocouples

High Dynamic range; +3,300,000 counts

PXI Trigger In/Out Capacitance, seven ranges, 10 nF to 10 mF Temperature (five basic RTD types) Frequency / Period measurement Pulse width, pos./neg., & duty cycle Totalizer/event counter Variable threshold DAC; all timing measure. Peak to Peak, Crest factor, Median Internal DMM temperature sensor Six wire Ohms (with force/sense) Inductance, six ranges 33 µH to 3.3 H DCV source 0 to +/-10.0 V ACV source 0 to 20 V pk-pk, 2 Hz to 75 KHz DC current source, 1 nA to 12.5 mA Leakage measurement Synthesized resistance source Extended Resistance measurements In Circuit Capacitance

√ √ √

√ √ √ √ √ √ √ √ √

√ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √

SMX2042

Multi-Function

DMM

330 MΩ

plus 10 mA plus 10 mA

√ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √

SMX2044 LCR Sourcing DMM

plus 33 Ω,

330 MΩ

√ √ √ √ √ √ √ √ √

Signametrics 8

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2.0 Specifications

2.1 DC Voltage Measurement

Input Characteristics

• Input Resistance 330 mV & 3.3 V Ranges: >10 GΩ ,

• Input Resistance 33 V & 330 V Ranges: 10.0 MΩ

Accuracy ± (% of reading + Volts) [1]

Range Full Scale

6 ½ Digits

330 mV 330.0000 mV

3.3 V 3.300000 V 33 V 33.00000 V 330 V 330.0000 V

Resolution 24 hours

23°C ± 1°C 100 ηV 0.003 + 4.5 µV 0.004 + 5.5 µV 0.007 + 8 µV 1 µV 0.002 + 10 µV 0.0025 + 12 µV 0.0045 + 17 µV 10 µV 0.003 + 250 µV 0.004 + 280 µV 0.007 + 330 µV 100 µV

0.004 + 1 mV 0.005 + 1.2 mV 0.008 + 1.5 mV

90 Days 23°C ± 5°C

One Year 23°C ± 5°C

[1] With reading rate set to 10 readings per second (rps) or slower, and within one hour of DCV zero, using Relative control.

DCV Noise Rejection Normal Mode Rejection, at 50, 60, or 400 Hz ± 0.5%, is better than 95 dB for reading rates of 10 rps or lower. Common Mode Rejection (with 1 kΩ lead imbalance) is better than 120 dB for these conditions.

2.2 DC Current Measurement

Input Characteristics

• Burden Voltage < 350 mV for all ranges

• Protected with 2.5A fuse ( 5x20mm, 250 V Fast)

Accuracy ± (% of reading + Amps) [1]

Range Full Scale

5 ½ Digits

3.3 mA 3.30000 mA 33 mA 33.0000 mA 330 mA 330.000 mA

2.5 A 2.50000 A

Resolution 24 hours

23°C ± 5°C

10 ηA 0.052 + 200 ηA 0.07 + 350 ηA 0.1 + 400 ηA

100 ηA 0.04 + 1 µA 0.06 + 2 µA 0.1 + 3 µA

1 µA 0.05 + 30 µA 0.055 + 40 µA 0.075 + 60 µA 10 µA 0.55 + 50 µA 0.6 + 200 µA 0.65 + 350 µA

90 Days 23°C ± 5°C

One Year 23°C ± 5°C

[1] With reading rate set to 10 rps or slower, and within one hour of DCI zero, using Relative control.

2.3 AC Voltage Measurements

Input Characteristics

• Input Resistance 1.0 MΩ, shunted by < 100 pF, all ranges

• Crest Factor 3 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

2.3.1 AC Voltage True RMS Measurement

Range Full Scale 6 ½ Digits Lowest specified Voltage Resolution

330 mV 330.0000 mV 5 mV [1]

3.3 V 3.300000 V 10 mV 33 V 33.00000 V 100 mV 250 V [2] 250.0000 V 1 V

[1] Between 5 mV and 10 mV, add 100 µV additional error to the accuracy table below. In many computer installations, if the DMM is not near a noisy board, usable voltage measurements of 1 mV can be obtained.

[2] Signal is limited to 8x10 32 kHz, or 8x10

Volt x Hz.

Volt Hz Product. For example, the largest frequency input at 250 V is

9 Signametrics

100 ηV 1 µV 10 µV 100 µV

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Accuracy ± (% of reading + Volts) [1]

Range Frequency 24 hours

23°C ± 1°C

330 mV

3.3 V

33 V

250 V

10 Hz - 20 Hz 20 Hz - 47 Hz 47 Hz - 10 kHz 10 kHz - 50 kHz 50 kHz - 100 kHz 10 Hz - 20 Hz 3.0 + 2 mV 3.1 + 2.2 mV 3.2 + 2.5 mV 20 Hz - 47 Hz 0.93 + 1.3 mV 0.96 + 1.5 mV 1.0 + 1.7 mV 47 Hz - 10 kHz 0.05 + 1 mV 0.055 + 1.1 mV 0.065 + 1.2 mV 10 kHz - 50 kHz 0.62 + 1.2 mV 0.65 + 1.3 mV 0.70 + 1.5 mV 50 kHz - 100 kHz 5.1 + 1.5 mV 5.2 + 1.7 mV 5.3 + 2 mV 10 Hz - 20 Hz 3.0 + 14 mV 3.1 + 16 mV 3.3 + 20 mV 20 Hz - 47 Hz 0.93 + 12 mV 0.96 + 14 mV 1.0 + 16 mV 47 Hz - 10 kHz 0.06 + 10 mV 0.065 + 11 mV 0.073 + 13 mV 10 kHz - 50 kHz 0.31 + 18 mV 0.33 + 21 mV 0.35 + 25 mV 50 kHz - 100 kHz 2.0 + 30 mV 2.2 + 35 mV 2.4 + 40 mV 10 Hz - 20 Hz 3.0 + 140 mV 3.1 + 160 mV 3.3 + 200 mV 20 Hz - 47 Hz 0.93 + 120 mV 0.96 + 130 mV 1.0 + 150 mV 47 Hz - 10 kHz 0.04 + 100 mV 0.045 + 110 mV 0.06 + 130 mV 10 kHz - 50 kHz 0.32 + 150 mV 0.4 + 170 mV 0.45 + 200 mV 50 kHz - 100 kHz 2.5 + 200 mV 2.8 + 240 mV 3.2 + 300 mV

3.0 + 350 µV 3.1 + 380 µV 3.2 + 430 µV

0.92 + 150 µV 0.93 + 170 µV 0.95 + 200 µV

0.13 + 100 µV 0.14 + 110 µV 0.15 + 120 µV

0.55 + 160 µV 0.6 + 200 µV 0.63 + 230 µV

5.3 + 350 µV 5.4 + 370 µV 5.6 + 400 µV

90 Days 23°C ± 5°C

One Year 23°C ± 5°C

ACV Noise Rejection Common Mode rejection, for 50 Hz or 60 Hz with 1 kΩ imbalance in either lead, is better than 60 dB.

2.3.2 AC Peak-to-Peak Measurement (SMX2044)

• Measures the peak-to-peak value of a repetitive waveform

ACV Range

330 mV 0.1 V 1.85 V 1 mV

3.3 V 1.0 V 18.5 V 10 mV 1.4 ±70 mV 33 V 10 V 185.0 V 100 mV 1.0 ±700 mV 250 V 100 V 850.0 V 1 V 1.0 ± 6 V

[1] Specified from 30Hz to 10 kHz. Input signal frequency of 30 Hz to 30 kHz.

Lowest specified

input voltage

(Vp-p)

Full Scale

reading (Vp-p)

Resolution

Typical Accuracy 23°C ± 5°C

One Year [1]

1.5 ±10 mV

2.3.3 AC Crest Factor Measurement (SMX2044)

•

Measures the crest factor (peak / RMS) of a repetitive waveform

ACV Range

330 mV 0.1 V 1.8 V 0.01

3.3 V 1.0 V 18 V 0.01 2.1 ±0.1 33 V 10 V 180 V 0.01 2.0 ±0.1 250 V 100 V 700 V 0.01 2.0 ±0.1

[1] Crest factor measurement requires signal frequency of 30 Hz to 30 kHz.

Lowest specified

input voltage

(Vp-p)

Highest specified input

voltages (Vp-p)

Resolution

Typical Accuracy 23°C ± 5°C

One Year [1]

2.2 ±0.3

Signametrics 10

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2.3.4 AC Median Value Measurement (SMX2044)

• Measures the mid-point between the positive and negativ e peaks of a repetitive waveform

• Used to determine the Threshold DAC setting for optimal frequency and timing measurements

ACV Range

330 mV 0.08 V

3.3 V 0.80 V 33 V 8 V 250 V 80 V

[1] Median measurements require a repetitive signal with frequency range of 30 Hz to 30 KHz.

Lowest specified input

voltage (Vp-p)

Full Scale

reading

±0.95 V

±9.5 V

±95.0 V

±350.0 V

Resolution

1 mV

10 mV 3% ±160 mV

100 mV 3% ±1.4 V

1 V 3% ±12 V

Typical Accuracy 23°C ± 5°C One Year [1]

2.0% ±17 mV

2.4 AC Current Measurement, True RMS

Input Characteristics

• Burden Voltage < 350 mV RMS all Ranges

• Crest Factor 3 at Full Scale, increasing to 7 at Lowest Specified Current

•

Protected with 2.5 A fuse ( 5x20 mm, 250 V Fast)

Range Full Scale 6 1/2 Digits Lowest Specified Current Resolution

3.3 mA 3.300000 mA 33 mA 33.00000 mA 330 mA 330.0000 mA 5 mA 100 nA

2.5 A 2.500000 A 50 mA 1 uA

Accuracy ± (% of reading + Amps)

Range Frequency 24 hours

3.3 mA

33 mA

330 mA

2.5 A

10 Hz - 20 Hz 20 Hz - 47 Hz 47 Hz - 1 kHz 1 kHz - 10 kHz 10 Hz - 20 Hz 20 Hz - 47 Hz 47 Hz - 1 kHz 1 kHz - 10 kHz 10 Hz - 20 Hz 20 Hz - 47 Hz 47 Hz - 1 kHz 1 kHz - 10 kHz 10 Hz - 20 Hz 1.8 + 4 mA 2.5 + 4.5 mA 2.7 + 5 mA 20 Hz - 47 Hz 0.66 + 4 mA 0.8 + 6 mA 0.9 + 6 mA 47 Hz - 1 kHz 0.6 + 3.8mA 0.63 + 3.8 mA 0.65 + 4 mA 1 kHz - 10 kHz 0.6 + 4mA 0.62 + 4.5 mA 0.7 + 5 mA

Note: All AC Current ranges have typical measurement capability to 20 kHz.

50 µA 500 µA

23°C ± 1°C

3.8 + 4 µA 2.7 + 4 µA 2.9 + 4 µA

0.9 + 4 µA 0.9 + 4 µA 1.0 + 4 µA

0.04 + 1.5 µA 0.08 + 3 µA 0.12 + 4 µA

0.12 + 4 µA 0.14 + 4 µA 0.22 + 4 µA

1.8 + 30 µA 2.6 + 30 µA 2.8 + 30 µA

0.6 + 30 µA 0.9 + 30 µA 1.0 + 30 µA

0.07 + 10 µA 0.15 + 20 µA 0.16 + 30 µA

0.21 + 30 µA 0.3 + 40 µA 0.4 + 40 µA

1.8 + 400 µA 2.7 + 400 µA 2.8 + 400 µA

0.6 + 400 µA 0.9 + 400 µA 1.0 + 400 µA

0.1 + 100 µA 0.17 + 180 µA 0.22 + 220 µA

0.3 + 300 µA 0.4 + 350 µA 0.6 + 400 µA

90 Days 23°C ± 10°C

1 nA 10 nA

One Year 23°C ± 10°C

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11 Signametrics

2.5 Resistance Measurements

2.5.1 2-wire and 4-wire

Accuracy ± (% of reading + Ω) [1]

Range [2] Full Scale

6 ½ Digits 33 Ω [3] 33.00000 Ω 10 µΩ 330 Ω 330.0000 Ω 100 µΩ

3.3 kΩ 3.300000 kΩ 1 mΩ 33 kΩ 33.00000 kΩ 10 mΩ 100 µA 0.0025 + 300 mΩ 0.0033 + 330 mΩ 0.006 + 350 mΩ 330 kΩ 330.0000 kΩ 100 mΩ 10 µA 0.0055 + 3.2 Ω 0.007 + 4 Ω 0.009 + 5 Ω

3.3 MΩ 3.300000 MΩ 1 Ω 1 µA 0.018 + 40 Ω 0.03 + 50 Ω 0.04 + 70 Ω 33 MΩ 33.0000 MΩ 100 Ω 330 MΩ [3] 330.00 MΩ 10 kΩ

Resolution Source

current 10 mA 1 mA 1 mA

100 nA 10 nA

24 hours 23°C ± 1°C

0.0038 + 1 mΩ 0.005 + 1.5 mΩ 0.008 + 2 mΩ

0.0037 + 4.5 mΩ 0.0046 + 5 mΩ 0.007 + 6 mΩ

0.0023 + 28 mΩ 0.003 + 32 mΩ 0.005 + 33 mΩ

0.12 + 400 Ω 0.13 + 500 Ω 0.2 + 600 Ω 1 + 50 kΩ 1.4 + 60 kΩ 2.0 + 80 kΩ

90 Days 23°C ± 10°C

One Year 23°C ± 10°C

[1] With reading rate set to 2 rps or slower, and within one hour of Ohms zero, using Relative control. [2] 4-wire ohms is available up to the 330 kΩ range. [3] 33 Ω and 330 MΩ ranges are only available with the SMX2042,44.

2.5.2 6-wire Guarded Resistance Measurement (SMX2044)

Typical additional error contributed by guarding

Range Source current 33 Ω 330 Ω

3.3 kΩ 33 kΩ 100 µA 0.03 + 1 Ω 330 kΩ 10 µA 0.35 + 10 Ω

10 mA 1 mA 1 mA

Accuracy ± (% of reading + Ω)

One Year 23°C ± 5°C [1]

0.3 + 4 mΩ

0.003 + 20 mΩ

0.005 + 100 mΩ

[1] This table should be used in conjunction with the 2-wire and 4-wire table above.

2.6 Leakage Measurement (SMX2044)

Accuracy ± (% of reading + Ω) [1]

Leakage Reading Voltage range

1.00 ηA to 100.00 ηA

100.00 ηA to 1000.00ηA

1000.00 ηA to 3.3 µA

-10 V to +10 V 2 + 350 pA

-9 V to + 9 V

-7 V to + 7 V

One Year 23°C ± 5°C [1]

1.2 + 2 ηA

1.5 + 20 ηA

[1] Error does not include external shunt resistor’s tolerance.

2.7 RTD Temperature Measurement (SMX2044)

RTD Type

pt385, pt3911, pt3916, pt3926 pt385, pt3911, pt3916, pt3926 Cu (Copper)

Cu (Copper)

Ro (Ω)

100, 200 Ω 0.01°C -150 to 650°C ±0.06°C

500, 1 kΩ 0.01°C -150 to 650°C ±0.03°C

Less than 12 Ω 0.01°C -100 to 200°C ±0.18°C for temperatures ≤ 20°C, ±0.05°C

Higher than 90 Ω 0.01°C -100 to 200°C ±0.10°C for temperatures ≤ 20°C, ±0.05°C

[1] With reading rate set to 2 rps or slower, using a 4-wire RTD. Measurement accuracy does not include RTD probe error.

Resolution Temperature

range

Temperature Accuracy 23°C ± 5°C [1]

One Year

otherwise

Signametrics 12

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2.8 Additional Component Measurements

2.8.1 Diode Characterization

• Available DC current values 100 ηA, 1 µA, 10 µA, 100 µA and 1 mA. SMX2042 and SMX2044 add 10

mA. SMX2044 has a variable current from 10 ηA to 12.5 mA using the DCI source.

• Typical Current Value Uncertainty 1%

• Typical Voltage Value Uncertainty 0.02%

•

Maximum diode voltage compliance 4 V

2.8.2 Capacitance Measurement (SMX2042, 44)

Accuracy ± (% of reading + Farads) [1]

Range Full Scale

4 ½ Digits 10 ηF 11.999 ηF 100 ηF 119.99 ηF

1 µF 1.1999 µF

10 µF 11.999 µF 1 ηF

100 µF 119.99 µF 10 ηF

1 mF 1.1999 mF

10 mF 11.999 mF

Resolution One Year

23°C ± 5°C 1 pF 2.1 ± 5 pF 10 pF 1.0

100 pF 1.0

100 ηF

1 µF

1.0

1.2 2

[1] Within one hour of zero, using Relative control. Accuracy is specified for values higher than 5% of the selected

range with the exception of the 10 ηF range, which measures down to 0 pF.

2.8.3 Inductance Measurement (SMX2044)

± (% of reading + inductance) [1]

Range Default

frequency

33 µH

330 µH

3.3 mH 4 kHz 3.3000 mH 33 mH 1.5 kHz 33.000 mH

330 mH 1 kHz 330.00 mH

3.3 H 100 Hz 3.3000 H

75 kHz 50 kHz

Full Scale 4 ½ Digits

33.000 µH 1 ηH 3.0% + 500 ηH

330.00 µH 10 ηH 2.0% + 3 µH

Resolution

100 ηH 1.5% + 25 µH

1 µH 1.5% + 200 µH

10 µH

100 µH

Accuracy 23°C ± 5°C

One Year [2]

2.5 + 3 mH 3 + 35 mH

[1] Within one hour of zero, and Open Terminal Calibration. [2] Accuracy is specified for values greater than 5% of the selected range.

2.8.4 In Circuit AC-Based Capacitance Measurements (SM2044)

Accuracy ± (% of reading + Farads) [1]

Range Full Scale

4 ½ Digits 33 ηF 32.99 ηF 330 ηF 329.9 ηF

3.3 µF 3.299 µF 33 µF 32.99 µF 10 ηF 5% ± 20 ηF

330 µF 329.9 µF 100 ηF 5% ± 1 µF

3.3 mF 3.299 mF

[1] Specified to 2/3 of range (ie. 22ηF on 33nF range). Within one hour from last AC-Caps Open calibration. Add

an error of 50e-6*R*C (%) due to paralled resistance.

Resolution One Year

23°C ± 5°C 10 pF 12% ± 250 pF 100 pF 5% ± 500 pF

1000 pF

1 µF 7% ± 50 µF

4% ± 1 ηF

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13 Signametrics

2.9 Timing Measurements (SMX2042, 44)

2.9.1 Threshold DAC

• The Threshold DAC is used for selecting a detection threshold to give optimal frequency and

timing measurements.

± (% of setting + volts)

Selected VAC

range [1]

330 mV -1.0 V to +1.0 V 0.5 mV 1.900 V 0.2% + 4 mV

3.3 V -10.0 V to +10.0 V 5.0 mV 19.00 V 0.2% + 40 mV 33 V -100.0 V to 100.0 V 50 mV 190.0 V 0.2% + 0.4 V 250 V -500 V to 500 V 500 V 850.0 V 0.2% + 4 V

Threshold range (DC

level)

Threshold

DAC

resolution

Highest allowed input

Vp-p

Typical one year setting

uncertainty

[1] This table should be used in conjunction with the AC volts section above.

2.9.2 Frequency and Period Measurement

ACV Mode

•

Input Impedance 1 MΩ with < 300 pF

Frequency Range 1 Hz - 100 Hz 100 Hz-1 kHz 1 kHz-10 kHz 10 kHz-100 kHz 100 kHz-300 kHz Resolution 1 mHz 10 mHz 100 mHz 1 Hz 1 Hz Uncertainty is ±0.002% of

reading ± adder shown Input Signal Range [1] 10% - 200%

4 mHz 20 mHz 200 mHz 2 Hz 5 Hz

of range

10% - 200%

of range

10% -200%

of range

10% - 200%

of range

45% -200%

of range

[

1] Input RMS voltage required for a valid reading. Do not exceed 250 V RMS input. For example, 10% -200%

of range indicates that in the 330 mVAC range, the input voltage should be 33 mV to 660 mV RMS.

ACI Mode

•

Input Impedance 10 Ω in the 3 mA and 30 mA ranges, 0.1 Ω in the 330 mA and 2.5 A ranges.

Frequency Range 1 Hz - 100 Hz 100 Hz-1 kHz 1 kHz-10 kHz 10 kHz-500 kHz Resolution 1 mHz 10 mHz 100 mHz 1 Hz Uncertainty 0.01% ±4 mHz 0.01% ±20 mHz 0.01% ±200 mHz 0.01% ±2 Hz

Input Signal Range,

3.3 mA, 330mA Ranges [1] Input Signal Range, 33 mA, 2.5A ranges

[1] Input current required to give a valid reading. For example, 10% -500% of range indicates that in the 3.3 mA range, the input current should be 0.33 mA to 16.5 mA.

10% -500%

of range

50% -100%

of range

10% - 500%

of range

50% - 100%

of range

10% -500%

of range

50% - 100%

of range

10% - 500%

50% - 100%

of range

2.9.3 Duty Cycle Measurement

Frequency Range 1 Hz to 100 Hz 100 Hz to 1 kHz 1 kHz to 10 kHz 10 kHz to 100 kHz

Resolution 0.02% 0.2% 2% 20%

Typical Uncertainty is ±0.03% of reading ± adder shown Full scale reading 100.00 % 100.00 % 100.00 % 100.00 %

0.03% 0.3% 3% 20%

2.9.4 Pulse Width

Signametrics 14

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± (% of reading + sec)

Polarity Frequency range Resolution Width range Typical

Uncertainty Positive or negative pulse widths

1 Hz to 100 kHz

2 µs 2 µs to 1 s 0.01 +/- 4 µs

2.9.5 Totalizer

• Active edge polarity: Positive or negative transition

• Maximum count: 10^9

•

Allowed rate: 1 to 30,000 events per second Uses Threshold DAC

•

2.10 Trigger Functions

2.10.1 External Hardware Trigger (at DIN-7 connector)

Trigger Input voltage level range High: +3V to +15V, Low: -15V to +0.8V Ttrigger High current drive Min. 1mA, Max 10mA (TTL or CMOS logic level) Timing Characteristics Trigger occurs within 2/Reading rate Trigger Activation Positive or Negative edge depending on trigger

command.

Internal Reading Buffer Up to 1,000 readings/sec into 64 locations reading buffer

Isolation of trigger input ±50 V from analog DMM inputs, and from computer

chassis earth ground.

2.10.2 PXI Bus Hardware Trigger Inputs (at PXI J2)

Trigger Input TTL or CMOS positive pulse Trigger Pulse Width Internal Reading Buffer up to 1,000 readings/sec into 64 readings buffer Selectable lines PXI_TRIG1,2,3,4,5,6,7 and PXI_STAR Isolation from DMM inputs ±330 V from any of the DMM 4 main inputs terminals

Minimum 250µS

2.10.3 PXI Bus Hardware Trigger Output (to PXI J2)

Trigger Output TTL or CMOS negative pulse. Positive edge = ready Trigger Pulse Width Activity A single pulse is issued for each A/D conversion (at 10

Selectable lines PXI_TRIG1,2,3,4,5,6 and PXI_STAR Isolation from DMM inputs ±330 V from any of the DMM 4 main inputs terminals

Approximately 140µS

or higher measurement rate)

2.10.4 Analog Threshold Trigger

• Captures up to 64 readings

•

Reading rate: 10 rps or higher

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15 Signametrics

2.11 Source Functions (SMX2044)

• Isolated to 300 V DC from the Chassis

• Current can be paralleled with multiple SMX2044s

•

Voltage can be put in series with multiple SMX2044s

2.11.1 DC Voltage Source

Parameter Closed Loop [1] Open Loop Output Voltage range -10.000 V to +10.000 V Typical Current source/sink at 5V output 5 mA 5 mA DAC resolution 18 bits 12 bits Accuracy 23°C ± 10°C One Year 0.015% ± 350 µV Typical settling time 3 S (rate set to 2/s) 1 mS Typical source resistance

250 Ω

1.0% ± 35 mV

[1] 10 rps or lower measurement rate is required for the closed loop mode.

2.11.2 AC Voltage Source

Parameter Closed Loop [1] Open Loop Output Voltage, sine wave 50mV to 7.1 V RMS (0.14 to 20.0V peak-to-peak) DAC resolution 16 bits 12 bits Typical Current Drive at 3.5V RMS 3.5 mA RMS Accuracy 18°C to 28°C One Year Typical settling time (f-out > 40 Hz) 10 s (rate set to 2 rps) 1.5 s Typical source resistance Frequency range / resolution 2 Hz to 75 kHz / 2 Hz Frequency stability 100 ppm ± 1 Hz

[1] 5 rps or lower measurement rate is required for the closed loop mode.

ACV spec ± 2 mV ACV spec + 0.8% ± 20 mV

250 Ω

2.11.3 DC Current Source

Range Compliance Voltage Resolution [1] Minimum level

1.25 µA

12.5 µA 125 µA

1.25 mA 4.2 V

12.5 mA 1.5 V

4.2 V 500 pA

4.2 V

5 ηA 10 ηA 1% + 100 ηA 50 ηA 100 ηA 1% + 500 ηA 500 ηA 1 µA 1% + 5 µA 5 µA 10 µA 1% + 50 µA

1 ηA 1% + 10 ηA

[1] Resolution without Trim DAC. The use of the Trim DAC can improve the resolution by a factor of 10, but it has to be set separately since it is not calibrated.

Accuracy 23°C ± 10°C One Year

Signametrics 16

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2.12 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, the System Calibration function must be performed once a day. System Calibration is a simple software operation that takes a few seconds. Do it by executing the DMMCalibrate() command, or selecting S-Cal in the control panel.

All three products are capable of continuous measurement as well as data transfer rates of up to 1,000 readings per second (rps). To achieve the 6-1/2 digit resolution, the DMM should be operated at 5 rps or slower. The maximum reading rate for 5-1/2 digits is 30 rps.

Accuracy vs. Reading Rates All of the above specifications apply to reading rates of 2 rps or lower. For higher reading rates, increase the noise floor for DCV, Resistance, and DCI by the square root of the increase in reading rate from 2 rps. For example, the noise floor for the 3.3 VDC range is 8 µV at 5 rps. At 20 readings per second, or 10x the reading rate, the noise increases by the square root of 10, or 3.16 times. The noise, then, at 20 readings per second is ± 25 µV.

The noise characteristics for the AC functions increases by the same number as the DC functions. For example, the noise floor for the 3.3 VAC, 20 rps, will have digit rattle of 8.7 mV vs. 2.75 mV at 2 rps.

Reading Rates vs. Noise Rejection The best AC (50 Hz, 60 Hz or 400 Hz) power line rejection is obtained at reading rates that are whole number divisions greater than 1 of the line frequency, as shown in the following table. For best AC line rejection you should use the reading rates checked. It is important to follow this table. Always use the lowest checked rate that is practical for the application.

Reading Rate (rps) Power Line frequency 50 Hz 60 Hz 400 Hz

0.1

0.2

0.5 1 2 5 10 15 √ 20 25 30 √ 40 50 60 √ 80 100 200 400

√ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √

√ √

√

√ √

√ √ √ √

Reading Rates vs. Digits of Resolution For reading rates of 10 readings per second (rps) and slower, the DMM has 6 ½ digits of resolution. For reading rates from 10 rps to 30 rps, the DMM has 5 ½ digits of resolution.

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17 Signametrics

2.13 Other Specifications

Temperature Coefficient, All Functions Less than 0.1 x accuracy specification per °C at

Reading Rate

• Up to 10 rps, 6 ½ digits

• Up to 30 rps, 5 ½ digits

Hardware Interface Single 3U PXI or CompactPCI slot

Overload Protection (voltage inputs) 330 VDC, 250 VAC

Isolation 330 VDC, 250 VAC from Earth Ground

Maximum Input (Volt x Hertz) 8x106 Volt x Hz normal mode input (across Voltage HI &

1x106 Volt x Hz Common Mode input (from Voltage HI or

Safety Designed to IEC 1010-1, Installation Category II.

Calibration Calibrations are performed by Signametrics in a computer

Temperature Range -10°C to 70°C, operating

-65°C to +85°C, storage

Size

DMM Internal Temperature ±2°C Measurement (SMX2042, 44)

Power +5 volts, 300 mA maximum

Note: Signametrics reserves the right to make changes in materials, specifications, product functionality, or accessories without notice.

(user selectable)

• 0.5 to 1,000 readings per second (rps)

23C ± 5°C

LO).

LO relative to Earth Ground).

with a 3°C internal temperature rise. All calibration constants are stored in a text file.

7” X 3.5” (Standard PXI/CompactPCI 3U format)

Accessories

Several accessories are available for the SMX2040 DMMs, which can be purchased directly from Signametrics, or one of its approved distributors or representatives. These are some of the accessrories avaialble:

• DMM probes SM-PRB ($15.70)

• DMM probe kit SM-PRK ($38.50)

• Delux probe kit SM-PRD ($95.00).

• Shielded SMT Tweezer Probes SM-PRSMT ($24.90).

• Multi Stacking Double Banana shielded cable 36” SM-CBL36 ($39.00).

• Multi Stacking Double Banana shielded cable 48” SM-CBL48 ($43.00).

• Mini DIN Trigger, 6-Wire Ohms connector SM2040-CON7 ($14.00).

• LabView VI’s library SM204x.llb ($99.00).

Signametrics 18

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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; three floppy disks containing the various software panels and drivers plus the calibration data specific for the unit, and this Operator's manual.

3.1 Setting the DMM

The SMX2040 series DMMs are PXI/CompactPCI Plug&Play devices and do not require any switch settings, or any other adjustments to the DMM prior to installation. The on ly sw itches are the PXI trigger input and output selection switches, capable of selecting one of the PXI triggers and PXI Start Trigger.

The SM40CAL.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 DMMs in the same chassis, the SM40CAL.DAT file must have a calibration record for each DMM. Append the unique calibration records of each DMM into one SM40CAL.DAT file using a text editor such as Notepad. The defalut location for the SM40CAL.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 chassis 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 chassis, causing personal injury and/or damage to your equipment!

This module is designed for 3U PXI and CompactPCI chassis. To prevent shock hazard do not plug it into other format chassis such as 6U without making shure that all sides of the DMM are covered.

Caution: Only install the DMM module with the power to the chassis turned OFF!

Use extreme care when plugging the DMM module(s) into a PXI or CompactPCI chassis. If possible, choose an empty slot away from any high-speed boards (e.g. CPU or other noisy modules) or the power supply. Please be patient during the installation process! Due to it’s shielding it is a tight fit. Watch for any interference b etween the module and the chassis. Gently push the DMM into the chassis, making shure the handle is correctly located. Once in, lock it in with the handle and tighten th e top and bottom screws to secure it into the chassis. Be patient!

3.3 Installing the DMM software package

To install the DMM, turn off the PXI/CompactPCI chassis, plug in the DMM into the PXI/CompcatPCI chassis, preferably away from the CPU or any other noisy card, than turn on the power. The first time you power up your computer with the DMM installed, your Windows system will detect the new DMM and will open the “New Hardware found” wizard. It will prompt you for a driver. Insert Disk1 which contains the necessary driver.

To complete the installation, run the ‘SETUP’ program provided on the Diks1. This takes care of all installation and registration requirements of the software. If you are installing the DMM on a computer that had an SMX2040 series install in it, you should first uninstall the old software. For a clean reintallation remove all INF files containing reference to the Signametrics DMM. Dependig on operatin g 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 SIGNAMETRICSSMX2040.INF. If present, these files will prevent “Found New Hardware” wizard from detecting the new DMM. Also, make sure you backup and remove the old calibration record (C:\SM40CAL.DAT).

3.4 DMM Input Connectors

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19 Signametrics

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 chassis or application may result.

F input con

igure 3-1. The DMM nectors.

V + This is the positive termin ode and inductance measurements, and for

, Ω al for all Volts, 2WΩ, capacitance, di sourcing of VDC, VAC and IDC. ents. The maximum input across V, Ω + and V, Ω - is 300 VDC or 250 V ode. When in the sourcing mode, the maximum

ed before damage occ

urs is 100 volts. input allow

WΩ measuremIt is also the Source HI for 4

mAC when in the measuring

V, Ω - This is the negative terminal for all Volts, 2WΩ, capacitance diode and inductance measurements, and or sourcing of VDC, VAC and IDC. It is also the Source LO for 4WΩ. Do not float this terminal or any other

DMM terminal more than 300 VDC or 250 VAC above Earth Ground. (Also, see Trig, 6W Guard below.)

I + This is the positive terminal for all Current measurements. It is also the Sense HI for 4WΩ measurements and

6WΩ guarded measurements. The maximum input across I, 4WΩ + and I, 4WΩ - is 2.5 A. Do not apply more than 5 V peak across these two 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 LO for 4WΩ measurements and 6WΩ guarded measurements. V, Ω - and I, 4WΩ - should never have more than 5 V peak across them.

TRIG GUARD Both the Trigger and Guard functions use the DIN-7 connector. This group of pins include the

positive and negative hardware trigger input lines and the two SMX2044 Guarded Measurement Force and Sense signals. The external trigger initiates reading(s) into the onboard buffer, and the 6W guard signals facilitate in-

Signametrics 20

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circuit resistor measurements by means of isolating a loading node. The DIN-7 plug can be ordered from Signametrics and is available at many electronic hardware distributors. The connector is generically referred to as a mini DIN-7 male. The trigger signal should be in the range of 3 V to 12 V peak. The two 6W guard signals should never have more than 5 V peak across them.

Warning! The DIN connector pins are protected to a maximum of 35 V with respect to the chassis and any other DMM terminal. Do not apply any voltages greater than 35 V to the DIN connector pins. Violating this limit may result in personal injury and/or permanent damage to the DMM.

DIN-7, Pin number Function 7 External Trigger, Positive terminal 4 External Trigger, Negative terminal 1 Guard Source (SMX2044) 6 Guard Sense (SMX2044)

DIN-7 Connector Pin Description, view from bracket side.

.5 Starting the Control Panel 3

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 “SMX2044.EXE”. If you do not hear the relays click, it is most likely due to an installation error. Another possible sour ce for an error is that the SM40CAL.DAT file does not correspond to the installed DMM.

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 SMX2040 front panel powers up in DCV, 2 readings per second, 330 V range. If the DMM is operated in Autorange, with an open input, you may hear the SMX2040 relays clicking every few seconds, as a range change occurs. This is perfectly normal with ultra high impedance DMMs such as the SMX2040. This phenomenon is caused by the virtually infinite input impedance of the 330 mV and 3.3 V DCV ranges. 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 SMX2040 will change ranges, causing the relay clicking. This is normal.

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21 Signametrics

3.6 Using the Control Panel

Figure 3-2. The Control Panel for the SMX2044. The three main groups include Measure, Source and

ange buttons. The 8 Range buttons are context sensitive such that only “330m, 3.3, 33 and 250 appear R when in AC Voltage Functions, “3.3m 33m 330m 2.5” appear when in Current Functions, 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. Using the software command language of the SMX2040 provides powerful capabilities. Some composite functions are not included in the control panel above.

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 2WΩ. For example, when using 2WΩ, 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 µV region), first apply a copper short to the V,Ω + & - input terminals, allow the reading to stabilize for a few seconds, and click on Relative. This will correct for any offsets internal to the SMX2040. The Relative button can also be used in the Percent and dB deviation displays

hown below), which are activated using the

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 menue. For instance, testing a circuit bandwidth with an input of 1V RMS, activate t 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

10.79mV from the reference at 100Hz.

Tools in the top menu.

Min/Max/Deviation from the Tools

peaking in the response of +56.24mV and a notch of –

Rate Box Controls the SMX2040 reading rate. 0.1 rps to 1,000 rps can be set. As measurement rate increases, so does the measurement noise. For best accuracy set to the lowest rate acceptable for the application. Also consider the line frequency (50/60 Hz) of operation when setting reading rates, as certain reading rates have more noise rejection at either 50 or 60 Hz. (See “Specifications” for details.) Generally, set the measurement rate to as low a rate as practical for the application. When measuring RMS values, th ere is no point setting the measurement rate to a value higher than 5 rps since the RMS circuitry has a settling time that is over a second. The capacitance and inductance functions are not affected by rate setting.

Note on Measurement Rate: All three products are capable of continuous measurement as well as data transfer rates of up to 1,000 rps. To achieve the 6-1/2 digit resolution and accuracy, the DMM should be operated at 10 rps or slower. The maximum reading rate for 5-1/2 digits is 30 rps.

Signametrics 22

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Range Can be set to AutoRange or manual by clicking on the appropriate range in the lower part of the Windows

pprop

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 ran ge, 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 330 mV and 3.3 V ranges have virtually infinite input impedance, while the 33 V and 330 V ranges have 10 MΩ 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 SMX2040 accuracy specifications. We recommend 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, or the SMX2044 on board temperature sensor indicates more than a 5°C change). This function takes less than 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.

ClosedLoop This check box selection is used in conjunction with the AC and DC Voltage-Source functions of the SMX2044. When checked, the DMM monitors the output level and continuously applies corrections to the output level. When not checked, the DMM is a 12 bit source vs. 16 bits in the ClosedLoop mode.

OpenCal This check box selection is used in conjunction with inductance measurement. It is necessary to perform Open Terminal Calibration using this control, prior to measuring inductance. This function characterizes both the internal DMM circuitry as well as the probe cables. To perform OpenCal, attach the probe cables to the DMM, leaving the other end of the probe cables open circuited. Then, activate the OpenCal button.

Sync With this check box selection is active, the DMM measurements are internally synchronized, which reduces the measurement rate, but allows full scale input swings to be settled in single measurement.

Sources Panel There are three function buttons in the Source group (SMX2044 only). The V, I, LEAK buttons

select one of three source functions, Voltage (DC and AC), IDC and Leakage. The Sources Panel is automatically enabled when one of the source functions is enabled. It can also be invoked using the Sources Panel selection under the

Tools menu. This panel allows the entry of values for all of the source functions, including Leakage.

The V-OUT Scroll bar and Text box are used to set the Voltage for DC and AC Volts as well as for Leakage. When sourcing ACV, the voltage is in RMS and the FREQ. Scroll bar and Text box control the frequency of the source. It is also used to control inductance frequency. When sourcing DC current, use the I-OUT set of controls. When measuring timing or freqeuncy the THRESH set of controls is used for comperator threshold. All of the source controls are context sensitive and will be enabled when

riate.

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23 Signametrics

4.0 DMM Operations and Measurements

Most of the SMX2040 measurement functions are accessible from the Windows Control Panel (Figure above). All of the functions are included in the Wind ows DLL driver library. To gain familiarity with the SMX2040 series DMMs, 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 µV to 300 VDC or 250 VAC. Use the V, Ω + and V, Ω - 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 (<100 µV), you should first short the DMM with a copper wire shorting plug across the V, Ω + and V, Ω - terminals and perform the 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 µVolts 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.

Signametrics 24

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4.1.2 True RMS AC Voltage Measurements

ACV is specified for signals greater than 1mV, from 10 Hz to 100 kHz. The ACV function is AC coupled, and measures the true RMS value of the waveform. As with virtually all true-RMS measuring meters, the SMX2040 may not read a perfect zero with a shorted input. This is normal.

ACV measurements, if possible, should have the NEUTRAL or GROUND attached to the SMX2040 V,Ω - terminal. See Figure 4-1, below. This prevents any “Common Mode” problems from occurring (Common Mode refers to floating the SMX2040 V,Ω LO above Earth Ground.) Common Mode problems can result in noisy readings, or even cause the computer 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.

Figure 4-1. Make Voltage measurements with the source ground attached to the SMX2040 V,Ω - to minimize “Common Mode” measurement problems.

4.1.3 AC Peak-to-Peak and Crest Factor Measurement (SMX2044)

Measurement of Peak-to-Peak, Crest Factor and AC Median values requires a repetitive waveform between 30 Hz and 100 kHz. The DMM must be in AC voltage measurement mode, with the appropriate range selected. Knowing the Peak-to-Peak value of the waveform is useful for setting the Threshold DA C (d escrib ed below). This latter function is a composite function, and may take over 10 seconds to perform.

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25 Signametrics

4.1.4 AC Median Value Measurement (SMX2044)

To better understand the usage of this function, you should note that the DMM makes all AC voltage measurements through an internal DC blocking capacitor. The voltage is thus “AC coupled” to the DMM. The measurement of the Median value of the AC voltage is a DC measurement performed on the AC coupled input signal. This measurement returns the mid-point between the positive and negative peak o f the waveform. The Median value is used for setting the comparator threshold level for best counter sensitivity and noise immunity. (It is difficult to measure the frequency of a low duty cycle, low amplitude AC signal since there is DC shift at the comparator input due to the internal AC coupling. The SMX2044 overcome this problem by allowing you to set the comparator threshold level). For further information on the usage of AC Median value and Peak-to-Peak measurements, and the Threshold DAC, see the “Frequency and Timing Measurements” section below.

This function requires a repetitive signal. The DMM must be in AC voltage measurement mode, with the appropriate range selected.

4.2 Current Measurements

The SMX2040, 42, 44 measure from 10 ηA to 2.5 A. Use the I, 4WΩ terminals, being certain to always leave the V,Ω + & - terminals disconnected. Use the AC/DC button to switch between AC and DC.

The Current functions are protected with a 2.5 A, 250 V fuse.

Warning! Applying voltages > 35 V to the I+, I- inputs can cause personal injury and/or damage to your DMM and computer! Think before applying any inputs to these terminals!

When making sensitive DC current measurements, be sure to use the Relative function to zero out any residual errors of the SMX2040. This is easily accomplished by opening all inputs to the SMX2040 and performing Relative in the appropriate DCI range.

Figure 4-2. AC and DC Current measurement connection.

4.2.1 Improving Current Measurements

hen making sensitive DC current measurements, be sure to use the Relative function to zero out any residual

erro M and performing

rs of the SMX2040. This is easily accomplished by disconnecting all terminals to the DM

Relative in the appropriate DCI range. Using the S-Cal (DMMCalibrate()) prior to activating Relative will improve accuracy further. Although the SMX2040 family is designed to withstand up-to 2.5A indefinitely, be awa 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 reco

Signametrics 26

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mmended that whenever

ractical, higher current measurements be limited to short time. The lower two ranges of DC current may be

p effected by relay contamination. If the measurements between 20mA and 50mA DC to the current terminals and clean the K2 relay using the DMMCleanRelay(0, 2,

200). Repeat this until the measurements are stable.

seem unstable or high, while in IDC measurement, apply

4.2.2 Low Level DC Curr

or low level current measurements use the

SMX urement function is facilitated by the DMM’s low

2040 can measure very low currents. This hidden meas

leakage front-end and a virtual 1

this VDC range, it is practical to measure down to 20pA. The maximum current

easured has more to do with the user’s acceptable burden voltage (the voltage drop across the

0.0MΩ input resistance. With a typical offset error of less than 100µV in

ent Measurements

V, Ω+ and V, Ω- terminals. Using the 33V DCV range, the

value that can be

0.0MΩ shunt) then the DMM limitations. Assuming a maximum burden voltage of 3.3V the maximum current level is 330ηA. This range is well within leakage measurements required in most semiconductor testing. It is also a very quite and stable. Since the DMM does not have an explicit low current function, it i

0.0M

necessary to calculate the current, which is equal to the measured voltage divided by

Ω.

4.2.3 Extended DC Current Measurements (SM2044)

The leakage measurement function can also be used to measure low-level currents. Using a relatively high value shunt resistor and setting the leakage test voltage to 0V allows measurements of super low level currents, without any burden voltage. Read the leakage current section of the manual for more details.

4.3 Resistance Measurements

esistance is measured with one of eight (six in the SMX2040) precision current sources, with the DMM displaying

R the resistance value. Most measurements can be made in the 2-wire mode. 4-wire ohms is used to make precision low resistance measurements. All resistan errors. See section section 4.3.5 for details.

ce measurement modes are susceptible to Thermo-Voltaic (Thermal EMF)

4.3.1 2-wire Ohm Measurements

The DMM measure using 330Ω to 33 MΩ ranges. The SMX2042 and SMX2044 add 33 Ω and 330 MΩ ranges. Use the V,Ω+, V,Ω- terminals, being certain to always disconnect the I+, I- terminals.

Most resistance measurements can be made using the simple 2-wire e

nd of the resistor, and the V,Ω- to the other end. If the resistor to be measured is less than 30 kΩ, you should null out any lead resistance errors by first touching the V,Ω+ and V,Ω- test leads together and then performing a Relative function. If making measurements above 300 kΩ, you should use shielded or twisted leads to minimize noise pickup. This is especially true for measurements above 1 MΩ.

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 SMX2040 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 .

For applications requiring resistance measurements higher than 330 MΩ, the Extended Resistance Measurement method is available with the SMX2044.

Ohms method. Simply connect V,Ω+ to one

4.3.2 4-wire Ohm Measurements

4-wire Ohms measurements are advantageous for making measurements below 330 kΩ, eliminating lead resistance errors. The Voltage (V,Ω) Input terminals serve as the current “Source” (i.e. they provide the current stimulus in the ohms measurement), and the I, 4WΩ 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 100 µΩ (10 µΩ for SMX2042, 44) to 330 kΩ. It is not not recommended to us 4WΩ when making measurements above 100 kΩ, although 4-wire ohms is allowed

27 Signametrics

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up to 330 kΩ. 4-wire measurements are disabled above 330 kΩ since the extra set of leads can actually degrade the accuracy, due to additional leakage and noise paths.

Figure 4-3. The I- and I+ sense leads should be closest to the body of the resistor when making 4WΩ mea

surements.

4.3.3 Using Offset Ohms function

Inadvertent parasitic leakage currents, Thermo voltaic voltages and other voltages in series can effect resistance measurements with the measured resistance. This is common particularly when doing in-circuit measurements, and it could manifest as having a significantly different readings when changing Ohms ranges. In addition to eliminating such error, this function can also be used to measure internal resistance of low value voltage sources such as variou batteries and supplies. Use the normal 2-Wire or 4-Awire Ohms connection, and set the Offset Ohms to the enabled or disabled state using the DMMSetOffsetOhms() function. When set TRUE, the measurement rate will be about

of the set DMM rate. Both negative and positive polarity voltages can be handled as long as the total voltage

1/10 including the Ohms source current times the measured resistance plus the parasitic voltage are less than 3.7V. To calculate this voltage consult the specification part of this manual for the specific current for each Ohms range. Th default value of this function is FAL

ue to it’s different hardware, the SMX2042 is different in that one of the DMM relays is being used to perform

D this

operation, which can be heard.

SE. This function is implemented for the SMX2040, SMX2042 and SMX2044.

4.3.4 6-wire Guarded Resistance Measurement (SMX2044)

The SMX2044 provides a guarded 6-wire resistance measurement method. It is used to make resistance measurements when the resistor-under-test has other shunting paths that can cause inaccurate readings. This method isolates the resistor-under-test by maintaining a guard voltage at a user-defined node. The gu

e shunting of the DMM Ohms source current from the resistor-under-test to other components. The Guard Source

th and Guard Sense terminals are provided at pins 1 and 6 of the DIN connector respectively.

Warning! The DIN connector pins are only protected to a maximum of 35 V with

ny other DMM terminal. Do not apply any voltages greater than 35 V to the DIN connector pins. Violating

a this limit may result in personal injury and/or permanent damage to the DMM.

Example: Assume a 30 kΩ resistor is in parallel with two resistors, a 510 Ω and a 220 Ω, connected in series. In normal resistance measurement, the 510 Ω and 220 Ω would shunt most of the DMM Ohms source current, causing

Signametrics 28

ard voltage prevents

respect to the chassis or

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an inaccurate reading. By sensing the voltage at the top of the 30 kΩ, and then applying this same voltage to the junction of the 510 Ω and 220 Ω, there is no current

MX2044 accurately measures the 30 kΩ resistor.

flow through the shunting path. With this “guarding”, the

Figure 4-4. 6-wire guarded in-circuit ohms measurement configuration.

The current compliance of the Guard Force is limited to a maximum of 20 mA and is short-circuit protected. The resistor connected between the low of the 4-wire terminals and the guard point is the burden resistor, or R

: R

the limited guard source current, this resistor can not be lower than R ohms source current for the selected range, and R Ω range and measuring a 300 Ω resistor imposes a limit on R resistor, R

, does not have this limit imposed on it, selecting the measurement polarity, Ra can become R

is the resistance being measured. For exa

bmin

of at least 15 Ω or greater. Since the top burden

versa. For cases where this limit is a problem, simply set the measurement polarity such that R

= Io * Rx / 0.02, where Io is the

bmin

mple, selecting the 330

is the higher of the

. Due to

and vise

two burden resistors.

To measure values greater than 330 kΩ using the 6-wire guarded method, it is necessary to select the 2-wire ohms function, and maintain the 6-wire connection as in Figure 4-4 above.

4.3.5 Leakage Measurements (SMX2044)

The SMX2044 measures leakage currents by applying a DC voltage across the load and measuring the current through it. An external shunt resistor, R voltage at which leakage is measured is set using DMMSetDCVSource(), and the value of R

DMMSetExternalShunt() (the default is 1 MΩ). Leakage current is read using DMMRead(), DMMReadStr() or DMMReadNorm() functions. Depending on the value of R

between –10V and +10 V. Specifically; the maximum voltage is limited to 10.2V – (R

) measurement range and accuracy depends on the shunt resistor being used. The range is set as 3.3V/RS, with

resolution of 10uV/R

. For instance, with RS equal to 1MΩ, the maximum leakage current is 3.3uA with resolution

of 10pA, and at full scale the maximum test voltage is 6.7V. The test voltage is adjusted whenever a measurement is made. Therefore, if the leakage current being measured varies significantly over time, it is best to repeatedly read the DMM allowing the DMM to make corrections to the internal source voltage, compensating for drop across the shunt. Performing open terminal calibration will imrove the accuracy of this function (use

DMMOpenTerminalCal()

with all terminals open). Refer to Figures 4-5. See section 2.6 for specifics. Setting

the source to closed loop mode, DMMSetSourceMode(), will improve the accuracy of the test voltage.

is used to sense the current. See Figures 4-5 for connection. The DC

is entered using

and the leakage current, the test voltage may be set

* IL). The leakage current

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29 Signametrics

Figure 4-5. Leakage Test Configuration. Measurement of reverse diode leakage at 3.3V.

4.3.6 Extended Resistance Measurements (SMX2044)

The Extended Resistance measurement funct

here the last forces a predefined current, this function forces sp

easurement is limited to pre defined current sources, this function has a variable voltage, and it limits current flow

m by an external sense resistor. To perform this measurement use the connection diagram in Figure 4-6. Enter the value of the sense resistor R

using DM

MMSetDCVSource(). Due to the avD is he other hand, the ability to set to some low

th function is fit for very high value resistance measurements. On t

ages is significant in applications where specific test voltage is revolt quired such as to prevent semiconductor’s turn-on, or prevent sensitive sensors’ damage due to access voltage or current. The DMM compensates for the voltage drop across the sense resistor as to provide the specified test voltage. Each time the DMM makes a measurement using DMMRead(), DMMReadStr() or the DMMReadNorm, it adjusts the test voltage. There are several limitations that should be considered while using this function. The internal voltage source of the SM2044 i limited to about +/-10.2V. Therefore the sum of the voltages across the sense resistor and the measured resistor is limited to this amount. Also the maximum voltage allowed across the sense resistor is limited to 3.3V. Exceeding either value will result in Over Range reading. The limit imposed by the shunt resistor may be expressed as V

< 3.3V, where VL is the test voltage, RX is the resistance being measured, and RS is the external sense resistor

value. The source voltage limit may be expressed as V set the value of the external shunt being used. Use the DMMSetDCVSource() to set the test voltage (the voltage across the resistor being measured). For high value resistances, the shunt should be of high value and vise ve

This function is useful for testing high value resistive elements such as cables, transform such as printed circuit boards, connectors and semiconductors.

As an examp er unt ol e, the lowest resistor one can measure will be 1.2122MΩ un V V

. The s ce volta imit is rea hen VL is .5V and th

si (1 Ω/5 ) = 10.2

nce 8.5V + 1.0M .001MΩ V.

le, consid a 1.0MΩ sh and a 4V test v tage. In this cas

. The sh t voltage

is at ere sin * 4V / = 3.3V which is the limit for

our ge l ched w set to 8 e measured resistance falls below 5.001MΩ

ion operates as complement of the standard resistance measurement.

ecified voltage. Where the normal resistance

MSetExternalShunt(), and set the test voltage with

ailability of a much higher test voltage than the normal resistance function,

L/RX

(1+RS/RL) < 10.2V. Use the DMMSetExternalShunt() to

rsa.

ers, and other leaky objects

its limit h ce 1.0MΩ 1.2122MΩ

Signametrics 30

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Figure 4-6. Extended Ohms range.

4.3.7 Effects of Thermo-Voltaic Offset

Resistance measurements are sensitive to Thermo-Voltaic (Thermal EMF) errors, which can be caused by poor test leads, relay contacts and other elements in the measurement path. These errors effect all measurement methods, including 2-Wire, 4-Wire, 6-Wire and 3-Wire (guarded 2-Wire ohms). 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. It is common to find relays that have more than 50 µV EMF. With several relay contacts in the path, the error is very significant. It is possible to measure it using the SMX2040 330mV 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,Ω+, V,Ω- terminals in 2-Wire, and I+, I- terminals in 4-Wire mode). To calculate the worst case error, 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.

SM2042 Range

33 Ω 330 Ω

3.3 kΩ 33 kΩ 330 kΩ

3.3 MΩ 33 MΩ 330 MΩ

Ohms Current

10 mA 1 mA 1 mA 100 uA 10 uA 1 uA 100 nA 10 nA

DMM Resolution

10 µΩ 1 mΩ 10 mΩ 100 mΩ 100 µΩ 10 mΩ 100 mΩ 1 Ω 1 mΩ 10 mΩ 100 mΩ 1 Ω 10 mΩ 100 mΩ 1 Ω 10 Ω 100 mΩ 1 Ω 10 Ω 100 Ω 1 Ω 10 Ω 100 Ω 10 Ω 100 Ω 100 Ω 1 kΩ 100 Ω 10 kΩ 1 kΩ 10 kΩ 100 kΩ

Error due to 10 µV EMF

Error due to 100 µV EMF

Error due to 1 mV EMF

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31 Signametrics

4.3.8 Guarding High Value Resistance Measurements (SMX2044)

Measuring high value resistors using the 2-Wire function require special attention. Due to the high impedances involved during such measurements, noise pickup and leakage could be very significant. To improve this type of measurement it is important to use good quality shielded cables with a low leakage dielectric. Even with a good dielectric, if a significant length is involved, an error would result due to leakage. Figure 4.7 exemplifies this error source. It is important to emphasize that in addition to the finite leakage associated with the distributed resistance,

, there must also be a voltage present between the two conductors, the shield and the center lead, for leakage

current to develop. Provided there was a way to eliminate this voltage, leakage would have been eliminated.

Figure 4-7. Error due to cable leakage.

The SM2044 provides an active guard signal that can be connected to the shield and prevent the leakage caused by the dielectric’s finite resistance. With the shield voltage guarded with Vx, as indicated in Figure 4-8, there is 0V between the shield and the high sense wire, and therefore no current flows through R

Figure 4-8. Guarding eliminates errors due to leakage associated with high resistance measurements.

4.4 RTD Temperature Measurement (SMX2044)

For temperature measurements, the SMX2044 measure and linearize RTDs. 4-wire RTD’s can be used by selecting the appropriate RTD type. Any ice temperature resistance between 25 Ω and 10 kΩ can be set for the platinum type RTDs. Copper RTDs can have ice temperature resistance values of 5 Ω to 200 Ω. The highest accuracy is obtained from 4-wire devices, because the resistance of the test leads is nulled out. The connection configuration for RTDs is identical to 4-wire Ohms.

4.5 Internal Temperature (SMX2044)

Signametrics 32

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A special on board temperature sensor allows monitoring of the DMM’s internal temperature. This provides the means to determine when to run the self-calibration function (S-Cal) for the DMM, as well as p r edicting the performance of the DMM under different operating conditions. W hen used properly, this measurement can enha the accuracy and stability of the DMM. It also allows monitoring of the chassis internal temperature, which is important for checking other instruments.

nce

4.6 Diode Characterization

The Diode measurement function i 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 ηA, 1 µA, 10 µA, 100 µA and 1 mA. The SMX2044 have an additional 10 mA range. The SMX2044 also has a variable current source which can be used concurrently with DCV measurement (see “Source Current / Measure Voltage”). This allows a variable current from 10 ηA to 12.5 mA. The maximum diode voltage compliance is approximately 4 V.

Applications include I/V characteristics of Diodes, LEDs, Low voltage Zener diodes, Band Gap devices, as well as IC testing and polarity checking. Typical current level uncertainty for diode measurements is 1%, and typical voltage uncertainty is 0.02%.

s used for characterizing semiconductor part types. This function is designed to

4.7 Capacitance Measurement (SMX2044)

The SMX2044 measure capacitance using a differential charge slew method, where variable currents are utilized to produce a dv/dt across the capacitor. Use short high quality shielded probe cables with no more than 500 pF. With the exception of the 10 ηF range, each of the ranges has a reading span from 5% of range to full scale. Capacitance values less than 5% of the selected range indicate zero. Since some large value electrolytic capacitors have significant inductance, as well as leakage and series resistance, the Autoranging function may not be practical. Because Capacitance measurement is sensitive to noise, you should keep the measurement leads away from noise sources such as computer monitors. For best measurement accuracy at low capacitance values, zero the DMM using the ‘Relative’ while in the 10 ηF range. The effect of the cable qu ality and its total capacitance is significant particularly on low value caps. For testing surface mount parts, use the optional Signametrics SMT Tweezer probes. See Figure 4-9 for connection.

Figure 4-9. Measuring capacitors or inductors is best handled with shielded probe wires.

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33 Signametrics

4.8 In-Circuit Capacitance Measurement (SMX2044)

A second method provided for measuring capacitors i

nction, the advantage of this method is that the default stimulus is set at 0.4 5V peak, which is lower than a

fu semiconductor junction on voltage. It may also be set over a wide ra ability of this function to measure capacitors that have a very low v a do using conventional methods. This test function operates by figuring the complex impedance and extracting from it both, the capacitance and resistance. The measurement is practical down to a few hundred Pico Farads, and up to several thousands micro Farads, with parallel resistances as low as 20Ω to 300Ω depending on range. Once set to this function, use DMMRead(), DMMReadStr() and DMMReadNorm() to measure the capacitance value. To ge the resistance value use DMMGetACCapsResist() following a read. Each of the ranges must be calibrated with open terminals prior to making measurements. Each range must be calibrated. Do this by activating the AC-Caps

unction, selecting the ran

f the AC source signal. This open Calibration operation must be performed with the measurement cable or probes plugged into the DMM, with the other end open. See figure 4-9 above for connection. If not modified by the DMMSetACCapsLevel() function, when making a measurement the DMM uses a default voltage of 0.45Vpk,

hich means that a sine wave that has a peak-to-peak amplitude of 0.9V. This level is used during both,

alibration and measurements. Since the DMM is optimized for this value, and it is well below most semiconductors

c On voltage, it is recommended not to change the level from this default value. The stimulus vo

0.1V peak to 5V peak using the DMMSetACCapsLevel() function. Any time the stimulus level is adjusted; open calibration must be carried out. The results of DMMOpenCalACCaps() are kept in memory until the DLL is unloaded. Repeating Open calibration periodically will result in improved accuracy. AC Capacitance measurement function must be used with a DMM reading rate of 10rps. Other functions of interest for this operations are

MMSetACCapsDelay() and SetACCapsFre

ge to be calibrated and issuing DMMOpenCalACCaps(). The last function normalizes

s the AC based method. Though not as accurate as the above

nge of voltages. A further advantage is the lue parallel resistance, which is impossible to

open

ltage can be set from

q().

4.9 Inductance Measure

he urce with a frequency range of 20 Hz to 75 kHz. Since

T SMX2044 measures inductance using a precision AC so indu e the appropriate generator frequency. In addition to

ctors can vary greatly with frequency, you should choos inductance, the inductor’s Q factor can be measured. A shielded, high quality cable is highly recommended. F best accuracy, perform the Open Terminal Calibration function within an hour of inductance measurements. The Open Terminal Calibration function must be performed with the cables plugged into the DMM, but with the other end open circuited. This process characterizes the internal signal path inside the DMM, the open application cable and the DMM circuitry.

For best measurement accuracy at low inductance values, zero the DMM often by using the ‘Relative’ function with the leads shorted. This must be done following Open Terminal Calibration operation. This Relative action measures and removes the inductance of the DMM signal path including that of the application cable being used.

ment (SMX2044)

.10 Characteristic Impedance Measurement (SMX2044)

To measure a transmission line’s characteristic impedance, measure the cable’s capacitance C (with the end of the cable open) and then it’s inductance L (with the end of the cable shorted). The cable’s impedance equals the square root of L/C. Be certain the cable is long enough such that both the capacitance and ind

ecified measurement range of the SMX2044.

uctance are within the

4.11 Trigger Operation

4.11.1 External Hardware Trigger

he Trigger functions provide for a stand-alone capture of measurements. The local controller supervises the

T oper s it back to the PXI bus. The reading

ation, and when conditions are valid, it captures data into its buffer, or send rate must be set to 10 rps or higher. The External Trigger’s isolated high and low input lines are provided at pins 7 (+) and 4 (-), respectively, on the DIN connector located on the front panel of the instrument. You may abort the External Trigger’s wait state using the Disarm command. It is important to note that the External Hardware Trigge is Wire-Ored with the PXI triggers. Therefore, while using the External Trigger, the PXI trigger input line selected

see section 4.11.4) must

( th

e External Hardware trigger must at a low logic level, or disconnected. Failing to do this will result in a disabeled

trigger. The PXI and External Hardware trigger software functions includes: DMMArmTrigger, which responds to

be at a low logic level (inactive). While using the PXI trigger inputs as the trigger source,

Signametrics 34

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posi lectable edge parameter. Read about

tive edge, DMMSetBuffTrigRead, and DMMSetTrigRead have a se

these functions in the Windows Command Language section (5.6) for details.

Warning! The DIN connector pins are only protected to a maximum of 30 V with respect to the chassis or any other DMM terminal. Do not apply any voltages greater than 30 V to the DIN connector pins. Violatin this limit may result in personal injury and/or permanent damage to the DMM.

4.11.2 Analog Threshold Trigger

This mode trigg

MM Analog trigger. The DMM’s local controller waits for the level crossing and captures up to 64 readings,

D which are saved on board; at the current DMM measurement function, range and rate. The reading rate must be set to 10 rps or higher. You can abort this mode by sending the DMM a Disarm command to the Analog Trigger.

ers the DMM at a specific input level. A command to the DMM sets a threshold value and arms the

4.11.3 Software Issued Triggered Operations

There are several software trigger functions. They cause the DMM to make a single or multiple measurements, w or without setteling readings. These include DMMSetBuffTrigRead, DMMSetTrigRead, DMMTrigger, DMMBurstRead, and DMMBurstBuffRead. Read about these functions in the Windows Command Language section (5.6) for details.

ith

4.11.4 Using the PXI bus Trigger Facilities

The SMX2040 series of Digital Multimeters are designed to interface to the PXI J2 Triggers. That includes the PXI_TRIG0 through PXI_TRIG6 and PXI_STAR trigger. The trigger to the DMM is a Wire-Ored function of the external trigger from the DIN-7 connector, and the PXI_TRIGn input. The data ready signal from the SMX2040 series can be selected to drive PXI_TRIG1 through PXI_TRIG6 or PXI_STAR trigger. Read section 4.10.1 to prevent Trigger input conflicts.

Figure 4-10. PXI Trigger input/output selection switch is located near PXI J2 connector towards the back of the DMM.

4.11.4.1 PXI Trigger Outputs

The DMM issues a Data Ready pulse each time the A/D is done making a measurement, indicating data is ready to be read. A short (about 140µs) negative pulse is issued for each measurement, with the positive edge indicating data is ready. The Trigger output is selected using S4, S5, and S6 DIP switch located near the PXI connector. The trigger pulse can be set to be output to any of the following lines.

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35 Signametrics

Switch Settings S6 S5 S4 0 0 0 Disables trigger output 0 0 1 PXI_TRIG1 0 1 0 PXI_TRIG2 0 1 1 PXI_TRIG3 1 0 0 PXI_TRIG4 1 0 1 PXI_TRIG5 1 1 0 PXI_TRIG6 1 1 1 PXI_STAR

Trigger Output Routing

4.11.4.2 PXI Trigger Inputs

The trigger input to the DMM is the wired-ored signal of the trigger input from the DIN-7 connector and the PXI bus trigger. Make sure that no signal is connected to the DIN-7 trigger input while the PXI trigger is in use. When using the DIN-7 trigger input make sure the the trigger input select switches are set to Disabled position, or the selected PXI Trigger input is at a logic low level. Read about the operation of the External Hardware trigger in the above sections, since that operation pertains to both, the external and the PXI trigger input operations. The Trigger input is selected using S1, S2, and S3 DIP switch located near the J2 connector of the DMM. The DMM trigger input may be selected from any of the following lines. Switch Settings S3 S2 S1 0 0 0 Disables trigger input * 0 0 1 PXI_TRIG1 0 1 0 PXI_TRIG2 0 1 1 PXI_TRIG3 1 0 0 PXI_TRIG4 1 0 1 PXI_TRIG5 1 1 0 PXI_TRIG6 1 1 1 PXI_STAR

* - Rev-B hardware and above.

Trigger input Routing

4.12 Frequency and Timing Measurements (SMX2042, 44)

While the maximum RMS reading is limited to the set range, you can use most of the timing functions even if the RMS voltage reading indicates Overrange. This is true as long as the input peak-to-peak value does not exceed 5.75 times the selected range ( 5.75 x 330 mV = 1.9 V p-p with the 330 mV range).

4.12.1 Threshold DAC

All timing measurements utilize the AC Voltage path, which is AC coupled. You need to select the appropriate ACV range prior to using the various frequency and timing measurement functions. The SMX2044 have a novel feature to accurately make these measurements for all waveforms. Unlike symmetrical waveforms such as a sine wave and square wave, non-symmetrical waves may produce a non-zero DC average at the frequency counter’s comparator input. Other DMMs have the comparator hard-wired to the zero crossing. The SMX2044 include a bipolar, variable Threshold DAC for improved performance of these measurements. The Threshold DAC allows the internal timing comparator to trigger at a specific DC level. Functions affected by the Threshold DAC include frequency, period, pulse-width, duty-cycle, and the totalizer.

The Threshold DAC has 12 bits of resolution. Depending on the selected ACV range, this bipolar DAC can be set from a few mV to effectively several hundred volts (referred to the input of the DMM), positive or negative. See the Specifications sections for the limits of AC Median Value measurements and Threshold DAC settin gs.

The best setting of the Threshold DAC is based on the AC Median Value and Peak-to-Peak measurement described earlier. For example, a 5 V logic signal with 10% duty cycle will result in median value of 2 V, whereas a 90% duty cycle signal will have a –2 V median value. Setting the Threshold DAC to the appropriate median value will result in reliable and accurate timing measurements in each case.

Signametrics 36

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Figure 4-11. AC coupled timing measurements with Threshold DAC. With the 3.3 ACV range selected, a 10% duty-cycle square wave with 5 V peak-to-peak value, presents a

peak-to-peak signal at the internal measuring circuits of –0.5 V to + 4.5 V. The AC Median Value is +2.0 V. By setting the Threshold DAC to the Median value, the internal measuring circuits are properly biased for best performance.

Figure 4-12. Comparator and Threshold DAC Settings

4.12.2 Frequency and Period Measurements

Both Freq. and Per check boxes are only visible when ACV or ACI functions are selected. These check boxes are used to make frequency or period measurements. Freq. measures from 1 Hz to 300 kHz. When activated, the

ontrol panel alternately updates the amplitude reading followed by the frequency reading. The reading rate is

c slow y is activated. In the Windows control panel, period (Per) is also selectable.

er than indicated when frequenc Once the frequency range is acquired, Frequency and Period have a maximum measurement time of about 1 second. It could take up to five measurements before the correct frequency range is auto-selected. This process is automatic. Once within range, the next frequency measurement is made at the last selected range.

Both Frequency and Period measurement performance can be improved by properly setting the Threshold DAC, novel feature of the SMX2044. See “Threshold DAC”, “AC Median Value”, and “Peak-to-Peak” measurements for further details.

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37 Signametrics

4.12.3 Duty Cycle Measurement

Duty Cycle of signals from 1 Hz to 100 kHz can be measured. The minimum positive or negative pulse width of the signal must be at least greater than 2 µs. When measuring duty cycle precisely, the voltage at which the measurement is made is important, due to finite slew rates of the signal. The Threshold voltage can be set for precise control of the level at which duty cycle is measured. For best measurement results, set the Threshold DA the Median value. T selected scale.

his is particularly important for signals with low duty-cycle and small amplitude relative to the

C to

4.12.4 Pulse Width

User selectable positive or negative pulse widths may be measured for signal frequencies of 1 Hz to 100 kHz and minimum pulse widths of 2 µs. The Thre d DAC feature allows measurements at a pre-defined signal level. See Threshold DAC above for more det

To measure pulse width, the DMM must be in the AC volts range appropriate for the input voltage. Keeping the peak-to-peak amplitude of the measured signal below 5.75 times the li on of the AC circuitry and gives the best performance.

near regi

shol

ails.

set range will guarantee the signal is within the

4.12.5 Totalizer Event Counter

he totalizer can be selected while the DMM is in the ACV mode. It is capable of counting events such as over-

T voltage excursions, switch closures, decaying resonance count, etc. The active edge polarity can be set for a positive or negative transition. A count of up to 10 events per second.

The Threshold DAC can be set for a negative or positive voltage value. See Threshold DAC above for more details.

can be accumulated. The maximum rate of accumulation is 30,000

Example One: To monitor and capture the AC line for positive spikes which exceed 10% of the nominal 120 V RMS value, first select ACV 250 V range, than set the Threshold DAC to 186.7 V. This value is the peak value of

120 V RMS plus 10% (120V + 10%) X times this value was exceeded.

Example Two: Defects in coils, inductors, or transformers can be manifested as an increased decay, or greatly attenuated resonance when stimulated with a charged capacitor. The Totalizer function can be utilized to count transitions above a preset Threshold voltage as in the figure below.

). Enable the Totalizer and read it periodically to get the number of

Figure 4-13. Measuring inductor Q by counting transitions of decaying resonance with preset threshold.

Signametrics 38

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4.13 Sourcing Functions (SMX2044)

The SMX2044 adds a number of sourcing functions, giving greater versatility for a variety of applications. All of the available sources, VDC, VAC, IDC, are isolated (floating with respect to the chassis). This allows sour cing with a significant common mode voltage as well as the ability to connect several SMX2044 units in parallel for increased DC current, or in series for increased DC voltage.

Two digital-to-analog converters (DACs) are used for the source functions, a 12 bit DAC, and a Trim DAC. The last augments the 12 bit DAC to form a 16 bit composite DAC and adds an ad ditional 8 bits of resolution. For functions requiring high precision, use both DACs by selecting the ClosedLoop mode, otherwise only the 12 bit DAC is utilized. DCI source is limited to the 12 bit DAC only.

All three source functions use the V,Ω+, and the V,Ω- terminals of the SMX2044.

4.13.1 DC Voltage Source

The SMX2044 has a fully isolated bipolar DC voltage source. Two modes of operation are available: fast settling or closed loop. In the Closedloop mode the DMM monitors the voltage source output, and updates it using the composite 16 bit DAC, at a rate proportional to the set measurement rate. The closedloop mode offers the best accuracy and resolution. A 10 rps or lower measurement rate is recommended for the Closedloop mode. In the fast settling mode, no adjustments are made and the 12 bit DAC is used. Up to ±10.0 V can be sourced, with 10 mA maximum drive. The output source resistance of the DCV source is approximately 250 Ω.

Figure 4-14. Sourcing DC voltage. The figure indicates the internal monitoring of the output in closed loop operation.

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39 Signametrics

4.13.2 AC Voltage Source

The AC voltage source is fully isolated. It has two modes of operation: fast settling or closed loop. In the Closedloop mode, the source voltage is monitored, and corrections are made to the composite 16 bit DAC at a rate proportional to the set measurement rate. A 10 rps or lower reading rate is recommended for the Closedloop mode. The Closedloop mode offers the best accuracy. In the fast settling mode, the source voltage is monitored and can be displayed, but no DAC adjustments are made. Both amplitude and frequency can be set. The frequency range is 2 Hz to 75 kHz, and the amplitude is up to 20 V peak-to-peak with 10 mA maximum peak current drive. The output impedance is approximately 250 Ω.

Figure 4-15. Generating AC voltage. The figure indicates the internal monitoring of the output in closed loop operation.

4.13.3 DC Current Source

The SMX2044 has a fully isolated unipolar DC current source with five ranges. It uses the 12 bit DAC to control current level. This source function is useful for parametric component measurements as well as for system verification and calibration, where a precise DC current is necessary to calibrate current sensing components.

For improved resolution of the current source, use the Trim DAC. It has to be set separately, since it is not included in the calibration record, or the control software. Use Further details are in Chapter 6.

DMMSetTrimDAC() command with a parameter of 0 to 100.

4.13.4 Source Current - Measure Voltage

When sourcing current and measuring voltage, there are two connection configurations: 1) Four wire connection, where the current sourcing terminals and the voltage sense terminals are connected to the load, as in 4-wire Ohms measurement function; and 2) Two wire connection, where the current source terminals also serve as voltage sense probes as in the 2-wire Ohms measurement configuration. The first method eliminates lead resistance errors. One application is in semiconductor diode characterization discussed in Component Testing above. See Current Source Output for range details. Voltage compliance is limited to 4 V in both configurations.

Signametrics 40

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Figure 4-16. Sourcing DC current and meas

uring voltage in the two wire configuration. This function can

be used for semiconductor parametric tests.

4.1 S

4 ynthesizing Resistance (SMX2044)

he SM2044 synthesizes resistance using an iterative method, which requires repeated reading of the DMM to

ake corrections to the synthesized value. While in synthesizing resistance, the readings return the measured value.

m There are two basic circuit types into which resistance is synthesized; current source, such as the resistance function of another Multimeter, and voltage divider type load, as in a voltage divid er circu it, where one of the two resistors in the network is being synthesized as in Figure 4-16. When synthesizing a resistance into a current source, it is important to consider its compliance voltage limits. For instance, a DMM’s 20k Ohms range will typically sources 100uA, and have a compliance limit of 2.5V. This means that the DMM current source does not behave as a curren source when the voltage at its terminals is allowed to exceed 2.5V. Therefore synthesizing a resistance value greater than 25kΩ (2.5V/100uA) will result in the SM2044 indicating an

unstable reading.

For improved accuracy, perform open terminal calibration by using the DMMOpenTerminalCal() function with all terminals are open.

The following are limits that must be observed while synthesizing resistances: Limitations synthesizing into current source:

1) The maximum load current, I

2) The maximum value that can be synthesized is 6.7/I

source compliance voltage.

3) Resistance settings resolution equals 0.1mV/ I

is 100Ω.

Limitations synthesizing into a voltage divider:

1) The maximum current the SM2044 can provide to the load is 10mA or 3.3/R

220), whichever is smaller. R

2) The approximate value that can be synthesized is between 0.1 * R

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, is 10mA or 3.3/RS whichever is smaller. RS is the external resistor.

– 220 or VC/IS, whichever is smaller. VC is the current

This means that with a source current of 1uA the resolution

, or (10 – Vx) / (Rx + Rs +

is the external resistor.

to about 100 * Rs

41 Signametrics

electing the appropriate external resistor is very important. It sets the accuracy and range of the synthesized value.

S Functions associated with the synthesis of resistance include DMMSetExternalShunt(), wh

external shunt, and DMMSetResistance(), which control the value to be synthesized. The external resistor shou be 100Ω to 10MΩ. Set the measurement to 10 or higher. 20rps is optimal. The Closed loop flag does not hav effect on this function. R

rocess. This will speed up the acquisition time when condition change.

Figure 4-17. Synthesizing resistance into a voltage divider circuit.

eselecting the function, or resetting the value has the effect of restarting the synthesis

ich sets the value of the

e an

Figure 4-18. Synthesizing resistance into a current source.

4.15 Interfacing to the SMX4032 series Relay Scanners

The SMX2040 series of Digital Multimeters are designed to interface to the SM4000 series relay scanners. The following section describes both, the hardware interface and the software functions required to implement a synchronized operation.

4.15.1 Triggering the SMX2040 DMMs

The SMX2040 series can accept a hardware trigger from many sources, including the SM4000 scanners. The latter can be setup to trigger a measurement any time the scanner selects a new channel. The interface requires a single jumper between the SM4000 Trig_com and Common lines, and a connection between the SM400 TRIG_out to the SMX2040 Trigger inputs. The various SMX4032 auto scanning operations can run independently

Signametrics 42

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0 +5V and

measurements following each channel selection.

ggered to take from the computer, whereby the Scanner selects channels from its Scan List table, and the DMM is tri

Figure 4-19. Trigger interfacing to an SMX2040 class of DMMs.

4.15.2 Multiplexing w th M 40 DMMs

For two wire measurements, the SMX2040 DMM must be connected to the A-Bus or the scanner, or to b Bus and sy c wiring capacitance. The latter will varies with the type of measurement. For insta Ohms measurements the DMM current source level could contribute significant delay due to the c time. For example, with 1,000pf cable capacitance, range, is 0.1µA which translates to 33ms (dt = C*dV/I). It is also recommended to set the appropriate n settling measurements for the DMM (a minimum of 4 is recommended regardless of measurement

C-Bus for 4-Wire measurements (assuming an SM4040 or SM4042 scanner). It is important to consider

stem settling time when making measurements. Time delays exist in any measurement system. These delays are

ontributed by various sources. These include the scanner’s relay actuation times, the DMM input settling and

ith e S X20

oth, the A-

nce, when making high value

apacitance charge

the source current of the SMX2044 DMM using the 33MΩ

umber of

rate).

4.15.3 Interface Commands and Timing

The sequence requiring the SMX2040 DMM to make triggered measurements generated by the SMX4032 starts with the preparation of the SMX4032. Set the SMX4032 desired configuration, with Trigger Output enabled and positive polarity. Each channel selection will generate a positive pulse with duration equal to the actuation time. This could be generated by one of the scanning. The SMX2040 must be set up for triggered readings by using the DMMSetTrigRead() command. In the following VisualBasic® example, the SMX2040 sends readings during the scan. Since it’s on board FIFO is limited to 5 readings, and the DMM must continue to send all readings during the scan, it is important to have a tight loop that reads the measurements fast enough so that no overrun error occurs. Refer to Figure 4-13 for proper trigger connection.

SCANTriggerOutState(nScan, Enabled, PosEdge) // Set trigger output to Positive edge. nReadings = 100 // Total number of measurements to take DMMSetTrigRead(nDmm, 4, nReadings, NegEdge) // Total of 100 readings and 4 settling readings

SCANAutoScan(nScan, nSteps) // Start auto scan For I = 0 to nReadings -1 // read values as they come while(DMMReadMeasurement(nDmm, reading) = NO // wait for each reading and store it Next SCANOpenAllChannels(nScan) // Good idea to open all channels when done

Figure 4-20. Triggered reading process and timing of SM4042 Scanner and an SMX2044 DMMs. Unlike the previous example, DMMSetBuffTrigRead() is not time critical since the DMM saves all

measurements to it’s on-board buffer, which is read after the scan is complete. However, this function is limited to a maximum of 64 readings per scan.

SCANTriggerOutState(nScan, Enabled, PosEdge) ‘ Set trigger output to Positive edge. nReadings = 50 ‘ Total number of measurements to take

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43 Signametrics

MMSetBuffTrigRead(nDmm, 4, nReadings, NegEdge) ‘ Use 4 settling readings each

CANAutoScan(nScan, nSteps) ‘ Set off AutoScan

S While DMMReady(nDmm) = NO ‘ wait for the DMM to indicate completion

end

W For I = 0 to nReadings -1 while(DMMReadBuffer(n

‘ read values stored in the buffer

Dmm, reading(I)) ‘ Store each reading Next SCANOpenAllChannels(nScan) ‘ Good idea to open all channels when done While SCANReady(nScan) = NO ‘ Since AutoScan is a polled operation, DoEvents ' Make sure Scanner is ready Wend

There are several SMX2040 family commands to considered for this operation:

DMMSetTrigRead(), DMMSetBuffTrigRead(), DMMReadMeasurement(), DMMReady(), DMMReadBuffe

r() and DMMReadBufferStr().

Referrin than t-Delay, for letion of the measurem e selection of the next channel.

g to figure 4.20, the total time it takes the DMM make a reading must be set to be shorter

comp ents prior to th

Signametrics 44

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5.0 SMX2040 DMM Windows Interface

5.1 Distribution Files

The main directory of the distribution diskette DMM software. Before installing the DMM or software, read the “Quick Install” page carefully. To install this software, enter the command "A:SET un Program" SETUP.EXE file name from the File Explorer te are compressed, and must be installed using the SETUP program.

he SMX2040 DLL is a protected-mode Microsoft® Windows™ DLL that will control the Signametrics DMM. It

T is pr application to demonstrate the DMM and the interface to the

ovided with a sample Visual Basic™ front-panel

LL ation about the files contained on the diskette. Some important

. Check the README.TXT file for more inform

D files to note are:

UP" in the "R menu of the Windows File Manager; or double-click on the

File Description

SM40CAL.DAT

SM204032.LIB

contains the Microsoft® Windows™ SMX2040

Tool Manager window. Most files on this disket

Configuration file containing calibration information for each DMM Do not write into this file unless you are performing an external calibration! This file is normally placed at the C:\ root directory by the setup program, and should be left there. It may cont records for several DMMs.

The Windows import library. Install in a directory pointed to by your LIB environment variable.

ain calibration

SM204032.DE

SM204032.DLL

SM204032.H

UserDMM.H

Msvbvm50.d

SM2044.vbw

SM2044.frx

SM2044.frm

SMX2040 driver DLL module definition file.

The 32 bi directory, in the Windows syst PATH. Th installation progra system directory (usually C:\WINDOWS\SYSTEM for Win98/95 or at C:\WINNT\SYSTEM32 for Windows NT).

Driver prototypes for the DLL, constant definitions, and error codes. Install in a directory pointed to by your INCLUDE environment variable.

Header file contain definitions to be used with the various measur

Visual Basic run-time interpreter. Usually, install in your C:\WINDOWS\SYSTEM (or equivalent) directory. If it is not already installed, run Msvbvm50.exe for proper extraction and registration.

Visual Basic project file

Visual Basic binary form file

Visual Basic file with main form

t driver DLL. This should be installed either in your working

em directory, or in a directory on your

e m installs this file in your Windows

header file. Contains the definitions of all the DMM’s functio n

ing all of the necessary DMM’s function, range, rate

e and source functions.

SM2044.vbp

File Description

2044glbl.bas

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Visual Basic project file

Visual Basic file with all global DMM declarations

45 Signametrics

SM2044.exe

Visual Basic DMM control panel executable

Msvcrt.dll System file. Installs in your C:\WINDOWS\SYSTEM

Windrvr.vxd

Win98/95 Virtual Device Driver. Installs by ‘setup’ in your

directory.

C:\WINDOWS\SYSTEM\VMM32 directory.

Windrvr.sys

Win NT Virtual Device Driver. Installs by ‘setup’ in your C:\WINNT\SYSTEM32\DRIVERS directory.

Install.doc

Installation instructions in MS Word

5.1.1 The SM40CAL.DAT file

The SM40CAL.DAT file contains calibration information for the specific DMM is it included. It determines th

verall analog performance for that DMM. You must not alter this file unless you are performing an external

o calibration of the DMM. This file may contain multiple records for more than one DMM. Each record starts w ith header line, followed by calibration data.

card_id 10123 type 2044 calibration_date 06/15/1999 ; The identification should match the last digits of the SN ad ; A/D compensation

72.0 20.0 v

dc ; VDC 330mV, 3.3V, 33V, 330V range

.0 0.99961

-3

0 .999991

-37.

-8

0 0.999795

1.00015

-8

.8 vac 5

.303 ; starting with the 330mV range, and last line is for the 250V range.

0.84 1.015461 23

0.0043 1.0256 23

0.0 1.02205 0

0.0 1.031386 0 idc ; IDC 3.3mA to 2.5A ranges. 1

-1450.0 1.00103

-176.0 1.00602

-1450.0 1.00482

-176.0 1.0 ia

1.6 0

1.69 1.00513

0.0 1.0142 2w-ohm ; Ohms 33, 330, 3.3k,...,330Meg ranges, offset and gain

12700.0 1.002259 ;in the SMX2040, the 1

1256.0 1.002307

110.0 1.002665

0.0 1.006304

0.0 1.003066 0

.0 1

0.0 1.00030 …

; VAC 1st line - DC offset.

c ; IAC 3.3mA to 2.5A ranges, offset and gain

1.02402

1.03357

.001848

0.995664

Subsequent lines: 1

entry is offset, 2nd is gain parameter

s. 1

entry is Offset the 2nd is gain parameters

entry is Offset the 2nd is gain, 3rd freq. comp

and last lines are placeholders

. .

first line identifies the DMM and the calibration date. The "card-id" is stored in ROM on each DMM.

The During

alization the

initi driv er reads information from the DMM hardware such as serial number, DMM type, and allocated

O space. Next it reads the corresponding calibration information from the SM40CAL.DAT file and makes sure

I/ there is compatibility between the hardware, the calibration rec

od and the software. If all is checked OK, it initialize

Signametrics 46

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DMM hardware. DMMInit accepts the name and location of the calibration file. A qualified technician may

the modify individual entries in the calibration file, then reload them using th

5.2 Using the SMX2040 Driver Wit

h C++ or Similar Software

e DMMLoadCalFile comma nd.

Install the SM204032.H and UserDMM.H header file in a directory th for header files. This header file is known t will need to convert the SM

mpiler.. Install SM204032.LIB

the co SMX2040 software must be installed prior to running any executable code. Install the SM204032.DLL where either your program will do a LoadLibrary call to load it, or on the PATH so that W DLL au

In using the SMX2040 driver, first call DMMInit to read the ca the DMM function. The DM clearly indicate the fun

Two functions are precision (double) re

All functions accept a D M er parameter, which must be set to the value nDmm, which w DMMInit() fu b ved as a string using ErrStr().

tomatically.

provided to return DMM readings. DMMRead returns the next reading as a scaled double-

nction. F DMMs this value will be 0,1,2..n. Most functions return an er

e retrie

204032.DEF an

M function constants are defined in

hey invoke. Use DMMSetRate to set the reading rate defined in the header file.

ction t

sult, and DMMReadStr returns the next reading as a formatted string ready to be displayed.

M -numb as returned by

or multiple ror code which can

DMM

Multiple Card Operations U er Windows

o work with Microso

d SM204032.LIB using ImpDef.exe and ImpLib.exe, provided with

in a directory that will be searched by the linker for import libraries. The

at will be searched by your C/C++ compiler

ft Visual C++™. To compile using Borland, you

in a location

indows will load the

libration information. Call DMMSetFunction to set the UserDMM.H header file, and have names that

Single .EXE operation

A g multiple DMMs from a single e cutable is the most common wccessin xe ay for running up to 10 DMMs using the W s DLL. A combination of several SMX and SMX2044s can beindow 2040s cont

Thread) g comman

( is used to control all of th e units. Make sure that prior to issuin

mand to define the DMM to be accessed.

using DMMInit(). The nDmm parameter is passed with each DLL co Since this configuration utilizes the DLL to service all DMMs, it must hand le a sin gle

ne at a e. For DMM pacitan

o tim example, when one reads DCV, and another reads Ca reading the DCV be Capacitance will dictate the measurement throughput. For improved performance, one can use the following:

fore it will proceed to take a Capacitance reading. Being a relatively slow measurement,

Multiple .EXE operation

By having several copies of SM204032.DLL, and renaming them, y

xecutables. For instance, having a copy named SM204032A.DLL i

e two executable files, MultiExe0.exe and MultiExe1.exe, each of the executables will run independently, making calls to the respective DLL. This can provide an execution throughput advantage over the method mentioned abov If using VisualBasic, the MultiExe.exe source code should define nDmm = 0, and MultiExe1.exe should define

Dmm = 1. In addition, the first should declare the SM204032.DLL and the second should declare

SM204432.DLL:

MultiExe0.exe VB function declarations:

Declare Function DMMInit Lib "sm204032.dll" (ByVal calFile As String) As Long Declare Function DMMRead Lib "sm204032.dll" (ByVal nDmm As Long, dResult As Double) As Long NDmm = 0

MultiExe1.exe VB function declarations:

Declare Function DMMInit Lib "sm20432A.dll" (ByVal calFile As String) As Long Declare Function DMMRead Lib "sm20432A.dll" (ByVal nDmm As Long, dResult As Double) As Long NDmm = 1

************************* Exmp2040.C Exmp2040.EXE

*********************************************

ou can run multiple DMMs with separate n C:\windows\system (Win98/95), and having

rolled, as long as the single .EXE

ds to any DMM, it is initialized

reading or control command

ce, the DLL must finish

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47 Signametrics

* * A simple Windows .EXE example for demonstrating the SMX2040,44 * DMMs using "C" * Sets Function to VDC, Range to 33V, rate to 10rps.

* Display five measurements using a Message box.

****

******************************************************************

* * M

ake sure SM204032.lib is included in the libraries. For Microsoft * Version 4.0 C++ and above, place under 'Source Files' in the * Workspace, along side with Exmp2040.c * PROJECT SETTINGS: * * /nologo /ML /W3 /GX /O2 /D "WIN32" /D "NDEBUG * /FR"Release/" /Fp"Release/Exmp2 *

opy both SM204

* C 032.DLL and SM204032.LIB to the project directory.

*******************************************************************/

****

efine WINAPI __stdcall

// #d

lude <windows.h>

#inc

lude <string.h>

#inc

f _Windows

#ifde #define _W

#end

lude "sm204032.h"

#inc // functions declarations and error codes.

lude "UserDMM.h"

#inc // All functions, range and rate info and function declarations.

ain(void){

int m // Address first DMM in the system

char ,"C:\\sm40cal.dat"); // initialize SMX2044, and read calibration file

alization ERROR !", "Startup SM204032 DLL",MB_OK); // Error m,VDC); // Set to DCV function ,_30V); // and to 33V range E_10); // 60 samples per sec // Clear string store // take 5 readings DMMReadStr(nDmm, ead); // read strcat(strMsg,Read); // Append each reading // insert space between readings

DC",MB_OK); // Show readings }

INDOWS

int I, nDmm = 0; char Read[16];

strMsg[256]; i = DMMInit(nDmm if(i<0) MessageBox(0,"Initi DMMSetFunction(nDm DMMSetRange(nDmm DMMSetRate(nDmm,RAT strcpy(strMsg,""); for(i=1; i<= 5; i++){

strcat(strMsg," "); } MessageBox(0,strMsg, "SM204032.DLL Read Resistance & V return 0L;

040.pch" /YX /Fo"Release/" /Fd"Release/" /FD /c

" /D "_CONSOLE" /D "_MBCS"

5.3 on Pane App

Visual Basic Fr t l lication

The e control panel for the SMX2040 DMM.

Visual Basic front panel application, SM2044.EXE, is an interactiv

Dur he hardware before the front panel is

ing loading, which takes a few seconds, it initializes and self calibrates t

displ

ayed.

The abeled V, I, etc. control the DMM function. As you push a function, the front panel application

push buttons l

will sw ge an de is selected by pushing the AutoRange

itch the DMM to the selected ran d function. A utorange mo

chec the D me state prior to operation. (This is an

k box. The S-Cal r t MM, leaving the DMM in the sa

inte er t from d ards and writes to the

rnal calibration only. It is diff en the external calibration, which uses external stan

SM rrect fo e to changes in operating

40CAL.DAT file. S-Cal is used to co internal offset a

temp

erature).

box ecalibra es

The eq. and per check boxes are context sensitive and appear in ACV and ACI. When freq. is enabled, the

frequency and amplitude are shown at the same time. In this mode, the reading rate per is enabled, the period is shown. The SMX2044 panel has additional capabilitie SMX2040 is detected.

Signametrics 48

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r any nd gain drifts du

is slower than indicated. When s, which are disabled if an

he source code file GLOBAL.BAS (in the V_BASIC directory of the distribution diskette) contains the function

T declarations and the various ranges, rates and other parameters, which are required. These definitions are th

uplicates of the “C” header files required to write Visual Basic applications which interact with the driver DLL,

d along wi ables required for this particular front-panel application.

th some global vari

3 Basic Simple Application

5. .1 Visual

The le panel application for VisualBasic that includes two files, Global.Bas and

following is a simp

Sim P ontains two objects; a Text Box to display the DMM readings, and a

ple anel.frm. It has a panel that c

Com a ding trigger.

m nd Button that acts as a rea

Glo .b contents:

bal as module file

Option Explicit ' Declare all functions we are going to be using: From SM204032.H file. Declare Function DMMInit Lib "sm204032.dll" (ByVal nDmm as long, ByVal calFile A Declare Function DMMSetRate Lib "sm204032.dll" (ByVal nDmm As Long, ByVal nR Declare Function DMMSetFunction Lib "sm204032.dll" (ByVal nDmm As Long, ByVal nFunc As Long) As Long Declare Function DMMSetRange Lib "sm204032.dll" (ByVal nDmm As Long, ByVal nRange As Long) As Long Declare Functi

' Definitions from UserDMM.H ' for DMMSetFunction() Global Const VDCFunc = 0 Global Const VACFunc = 4 Global Const Ohm2Func = 21 Global nDmm as Long

' for DMMSetRange() Global Const Range0 = 0

al Const Range1 = 1

Glob

al Const Range2 = 2

Glob

al Const Range3 = 3

Glob 'for DMMSetRate(): Rea

Global Const RATE_5 = 5 '5 rps Global Const RATE_10 = 10 '10 rps Global Const RATE_30 = 30

bal variables

'Glo

al nDmm As Long ' Globa

Glob l store for the DMM number

on DMMRead Lib "sm204032.dll" (ByVal nDmm As Long, dResult As Double) As Long

ding rates

s String) As Long

ate As Long) As Long

S anel.frm Form file contents: impleP

Private Sub Form_Load() 'Fomr_Load allways gets executed first. Dim i As Long nDmm = 0 ‘Set to first DMM in the system i = DMMInit(nDmm,"C:\sm40cal.dat") 'Initialize and load cal file i = DMMSetFunction(nDmm, VDCFunc) 'Set DMM to DCV function i = DMMSetRange(nDmm, Range2) 'Select the 33V range i = DMMSetRate(nDmm, RATE_10) 'Set measurement rate to 10 rps End Sub

Private Sub ReadBotton_Click() 'Read Botton Click action. Dim i As Long 'Any time this botton is pressed Dim dReading As Double 'the DMM takes a reading and displays it. i = DMMRead(nDmm, dReading) 'Take a reading TextReading.Text = dReading 'display it in a Text box. End Sub

5.4 Windows DLL Default Modes and Parameters

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49 Signametrics

fter initialization, the Windows DLL default modes and A

• Autoranging: Off

• Function: DC Volts

• Range: 330V

•

Relative: Off

• Synchronized Mode: Off

• Measurement rate: 10 rps

• Temperature units are set to

•

Offset Ohms: Off AC Caps level: 0.45V

•

Peak.

parameters on your DMM are set up as follows:

°C

5.5 Using MX2040 DLL with LabWindow

the S s/CVI®

When using the SMX2040 DLL wi ou should read the LabWin.txt file included with the software diskette.

th LabWindows/CVI, y

An example appl SMX2040 DLL calls from LabWindows/CVI ® is shown below. It contains funct e_ohms() and measure_vdc(), with sample calls to the SMX2 040.

NOTE: Although these me Test Executive, they are no

/* function: measure_ohms int measure_ohms(double short ret, i; DMMSetFunction DMMSetAutoRan /* to settle auto-ra for( i = 0 ; i < 4 ; i+ return ret; } /* function: measure_vdc, purpose: measure DC Volts */ int measure_vdc(double Vr short ret, i; DMMSetFunction DMMSetAutoRan /* to settle auto-ra for( i = 0 ; i < 4 ; i+ return ret; }

ication of

ions measur

asurement functions use LabWindows/CVI® and the LabWindows/CVI(R) t necessarily coded to LabWindows® instrument driver standards.

, purpose: measure 2-wire ohms */ OHMreading) {

s (0, OHMS2W);

ge (0, TRUE);

nge and function changes ignore three readings */

+ ) ret = DMMReadNorm (0, & OHMreading);

eading) {

(0, VDC);

ge (0, TRUE);

nge and function changes ignore three readings */

+ ) ret = DMMReadNorm (0, &Vreading);

Signametrics 50

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5.6 Windows Command Language

The following section contains detailed de se commands that pe y the SM204 ither be retrieved as a st g DMMErrStri UserDMM.H file ll the pertinen for the various functions is based on “C” f s DLL containing these functions as int values to b c long type). TRUE

1 and FALSE i is also differe .

rtain to onl

ring usin

contains a

sumes all

s 0 (which

scriptions of each function of the Windows command language. Tho

0 are indicated. Most functions return an error code. The code can e

ng function, or looked up in the SM204032.H header file. The

t definitions for the DMM ranges functions etc. The following description unction declarations. Keep in mind that the Window e windows 32bit integers (corresponds to VisualBasi nt from VisualBasic where True is –1 and False is 0)

DMMArmAnalogTrigger

SMX20

40 ;

X20

;

Description r

Remarks This function is usable for VDC, VAC, Ohms, IAC, and IDC. Setup the

The dThresh value is in base units, and must be within the DMM range setting . For

Arm DMM fo analog level trigger operation.

#include

int DMMArmAnalogTrigger(int nDmm, int

analog level trigger operation. Foll

easure

m ments continuously, waiting for a value which When this occurs, a trigger is produced with identical processing as in

ArmTrigger. Threshold crossing sense is determined by the first measurement

DMM

following the call o set threshold, dThresh DMM. If the first measurement is greater th smaller than dThresh will trigger. For exam reading after arming the D the DMM. On the other hand, i the DMM is 0.500000 V, then 1.000001 V (or gre

example, in the 330 mV range, dThresh must be within -0.330000 and +0.330000. In the 33 kΩ, range dThresh must be between 0.0 and 33.0e3.

Following an analog level trigger event, the DMM makes iSamples readings at the set function, range, and reading rate, and stores them in an internal buffer. Autoranging is not allowed when using DMMAnalogTrigger. Between the time the DMMArmAnalogTrigger is issued and the time the buffer is read, no other com should be sent to the DMM. One exception is the DMMDisArmTrigger command.

"sm2

04032.h"

iSamples, double FAR *dThresh)

SMX2040 for

owing reception of this command the DMM makes

exceeds the threshold, dThresh.

f DMMArmAnalogTrigger. If that measurement is lower than the

, subsequent measurements greater than dThresh will trigger the

an dThresh, subsequent measurements ple, if dThresh is 2.00000 V and the first

MM is 2.500000 V, then 1.999999 V (or smaller) will trigger

f dThresh is 1.000000 V and the first reading after arming

ater) will trigger the DMM.

mand

Use the DMMReady to monitor when the DMM is ready. When ready, you read up-to iSamples, using DMMReadBuffer or DMMReadBufferStr functions. Once DMMReady returns TRU

E, it should not be used again prior to

reading the buffer, since it prepares the buffer for reading when it detects a ready

dition.

con

can

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51 Signametrics

terParame Type/Description

nDmm

iSamples

dThresh

eturn Value e retu

R Th rn value is one of the following constants.

Meaning

Value

DMM_OKAY

Negativ

Example DMMArmAnalogTrigger(0,64,1.5);

for(i=0; i < 64 ; i++) Buffer[i] = DMMReadBuffer(0);

DMM ger

ArmTrig

SMX2040 ; SMX2042

Description

e value

double Buffer[64];

while( ! DMMReady(0));

; SMX2044 ;

Arm DMM for external trigger operation.

#include "sm204032.h"

int DMMArmTrigger(int nDmm

int Identifies the DMM. DMMs ar

int The num

This number must be between 1 and 64, inclusive.

double FAR Analog level trigger thresh

Ope

ration successfully terminated

Error code.

ber of samples the DMM takes following a trigger pulse.

, int iSamples)

e numbered starting with zero.

old value

Remarks

Setup the SMX2040 for external hardware trigger operation. Following reception of this command, the DMM enters a wait state. After reception of an external trigger pulse, the DMM makes iSamples readings at the set function, range, and reading rate; and stores them in an internal buffer. No autoranging is allowed for external trigger op eratio n Between th other command should be sent to the DMM. One exception is the DMMDisarmTrigger com

Use the DMMR reading of iSamples). When ready, you can read up to iSamples, using

DMMReadBuf

TRUE, it shoul e it prepares the buffer for reading when it detects a ready condition.

Parameter

nDmm

iSamples

e time the DMMArmTrigger is issued and the time the buffer is read, no

mand. This function is usable for VDC, VAC, Ohms, IAC and IDC

eady to monitor when the DMM is ready (following trigger and the

fer or DMMReadBufferStr functions. Once DMMReady returns

d not be used again prior to reading the buffer, sinc

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

int The number of samples the DMM takes following a trigger pulse.

This numb

er must be between 1 and 64, inclusive.

Return Value The return value is one of the following con

Signametrics 52

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stants.

Value Meaning

DMM_

Negative Value

Exa

mple double Buffer[64];

DMMArmTrigger

for(i=0; i < 64 ; i++) Buffer[i] = DMMReadBuffer(0);

DMMBurstBu

; SMX2042

Description Setup the DMM for Triggered operation.

Remarks

OKAY

while( ! DMMReady(0));

ffRead

; SMX2044 ; SMX2040

#include "sm204032.h" #include "UserDMM.h"

int DMMBurstBuffRead(int nDmm, int iSettle, int iSamples)

Following reception of this command the DMM enters a burst read mode, where it takes iSettle + 1 readings at the set measurement function, range, and reading rate; and saves the last reading to the on-board buffer. This process repeats for iSamples. No other DM command should be issued to the DMM until the it completes the operation, and the buffer is read. One exception is the DMMDisarmTrigger command, which terminates the process. No autoranging is allowed in this mode. This function is usab le for VDC, VAC, Ohms, IAC, IDC, and RTD measurements. Measurement rate should be set to 10rps or higher. The total time it takes to complete this process is equal to iSamples * ( iSettle + 1) / (measurement rate).

Use the DMMReady to monitor if the has completed the operation, and is ready. When ready, read up to iSamples, using DMMReadBuffer or DMMReadBufferStr functions Once DMMRead since it clears som

dition.

con

Operation successfull inated

Error code.

(0,64);

y returns TRUE, it should not be used again until the buffer is read,

e flags in preparation for buffer read

y term

ing when it detects a ready

Type/Description

Parame

iDmm

iSettle

iSamples

Return Value The return valu he following constants.

Value

DMM_OKAY

Negative Value

Example

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ter

Meaning

double Buffer[50];

int Identifies the DMM. DMMs are numbered starting with zero.

int The number of settling measurements prior to read value. Mu set between 0 and 250. Recommended value is 4.

int The nu

number of trigger pulses. This num inclusive.

e is one of t

Operation successfully terminated

Error code.

mber of samples the DMM takes following the same

ber must be between 1 and 64,

53 Signametrics

st be

DM stBuffRead(0, 4, 50); // 4 settling readings for

Buffer[i] = DMMReadBuffer(0);

MBur each

// measurement, and take 50 readings

ile( ! DMMReady(0) ); // wait for completion

o f r(i=0; i <

// on-board b

50 ; i++) // read 64 readings from DMM’s uffer

DMMBurstRead

SMX2040 ; SMX2042

; SMX2044 ;

Description Setup the DMM for multiple read

come.

#inc

lude "sm2 lude "User

#inc

int DMMBurs

Remarks Set the DMM to take multiple measurements, sendi

This function is e DMMSetTrigRead function, with the exception that it does not wait for a hardware trigger to start making measurements. Following reception of this c at the se computer. This process repeats for until iSa using the DMMReadMeasurement command as fast as they become available will prevent an Overrun communication error, which is an indicatio n that the ra which measurements are read from the bus do not keep up with the DMM transmission. The DMM has five readings FIFO to lessen this problem. No autoranging is allowed in this mode. This function is usable for VDC, VAC, Ohms, IAC, IDC, and RTD measurements. Measur

plete this process is equal to iSamples * ( iSettle + 1) / (measurement rate).

to com

Use the DMMRead read the data. Read as many samples as iSamples to guarantee proper conclusion of this capture process.

04032.h"

DMM.h"

tRead(int nDmm, int iSettle, int iSamples)

similar to th

omman burst read mode, where it takes iSettle + 1 readings

d the DMM enters a

t measu n, range, and reading rate; and sends the last reading to the

rement functio

mpels ements are read, it is necessary to read the samples from the DMM

measur

ement rate should be set to 10rps or higher. The total time it takes

Measurement to monitor when reading becomes available, and to

ings operation, sending back measurements as they

iSamples. Following the issue of this command, and

ng readings back to the computer.

. This te at

Parame

nDmm

iSettle

iSamples

Return Value The return valu

Value

DMM_OKAY

Negative Value

Example double Reading DMMBurstRead(0, 10, 250); // settle 10 reads., 250 samples

Type/Description

ter

int Identifies the DMM. DMMs are numbered st

int The number of settling measurements prior to read value. Must be set between 0 and 250. Recommended value is 4.

Meaning

for(i=0; i < 250 ; i++) // read 250 meas. as they come

int The number of samples the DMM takes following the sam number of trigger pulses. This number must be between 1 and 32,000, inclusive.

e is one of the following constants.

Operation successfully terminated

Error code.

[250];

arting with zero.

Signametrics 54

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while( ! DMMReadMeasurement(0 , Reading[i]) );

DMMCalibrate

SMX2040 ; SM 2

X2042 ; SMX 044 ;

Descriptio Internally calibrates the DMM.

int DMMCalibrate(int nDmm)

Remarks his function re-calibrates the DMM, and return s it to the current operating mode.

Return Value owing constants.

Example status = DMMCalibrate(0); /* a quick internal cal.*/ Comments d is the same as the S-Cal command in the

DMM lay

SMX2040

"sm204032.h"

Type/Description

Parameter

nDmm

Value

Meaning

DMM_OKAY

Negativ

e Value

#include

The return value is one of the foll

This performs an internal DMM calibration an VB Control Panel. It is not related to the external calibration represented in the SM40CA .DAT file.

CleanRe

; SMX2042 ; SMX2044 ;

int Identifies the DMM. DMMs are numbered starting with zero.

DMM is OK.

Erro

Des an specified relay.

cription Cle

#include "sm204032.h"

int DMMCleanRelay(int nDmm, int iRelay, int iCycles)

Remarks This function cleans iRelay by vibrating the contact iCycles . This function is useful for

removing oxides and other depos are particularly sensitive to K2 contact resistance and therefore shou ld be cleaned periodically. It is also useful for making sound in computer without a speaker.

Parameter

iRelay

iCycles

nDmm

Return Value Integer error code..

Value

Type/Description

int The relay to clean. 1 for K2, 2 for K2 and 3 for K3.

int The numer of times the relay contac is shken. 1 to 1000.

int Identifies the DMM. DMMs are numbered starting with zero.

Meaning

its from the relay contacts. DC Current measurements

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55 Signametrics

DMM_OKAY

Operation su

ccessfully completed.

Negativ

Exa int status = DMMCleanRelay(0, 2, 100); // Shake K2 1000

mple

e Value

Error code

DMMClearMinMax

SMX2040 ; ; SMX2044 ;

escription e.

D Clears the Min/Max storag

int DMMGetMin(int nDmm)

Remarks This function clears the Min/Max values, and initiates a new Min/Max accumulation. See

Return Value Integer error co

SMX2042

Param

nDmm

Value

#include "sm204032.h"

MGetMin

DM for more details.

eter

Type/Description

int Identifies the DMM. DMMs ar

de..

Meaning

e numbered starting with zero.

Ope sfully completed.

DMM_OKAY

Negativ

xample int status = DMMClearMinMax(0);

e Value

ration succes

Error code

DMMClosePCI

SMX2040 ; ; SMX2044 ;

Description pecified DMM. Not for user applications.

#include "sm204032.h"

int DMMClosePCI(int nDmm)

Remarks

eturn Value Integer error code.

SMX2042

Parameter

nDmm

Close the PCI bus for the s

This function is limited for servicing the DMM. It has no use in normal DMM operation. See also DMMOpenPCI() function.

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

Value

Meaning

DMM_O

KAY

Signametrics 56

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Operation

successfully completed.

Negative Value

Error code

Example int status = DMMClosePCI(0);

DMMDelay

SMX2040 ; SMX2042 ; SMX2044 ;

Description Wait for a given time. #include "sm204032.h"

int DMMDelay(double dTime)

Remarks een 0.0 and 100.0

Parameter

dTime

eturn Value The return value is one of the following constants.

Value

DMM_OKAY

Example lay(1.2); /* wait for 1.2 Sec */

Delay of dTime seconds. dTime must be a positive double number betw seconds.

Type/Description

double Delay time in seconds.

Meaning

Operation successfully terminated

Error

egative Value

code

DMMDe

DMMDisableTrimDAC

SMX2040  SMX2042 ; SMX2044 ;

Description f the Trim DAC.

int DMMDisableTrimDAC(int nDmm)

Terminate the operation o

#include "sm204032.h"

Remarks

Parame

nDmm

Return Value

Integer error code.

Value

DMM_OKAY

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This function disables the Trim DAC. Since usage of the Trim DAC consumes a lot of the on-b not in use. See DMMSetTrimDAC, DMMSetDCVSource and DMMSetACVSource

more details

for .

ter

Type/Description

Meaning

oard microcontroller’s resources it must

int Identifies the DMM. DMMs are numbered starting with zero.

Operation successfully completed.

57 Signametrics

be turned off with this function when

Erro

r code

Example

Negative Value

DMMDisableTrimDAC(0); // Remove Trim DAC from operation

DMMDisArmTrigger

SM ;

X2040 ; SMX2042 ; SMX2044

Description Abort trigger operation.

int DMMDisArmTrigger(int nDmm) Remarks his function sends the DMM a trigger termination command. If the DMM is waiting

T for a trigger, it will exit the wait mode, and be ready for a new operation . I following an external hardware or analog level trigger arm command (DMMArmAnalogTrigger, DMMArmTrigger, or DMMTrigger ). It can be used with no limitation.

t can be used

Parameter

nDmm

Return Value code

Integer error

Value

DMM

Negat

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

gMeanin

_OKAY

ive Value

Operation successfully completed.

code

Error

DMMDu

tyCycleStr

SMX2040  SMX2042 ; SMX2044 ;

Description ng format.

int DMMDutyCyc

Remarks This function is the string version of DMMReadDutyCycle. The

Return percent duty cycle of an AC signal in stri

#include "sm204032.h"

leStr(int nDmm, LPSTR lpszReading)

stored at the location pointed to by lpszReading. See DMMReadDutyCycle details.

measurement result is

for more

Parame

nDmm

lpszRead

Return Value

Value

DMM_OKAY

ter

Type/Description

ing

The return value is one of the following constants.

Meaning

Signametrics 58

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int Identifies the DMM. DMMs are numbered starting with zero.

LPSTR Points to a buffer (at least 16 characters long) to hold t

result.

Valid return.

Negative Va

lue

Error code

Example char cBuf[17]

; int status = DMMDutyCycleStr(0, cBuf);

DMMErrString

SMX2040 ; S ; SMX2044 ;

Description Return the string the error code.

Remarks tion re g containing the error description which corresponds to the

MX2042

Parameter

iErrorC

iBuffLength

lpszError

ode

describing

#includ

int DMMEr ring(int iErrorCode, LPSTR lpszError, int

This func

iErrorCo

e "sm20

Type/Description

4032.h"

rSt iBuffLength)

turns a strin

de. The error string is placed at lpszError.

int Error code.

int The maximum available length of the string buffer

LPSTR Points to a buffer (at least 16 characters long) to hold the error string.

Return Value The return value is the length of the error string or one of the following constants.

Meaning

Value

Negative Value

Error code

Example char cBuf[48];

int length = DMMErrString( -3, cBuf, 48);

DMMFrequencyStr

SMX2040  SMX2042 ; SMX2044 ;

Description Return the next DMM frequency reading, formatted for printing.

#include "sm204032.h"

int DMMFrequencyStr(int nDmm, LPSTR lpszReading)

Remarks This function makes frequency measurement and returns the result as a string formatted

for printing. The print format is fixed to six digits plus units, e.g., 05.001 Hz. If the DMM is in autorange, be certain to take an amplitude reading before using this command. It may take several calls to DMMFrequencyStr() to get the measured frequency, because the DMM frequency counter uses a frequency ranging scheme which gets activated only when a frequency or period reading function is received. If the previously measured frequency was 1 Hz and the frequency being measured is 300 kHz (or vise versa), it might take as many as six calls to DMMFrequencyStr() or any of the other frequency measurement functions, to read the correct frequency. This function is a Secondary function which requires the DMM to be in either VAC or IAC function and at the appropriate range.

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59 Signametrics

Parameter Type/Description

nDmm

lpszRead

ing

Identifies the DMM. DMMs are numbered starting with zero.

int

LPSTR Points to a buffer (at least 16 characters lo

converted

result.

Return Value The return value is one of the following constants.

Meaning

Value

DMM_

Negative Va

OKAY

CNT_RNG

lue

Example char cBuf[1

Operation successfully completed.

Frequency counter is over or under range.

Error code

7];

int status;

atus = DM

st MFrequencyStr(0, cBuf);

ng) to hold the

Signametrics 60

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DMMGetACCapsR

SMX2040  SMX2042  SMX2044

;

Description Return the resist

#include "sm204032.h"

int DMMGetACCapsRint nDmm, double *lpdResult)

Remarks This function retrieves the resistance value from las

measurement. It perform ing and conversion required, and returns the result as a 64-bit double-precisi point number in the location pointed to by lpdResult. Returned resul section

Parameter

nDmm

lpdResult

urn Value The re

Ret turn value is one of the following constants.

Meaning

Value

DMM_OKAY

Negative Value

4.8 of this ma

Type/Description

ance component of the last AC Caps measurement.

t reading of AC based Capacitance

s all scal

on floating-

t is a val rcuit Capacitance Measurements in

ue in ohms. Read about In-Ci

nual.

int Identifies the DMM. DMMs are numbered starting with zero.

double * Points to the location to hold the resistance value.

DMM initialized successfully.

Error code

Over range occurred, implying a very high parallel resistance value.

Example

OVER_RNG

double d; int status; stat MGetACCapsR(0, &d);

us = DM

DMMGetBusInfo

SMX2040 ; SMX2042 ; SMX2044 ;

Description

Remarks This function reads the PCI bus and slot numbers of the selected DMM. It provides

Returns the PCI Bus and Sl ot numbers for the selected DMM.

int DMMGetBusInfo(int nDmm, int *bus, int *slot)

means to relate the physical card locat a DMM in the PCI system tree. This function actually scans the hardware rather then look up the information in the registry.

ion to the nDmm value by detecting the location of

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61 Signametrics

Parameter Type/Description

nDmm

bus

slot

Return Value The return value is one of the following constants.

Meaning

Value

DMM_OKAY

Negative number

Example int bus, slot; // Find on which bus, and slot the DMM is at

DMMGet alDate(3,

int Identifies the DMM. DMMs are numbered starting with zero.

int *

a pointer to integer at which the bus number is stored (0 to 255)

int * A pointer to a

15)

Operation was successful.

Error code

C &bus, &slot); // DMM#3

n integer where the slot number is stored (0 to

DMMGetCalDate

MX2040 ; SMX2042 ; SMX2044 ;

Description Retu

rn the calibration date string from the DMM.

int DMMGetCalDate(int nDmm, LPSTR lpszCalDate)

Remarks ibration date string from the structure.

Parameter

nDmm

lpszCalD

eturn Value The return value is one of the following constants.

Value

any positive number

Negativ

Example char cBuf[1

DMMGet

SMX2040 ; SM 2

X2042 ; SMX 044 ;

This function reads the cal

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

ate

Meaning

e number

int status; status = DMMGetCalDate(0, cBuf);

LPSTR Points to a b cal date string.

Length of the date string

Error code

6];

uffer (at least 16 characters long) to hold the

Descriptio Get dB deviation from the reading at the time relative was activated.

#includ

Signametrics 62

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e "sm204032.h"

int DMMGetdB(int nDmm, double FAR *lpdDev)

Remarks ble floating value that is the dB deviation relative to the

Parame

nDmm

lpdDev

Return Value Integer error code..

Value

DMM_OKAY

Negative Value

This function returns a dou re

ading made just before the relative function was activated. This function is useful in determining measurement errors in dB. It can be used fo DC evaluation.

Type/Description

ter

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Pointer where the dB value is to be saved.

Meaning

Operation successfully completed.

Error code

r bandwidth measurements or

Example double FAR dB; int status = DMMGetdB(0, &dB);

DMMGetdBStr

X2040 ; SMX2044 ; SM

Description Get dB deviation from the readin g at the time relative was activated.

include "sm204032.h"

Remarks This function is the same as the DMMGetdB(), with the exception that it returns a string.

Parameter

nDmm

lpszDB

Return Value Integer string length if successful, or an error code..

Value

int DMMGetdBStr(int nDmm, LPCSTR lpszDB)

See DMMGetdB() for more details.

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

LPCSTR Points to a buffer (at least 16 characters long) to hold th e

resu

lt. The return value will consist of a leading sign a floatin g-point,

and a ‘dB’ units specifier

Meaning

Negative Value

Example char cBuf[32]; int strLength = DMMGetdBStr(0, cBuf);

DMMGetCJTemp

SMX2040 ; SMX2042 ; SMX2044 ;

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Error code

63 Signametrics

Des the currently set cold junction temperature.

cription Retrieve

#include "sm20403

int DMMGetCJTemp(int nDmm, double *lpdTemp)

2.h"

emarks ncion temperature. For more details see DMMSetCJTemp()

Parame

nDmm

lpdTemp

Return Value The return valu

Value

DMM_O

Negativ

Example

DMMGetCJTemp(0, &temp);

Get the currenly set cold ju function.

Type/Description

ter

int Identifies the DMM. DMMs are numbered starting with zero.

Meaning

KAY

e Value

double * Points to the location to hold the temperature.

e is one of the following constants.

Operation successfully terminated

code.

Error

DMMGetDeviation

SMX2040 ; SMX2042 ; SMX2044 ;

Description Get percent deviation from the reading at the time relative was activated.

#include "s

int DMMGetDevia

m204032.h"

tion(int nDmm, double FAR *lpdDev)

Remarks This function returns a d

reading made just before the relative n w his func quantifying measurement errors. It can be used for ba evaluation, or percent variation of a device under test over t

Parameter

nDmm

lpdDev

Return Value Integer error co

Value

DMM_OKAY

Negative Value

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Poi

de..

Meaning

Operation successfully completed.

Error code

Example double FAR error;

int status = DMMGetDeviation(0, &error);

ouble floating value that is the percent deviation relative to the

functio as activated. T tion is useful in

n measur

dwidth ements or DC

emperature.

nter where the deviation value is to be saved.

Signametrics 64

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DMMGetDeviatStr

SMX2040 ; S X2044 ;

MX2042 ; SM

Description ent deviat reading at the time relative was activated.

Rem ction is the same as the DMMGetDeviation(), with the exception that it returns

arks This fun

Parame

nDmm

lpszDev

Return Value Integer string length if successful, or an error code.

Value

Negative Value

Example char cBuf[32];

Get perc ion from the

#include "sm204032.h"

int DMMGetDeviatStr(int nDmm, LPCSTR lpszDev)

a string. See DMM

Type/Description

ter

Meaning

Error code

int strLength = DMMGetDeviatStr(0, cBuf);

GetDeviation() for more details.

int Identifies th MM. DMMs are numbered sta

LPCSTR Points to a buffer (at least 16 characters long) to hold th e

result. The return valu and a % units specifier

e D rting with zero.

e will consist of a leading sign a floating-poin t,

DMMGetFuncRange

SMX2040 ; S 2044 ;

Description

int MMGetFu cD

Remarks This function returns the combined DMM function/range code. See UserDMM.h for the

MX2042 ; SMX

Get DMM range code.

#include "sm204032.h" #include "UserDMM.h"

complete set of codes.

Parame

nDmm

Type/Description

ter

n Range(int nDmm)

int Identifies the D

MM. DMMs are numbered starting with zero.

Return Value Integer value corresponding to the currently set DMM function/range

The following are a few examples of the returned value.

Meaning

Value

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, or an error code.

65 Signametrics

Positive value

Negative Value

See UserDM

r code

Erro

M.h for function/range codes.

Example if(DMMGetFnRange == VDC_300mV) p

selected");

rintf("Lowest VDC range

DMMGetFunction

SMX2040 ; SMX2042 ; SMX2044 ;

Description Get DMM function code.

#include "sm204032.h"

#include "UserDMM.h"

int DMMGetFunction(int nDmm)

Remarks This function returns the DMM function code.

Parameter

nDmm

Return Value function, or an error code.

Integer value corresponding to the current

Value

Positive value

Type/Description

int Identifies the DMM nuber. Zero being the first.

Meaning

See UserDMM.h for function codes.

Negative Value

Example if(DMMGetFunc

DMMG er

SMX2040 ; SMX2042

Description

Remarks s function ret ware version of the on-board controller.

eturn Value Integer value. The return value is the version value or an error code.

etGrdV

Parameter

nDmm

; SMX2044 ;

Get DMM firmware version.

#include "sm204032.h"

int DMMGetGrdVer int nDmm

Thi urns the DMM firm

Type/Description

Error code

tion == VDC) printf("VDC Function selected");

( )

int Identifies the DMM. DMMs are numbered starting with zero.

Value

Meaning

Signametrics 66

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Positive Value

Versi

Negative

ample firmwarever = DMMGetGrdVer(0);

Value

Error code

DMMGetHwVer

SMX2040 ; ; SMX2044 ;

Description f the DMM.

int DMMGetHwVer(int nDmm)

Remarks hardware version. A returned value of 0 corresponds to

Return Value DMM hardwar

SMX2042

Parameter

nDmm

Val

Meaning

Get the hardware version o

#include "sm204032.h"

This function returns the DMM Rev_, 1 corresponds to Rev_A, 2 to Rev_B etc.

Type/Description

int Identifies th

e code or an error code.

e DMM. DMMs are numbered starting with zero.

Positive value

Negative

Example int HWVer = DMMGetHwVer(0);

Value

Hardware version code

code

Error

DMMGe

SMX2040 ; S 2044

Descriptio Get DMM ID code.

Remarks This

tID

MX2042 ; SMX ;

#include "sm204032.h"

int DMMGetID(int nDmm)

function returns the DMM identification code. Each DMM has a unique ID code

that must match the calibration file

Parameter

nDmm

Type/Description

card_ID field in SM40CAL.DAT.

int Identifies the DMM. DMMs are num

with zero.

bered starting

Return Value

Value

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Integer value card ID code (serial number) or an error code.

Meaning

67 Signametrics

DMM_E_DMM

Invalid DMM number.

Example int id = DM

MGetID(0);

DMMGetManDate

SMX2040 ; SMX2042 ; SMX2

Description nu hardware

emarks This function returns the DMM manufacturing date which is read from the hardware.

Paramet

nDmm

month

day

Get Ma facturing date stamp from the DMM

#include sm204032.h

int DMMGetManDate(int nDmm, int *month, int *day, in

The specific manufactur

Type/Description

044 ;

" "

t *year)

month, day and year are returned as integers. This is used to track the DMM to a

ing date.

int Identi with zero.

int * A pointer to an integer where the m

int * A pointer to an integer where the day is stored

fies the DMM. DMMs are numbered starting

onth is stored

year

Return Value

Value

DMM_OKAY

DMM_E

Example int month, day, year, status

DMMGe

tMax

Integer error code or.

Meaning

_DMM

status = DMMGetManDate(0, &month, &day, &year);

int * A pointer to an integer where the year is stored

Operation was successful.

Invalid DMM number.

SMX2040 ; SMX2044 ;

Description

int DMMGetMax(

Remarks This function returns a double f

Get Maximum reading history.

#include "sm204032.h"

int nDmm, double FAR *lpdMax)

loating value that is the maximum (of the Min/Max

function) value since either a funct DMMClearMinMax func functions (those that are read usi This value is updated every time one of those functions

tion was made. This is only applicable to Primary read

ion change, range change or call to the

ng DMMRead, DMMReadStr or DMMReadNorm).

is used.

Parameter

Type/Description

Signametrics 68

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nDmm

int Identifies the DMM. DMMs are numbered starting with

zero.

lpdMax

Return Value Integer error code..

Meaning

Value

DMM_OKAY

Negative Value

double FAR * Pointer where the Max value is to be saved.

Operation successfully completed.

Error code

Example double FAR Mx; int status = DMMGetMax(0, &Mx);

DMMGe

SMX2040 ; SM 2

Descriptio Returns the maximum as a formatted string.

(int nDmm, LPSTR lpszReading)

Remarks This function is the string version of DMMGetMax. It returns the result as a string

tMaxStr

X2042 ; SMX 044 ;

#include "sm204032.h"

int DMMGetMaxStr

formatted for printing. The print format is de

MMGetMax for more details.

termined by the range and function. See

Parameter

nDmm

lpszRead

Return Value return valu ng constants, or the string length is OK.

Value

DMM_OKAY

Negative Value

Example char cBuf[17];

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

ing

The e is one of the followi

Meaning

int status = DMMGetMaxStr(0, cBuf);

LPSTR Points to a buffer (at least 16 characters long) to hold the result.

Valid return.

Error code

DMMGetMin

SMX2040 ; SM 2044

Description Get Minimum reading history.

int DMMGetMin(

X2042 ; SMX ;

lude "sm204032.h"

#inc

int nDmm, double FAR *lpdMax)

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69 Signametrics

Remarks This function returns a d

nction) value since either a function change, range change or a call to the

fu DMMClearMinMax() fu functions (those that are rea This value is updated every time one of those functions is used.

ouble floating value that is the minimum (of the Min/Max

nction was made. This is only applicable to Primary read

d using DMMRead, DMMReadStr or DMMReadNorm).

Parameter

nDmm

lpdMax

Return Value Integer error cod

Value

DMM_OKAY

Negative Value

Example FAR M s = DMMGetMin(0, &Min);

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Pointer where the Min value is to be saved.

e..

Meaning

Opera sfully completed.

tion succes

Erro

code

double in; int statu

DMMGetMinS

SMX2040 ; SMX2042 ;

Description Returns the minimu

SMX2044 ;

m as a formatted string.

#include "sm204032.h"

nDmm, LPSTR lpszReading)

Remarks This function is the string version of DMMGetMin. It r

Parameter

nDmm

lpszReading

Return Value The return value i he following constants, or the string length is OK.

Value

DMM_OKAY

Negativ

xample

E char cBuf[17];

int DMMGetMinStr(int

eturns the result as a string

formatted for printing. The print format is determined by the range and funct

DMMGetMin for more details.

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

LPSTR Points to a buffer (at least 16 characters

result.

s one of t

Meaning

Valid return.

e Value

int statu

Error code

s = DMMGetMinStr(0, cBuf);

long) to hold the

DMMGetRange

SMX2040 ; ; SMX2044 ;

SMX2042

ion. See

Signametrics 70

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escription Get DMM range code.

#include "sm204032.h" #include "UserDMM.h"

Remarks function re e code.

Parame

nDmm

Return Value Integer value corresponding to the currently set DMM range, or an error code.

Value

Zero or positive value

Negative Value

Example int id;

int DMMGetRange(int nDmm)

This turns the DMM rang

Type/Description

ter

int Identifies the DMM. DMMs are numbered starting

with zero.

Meaning

Range; zero being the lowest

Error code

if(DMMGetRange == 0) printf("Lowest range selected");

DMMGetRate

SMX2040 ; SMX2042 ; SMX2044 ;

Description Get DMM reading rate

#include "sm204032.h"

int DMMGetRate(int nDmm, doub

le FAR *lpdRate)

Remarks This function returns a double floating rate in readings per secon

Parameter

nDmm

lpdRate

Return Value Integer value ver r an error code.

Value

Negative Value

Example

int status; double FAR ra

Type/Description

nt Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Poin

sion code o

Meaning

rror code

ter where the rate is saved.

te;

status = DMMGetRate(0, &rate);

DMM etSourceFreq

SMX2040   SMX2044 ;

escription Source frequency.

D Get the currently set ACV

SMX2042

#include "sm204032.h"

71 Signametrics

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int DMMGetSourceFreq(int nDmm, double FAR *lpdFreq)

Remarks This function returns a double floating value that is the currently set ACV source

frequency of the the stimulus for the various Inductance measurement ranges.

SMX2044. It can be used to display or verify the default frequency of

Parameter

nDmm

lpdFreq

Return Value Integer error code..

Value

DMM_OKAY

Negative Value

Example dou

DMMG pe

etTCTy

SMX2040 ; SMX2042

Description Get the themocouple type currently selected.

#include "sm204032.h"

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Pointer where the frequency value is to be saved.

Meaning

Operation successfully completed.

Error code

ble FAR f; int status = DMMGetSourceFreq(0, &f);

; SMX2044 ;

#include "UserDMM.h"

int DMMGetTCType(int nDmm)

Remarks This function returns the Themocouple type currently selected.

Parameter

nDmm

Return Value DMM type Integer or an error code.

Value

Btype to

Negative Value

Exa int TCtype = DMMGetTCType(0);

mple

Type/Description

int

Identifies the DMM. DMMs are numbered starting with zero.

Meaning

TType

Type of thermocup

Error code

le as specified in UserDMM.h file

DMMGetType

SMX2040 ; SMX2042 ; SMX2044 ;

Description Get the type of the DMM.

#include "sm204032.h"

int DMMGetType(int nDmm)

Signametrics 72

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Remarks This function return

s the DMM type.

Parame

nDmm

Return Va DMM type Integer or an error code.

lue

Value

2040

2042

2044

Negative Val

Example int type = DM

ter

Type/Description

int Identifies the DMM. DM

Meaning

SMX204

SMX2042 is at nD

SMX2044 is at nDmm slot

Error code

MGetType(0);

0 is at nDmm slot

DMMGetVe

SMX2040 ; SMX2044 ;

Description M softwa

Get DM

#include 032.h"

"sm204

re driver version.

Ms are numbered starting with zero.

mm slot

int DMMGetVer(int nDmm, double FAR *lpfResult )

marks This function returns the DMM software driver version, which is a double floating value.

Parameter

nDmm

lpfResul

Return Value Integer error code.

Value

Negative Value

Type/Description

int Identifies the D

Meaning

double FAR *

Error code

MM. DMMs are numbered starting with zero.

Pointer to the location which holds the version .

Example int status; double ver;

status = DMMGetVer(0, &ver);

DMMInit

SMX2040 ; SMX2042 ; SMX2044 ;

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73 Signametrics

Description Initialize a DMM.

#include "sm2

int DMMInit(i

04032.h"

nt nDmm, LPCSTR lpszCal)

Remarks This function m ed. It opens the driver for the

specified DMM. The first DMM being 0, the second 1, etc... It also initializes the DMM hardware oes extensive self test to th software and reads the appropriate calibration record for the respective DMM from the file specified by lpszCal.

Parameter

nDmm

lpszCal

Return Value The return value is one of the followi

Value

DMM_

Negative Val

Example int i = DMMInit(0,"C:\SM40CAL.dat");// Initialize 1st DMM

Type/Description

Meaning

OKAY

ust be the first function to be execut

and d e DMM hardware. It then initializes the

int

Identifies the DMM. DMMs are numbered starting with zero.

LPCSTR Po constants for th from the file n

DMM initialized successfully.

Error code

ints to the name of the file containing the calibration

e DMM. Calibration information is normally read

amed SM40CAL.DAT located in the current directory.

ng constants.

DMMIsAutoRange

SMX2040 ; SMX2042 ; SMX2044

;

Description Get the status o

#include "sm2

IsAu

Remarks This function return

Parame

nDmm

int DMM toRange(int nDmm)

Type/Description

ter

f the autorange flag.

04032.h"

int Identifies th

s the DMM autorange flag state.

e DMM. DMMs are numbered starting with zero.

Signametrics 74

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Return Value TRUE, FALSE or an error code.

Value

Meaning

A d.

TRUE

FALSE

DMM_E_DMM

utoranging mode is selecte

utoranging mode is not selected.

I number.

nvalid DMM

Example int autorange = DMMIsAutoR

ange(0);

DMMIsInitialized

SMX2040 ; SMX2042 ; SMX2044 ;

Description et the status of the DMM.

int DMMIsInitialized(int nDmm)

Remarks nd

Parame

nDmm

Return Value TRUE, FALSE o

Value

#include "sm204032.h"

This function returns the status of the DMM. If TRUE, the DMM has been initialized a is active. If FALSE the DMM is not initialized and should not be addressed. This function is used for maintenance and is not needed under normal operation.

Type/Description

ter

int Identifies the D

r an error code.

Meaning

MM. DMMs are numbered starting with zero.

TRUE

FALSE

DMM_E_DMM

Example int active = DMMIsInitialzied(0);

DMM

SMX2040 ; ; SMX2044 ;

Description

#include "sm204032.h"

int DMMIsRelative(int nDmm)

Remarks This function returns the DMM Relative flag state.

IsRelative

SMX2042

Get the status of the Relative flag.

Parameter

nDmm

Type/Description

DMM is initialized and active.

DMM is not initialized.

Invalid DMM number.

int Identifies the DMM. DMMs are numbered starting with zero.

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75 Signametrics

eturn Value Integer TRUE, FALSE or an error code. R

Value

Meaning

TRUE

FALSE

Negative Value

Relative mode is selected.

Relative

Error code

mode is not selected.

Example int rel = DMMIsRelative(0);

DMMLoadCalFile

SMX2040 ; SM ;

Description Reload calibratio

Remarks cti the calibration record. This is useful in

X2042 ; SMX2044

#include "sm20403

int DMML e(int nDmm, LPCSTR lpszCal)

This fun on is provides the capability to reload making limited calibration adjustments to the DMM. By having a copy of the original calibratio file ‘SM40C then reloading it using DMMLoadCalFile, one can instantly verify the corrections made. Make sure the ‘SM40CAL.D calibration.

oadCalFil

n AL.DAT’ open with an editor, and modifying calibration entries,

n record from file.

2.h"

AT’ file itself is not altered since that will void the

Parameter

nDmm

lpszCal

Return Value The return value is one of the following co

Value

DMM_O

Negativ

Example ad a modified copy of the original calibration file to verify correction made

Type/Description

int Identifies the DMM. DMMs are n

LPCSTR

constants

Meaning

KAY

e Value

Cal record loaded successfully.

Error code

/* Lo

specific en

to a

try */

umbered starting with zero.

Points to the name of the file containing the calibration for the DMM.

nstants.

int i = DMMLoadCalFile(0, "C:\CAL_A.dat");

Signametrics 76

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DMMOpenPCI

MX2040 ; SMX2042 ; SMX2044 ;

escription Open the PCI bus for the specified DMM. Not for user application.

#include "sm20403

int DMMO nDmm)

Remarks cti . It has no use in normal DMM operation..

Parame

nDmm

Return Value Integer error code.

Value

DMM_O

Negative Value

This fun on is limited for servicing the DMM See also

ter Type/Description

Meaning

KAY

penPCI(int

DMMClosePCI() function.

Operation succ

Error code

2.h"

int Identifies the DMM. DMMs are numbered starting with zero.

essfully completed.

Example int status = DMMOpenPCI(0);

DMMOpenCal

SMX2040  SMX2042

ACCaps

 SMX2044 ;

Description

i (int nDmm)

Remarks nge of the AC Capacitance measurement path

Parameter

nDmm

Calibrate the AC based in circuit capacitance function.

#include "sm204032.h"

nt DMMOpenCalACCapsl

This function characterizes the selected ra and source, whic should be perform with the test leads c the specific frequen complete the process. Make sure to perform this operation for each range you intend to use.

Type/Description

h is required prior to making measurements. For better accuracy it

ed frequently. The Open Terminal calibration should be performed

onnected and open. This function characterizes the stimulus source at cy associated with the selected range. It takes about fifteen seconds to

int Identifies the DMM. DMMs are numbered starting with zero.

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77 Signametrics

Return Value Integer error co

Meaning

Value

DMM_OKAY

Negativ

e Value

de.

Ope

ration successfully completed.

Error code

Example int status = DMMOpenCalACCaps(0);

DMMOpenTerminalCal

SMX2040  SM 2044

Description s.

#include "sm204032.h"

Remarks This function characterizes the Inductance measurement path and source, which is

X2042  SMX ;

Calibrate the Inductance measurement function with open terminal

int DMMOpenTerminalCal(int nDmm)

required prior to making inductance measurements. It should be performed within one hour, before using the inductance measurements. For better accuracy it should be performed more frequently. The Open Terminal calibration should be performed with the test leads open. The DMMOpenTerminalCal sweeps the inductance stimulus source across the full bandwidth, and makes measurements at several points. It takes about twenty seconds to complete the process. For a complete characterization of the Inductance measurement system it is also necessary to perform the inductance zero operation with the inductance range and frequency selected, using the Relative function and with the probes shorted.

Parameter

nDmm

Return Value Integer error code.

Value

DMM_OKAY

Negative Value

Example int status = DMMOpenterminalCal(0);

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

Meaning

Operation successfully completed.

Error code

DMMPeriodStr

SMX2040  SMX2042 ; SMX2044 ;

Description Return the next DMM period reading, formatted for printing.

#include "sm204032.h"

int DMMPeriodStr(int nDmm, LPSTR lpszReading)

Signametrics 78

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emarks This function makes a period measurement and returns the result as a string formatted for

g. The print format is fixed to five digits plus units, e.g., 150.01 ms. See

printin

DMMFrequencyS

tr() for more details.

Parame

nDmm

lpszReading

ter

Type/Description

int Identi

fies the DMM. DMMs are numbered starting with zero.

LPSTR Points to a buffer (at least 16 charac converted result. The return value will consis floating-point value in exponential notation, and a units specifier.

Return Value

Value

DMM_OKAY

Negative Val

DMM_CN

The return value is one of the following constants.

Meaning

Operation successfu

T_RNG

Error code

Period measurement H/W is over or under range.

Example char cBuf[17];

int status; status = DMMPeriodStr(0, cBuf);

ters long) to hold the

t of a leading sign, a

lly terminated

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79 Signametrics

DMMPol

ledRead

SMX2040 ; SMX2042 ; SMX2044

;

Description Tests the DMM for ready status, and returns the next floating-point r

#include "sm2

nt DMMPolle

Remarks olledR not ready it will return

Parameter

nDmm

lpdResul

Return Value the following constants.

Value

FALSE

TRUE

i dRead(int nDmm, double FAR *lpdResult)

DMMP FALSE

will be p more det communication failure.

Type/Description

The return value is one of

Meaning

04032.h"

ead polls the DMM for readiness. If the DMM is

. If the , and the reading

DMM is ready with a new reading it will return TRUE

laced a pointed to by lpdResult. See DMMPolledReadCmd for

t the location

ails. D MReady to check for readiness since it will cause

o not use DM

entifies the DMM. DMMs are numbered starting with zero.

int Id

double FAR * Points to the location to hold the next reading.

DMM is not ready

DMM is ready, and reading is placed at lpdResult

eading.

Error code

edRead(0, &d)) fprintf(“%9.4f\n”,d);

Example

Negative Value

double read;

DMMPoll

if(

DMMPolledReadCmd

SMX2040 ; SMX2042 ;SMX2044 ;

Description Send DMM mand.

#include "sm204032.h"

int DMMP ( )

R If the DMM is not bus

emarks y with a prior Polled read process, this function will trigger the

DMM to execute a single one of the following functions to use the polled read command: VDC, VAC, IDC 2-wire, 4-wire, 6-wire, or RTD function. Composite functions such as Capacitanc Inductance, Peak-to-Peak etc. are not capable of polled read must be 10 rps or higher. If FALSE is returned, the DMM is busy processing a prior polled read. A DM entered the busy st This function is useful where it is necessary to conserve CPU time and make the DMM a polled device. Use DMMPolledRead or DMMPolledReadStr to test for readiness and read measurement. Do not use DMMReady to check for readiness since it will cause communication failure.

Polled Read com

olledReadCmd int nDmm

read command. The DMM must be set to a specific range and

operation. Measurement rate

M_OKAY indicates the DMM accepted the read command and

ate. The DMM remains busy until it is ready with the next reading.

, IAC, e,

Signametrics 80

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Parameter Type/Description

nDmm

Return Value DMM_OKAY if command accepted, else FALSE or an error code.

Meaning

Value

FALSE

DMM_OKA

Negativ

Example t status

DMMPo adStr

in = DMMPolledReadCmd(0);

lledRe

e Value

SMX2040 ; SMX2042 ; SMX2044 ;

Description is ready DMM formatted for printing.

lledR eading)

Remarks This function is

If DMM

#include 032.h"

int DMMPo eadStr(int nDmm, LPSTR lpszR

details.

int Identifies the DMM. DMMs are numbered starting with zero.

DMM is busy and can’t execute a polled read comm

Operation successfu

Error code

l. DMM entered busy state

and.

, return the next reading from the

"sm204

the string version of DMMPolledRead. See DMMPolledRead for more

Parame

nDmm

lpszReading

Return Value ng length is OK.

Value

FALSE

TRUE

Negative Va

Example char strMsg

DMMRe

SMX2040 ; SMX2042 ; SMX2044

ter

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

LPSTR Points to a buffer (at least 16 characters long) to hold the

converted result. The return value will consist of a leading sign floating-poi

The return value is one of the following constants, or the stri

Meaning

DMM is not ready

DMM is ready, and reading is placed

Erro

lue

if(DMMPolledReadStr(0, strMsg)) MessageBox(0,strMsg,

MX2044",M

"S B_OK); // display readings;

r code

[32];

nt value in exponential notation, and a units specifier.

at lpszReading

;

, a

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81 Signametrics

Description Return the next floating-point reading from t

#include "sm204032.h"

int Read(int nDmm, double FAR *lpdResult) DMM

em reads the next result from the DMM, performs all scaling and conversion

R arks DMMRead

required, an location pointed to by selected using DMMSetFunction() and DMMSetFuncRange() )

d returns the result as a 64-bit double-precision floating-point number in the

lpdResult. It can read all the Primary functions (those that can be

he DMM.

Parameter

nDmm

lpdResult

Return Value

Value

DMM_OKAY

Negative Value

DMM_E_RANGE

Example double d;

DMMRea

dBuffer

SMX2040 ; SMX2042 SMX2044

Description Return the next double floating-point

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Points to the location to hold the next reading .

The return value is one of the following constants.

Meaning

DMM initialized successfully.

Error code

over range error occurred.

DMM

int status; status = DMMRead(0, &d);

; ;

#include "sm204032.h"

int DMMReadBuffer(int nDmm, double FAR *lpdResult)

reading from the DMM internal buffer.

Rem ext measurement from the DMM internal buffer, pointed to by an internal

arks Read the n

buffer pointer, and precision floating-point number in the location pointed to by lpdResult. See

DMMArmTrigger() functions for more detail.

Parame

nDmm

lpdResult

Return Value The return value is one of the following constants.

Value

DMM_OKAY

Negative Value

ter

Type/Description

Meaning

Signametrics 82

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increment the pointer. Store the measurement as a 64-bit double-

int Identifies the DMM. DMMs are num

double FAR * Points to the location which holds the frequency.

Operation successfully completed.

Error Code

bered starting with zero.

Example double Buffer[10];

int status; DMMArmTrigger(0,10); // Set up for 10 triggered samples while( ! DMMReady(0)); for(i=0; i < 10 ; i++) status = DMMReadBuffer(0, &Buffer[i]);

DMMReadBuf

SMX2040 ; SMX2042

ferStr

; SMX2044 ;

Description

Remarks The same as DM its.

Parame

nDmm

lpszReading

Return Value The return value is one of the following constants.

Value

DMM_OKAY

Negative Value

Return the next reading, formatted for printing.

#include "s

int BufferStr(int nDmm

DMMRead , , LPSTR lpszReading)

Measurements are stored as a null terminated string at the location pointed to by

szReading.

ter

Type/Description

Meaning

m204032.h"

MReadBuffer() except the reading is formatted as a string with un

int Identifies the DMM. DMMs are numbered starting with zero.

LPSTR Points to the location which

string.

peration successfully completed.

Erro

r code

holds the formatted reading

Example char Buf[17]; ; // take a single triggered sample

DMMReadBufferStr(0,

DMMArmTrigger(0,1) while( !DMMReady(0

));

Buf);

DMM emp

SMX2040 ; SMX2044 ;

Description

int DMMReadCJTemp(int , double *lpdTemp )

ReadCJT

; SMX2042

Read cold junction temperature for thermocouple measurement.

#include "sm204032.h"

nDmm

83 Signametrics

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Remarks Read the cold juncion temperature sensor for su

measurements. When measuring temperature using thermocouples it is necessary to establish a reference or cold junction temperaturem. This is the temperature at which the them card’s c using th voltage

ooper easuring the cold junction sensor is func ReadCJTemp() function reads the sensor output (0 to + d converts it to cold junction temperature using the built

ocouple wires are connected to the DMM or to the switching

wires. One way to do this is by m

tion. DMM

/-3.3V), an in equation Temp = b + (Vcjs – a)/m. The default values of a, b designed specifically for the temperarute sensor of the SM40T The value o thermocouple mea

f the cold junction temperature is saved internally for subsequent

surements as well as return at the location pointed to by

lpdTemp.

bsequent thrermocouple

and m are

terminal block.

Parame

nDmm

lpdTemp

Return Va The return value is one of the following constants.

lue

Value

DMM_OKAY

Negative Val

Example DMMReadCJT

ter Type/Description

int Identifies th

Meaning

double * Points to the location to hold the tem

Operation successfu

Error code.

emp(0, &temp);

e DMM. DMMs are numbered starting with zero.

lly terminated

DMMReadCrestFactor

SMX2040  SMX2042 ; SMX2044

Description CV sig

Return A nal’s Crest Factor.

#include 04032.h"

int DMMReadCrestFactor(int nDmm, double FAR *lpdResult)

;

"sm2

perature.

arks This is a Seco

Rem ndary function and the DMM must be in ACV measurement function, and

a valid range must b location pointed to by several sub functions, and could take over 10 seconds to perform. See the Crest measurement section of the manual for more detail.

Parame

nDmm

lpdResult

ter

Type/Description

Signametrics 84

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e set. A double-precision floating-point Crest Factor is stored in the

lpdResult. This measurement is a composite function, utilizing

int Identifies the DMM. DMMs are numbered st

double FAR * Points to the location to hold the Crest Factor.

arting with zero.

Factor

Return Va The return value is one of the following constants.

lue

Value

Meaning

DMM_OKAY

Negative Val

Example F; int st

double C atus = DMMReadCrestFactor(0, &CF);

Operation successfu

Error code

lly completed.

DMMReadDutyCycle

SMX2040  SMX2042 ; SMX2044

Description ercent

Remarks on measurement function, and a

Parameter

nDmm

Return p

#include

int DMMReadDutyCycle(int nDmm, double

This is a Sec valid range m double-precision floating-point measured duty cycle is effected by the setting of the Thre

Type/Description

;

duty cycle of ACV signal.

04032.h"

"sm2

FAR *lpdDcy)

dary function and the DMM must be in AC

us signal. It is stored as

t be set. It returns percent duty cycle of the

numbers in the location pointed to by lpdDcy. The

shold DAC.

Identifies the DMM. DMMs are numbered starting with zero.

int

lpdDcy

Return Value he return value is one of the following constants.

Value

DMM_OKAY

Negativ

Example

Meaning

e Value

double dcy; int state; state = DMMReadDutyCycle(0, &dcy);

double FAR * Points to the location which holds the duty cycle.

Operation successfully completed.

Error code

DMMReadFrequency

SMX2040  SMX2042 ; SMX2044

Description he next

Return t double floating-point frequency reading from the DMM.

#include "sm204032.h"

int DMMReadFrequency(int nDmm, double FAR *lpdResult)

;

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85 Signametrics

Rem counter is not engaged, select it. Make a single frequency measurement,

arks If frequency

and store the result as a 64-bi pointed to by lpdRe

sult. See DMMFrequencyStr() for more details.

t double-precision floating-point number in the location

Parame

nDmm

lpdResul

Return Va The return value is one of the following constants.

Example double d;

lue

Value

DMM_OKAY

DMM_

DMM_E_

DMM_C

DMMRea ySt

ter

Type/Description

Meaning

E_INIT

DMM

NT_RNG

int status = DMMReadFrequency(0, &d);

dFrequenc r

int Identi

double FAR * Points to the location to hold the freq

Operation successfu

DMM is uninitialized. Must be initialize prior to using any fu nction

Invalid DMM number.

Frequency counter is over or under

fies the DMM. DMMs are numbered starting with zero.

lly completed.

SMX2040  SMX2042 ; SMX2044 ;

uency.

range.

Description the DMM.

Remarks This is the string version of DMMReadFrequency(). It returnes a form

Return Value

Return the next string containing frequency reading from

#include "sm204032.h"

int

DMMReadFr

containing the measured frequency. For more details read about

DMMReqadFrequency()

Parameter

nDmm

lpszFreq

Value

DMM_OKAY

Negative val

Type/Description

uency

The return value is one of the following constants.

Meaning

equencyStr(int nDmm, LPSTR lpszFrequency)

int Identifies the DMM. DMMs are numbered starting with zero.

LPSTR Points to the location which holds the formatted reading

string. Allow minimum of 64.

Op mpleted.

eration successfully co

ror code

ated string

Example char buffer[64];

int status = DMMReadFrequencyStr(0, buffer);

Signametrics 86

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DMMReadInductorQ

SMX2040  SMX2042  SMX2044 ;

Description Return inductor’s

#include "sm2040

MMReadIn

int D

Remarks is a Seconda

Parame

nDmm

lpdResult

Return Value The return value is one of t

Value

DMM_

Negativ

This ry function and the DMM must be in the Inductance measurement function, and a val Resulting Q is by lpdResult.

ter

Type/Description

Meaning

OKAY

e Value

Q value.

32.h"

ductorQ(int nDmm, double FAR *lpdResult)

id inductance val

stor -precision floating-point number in the location pointed to

ed as double

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Points to the location to hold the inductor’s Q.

Operation

Error code

ue must have been read prior to using this function.

he following constants.

successfully completed.

Example double Q;

int status = DMMReadInductorQ(0, &Q);

DMMReadMeasurement

SMX2040 ; SM

Description Return a readin

int DMMReadMeasurement(int nDmm, double F

Remarks This measurem function is designed to read triggered measurements from the

X2044 ;

g which is the result of DMMSetTrigRead operation.

#i 04032.h"

nclude "sm2

AR *lpdRead)

ent reading

DMM. It is a fast reading function. It returns FALSE while no new reading is ready. If a

is ready the form of a 64-bit double-

reading precision floating-poi returned s in base uni

1.0 Mohm measurement. This function is designed to read bursting measurements form the DMM, resulting from DMMSetTrigRead and DMMBurstRead operations.

Parameter

nDmm

Type/Description

, TRUE is returned, and the result in

nt number is placed at the location pointed to by

value i ts. That is, it will returns 0.3 for a 300mV input and 1e6 for

int Identifies the DMM. DMMs are numbered starting with zero.

lpdRead.The

lpdRead

Return Value

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Integer value version code or an error code.

double FAR *

Pointer to a location where the reading is saved.

87 Signametrics

Value Meaning

TRUE

FALSE

TIMEOU

OVERR

Other N

Example eadin DMMBurstRead(0, 4, 150); // 4 settel., 150 samples

while( DMMReadMeasurement(0 , Reading[i]) == FALSE );

DMM ian

ReadMed

SMX2040  SMX2042

Des al’s Median value.

cription Return ACV sign

egative Value

double R g[150];

for(i=0 150 ; i++)

// wa ll measur

; i < // read 150 measurements

it for a ements to be ready, and read them.

; SMX2044 ;

#include "sm204032.h"

int DMMReadMedian(int nDmm, double

Measurement was read into *lpdRead

No measurement is available

Communication timeout. No reading available within 9s.

Communication overrun. C

Error code

PU did not keep up with DMM transmission.

FAR *lpdResult)

Remarks ion and the DMM must be in ACV measurement function, and

Parame

nDmm

lpdResult

Return Value The return value is one of the following constants.

Value

DMM_OKAY

Negati

Example Medi Median(0, &Median);

DMMRea

double an; int status = DMMRead

dNorm

This is a Secondary funct

valid range must be set. A double-precision floating-point Median voltage result is

a stored in the location pointed to by lpdResult. This measurement is a which utilizes several sub functions, and could take over 10 seconds to perform Median measurement section of the manual for more detail.

ter

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Po

Meaning

Operation successfully completed.

ve Value

Error code

ints to the location to hold the median voltage.

composite function

. See the

SMX2040 ; SMX2042 ; SMX2044 ;

Description

int DMMReadNorm(int

Take a reading that is in base value.

de "sm204032.h"

#inclu

Remarks This Primary read function is similar to DMMRead(). It returns a

Signametrics 88

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nDmm, double FAR *lpdRead)

double floating-point reading. The returned value is corrected for base

turns 0.3 for a 300 mV input and 1e6 for 1.0 MOhm.

units. That is, it

Parameter

nDmm

lpdRead

Return Value e.

Value

DMM_E_RANGE

DMM_E_DMM

DMM_O

Example double reading; int status = DMMReadNorm(0, &reading);

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR * Pointer to a location where the reading is saved.

Integer value version code or an error cod

Meaning

Over/Under range error.

KAY

Invalid DMM number.

Valid return.

DMMReadPeakToPeak

SMX2040  SM 2044

Description Return ACV si

X2042 ; SMX ;

gnal’s peak-to-peak value.

#include "sm204032.h"

int DMMReadPeakToPeak(int nDmm, double FAR *lpdResult)

Rem is is a Secondary function and the DMM must be in ACV measurement function, and

arks Th

a valid range must b is stored in the location pointed to by lpdResult. This measurement is a composite function which utilizes several sub functions, and could take ove

Parame

nDmm

lpdResul

Return Value

Value

DMM_OKAY

Negative Value

Example double ptp;

DMMRe iod

adPer

ter

Type/Description

The return value is one of the following constants.

Meaning

SMX2040  SMX2042 ; SMX2044

e set. A double-precision floating-point peak-to-peak voltage result

r 10 seconds to perform.

int Identifies the DMM. DMMs are n

double FAR * Points to the location to hold the Peak-to-Peak

Operation successfully completed.

Error code

int status = DMMReadPeakToPeak(0, &ptp);

umbered starting with zero.

;

value.

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89 Signametrics

Description Return the next double floating-point period reading from the DMM.

#include "sm204032.h"

int DMMReadPeriod(int nDmm, double FAR *lpdResult)

Rem rks This is a Secondary function and the DMM must be in ACV measurement function, and

a valid range must be set It makes a single period measurement, and stores the resul double-precision floating-point number in the location pointed to by lpdResul

DMMFre

quencyStr() for more details.

t as a

t. See

Parameter

nDmm

lpdResul

Return Value The return value is one of the following const

Value

DMM_OKAY

Negative Val

DMM_C

Example

DMMReadStr

Type/Description

int Identifies the DMM. DMMs are numbered startin

Meaning

NT_RNG

double d; int status; status MReadPer

double FA

Operation successfu

Error code

Period measurement hardware is over or under range.

= DM iod(0, &d);

R * Points to the location which holds the period.

ants.

lly completed.

SMX2040 ; SMX2042 ; SMX2044 ;

Description Return the next reading from the DMM formatted for printing.

#include "sm204032.h"

g with zero.

int DMMReadStr(int nDmm, LPSTR lpszReading)

Remarks This function is the string version of DMMRead(). It reads the next Primary

measurement result, performs all scaling and conversion required, and returns the result as a string formatted for printing. The print format is determined by the range and function. See DMMRead() for more details.

Parameter

nDmm

lpszReading

Return Value The return value is one of the following constants, or the string length is OK.

Value

Type/Description

Meaning

Signametrics 90

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int Identifies the DMM. DMMs are numbered starting with zero.

LPSTR Points to a buffer (at least 16 characters long) to hold the

converted result. The return value will consist of a leading sign, a

floating-point value in exponential notation, and a units specifier.

DMM_OKAY

Valid return.

Negative Value

DMM_E_RANGE

Example status = DMMReadingStr(0, cBuf);

char cBuf[17]; int

Error code

DMM over range error occurred.

DMMReadTotalizer

SMX2040 ; SMX2044 ;

Description

DMMRea m)

Remarks This function re see

Return Value The return value is the totalized count, or if negative one of the following constants.

 SMX2042

Parameter

nDmm

Read the totalized value accumulated by the Totalizer function.

#include "sm204032

long dTotalizer(int nDm

DMMStartTotalize.

Type/Description

.h"

ads the total value accumulated by the Totalizer function. For details

int Identifies the DMM. DMMs are numbered starting with zero.

Example

Value

Negative Value

Meaning

Error code

long total = DMMReadTotalizer(0);

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91 Signametrics

DMMReadWidth

SMX2040  SMX2042 ; SMX2044

;

Description Return the posit

#i 4032.h"

nclude "sm20

int DMM

Remarks This is a Secondary function and the DMM must be in ACV measurement

a valid range must be set. It returns t These parameters are stored as double-precision floating-point numbers in the loca pointed to by lpdPwid and lpdNwid. The measured widths are affected by the settin the Threshold D

Parameter

nDmm

lpdPwid

lpdNwid

Return Value The return value is one of the following constants.

Value

DMM_

Type/Description

Meaning

OKAY

ive and negative pulse widths.

Read Dmm, double FAR *lpdPwid, double FAR *lpdNwid)

Width(int n

wo parameters: positive and negative pulse widths.

AC.

int Identifies the DMM. DMMs are n

double FA

double FAR * Points to the location which holds the negative width.

Operation successfully completed.

R * Points to the location which holds the pos itive width.

umbered starting with zero.

function, and

tion

g of

Negative Va

Example double pw,nw; int state; state = DMMReadWidth(0, &pw, &nw);

lue

Error code

DMMReady

SMX2040 ; S ; SMX2044 ;

Description Return the of the DMM following trigger operation.

Remarks Following the completion of an tirggered measurement event, be it hard w are or software,

MX2042

Parame

nDmm

ready state

#includ sm204032.h"

int DMMReady(int n

the DMM indicates the completion. The DMMReady function checks the DMM and returns TRUE i DMMReady fu flags have been clea DMMArmTrigger, DMMTrigger, DMMReadBuffer and DMMPolledReaed for more details on this function.

ter

e "

Dmm)

f ready, and FALSE otherwise. Once a TRUE status is returned, the

nction should not be used again since a TRUE also indicates that some

r, which allow further operations. See DMMArmAnalogTrigger,

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

Signametrics 92

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Return Value The return value is one of the following constants.

Value

Meaning

TRUE

FALSE

Negative Va

Example double Buff

for(i=0; i < 10 ; i++) DMMReadBuffer(0, &Buffer[i]);

lue

DMMTrigger(0,10); while( ! DM

DMM is done and buffer is ready to be read.

DMM is not ready.

Error code

er[10];

MReady(0) );

DMMSetACCapsDelay

SMX2040  SMX2042  SMX2

Description me itance.

tACCapsDelay(int nDmm, double ldDelay)

Remarks This Secondary function sets the AC based capacitance measurement delay, which is the

Set the asurement delay of AC based Capac

#include #include "UserDMM.h"

int DMMSe

time the measurement system settles. The DMM

an set this function from 0.0 to 10.0 seconds. Since the DMM is optimized for the

c defalut value, it is possible

044 ;

" "

sm204032.h

’s default value is 2.0s. This function

that changing this value will introduce additional error.

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

double The time the DMM is allowed to settle the measurement.

Can be set beetween 0 and 10.0 seconds.

Integer error code.

Meaning

KAY

e Value

DMMSetACCapsDelay(0, 0.25); // Set measurement delay to 0

Operation successfully completed.

Error code

Return Value

Example

Parameter

nDmm

ldDelay

Value

DMM_O

Negativ

DMMSetACCapsLevel

SMX2040  SM

Description Set the DCV so

int DMMSetACCapsLevel

X2042  SMX2044 ;

urce output level.

#include "sm2 #include "User

04032.h" DMM.h"

.25s

(int nDmm, double ldVolts)

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93 Signametrics

Remarks This Secondary function sets the AC peak voltage level for th e AC based Capacitance

measurem sets an internal register to ldVols rather than setting the output level itself. This value is used on any of the AC Caps calibration and measure ent. Following setting of this function, i calibration of the AC Capacitance ranges to be used. Since th e DMM is optimized for the defalut v ue, it is reco value.

ent function. It actually

m t is necessary to perform open

al mmended not to use this function and keep the default 0.45V peak

Parame

nDmm

ldVolts

Return Value Integer error code.

Value

DMM_

Negative Value

Example DMMSetACCapsLevel(0, 0.35); // Set source to 0.7V peak-to-peak

Type/Description

ter

int Identifies the DMM. DMMs are numbered starting with zero.

double Peak value of AC voltage to be set. Can be 0.1V to 5.0V

Meaning

OKAY

Operation succe

Error code

ssfully completed.

DMMSetACVSource

SMX2040  SM

Description Set the ACV so

int DMMSetACVSource(int nDmm, double FAR

X2042  SMX2044 ;

urce output level and frequency.

#include "sm20 #include "User

4032.h"

DMM.h"

ldVolts, double FAR ldFreq)

Remarks This Secondary ets the AC voltage source to RMS amplitude of ldVolts, and

the frequency to ldFreq. The DMM must be in VAC_SRC operation for this function to execute y. When the DMM is i

properl n VAC_SRC operation, and the

DMMSetACVSource is applied, reading the DMM (DMMRead, DMMReadStr) will return th urement of th source DAC. If better accuracy is needed it can be accomplished by selecting the ClosedLoop mode (DMMSetSourceMode). This mode engages the Trim DAC, which augments the 12 bit DAC to produce 16 effective bits. In the ClosedLoop mode, the source level is reading is equal to ld level, it is necessary rps when using the Closed Loop mode. Tw VAC_SRC mode, the 3.3 V and the 330 m DMM will automatically s

Parame

nDmm

ldVolts

ldFreq

Return Value Integer error code.

ter

e meas e output voltage. This function acts on the main 12 bit

Type/Description

function s

adjusted any time the DMM is read, making small corrections until the

Volts. However, for the ClosedLoop mode to update the source

to read the DMM multiple times. Update rate should not exceed 5

o ACV measurement ranges are available in

V. If the Autorange mode is enabled, the

elect the appropriate range.

int Identifies the DMM. DMMs are numbered starting with

double FAR AC RMS voltage to be set. Range: 0.05 to 7.25 V RMS

double FAR DC voltage to be set. Range: 2 Hz to 76 kHz

zero.

Signametrics 94

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Value Meaning

Operation successfully completed.

Error code

Example

DMM_O

Negativ

KAY

e Value

double reading; int I; DMMSetACVSource(0, 7.0, 1000.0); // source 7V and 1kHz DMMSetSourceMode(0, CLOSED_LOOP); // Closed loop mode for(I=0;I<100;I++) DMMRead(0,&read

DMMSetAuto

SMX2040 ; SMX2042

Description

int DMMSetA

Remarks This function en

Paramete

nDmm

Range

; SMX2044 ;

Enable/Disable autorange operation of DMM

lude "sm2

#inc

Type/Description

ing); // update 100 times

04032.h"

utoRange(int nDmm, BOOL bAuto)

ables or disables autorange operation of the DMM.

int Identifies the DMM. DMMs are numbered starting with zero.

bAuto

Return Value The return value is one of the following constants.

Meaning

Value

DMM_OKAY

Negative Value

Example status = DMMSetAutoRange(0, TRUE); /* enable autoranging */

DMMSetBuffT

; SMX2042

Description Setup the DMM for Triggered operation.

int DMMSetBuffTrigRead(int nDmm, int iSettle, int iSamples, int iEdge)

rigRead

; SMX2044 ; SMX2040

#include "sm204 #include "UserDM

BOOL Determines whether or not autoranging is done. The value

TRUE enables autoranging, FALSE disables it.

Function succeeded.

Error code

032.h" M.h"

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95 Signametrics

Remarks is

Setup the SMX2040 for external hardware trigger operation. Following reception of th command the DMM enters a wait state. After reception of an external trigger edge of iEdge polarity, the DMM takes iSettle + 1 readings at the set measurement function, range, and reading rate; and stores the last reading in th e in an internal buffer. This process is repeated for iSamples. This function is particularly useful in conjunction wit a triggering in this mode. The number of trigger edges must be equal or greater than iSamples to

erly termin een the time the DMMSetBuffTrigRead is issued

prop ate this mode. Betw and the time the buffer is read, no other command should be sent to the DMM. One exception is the VAC, Ohms, IAC, IDC and RTD measurements.

Use the DMMReady to monitor when the DMM is ready (following trigger(s) and the

ading of iSam

re ples). When ready, you can read up to iSamples, using

DMMReadBuffer or DMMReadBufferStr functions. Once DMMReady returns TRUE, it should not be used again prior to reading

for reading when it detects a ready condition.

struments such as the SM4042 relay scanner. No autoranging is allowed in

DMMDisarmTrigger command. This function is usable for VDC,

the buffer, since it prepares the buffer

Parameter

nDmm

iSettle

iSamples

iEdge

Return Value The return value is one of the following constants.

Value

DMM_

Negativ

xample double Buffer[64];

for(i=0; i DMMReadBuffer(0, &Buffer[i]);

DMMSetCapsAveSamp

SMX2040 SMX2042 SMX2044

 ; ;

Type/Description

int Identifies the DMM. DMMs are numbered starting with zero.

int The number of setteling measurements, prio

be set between 0 and 120. Recommanded value i

int

The number of samples the DMM takes following the same

num

ber of trigger pulses. This number must be between 1 and 64,

inclusive.

Int The ed edge, and

Meaning

OKAY

e Value

DMMSetBuffTrigRead(0, 4, 64, 0); // Negative edge, 4

etteling d 64 samples/triggers

//s while( ! DMMReady(0) ); // wait for completion

Operation successfully terminated

Error code.

readings, an

< 64 ; i++) // read buffer

ge polarity of the trigger signal. 1 for Positive, or leading

0 for negative or trailing edge trigger.

r to read value. Must

s 4.

Description Tunes the capacitance m ent function parameters for higher measurement speed.

#include "sm204032.h"

Int DMMSetCapsAveSamp(int nDmm, int iAverage, int iSamples)

Remarks This function should be used carefully since it modifies the capacitance function basic

measurement parameters; the avera sampled, iSamples. This function is provided only for cases where it is necessary to

Signametrics 96

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easurem

ges value, iAverage, and the number of points

improve measurement speed. W

ification provided for capaci

spec

d have profound efect on the operation of the function. Any time a capacitance range

coul is change, these values are set t iAverage, and iSamples will red about 50ms.

hen using this function keep in mind that the accuracy

tance is not guaranteed. Also, modifying these values

o the default values. For instance, values of 1 and 3 for

uce measurement time on the 12nF range from 0.8s to

Parame

nDmm

iAverage

iSample

Return Value

Value

DMM_OKAY

Negative Value

Example status

Type/Description

ter

int Identifies the DMM. DMMs are numbered starting

int The average value, must be set between 1 and 100.

The return value is one of the following constants.

Meaning

int The number of samples must be set to at least 3.

Valid return.

Error code

int = DMMSetCapsAveSamp(0,1,3);

DMMSetCJTemp

SMX2040 ; S ; SMX2044 ;

Description Set cold ju perature for thermocouple measurement.

int (int nDmm, double dTemp)

MX2042

nction tem

#includ sm204032.h"

e "

DMMSetCJTemp

with zero.

Remarks Set the cold junction temperature for subsequent thermocouple measurements. When

measuring temperature using thermocouples it is necessary to establish a reference or cold junction temperature. This is the temperature at which the thermocouple wires are

the DMM or to the switching card’s cooper wires. One way to do this is by

value using DMMSetCJTemp() function. dTemp must be entered

perature units.

int Identifies th

double The cold junction temperature. Must be set between 0

C or the corresponding oF.

Operation successfu

Error code.

p(0, 22.5);

e DMM. DMMs are numbered starting with zero.

C and

lly terminated

Return Value

Example

connected to simply entering this using the currently set tem

Parame

nDmm

dTemp

Value

DMM_OKAY

Negative Val

Type/Description

ter

The return value is one of the following constants.

Meaning

DMMSetCJTem

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97 Signametrics

DMMSetCompThreshold

SMX2040  SMX2044 ;

Description Th

int DMMSetCompThreshold(int nDmm, double FAR ldThreshold)

R arks This Secon

em dary function sets the output of the Threshold DAC. To use this function, the

Parameter

nDmm

ldThresh

Return Value

Value

Set the reshold DAC level.

#include #include

DMM must comparator. It is co function is associated with the following functions: Totalizer, Frequency counter, Period, Pulse width and Duty Cycle meas

lected ACV range. For instance, when the 250 V AC range is selected, the allowed

se range of ldThreshold is –5

Type/Description

old

Integer error code.

Meaning

sm204032.h

" "

UserDMM

" .h"

be in AC volts. This function sets the detection threshold of the AC

mpared by the comparator to the AC coupled input voltage. This

urements. ldThreshold range is determined by the

00 V to +500 V. See the specification section for more details.

int Identifies the DMM. DMMs are numbered starting with zero.

double FAR DC voltage to be set. Allowed range depends on

selected ACV range.

Operation successfully completed.

Error code

Example

DMM_OKAY

Negative Value

DMMSetCompThreshold(0,28.5); // Set comp. threshold to 28.5V

DMMSetCounterRng

SMX2040  SMX2042 ; SMX2

Description fre

int DMMSetCounterRng(int nDmm, int ange)

R arks This functio

em n forces the auto-ranging frequency counter to a specific range, frange. Use

Parame

Set the quency counter to a specific range.

#include #include

this function time necessary for t removing the requirement to make multiple frequency measurements in order to allow the counter to range. All ranges are

Type/Description

ter

044 ;

sm204032.h

" "

UserDMM

" .h"

he approximate frequency to be measured is known. It will eliminate the

if t

he counter to autorange to the appropriate range. Saves time by

defind in UserDMM.h file.

nDmm

frange

Signametrics 98

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int Identifies the DMM. DMMs are numbered starting with zero.

int The range to be set is a value between 0 and 7. See UserDMM.h

Return Value Integer error code.

Value

Meaning

Operation successfully completed.

Error code

Example

DMM_O

Negativ

KAY

e Value

DMMSetCounterRng(0, COUNTR_320HZ); // Set counter to measur frequency between 65Hz to 320Hz

DMMSetDCISource

SMX2040  SM

Description Set the DCI sou

int DMMSetDCISo

Remarks This Secon tion sets the DC current source to ldAmps. The DMM must be in

X2042  SMX2044 ;

rce output level.

#include "sm2 #include "User

IDC_SRC

be selec applied, measurem needed it can be accomplished by s DMMSetTrimDAC function. There are five current source ranges. The D output (load) voltage.

04032.h" DMM.h"

dary func

for this function to execute properl

ted peration, and the DMMSetDCISource is

. When the DMM is in IDC_SRC o

re M (DMMRead or DMMReadStr) will return the outpu t v oltage

ading the DM

ent. This fun

urce(int nDmm, double FAR ldAmps)

y. Further, the appropriate DCI range must

ction acts on the main 12 bit source DAC. If better resolution is

etting the Trim DAC by using the

MM reads the

e a

Parame

nDmm

ldAmps

Return Value Integer error code.

Example

Value

DMM_OKAY

Negative Value

ter

Type/Description

t Identifies the DMM. DMMs are numbered starting with zero.

ble FAR DC current to be set. Can be 0 to 1.25 X selected range

dou

Meaning

Operation successfully completed.

Error code

DMMSetRange(0, _1uA) // Select 1uA source range DMMSetDCISource(0, 1.1e-6); // Set source to 1.1uA

DMMSetDCVSource

SMX2040  SMX2042  SMX2044

Description Set the DCV so

#include "sm2 #include "UserDM

int DMMSetDCVSource(int nDmm, double FAR ldVolts)

;

urce output level.

04032.h"

M.h"

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99 Signametrics

Signametrics SMX2040, SMX2042, SMX2044 Operator's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual