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Dual Measurement Multimeter
GDM-8261
USER MANUAL
GW INSTEK PART NO. 82DM-82610EB1
ISO-9001 CERTIFIED MANUFACTURER
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This manual contains proprietary information, which is protected by
copyrights. All rights are reserved. No part of this manual may be
photocopied, reproduced or translated to another language without
prior written consent of Good Will company.
The information in this manual was correct at the time of printing.
However, Good Will continues to improve products and reserves
the right to change specifications, equipment, and maintenance
procedures at any time without notice.
Good Will Instrument Co., Ltd.
No. 7-1, Jhongsing Rd., Tucheng Dist., New Taipei City 236, Taiwan (R.O.C.).
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Table of Contents
Table of Contents
SAFETY INSTRUCTIONS .................................................... 6
Safety Symbols .................................................... 6
Safety Guidelines ................................................ 7
GETTING STARTED .......................................................... 10
GDM-8261 Characteristics ................................ 11
Front Panel Overview ........................................ 12
Rear Panel Overview ......................................... 18
Set Up ............................................................... 20
BASIC MEASUREMENT .................................................... 23
Basic Measurement Overview ........................... 25
AC/DC Voltage Measurement ........................... 27
AC/DC Current Measurement ........................... 32
2W/4W Resistance Measurement ..................... 34
Diode Test ......................................................... 37
Continuity Test .................................................. 38
Frequency/Period Measurement ....................... 41
Temperature Measurement ............................... 43
DUAL MEASUREMENT .................................................... 49
Dual Measurement ........................................... 49
ADVANCED MEASUREMENT ........................................... 55
Advanced Measurement Overview .................... 56
dBm/dB/W Measurement ................................. 58
Max/Min Measurement..................................... 61
Relative Value Measurement ............................. 62
Hold Measurement ........................................... 64
Compare Measurement ..................................... 65
Math Measurement ........................................... 68
SYSTEM/DISPLAY CONFIGURATION .............................. 74
Refresh Rate Setting .......................................... 75
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GDM-8261 User Manual
View Serial Number ........................................... 75
Trigger Setting ................................................... 76
Digital Filter Setting .......................................... 79
Display Setting .................................................. 81
Measurement Configuration Settings ............... 82
ADC Setting ....................................................... 87
Frequency / Period Settings .............................. 91
Identification Settings ....................................... 94
STORE/RECALL ............................................................... 95
Store Measurement Record ............................... 96
Recall Measurement Record .............................. 97
Save Instrument Settings .................................. 98
Recall Instrument Settings ................................ 99
SCANNER (OPTIONAL) ................................................. 101
GDM-SC1 Scanner Specifications ................... 102
Scanner Installation ........................................ 102
Setup Scan ...................................................... 110
Run Scan ......................................................... 117
DIGITAL I/O ................................................................... 120
Digital I/O Terminal Configuration ................. 121
REMOTE CONTROL ....................................................... 127
Configure Interface .......................................... 129
Web Control Interface ..................................... 156
Command Syntax ............................................ 160
Command Set .................................................. 161
FAQ ................................................................................ 205
APPENDIX ...................................................................... 206
Firmware Version ............................................ 207
Fuse Replacement ........................................... 208
Menu Tree ....................................................... 210
Specifications .................................................. 212
EC Declaration of Conformity .......................... 221
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Table of Contents
INDEX ............................................................................ 222
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GDM-8261 User Manual
WARNING
Warning: Identifies conditions or practices that could
result in injury or loss of life.
CAUTION
Caution: Identifies conditions or practices that could
result in damage to the GDM-8261 or to other property.
DANGER High Voltage
Attention Refer to the Manual
Protective Conductor Terminal
Earth (ground) Terminal
Do not dispose electronic equipment as unsorted
municipal waste. Please use a separate collection facility
or contact the supplier from which this instrument was
purchased.
SAFETY INSTRUCTIONS
This chapter contains important safety instructions that
you must follow when operating the GDM-8261 and
when keeping it in storage. Read the following before any
operation to insure your safety and to keep the
GDM-8261 in the best possible condition.
Safety Symbols
These safety symbols may appear in this manual or on the GDM-8261.
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SAFETY INSTRUCTIONS
General Guideline
CAUTION
Make sure that the voltage input level does not exceed
DC1000V/AC750V.
Make sure the current input level does not exceed 10A.
Do not place any heavy object on the GDM-8261.
Avoid severe impact or rough handling that can lead to
damaging the GDM-8261.
Do not discharge static electricity to the GDM-8261.
Use only mating connectors, not bare wires, for the
terminals.
Do not block or obstruct the cooling fan vent opening.
Do not perform measurement at the source of a
low-voltage installation or at building installations
(Note below).
Do not disassemble the GDM-8261 unless you are
qualified as service personnel.
(Note) EN 61010-1:2010 specifies the measurement categories and
their requirements as follows. The GDM-8261 falls under category
I or II.
Measurement category IV is for measurement performed at the
source of low-voltage installation.
Measurement category III is for measurement performed in the
building installation.
Measurement category II is for measurement performed on the
circuits directly connected to the low voltage installation.
Measurement category I is for measurements performed on circuits
not directly connected to Mains.
Power Supply
WARNING
AC Input voltage: 100/120/220/240 V AC ±10%,
45Hz to 66Hz / 360Hz to 440Hz
The power supply voltage should not fluctuate more
than 10%.
Connect the protective grounding conductor of the
AC power cord to an earth ground, to avoid electrical
shock.
Safety Guidelines
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GDM-8261 User Manual
Fuse
WARNING
Fuse type: 0.315AT 100/120VAC
0.125AT 220/240 VAC
Make sure the correct type of fuse is installed before
power up.
To avoid risk of fire, replace the fuse only with the
specified type and rating.
Disconnect the power cord before fuse replacement.
Make sure the cause of a fuse blowout is fixed before
fuse replacement.
Cleaning the
GDM-8261
Disconnect the power cord before cleaning.
Use a soft cloth dampened in a solution of mild
detergent and water. Do not spray any liquid into the
GDM-8261.
Do not use chemicals or cleaners containing harsh
material such as benzene, toluene, xylene, and acetone.
Operation
Environment
Location: Indoor, no direct sunlight, dust free, almost
non-conductive pollution (Note below)
Temperature: Full accuracy for 0°C to 55°C.
Humidity: Full accuracy to 80% RH at 40°C
(Note) EN 61010-1:2010 specifies the pollution degrees and their
requirements as follows. The GDM-8261 falls under degree 2.
Pollution refers to ―addition of foreign matter, solid, liquid, or
gaseous (ionized gases), that may produce a reduction of dielectric
strength or surface resistivity‖.
Pollution degree 1: No pollution or only dry, non-conductive pollution
occurs. The pollution has no influence.
Pollution degree 2: Normally only non-conductive pollution occurs.
Occasionally, however, a temporary conductivity caused by
condensation must be expected.
Pollution degree 3: Conductive pollution occurs, or dry,
non-conductive pollution occurs which becomes conductive due to
condensation which is expected. In such conditions, equipment is
normally protected against exposure to direct sunlight, precipitation,
and full wind pressure, but neither temperature nor humidity is
controlled.
Storage
Environment
Location: Indoor
Temperature: −40°C to 70°C
Disposal
Do not dispose this instrument as unsorted municipal
waste. Please use a separate collection facility or contact
the supplier from which this instrument was purchased.
Please make sure discarded electrical waste is properly
recycled to reduce environmental impact.
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SAFETY INSTRUCTIONS
Green/ Yellow:
Earth
Blue:
Neutral
Brown:
Live (Phase)
Power cord for the United Kingdom
When using the GDM-8261 in the United Kingdom, make sure the power
cord meets the following safety instructions.
NOTE: This lead / appliance must only be wired by competent persons
WARNING: THIS APPLIANCE MUST BE EARTHED
IMPORTANT: The wires in this lead are coloured in accordance with the
following code:
As the colours of the wires in main leads may not correspond with the
coloured marking identified in your plug/appliance, proceed as follows:
The wire which is coloured Green & Yellow must be connected to the Earth
terminal marked with either the letter E, the earth symbol or coloured
Green/Green & Yellow.
The wire which is coloured Blue must be connected to the terminal which is
marked with the letter N or coloured Blue or Black.
The wire which is coloured Brown must be connected to the terminal marked
with the letter L or P or coloured Brown or Red.
If in doubt, consult the instructions provided with the equipment or contact
the supplier.
This cable/appliance should be protected by a suitably rated and approved
HBC mains fuse: refer to the rating information on the equipment and/or
user instructions for details. As a guide, a cable of 0.75mm2 should be
protected by a 3A or 5A fuse. Larger conductors would normally require 13A
types, depending on the connection method used.
Any exposed wiring from a cable, plug or connection that is engaged in a live
socket is extremely hazardous. If a cable or plug is deemed hazardous, turn
off the mains power and remove the cable, any fuses and fuse assemblies. All
hazardous wiring must be immediately destroyed and replaced in accordance
to the above standard.
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GDM-8261 User Manual
Characteristics
GDM-8261 Characteristics ..................................... 11
Panel Overview
Front Panel Overview ............................................. 12
Measurement Keys (upper row) ............................. 13
Measurement Keys (lower row) ............................. 16
Rear Panel Overview .............................................. 18
Setup
Tilt Stand ............................................................... 20
Power Up ............................................................... 21
GETTING STARTED
This chapter describes the GDM-8261 in a nutshell,
including an Overview of its main features and front /
rear panel introduction. After going through the
Overview, follow the Power-up sequence to properly
setup the GDM-8261.
Please note the information in this manual was correct at
the time of printing. However as GW Instek continues
to improve its products, changes can occur at any time
without notice. Please see the GW Instek website for the
latest information and content.
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GETTING STARTED
Performance
High DCV accuracy: 0.0035%
High current range: 10A
High Voltage range: 1000V
High ACV frequency response: 300kHz
Features
6
2
1
digits
Multi functions: ACV, DCV, ACI, DCI, 2W/4W R, Hz,
Temp, Continuity, Diode test, MAX/MIN, REL, dBm,
Hold, MX+B, 1/X, REF%, dB, Compare, Statistics.
Manual or Auto ranging
AC true RMS
Interface
Voltage/Resistance/Diode/Temperature input
Current input
4W sense input
USB device/RS232/GPIB(optional)/LAN(optional)
for remote control
9-pin digital I/O
16 channel scanner (optional)
Optional Items
16 channel scanner
GPIB port
Ethernet port
GDM-8261 Characteristics
The GDM-8261 is a portable, dual-display digital
multimeter suitable for a wide range of applications, such
as production testing, research, and field verification.
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GDM-8261 User Manual
Measurement
Keys
Input Hi
Terminal
Sense Hi
Terminal
Sense Lo,
DC/AC 1A Terminal
Power Switch
Main
Display
DC/AC 10A
Terminal
Input Lo
Terminal
AMPS Fuse
Holder
Main Display
Output On/Off Key
CAT 1000V
CAT 600V
ON/OFF
REAROUTCVCCSWEEPFILTRCLSTOCOMP2ND
dBmEXTSHIFTERRLIMITAUTOMATH4W2WDCAC
AVmm
HzWkM
WSFC
mdB
%
AVmm
HzWkM
WSFC
RMTMAXMINRELHOLDSMFAUTO4W2WDCAC
TEMP
/
Hz/P2/4WACV DCV ACI DCI
HOLD MX/MNRELTRIGAUTO 2ND
SENSORdBMATHSTORE dBmSTEPSCAN RECALL
MENUREL# FILTERINT/EXTCOMPRATE
ENTER LOCAL
POWER
RANGE CHOICES
/ EXITSHIFT
GDM-8261
MAX
W
4W
1.2A
MAX
DC1000V
AC 750V
MAX
10A
500V
MAX
INPUT
SENSE
HI
LO
FUSE
T1.25A
V
W
250V
MAX
200Vpk
COM
Digit Dual Measurement Multimeter
6
1
2
Power Switch
POWER
Turns On or Off the main
power. For the power up sequence, see
page 21.
Main Display
Shows measurement results and parameters.
For display configuration details, see page 81 (light
setting).
Sense Lo
DC/AC 1A
Terminal
AMPS Fuse
Holder
FUSE
T1.25A
250V
As a fuse, protects the instrument from
over-current. Rating: T1.25A, 250V.
For the fuse replacement procedure, see
page 209.
As a sense terminal, accepts 4W Ω
measurement LO connection. For
details, see page 33
Also accepts current input
DC: 100μA~1A
AC:1mA~1A
For details see page 32.
Front Panel Overview
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GETTING STARTED
Sense HI
Terminal
W
4W
SENSE
Accepts HI sense line in 4W resistance
measurement. For details, see page 33.
Input Lo Terminal
500V
MAX
COM
Accepts ground (COM) line in all
measurements except the sense line in
4W Resistance (page 33).
The maximum withstand voltage
between this terminal and earth is
500Vpk.
Input Hi Terminal
MAX
DC1000V
AC 750V
INPUT
V W
Used as an input port for all
measurements except for DC/AC
Current measurements.
DC/AC 10A
Terminal
MAX
10A
Accepts DC/AC Current input.
For DCI or ACI details, see page 32.
Main Display
Output On/Off
key
ON/OFF
Turns the display on or off. When the
display is turned off, all panel keys
except the Output On/Off key become
disabled. The Output On/Off key is On
by default.
SHIFT/EXIT
/ EXITSHIFT
The Shift key is used to select the
secondary functions assigned to
each front panel key. When pressed,
the SHIFT indicator appears in the
display.
As the Exit key, it gets out of the
parameter configuration mode and
goes back to the measurement result
display mode.
ACV
ACV
Measures AC Voltage (page 27).
Measurement Keys (upper row)
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GDM-8261 User Manual
SHIFT → ACV
(SCAN)
/ EXITSHIFT
ACV
SCAN
Starts the optional scan
measurement (page 110).
DCV
DCV
Measures DC Voltage (page 27).
SHIFT → DCV
(STEP)
/ EXITSHIFT
DCV
STEP
Starts the step measurement (page
110) using the optional scanner.
ACI
ACI
Measures AC Current (page 32).
SHIFT → ACI
(RECALL)
/ EXITSHIFT
ACI
RECALL
Recalls a normal measurement
result, standard deviation
measurement readings (page 97) or
scan measurement results (page
118).
DCI
DCI
Measures DC Current (page 32).
SHIFT → DCI
(STORE)
/ EXITSHIFT
DCI
STORE
Stores a measurement result (page
96).
2/4W
(Resistance)
2/4W
Measures 2-wire or 4-wire
Resistance (page 33).
SHIFT → 2/4W
(MATH)
/ EXITSHIFT
2/4W
MATH
Enters the Math measurement mode
(page 68).
/
(Diode/
Continuity)
/
Tests Diode (page 37) or Continuity
(page 38).
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GETTING STARTED
SHIFT →
/
(dBm)
/ EXITSHIFT
/
dBm
Measures dBm (page 58).
Hz/P (Frequency/
Period)
Hz/P
Measures Frequency or Period (page
41).
SHIFT + Hz/P
(dB)
/ EXITSHIFT
Hz/P
dB
Measures dB (page 59).
TEMP
(Temperature)
TEMP
Measures Temperature (page 43).
SHIFT + TEMP
(SENSOR)
/ EXITSHIFT
TEMP
SENSOR
Selects the type of thermocouple
used in the Temperature
measurement (page 44).
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GDM-8261 User Manual
AUTO/ENTER
AUTO
ENTER
As the AUTO key, selects the
measurement range automatically.
As the Enter key, confirms the
entered value.
SHIFT → AUTO
(RATE)
/ EXITSHIFT
AUTO
RATE
ENTER
Selects the measurement update
rate: Slow, Medium, or Fast (page
25).
Up/Down
RANGE
Selects the parameter in various
occasions: higher ( ) or lower
( ).
HOLD
HOLD
Activates the Hold function (page
64).
SHIFT → HOLD
(COMPare )
/ EXITSHIFT
HOLD
COMP
Activates the Compare
measurement (page 65).
TRIG (Trigger)
TRIG
Triggers sample acquisition
manually (page 76).
SHIFT → TRIG
(Int/Ext Trigger)
/ EXITSHIFT
TRIG
INT/EXT
Selects the Internal or the External
trigger source (page 76).
Left/Right
HOLD TRIG
CHOICES
Selects parameters in various menus:
left ( ) or right ( ).
REL
REL
Measures the Relative value (page
62).
Measurement Keys (lower row)
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GETTING STARTED
SHIFT → REL
(RELative base )
/ EXITSHIFT
REL
REL#
Manually sets the reference value for
the Relative value measurement
(page 62).
MX/MN
(MAX/ MIN)
MX/MN
Measures the Maximum or the
Minimum value (page 61).
SHIFT → MX/MN
(FILTER)
/ EXITSHIFT
MX/MN
FILTER
Selects the digital filter type for the
signal sampling (page 79).
2nd (Display) /
LOCAL
2ND
LOCAL
As the 2nd key, selects the
measurement item on the 2nd
display (page 49). Pressing and
holding for more than 1 second
turns off the 2nd display.
As the Local key, releases the remote
control and returns the instrument
to local panel operation (page 129).
SHIFT → 2nd
(Menu)
/ EXITSHIFT
2ND
MENU
LOCAL
Enters the configuration mode for;
System Settings, Measurement
Settings, ADC Settings,
Frequency/Period Settings, I/O
Settings, TX TERM Settings and
Scanner Settings.
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GDM-8261 User Manual
RS232
CAL KEY
DIGITAL I / O
SER.NO. LABEL
50 , 60 , 400Hz
25VA MAX.
LINE RATING
FUSE LINE
100VAC
120VAC
220VAC
240VAC
0.315AT
0.125AT
TEST LEADS BEFORE REPLACING FUSE
DISCONNECT POWER CORD AND
16 CHANNEL
SCANNER
MAX. RATING
250V , 2A
RS-232C
Port
Optional
Scanner Port
Power Cord
Socket
Fuse
0.315AT/
0.125AT
CAL Key
Port
Optional
Communication port
USB Device
Port
Digital I/O
Port
Power Cord
Socket
100
220
120
240
Accepts the power cord. AC
100/120/220/240V ±10%,
45Hz~66Hz, 360Hz~440Hz.
For power on sequence, see page 21.
Fuse Socket
100
220
120
240
Holds the main fuse:
100/120 VAC: 0.315AT
220/240 VAC: 0.125AT
For fuse replacement details, see page
208.
RS-232C port
RS232
Accepts an RS-232C cable for remote
control; DB-9 male connector.
For remote control details, see page
130.
Rear Panel Overview
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GETTING STARTED
USB device port
Accepts a USB device cable for remote
control; Type A, female connector.
For remote control details, see page
129.
CAL key port
CAL KEY
Reserved for internal purposes such as
firmware updates and calibration.
Digital I/O port
DIGITAL I / O
Accepts a digital I/O cable for the
Hi/Lo limit tests; DB-9 pin, female
connector.
For digital I/O details, see page 121.
Optional slot x1
Accepts the optional 16 channel scanner module. For
scanner details, see page 101.
16 CHANNEL
SCANNER
MAX. RATING
250V , 2A
Optional
Communication
port
Accepts an optional GPIB or Ethernet
card.
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Set Up
Tilt stand steps
Pull out the
handle sideways
and rotate it.
Place the unit
horizontally,
Or in the tilt
stand position.
Place the handle
vertically for hand
carry.
Tilt Stand
GDM-8261 User Manual
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Power Up
Steps
1. Ensure the correct line voltage is
lined up with the arrow on the fuse
holder. If not, see page 208 to set the
line voltage and fuse.
10 0
22 0
1
2
0
2
4
0
2. Connect the power
cord to the AC
Voltage input.
Note
Make sure the ground connector on the power
cord is connected to a safety ground. This will
affect the measurement accuracy.
3. Push to turn on the
main power switch on
the front panel.
4. The display shows the model name and the version
for a few seconds.
Example: GDM-8261, V1.00
5. Followed by the default measurement settings.
6. And the interface I/O settings.
GETTING STARTED
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GDM-8261 User Manual
7. Then the default setting appears.
Example: DCV, Auto, 100mV range
Vm
SDC
AUTO
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BASIC MEASUREMENT
ACV
DCV
ACI
DCI
2/4W/Hz/P
TEMP
Overview
Basic Measurement Overview ................................ 25
Refresh Rate ........................................................... 25
Reading Indicator ................................................... 26
Manual/Automatic Triggering ................................ 27
Voltage
AC/DC Voltage Measurement ................................. 27
Select Voltage Range .............................................. 28
Voltage Conversion Table ....................................... 30
Crest Factor Table ................................................... 31
Current
AC/DC Current Measurement ................................ 32
Select Current Range .............................................. 33
Resistance
2W/4W Resistance Measurement ........................... 34
Select Resistance Range ......................................... 35
Diode
Diode Test .............................................................. 37
Continuity
Continuity Test ....................................................... 38
Set Continuity Threshold ........................................ 39
Select Beeper Setting ............................................. 40
Frequency/
Period
Frequency/Period Measurement ............................ 41
Select Frequency/Period Voltage Range ................. 42
continued next page
BASIC MEASUREMENT
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GDM-8261 User Manual
Temperature
Temperature Measurement .................................... 43
Select Thermocouple Type ..................................... 44
Set Reference Junction Temperature (T-CUP) ........ 45
Select Temperature Sensor Type ............................ 46
Set User RTD ......................................................... 47
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BASIC MEASUREMENT
Background
Basic measurement refers to the eight types of
measurements assigned to the upper row keys on the front
panel.
ACV
DCV
ACI
DCI
2/4W/Hz/P
TEMP
Measurement
type
ACV
AC Voltage
DCV
DC Voltage
ACI
AC Current
DCI
DC Current
2/4W
2-wire and 4-wire Resistance
Diode/Continuity
Hz/P
Frequency/Period
TEMP
Celsius/Fahrenheit Temperature
Advanced
measurement
Advanced measurement (page 55) mainly refers to the
operation using the result obtained from one or more of the
basic measurements.
Background
Refresh rate defines how frequently the GDM-8261
captures and updates measurement data. A faster refresh
rate yields a lower accuracy and resolution. A slower
refresh rate yields a higher accuracy and resolution.
Consider these tradeoffs when selecting the refresh rate.
For DC measurements, the frequency of the refresh rate
depends on the rate settings (S, M, F) and the ADC speed
settings (Accurate, Quick) (page 90 ).
For AC measurements, the refresh rate (S, M, F) is
directly tied to the AC bandwidth settings (page 84).
For further details, please see the specifications.
Basic Measurement Overview
Refresh Rate
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GDM-8261 User Manual
Refresh Rate
Function
S M F
(Readings/s)
Continuity / Diode
100
200
300
DCV/DCI/100Ω~
100MΩ (Accurate)
5
60
240
DCV/DCI/100Ω~
100MΩ (Quick)
30
600
2400
ACV/ACI
1.2
(sec/reading)
3.38
30
Frequency / Period
1
10
100
Selection steps
1. Press the Shift key followed by
the AUTO (RATE) key. The
refresh rate switches to the next.
/ EXITSHIFT
AUTO
RATE
2. The refresh rate indicator shows
the current status.
S→M→F→S
Background
The reading indicator next to the 1st display flashes
according to the refresh rate setting.
V
When no data is
captured
When there is no captured data, the reading indicator
flashes once every two seconds (slower than the normal
refresh rate), indicating the DMM is in standby mode.
Reading Indicator
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BASIC MEASUREMENT
Automatic
triggering
(default)
The GDM-8261 triggers according to the refresh rate.
See the previous page for refresh rate setting details.
Manual
triggering
Press the Trig key to trigger
measurement manually. The trigger
must be set to external (EXT) for
manual triggering. See page 76.
TRIG
Voltage type
AC
0 ~ 750V
DC
0 ~ 1000V
1. Activate ACV/
DCV
Press the ACV (AC Voltage) key or
DCV (DC Voltage) key.
ACVorDCV
2. ACV/DCV
mode display
appears
Vm
SAC AUTO
AC or DC + V
Indicates AC, DC voltage
AUTO
Indicates Automatic range selection
100mV
2nd display shows the Voltage range
3. Connect the
test lead and
measure
Connect the test lead between the V
and the COM port. The display
updates the reading.
INPUT
V W
COM
Manual/Automatic Triggering
AC/DC Voltage Measurement
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GDM-8261 User Manual
Auto range
To turn the automatic range selection
On/Off, press the AUTO key.
AUTO
Manual range
Press the Up or the Down key to select
the range. The AUTO indicator turns
Off automatically. If the appropriate
range is unknown, select the highest
range.
Selection list
Range
Resolution
Full scale @ slow rate
100mV
0.1µV
119.9999mV
1V
1µV
1.199999V
10V
10µV
11.99999V
100V
100µV
119.9999V
750V (AC)
1mV
750.000V
1000V (DC)
1mV
1000.000V
Note:
For more detailed parameters, see the
specification s on page 212.
DC Voltage
Range Note:
DC voltages with AC components cannot be accurately
measured if the DC+AC component exceed the ADC
dynamic range for the selected DC range. Any voltage
exceeding the ADC dynamic range will be clipped at the
upper/lower range limit. Under these conditions the range
that is chosen with the Auto range function may be too
small.
Example:
A
+2V
0V
-2V
C D
B
E
DC 1V Range
A,B: Input exceeds the ADC
dynamic range.
C,D: The DCV offset causes
the input to exceed the upper
ADC dynamic range.
E: The DCV offset causes the
input to exceed the lower
ADC dynamic range.
Select Voltage Range
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BASIC MEASUREMENT
The DC voltage range should be manually selected when
any of the following conditions are true:
1. When DCV measurement is used.
2. When the signals being measured contain both DC
and AC components.
3. When the amplitude of the AC component in the
measured signal is higher or lower than the dynamic
range of the range being currently selected by
auto-range function.
DCV Voltage
Range Selection
List
DCV Range
ADC Dynamic Range
DC100mV
max±200mV
DC1V
max±2V
DC10V
max±20V
DC100V
max±200V
DC1000V
max±1000V
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GDM-8261 User Manual
Waveform
Peak to Peak
AC
(True RMS)
DC
Sine
PK-PK
2.828
1.000
0.000
Rectified Sine
(full wave)
PK-PK
1.414
0.435
0.900
Rectified Sine
(half wave)
PK-PK
2.000
0.771
0.636
Square
PK-PK
2.000
1.000
0.000
Rectified
Square
PK-PK
1.414
0.707
0.707
Rectangular
Pulse
PK-PK
X
Y
2.000
2K
K=
)2
( DD
D=X/Y
2D
D=X/Y
Triangle
Sawtooth
PK-PK
3.464
1.000
0.000
Voltage Conversion Table
This table shows the relationship between AC and DC reading in various
waveforms.
30
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BASIC MEASUREMENT
Background
Crest factor is the ratio of the peak signal amplitude to the
RMS value of the signal. It determines the accuracy of AC
measurement.
If the crest factor is less than 3.0, voltage measurement will
not result in error due to dynamic range limitations at full
scale.
If the crest factor is more than 3.0, it usually indicates an
abnormal waveform as seen from the below table.
Waveform
Shape
Crest factor
Square wave 1.0
Sine wave 1.414
Triangle
sawtooth
1.732
Mixed
frequencies
1.414 ~ 2.0
SCR output
100% ~ 10%
1.414 ~ 3.0
White noise
3.0 ~ 4.0
AC Coupled
pulse train
>3.0
Spike
>9.0
Crest Factor Table
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GDM-8261 User Manual
Background
The GDM-8261 has two input ports for current
measurement. A LO port for current less than 1.2A and a
10A port for measurements up to 10A.
The GDM-8261 also features a ―Current Input Port
Auto-Detect‖ feature (default, off). For details, see page
86.
Current type
AC
0 ~ 10A
DC
0 ~ 10A
1. Activate ACI/
DCI
Press the ACI (AC Current) key or
the DCI (DC Current) key.
ACI
or
DCI
2. ACI/DCI mode
display appears
A
SAC AUTO
AC or DC + A
Indicates AC or DC Current
(Note: AC = true RMS)
AUTO
Indicates Automatic range selection
10A
2nd display shows the Current range
3. Connect the
test lead and
measure
Connect the test lead between the 10A and COM port or
LO and COM port, depending on the current.
For current ≤ 1.2A use the LO port; For current up to
10A use the 10A port. The display updates the reading.
0~1.2A
LO
COM
MAX
10A
1.2A
MAX
0~10A
LO
COM
MAX
10A
1.2A
MAX
AC/DC Current Measurement
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BASIC MEASUREMENT
Auto range
To turn the automatic range
selection On/Off, press the AUTO
key.
AUTO
Manual range
Press the Up or the Down key to
select the range. AUTO indicator
turns Off automatically. If the
appropriate range is unknown, select
the highest range.
Selection list
Range
Resolution
Full scale @ slow rate
100µA(DC only)
0.1nA
119.9999µA
1mA
1nA
1.199999mA
10mA
10nA
11.99999mA
100mA
0.1µA
119.9999mA
1A
1µA
1.199999A
10A
10µA
10.00000A
DC Current
Range Note:
DC currents with AC components cannot be accurately
measured if the DC+AC component exceed the ADC
dynamic range for the selected DC range. Any current
exceeding the ADC dynamic range will be clipped at the
upper/lower range limit. Under these conditions the
range that is chosen with the Auto range function may be
too small.
A
+2mA
0A
-2mA
C D
B
E
DC 1mA Range
A,B: Input exceeds the ADC
dynamic range.
C,D: The DCI offset causes
the input to exceed the
upper ADC dynamic range.
E: The DCI offset causes the
input to exceed the lower
ADC dynamic range.
Select Current Range
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GDM-8261 User Manual
The DC current range should be manually selected when
the following conditions are true:
1. When DCI measurement is used.
2. When the signals being measured contain both DC
and AC components.
3. When the amplitude of the AC component in the
measured signal is higher or lower than the dynamic
range of the range being currently selected by
auto-range function.
DCI Current Range
Selection List
DCI Range
ADC Dynamic Range
DC 100uA
max±2mA
DC 1mA
max±2mA
DC 10A
max±40mA
DC 100A
max±200mA
DC 1A
max±1.2A
DC 10A
max±10A
Measurement
type
2-wire
Uses the standard V-COM ports.
Recommended for measuring resistances
larger than 1kΩ.
4-wire
Compensates the test lead effect using the
4W compensation ports, in addition to the
standard V-COM ports.
Recommended for measuring sensitive
resistances smaller than 1kΩ.
1. Activate
resistance
measurement
For 2-wire resistance measurement,
press the 2W/4W key once.
2/4W
For 4-wire resistance measurement,
press the 2W/4W key twice.
2/4W
2/4W
2W/4W Resistance Measurement
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BASIC MEASUREMENT
2. 2W/4W
resistance mode
display appears
W
S2WkAUTO
2W or 4W + Ω
Indicates 2W or 4W Resistance mode
AUTO
Indicates Automatic range selection
1K
2nd display shows the Resistance range
3. Connect the
test lead and
measure
Connect the test lead. For 2-wire resistance, use the Ω (V)
and the COM port. For 4-wire resistance, use the Ω (V)
and the COM port, plus the 4W sense, and LO port for
sensing. The display updates the reading.
2W connection
INPUT
V W
COM
4W connection
W
4W INPUT
SENSE
HI
LO
V W
COM
Auto range
To turn the automatic range
selection On/Off, press the AUTO
key.
AUTO
Manual range
Press the Up or the Down key to
select the range. AUTO indicator
turns Off automatically. If the range
is unknown, select the highest range.
Selection list
Range
Resolution
Full scale @ slow rate
100Ω
0.1μΩ
119.9999Ω
1kΩ
1μΩ
1.199999kΩ
10kΩ
10μΩ
11.99999kΩ
100kΩ
100μΩ
119.9999kΩ
1MΩ
1Ω
1.199999MΩ
Select Resistance Range
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GDM-8261 User Manual
10MΩ
10Ω
11.99999MΩ
100MΩ
100Ω
119.9999MΩ
Note
For more detailed range, see the specification s at
page 212.
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BASIC MEASUREMENT
Background
Diode test checks the forward bias characteristics of a
diode by running a constant forward bias current, approx.
1mA, through the DUT.
1. Activate diode
test
Press the
/
key once.
/
2. Diode mode
display appears
V
S
/ + V
Indicates Diode test
DIODE
2nd display shows the title
3. Connect the
test lead and
measure
Connect the test lead between the
/
and COM port; Anode-V,
Cathode-COM. The display updates
the reading.
INPUT
V W
COM
Diode Test
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GDM-8261 User Manual
Background
Continuity test checks that the resistance in the DUT is
low enough to be considered continuous (of conductive
nature).
1. Activate
continuity test
Press the
/
key twice.
/ /
2. Continuity
mode display
appears
W
S
+ Ω
Indicates Continuity test
CONT
2nd display shows the title
3. Connect the
test lead and
measure
Connect the test lead between the Ω
and the COM port. The display
updates the reading.
INPUT
V W
COM
Continuity Test
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BASIC MEASUREMENT
Background
Continuity threshold defines the maximum resistance
allowed in the DUT when testing the continuity.
Threshold Range
0 ~ 1000Ω, 1Ω resolution, 10Ω default
1. Activate
threshold setting
1. Press the Shift key, the 2nd
key,
the Right key. The measurement
menu appears.
/ EXITSHIFT
2ND
MENU
TRIG
2. Press the Down key, the Right
key, the Enter key. The
continuity threshold setting
appears.
TRIG
AUTO
ENTER
W
2. Edit threshold
1. Move the cursor (the flashing
digit) using the Left/Right key.
HOLD TRIG
2. Change the value using the
Up/Down key.
Range:
1 ~ 1000Ω, 1Ω resolution, default 10Ω
3. Go back to the
default display
Press the Enter key to confirm the
edited threshold. Press the Exit key
to go back to the default display.
AUTO
ENTER
/ EXITSHIFT
Set Continuity Threshold
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GDM-8261 User Manual
Background
Beeper setting defines how the GDM-8261 notifies the
continuity test result to the user. When the Beeper setting
is off it will also turn the keypad sound off.
Beeper
parameter
Pass
Beeps when the test result is pass
Fail
Beeps when the test result is fail
Off
Beep function is turned Off
1. Activate
beeper setting
menu
1. Press the Shift key followed by
the 2nd (Menu) key. The system
menu appears.
/ EXITSHIFT
2ND
MENU
2. Press the Down key. The beep
menu appears.
3. Press the Down key. The beep
setting appears.
2. Select the
beep setting
To change the setting, press the
Up/Down key.
Beeper type:
Pass (beep when pass), Fail (beep when
fail, default), Off (beep off)
3. Go back to the
default display
Press the Enter key to confirm.
Press the Exit key to go back to the
default display.
AUTO
ENTER
/ EXITSHIFT
Select Beeper Setting
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BASIC MEASUREMENT
1. Activate
frequency/period
measurement
To measure Frequency, press the
Hz/P key once.
Hz/P
To measure the Period, press the
Hz/P key twice.
Hz/P Hz/P
2. Frequency
(Period) mode
display appears
HzM
SAUTO
Hz (S)
Indicates Frequency (period) measurement
AUTO
Indicates Automatic range selection
FREQ
(PERIOD)
2nd display shows the measurement mode
3. Connect the
test lead and
measure
Connect the test lead between the V
and the COM port. The display
updates the reading.
INPUT
V W
COM
Frequency/Period Measurement
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GDM-8261 User Manual
Frequency/Period
mode
To select between period/frequency
voltage range, press the 2nd key
twice.
2ND 2ND
Auto range
To turn the automatic range
selection On/Off, press the AUTO
key.
AUTO
Manual range
Press the Up or the Down key to
select the range. AUTO indicator
turns Off automatically. If the
appropriate range is unknown, select
the highest range.
Range
Frequency
3Hz~300kHz
Period
3.3µs ~333.3ms
Voltage
Range
100mV~750V
Select Frequency/Period Voltage Range
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BASIC MEASUREMENT
Background
The GDM-8261 can measure temperature using either
thermocouples or RTD sensors. For thermocouples, the
GDM-8261 accepts a thermocouple input and calculates
the temperature from the voltage fluctuation. The
thermocouple type and reference junction temperature
are also considered.
For RTD sensors, the GDM-8261 calculates voltage
based on the resistance of the chosen RTD.
1. Activate
temperature
measurement
For Celsius units, press the TEMP
key once.
TEMP
For Fahrenheit units, press the
TEMP key twice.
TEMP
TEMP
2. Temperature
mode display
appears
C
S
°C
Indicates Temperature measurement
TYPE J
2nd display shows the
thermocouple/RTD type
3. Connect the
test lead and
measure
Connect the sensor lead between the V and the COM
port for thermocouple and 2W RTD measurements. For
4W RTD measurements, also connect the sense HI and
LO ports to the sensor. The display updates the reading.
Thermocouple
INPUT
V W
COM
2W RTD
INPUT
V W
COM
4W RTD
W
4W INPUT
SENSE
HI
LO
V W
COM
Temperature Measurement
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GDM-8261 User Manual
Range
RTD: -200°C ~ +600°C (sensor dependent)
Thermocouple: -210°C ~ +1820°C (sensor dependent)
Background
The GDM-8261accepts thermocouple inputs and
calculates the temperature from the voltage difference of
two dissimilar metals. Thermocouple type and reference
junction temperature are also considered.
Parameter
Thermocouple
Range
Resolution
E
-200 to +1000°C
0.002 °C
J
-210 to +1200˚C
0.002 °C
T
-200 to +400°C
0.002 °C
K
-200 to +1372˚C
0.002 °C
N
-200 to +1300˚C
0.003 °C
R
-50 to +1768˚C
0.01 °C
S
-50 to +1768˚C
0.01 °C
B
+350 to +1820˚C
0.01 °C
1. Open sensor
selection menu
Press the Shift key, then the TEMP
(Sensor) key. The sensor selection
menu appears on the display.
/ EXITSHIFT
TEMP
SENSOR
2. Select sensor
type
Press the Left and Right arrow keys
and select T-CUP (thermocouple).
HOLD TRIG
3. Select sensor
Press the Down key twice. The
sensor selection menu appears on
the display.
Select Thermocouple Type
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BASIC MEASUREMENT
4. Select sensor
type
Press the Up/Down key. The
thermocouple type switches to the
next one.
5. Confirm and
go back to the
default display
Press the Enter key to confirm.
Press the Exit key to go back to the
default display.
AUTO
ENTER
/ EXITSHIFT
Background
When a thermocouple is connected to the GDM-8261,
the temperature difference between the thermocouple
lead and the GDM-8261 input terminal should be taken
into account and be cancelled; otherwise an erroneous
temperature might be added.
Type
Range
Resolution
SIM
(simulated)
0 ~ +50°C
0.01°C
The terminal temperature is manually defined by the user.
Default value: 23.00
1. Open
reference
junction menu
Press the Shift key, then the TEMP
(Sensor) key. The sensor selection
menu appears on the display.
/ EXITSHIFT
TEMP
SENSOR
Press the Left and Right arrow keys
and select T-CUP (thermocouple).
HOLD TRIG
Press Down, Right arrow key and
then Down again. The reference
junction selection menu appears on
the display.
TRIG
Set Reference Junction Temperature (T-CUP)
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GDM-8261 User Manual
2. Edit reference
temperature
Use the Left/Right key to move the
cursor, and use the Up/Down key to
change the value.
Default: 23.00
HOLD TRIG
Press the Enter key to confirm the
value, or the Exit key to cancel. The
display goes back to the previous
menu.
AUTO
ENTER
(confirm)
/ EXITSHIFT
(cancel)
Background
The GDM-8261 supports a number of thermocouple
types as well as 2 or 4 wire RTD. It is important to
specify the type of temperature sensor used.
Parameter
RTD type
Range
Resolution
All (based on
PT100)
-200~600°C
0.001°C
1. Open sensor
selection menu
Press the Shift key, then the TEMP
(Sensor) key. The sensor selection
menu appears on the display.
/ EXITSHIFT
TEMP
SENSOR
2. Select sensor
type
Press the Left and Right arrow keys
to highlight the 2WRTD or 4WRTD
sensor type. Press the down key to
go to the next menu level.
HOLD TRIG
Select Temperature Sensor Type
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BASIC MEASUREMENT
3. Select sensor
Press the Up and Down keys to
highlight the RTD sensor type.
RTD Type:
PT 100, PT 3916, PT 385, F 100, D 100,
USER
4. Confirm and
go back to the
default display
Press the Enter key to confirm.
Press the Exit key to go back to the
default display.
AUTO
ENTER
/ EXITSHIFT
Background
The USER setting allows any custom RTD sensor
coefficients to be used. The USER setting can configure
the alpha, beta and delta coefficients, as defined by the
Callendar–Van Dusen equation.
Coefficient range
Alpha
0.000000~10.00000
Beta
0.000000~10.00000
Delta
0.000000~10.00000
1. Open sensor
selection menu
Press the Shift key, then the TEMP
(Sensor) key. The sensor selection
menu appears on the display.
/ EXITSHIFT
TEMP
SENSOR
2. Select sensor
type
Press the Left and Right arrow keys
and select 2WRTD or 4WRTD
HOLD TRIG
Set User RTD
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GDM-8261 User Manual
Press the Down key twice. The RTD
selection menu appears on the
display.
Use the Up/Down keys to select
USER.
3. Open USER
type menu
Press Enter. The alpha coefficient
menu appears on the display.
AUTO
ENTER
4. Edit coefficient
values
Use the Left/Right key to move the
cursor, and use the Up/Down key to
change the coefficient value.
Default: 0.00385
HOLD TRIG
Press the Enter key to confirm the
value and move onto to the next
coefficient.
Default: Alpha 0.00385, Beta
00.10863, Delta 1.49990
AUTO
ENTER
(confirm)
Press the Exit key to cancel at any
time. The display goes back to the
previous menu.
/ EXITSHIFT
(cancel)
48
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DUAL MEASUREMENT
Background
The dual measurement mode allows you to use the 2nd
display to show another item, thus viewing two different
measurement results at once.
When the multimeter is used in dual measurement mode,
both displays are updated from either a single
measurement or from two separate measurements.
If the primary and secondary measurement modes have
the same range, rate and rely on the same fundamental
measurement, then a single measurement is taken for
both displays; such as ACV and frequency/period
measurements.
If the primary and secondary displays use different
measurement functions, ranges or rates, then separate
measurements will be taken for each display. For example,
ACV and 2W/4W resistance measurements.
Example Dual
Measurement
Applications
Combination
Applications
DCV
ACV
Measure DC signals that have AC
components*.
For example:
Measure the DC offset and AC noise
from an amplifier output.
Measure the DC output voltage and
ripple from a DC power supply.
* Ripple or the AC noise frequency
must be within the DMM’s
measurable AC bandwidth for the
noise to be measured.
DUAL MEASUREMENT
Dual Measurement
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GDM-8261 User Manual
Amplifier Output
INPUT
V W
COM
V
V
o
T
AMP
V
o
AC Noise
DC offset
DC Power Supply Output
DC output
DC
Power
Supply
INPUT
V W
COM
V
AC rippleV
T
DCV
DCI
Monitor the voltage and current
present on a component in a circuit
or the output voltage and current of
a DC power supply.
Monitor Voltage and Current
INPUT
V W
V
A
LO
COM
0~1.2A
0~10A
Load
DC
Power
Supply
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DUAL MEASUREMENT
ACV
Hz
Measure the frequency response of
devices such as amplifiers or
buffers*.
* The frequencies of the amplifier
output must be within the DMM’s
measurable AC bandwidth for the
amplitude at a spot frequency to be
measured accurately.
Frequency Response
INPUT
V W
COM
V
V
o
f
AMP
V
o
V
in
V
in
f
The following table shows the available measurement
combinations.
1st Display
[2]
2nd Display
[2]
ACV
DCV
ACI
DCI
Hz/P
2W/4W
[1]
ACV
● ● ● ● ●
—
DCV
● ● ● ● ●
—
ACI
● ● ● ● ●
—
DCI
● ● ● ● ●
—
Hz/P
● ● ● ● ●
—
2W/4W
[1]
— — — — —
●
Note
[1] 2W/4W measurements in combination with other
measurements are possible but may not be practical as
the measurement accuracy is not guaranteed.
[2] When two different measurements are taken, there is a
switching delay between the first measurement and the
second measurement.
1st Measurement
item setting
Choose a basic measurement from
the above table. Example: press the
ACI key.
Page 23
Example:
ACI
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GDM-8261 User Manual
2nd
Measurement
item setting
Press the 2nd key, then the target
item (example: ACV). The display
updates the measurement result.
(example: ACI + ACV)
2ND
ACV
2ND
AUTOAC
V
Am
SAUTOAC
1st Display
Shows the primary measurement result
2nd Display
Shows the secondary measurement
result
2ND
Indicates that dual measurement is
active
Editing 1st or
2nd
measurement
item settings
After the secondary measurement function has been
activated, the rate, range and measurement item can be
edited for either the primary or secondary display. Note
however, it is more practical to configure the first or
second measurement items before activating dual
measurement mode.
1. Select active
display
Toggle whether the primary or
secondary display is the active
display by pressing the 2ND key:
Primary display: 2ND is not
visible on the display
Secondary display: 2ND is
visible on the display
Do not hold the 2ND key. This will turn
the dual measurement off.
2ND
(toggle
active display )
2. Edit active
display settings
Edit the range, rate or measurement
item for the active display in the
same way as for single measurement
operation. See the Basic
Measurement chapter for details.
Page 23
Turn Off 2nd
Measurement
To turn Off the 2nd measurement,
press and hold the 2nd key for more
than 1 second.
2ND
(hold
1 sec.)
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DUAL MEASUREMENT
Connect the test
leads and
measure
When using the dual measurement function, the
connection method and number of test leads required
depends on the measurement combination. Use the
connect diagrams below as guide when taking dual
measurements.
Voltage and Frequency/Period Measurement
INPUT
V W
COM
2W/4W Resistance Measurement
W
4W INPUT
SENSE
HI
LO
V W
COM
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GDM-8261 User Manual
Voltage/Frequency/Period and Current
Measurement
W
4W INPUT
SENSE
HI
LO
V W
COM
0~1.2A
0~10A
Load
Note: DC Current measurements will be displayed
as a negative value as the polarity of the current
leads has been reversed.
Please take into account the resistance of the test
leads and internal resistance of the current
connection as it is in series with the test circuit.
The above measuring configuration is used to
measure the voltage present on the resistance
under test and the current through the resistance
under test when using the DCI/DCV or ACI/ACV
dual measurement function.
54
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ADVANCED MEASUREMENT
/
dBm
Hz/PdBMX/MN
FILTER
REL
REL#
HOLD
COMP
TRIG
INT/EXT
2/4W
MATH
Overview
Advanced Measurement Overview ......................... 56
Refresh Rate ........................................................... 56
Reading Indicator ................................................... 57
Common Attribute: Manual/Automatic Triggering . 57
dBm/dB
dBm/dB/W Measurement ...................................... 58
Measure dBm/W .................................................... 58
Measure dB ............................................................ 59
Max/Min
Max/Min Measurement .......................................... 61
Relative
Relative Value Measurement .................................. 62
Hold
Hold Measurement ................................................ 64
Compare
Compare Measurement .......................................... 65
Math
Measure MX+B ....................................................... 68
Measure 1/X ........................................................... 70
Measure Percentage ............................................... 70
Statistics Calculations ............................................ 71
ADVANCED
MEASUREMENT
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GDM-8261 User Manual
Background
Advanced measurement mainly refers to the type of
measurement which uses the result obtained by one of
the basic measurements: ACV, DCV, ACI, DCI, 2/4W,
Diode/Continuity, Frequency/Period, and Temperature.
/
dBm
Hz/PdBMX/MN
FILTER
REL
REL#
HOLD
COMP
TRIG
INT/EXT
2/4W
MATH
Advanced
Measurement
Basic Measurement
AC/DCV
AC/DCI
2/4W
Hz/P
TEMP
dB
● — — — —
—
dBm
● — — — —
—
Max/Min
● ● ● ● ●
—
Relative
● ● ● ● ●
—
Hold
● ● ● ● ●
—
Compare
● ● ● ● ●
—
Math
● ● ● ● ●
—
Background
Refresh rate defines how frequently the GDM-8261
captures and updates measurement data. A faster refresh
rate yields a lower accuracy and resolution. A slower
refresh rate yields a higher accuracy and resolution.
Consider these tradeoffs when selecting the refresh rate.
For DC measurements, the frequency of the refresh rate
depends on the rate settings (S, M, F) and the ADC speed
settings (Accurate, Quick) (page 90 ).
For AC measurements, the refresh rate (S, M, F) is
directly tied to the AC bandwidth settings (page 84).
For further details, please see the specifications.
Advanced Measurement Overview
Refresh Rate
56
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ADVANCED MEASUREMENT
Refresh Rate
Function
S M F
(Readings/s)
Continuity / Diode
100
200
300
DCV/DCI/100Ω~
100MΩ (Accurate)
5
60
240
DCV/DCI/100Ω~
100MΩ (Quick)
30
600
2400
ACV/ACI
1.2
(sec/reading)
3.38
30
Frequency/Period
1
10
100
Selection steps
1. Press the Shift key followed by
the AUTO (RATE) key. The
refresh rate switches to the next.
/ EXITSHIFT
AUTO
RATE
2. The refresh rate indicator shows
the current status.
S→M→F→S
Background
The reading indicator next to the 1st display flashes
according to the refresh rate when the captured data is
updated on the display.
Vm
When no data is
captured
When there is no captured data, the reading indicator
flashes once every two seconds (slower than the normal
refresh rate), indicating the DMM is in the waiting mode.
Automatic
triggering
(default)
The GDM-8261triggers according to the refresh rate. See
the previous page for refresh rate setting details.
Reading Indicator
Common Attribute: Manual/Automatic Triggering
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GDM-8261 User Manual
Manual
triggering
Press the Trig key to trigger the
measurement manually. The trigger
must be set to external (EXT) for
manual triggering. See page 76.
TRIG
Applicable to
ACV DCV
Background
Using the ACV or DCV measurement result, the
GDM-8261 calculates the dB, dBm or W value based on
a reference resistance value in the following way.
dBm
10 x log10 (1000 x Vreading2 / Rref)
dB
dBm – dBmref
W Vreading2/Ref
Parameters
Vreading
Input Voltage, ACV or DCV
Rref
Reference resistance simulating an
output load
dBmref
Reference dBm value
Activate dBm
Press the Shift key followed by the
/
key. The 1st display shows
dBm, and the 2nd display shows the
reference resistance.
/ EXITSHIFT
/
dBm
dBm result
appears
W
dB
SDC
m
dBm
Indicates dBm measurement
600Ω
2nd display indicates the reference
resistance
dBm/dB/W Measurement
Measure dBm/W
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ADVANCED MEASUREMENT
Select reference
resistance
To change the reference resistance,
press the Up/Down key. The new
resistance appears in the 2nd display.
The following is the resistance list.
2 4 8
16
50
75
93 110
124
125
135
150
250
300
500
600
800
900
1000
1200
8000
View result in
Watts
When the reference resistance is less than 50Ω, it is
possible to calculate the watt value. If the reference
resistance is greater than 50Ω then this step can be
ignored.
To calculate the power, press the
Shift key followed by the
/
key
again.
/ EXITSHIFT
/
dBm
Watt result
appears
W
dB
SDC
m
W
W Indicates W measurement
16Ω
2nd display indicates the reference
resistance
Deactivate
dBm/W
measurement
To cancel the dBm/W
measurement, press the Shift key
followed by the
/
key, or simply
activate another measurement.
/ EXITSHIFT
/
dBm
Background
dB is defined as [dBm−dBmref]. When the dB
measurement is activated, the GDM-8261 calculates the
dBm using the reading at the first moment and stores it
as dBmref.
Activate dB
Press the Shift key followed by the
Hz/P key. The 1st display shows dB,
and the 2nd display shows the
current Voltage reading.
/ EXITSHIFT
Hz/P
dB
Measure dB
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GDM-8261 User Manual
dB result appears
dB
SDC
Vm
dB
Indicates dB measurement
-00.617mV
Indicates the present Voltage reading
dBmref
Press the 2nd key to see the dBm
ref value.
2ND
Deactivate dB
measurement
To cancel the dB measurement,
press the Shift key followed by the
Hz/P key, or simply activate another
measurement.
/ EXITSHIFT
Hz/P
dB
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ADVANCED MEASUREMENT
Applicable to
ACV
DCV
ACI
DCI
2/4W
Hz/P
TEMP
Background
Maximum and Minimum measurement stores the highest
(maximum) or lowest (minimum) reading and shows it on
the 1st display when the 2nd key is pressed.
1. Activate
Max/Min
For Max measurement, press the
MX/MN key once.
MX/MN
For Min measurement, press the
MX/MN key twice.
MX/MN
MX/MN
2. Max (Min)
result is
activated
MAXS
V
MAXAUTOAC
MIN (MAX)
Indicates Min (Max) measurement is
activated
1V
2nd display shows the Min (Max) range
View Max
(Min)value
Press the 2nd key to view the Max
(Min) value.
2ND
Max (Min)
measurement
appears
V
MAXS
MAXAUTOAC
2nd display
Indicates that the Max (Min) value is
displayed on the 1st display
1st display
Shows the Max (Min)value at full scale
Deactivate
Max/Min
measurement
To cancel the Max/Min
measurement, press the MX/MN
key for 2 seconds, or simply activate
another measurement.
MX/MN
(hold for 2
seconds)
Max/Min Measurement
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GDM-8261 User Manual
Applicable to
ACV
DCV
ACI
DCI
2/4W
Hz/P
TEMP
Background
Relative measurement stores a value, typically the data at
the moment, as the reference. The following measurement
is shown as the delta between the reference. The reference
value will be cleared upon exit.
1. Activate
Relative
measurement
Press the REL key. The
measurement reading at the
moment becomes the reference
value.
REL
2. Relative
measurement
display appears
V
RELSAC
REL
Indicates Relative value measurement
2nd display
Shows the measurement range.
1st display
Shows the delta between the current
measurement data and the reference value
View reference
(REL) value
Press the 2nd key to view the
reference (REL) value.
2ND
Reference
(REL)
measurement
display appears
V
2nd display
Indicates that the reference (REL) value is
displayed on the 1st display
1st display
Shows the reference (REL)value at full
scale
Manuall y set
the reference
value
1. To set the reference (REL)
value manually, press the Shift
key followed by the REL key.
The setting appears.
/ EXITSHIFT
REL
REL#
Relative Value Measurement
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ADVANCED MEASUREMENT
V
REL
Indicates Relative measurement
1st display
Shows the reference value (to full scale)
2nd display
Indicates Relative value modification
2. Use the Left/Right key to
move the flashing point
(cursor), and use the
Up/Down key to change the
value.
HOLD TRIG
3. Press the Enter key to confirm
the value, or the Exit key to
cancel. The display switches to
measurement.
AUTO
ENTER
(confirm)
/ EXITSHIFT
(cancel)
Deactivate
Relative
measurement
To cancel the Relative
measurement, press the REL key
again, or simply activate another
measurement.
REL
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GDM-8261 User Manual
Applicable to
ACV
DCV
ACI
DCI
2/4W
Hz/P
TEMP
Background
The Hold Measurement function retains the current
measurement data and updates it only when it exceeds
the set threshold (as a percentage of the retained value).
1. Activate Hold
measurement
Press the Hold key.
HOLD
2. Hold
measurement
display appears
V
HOLDSAC
HOLD
Indicates Hold measurement
2nd display
Shows the Hold threshold
1st display
Shows the measurement data.
3. Select hold
threshold
Select the hold threshold using the
Up/Down key. The 2nd display
changes accordingly.
Range
0.01%, 0.1%, 1%, 10%
Deactivate Hold
measurement
To cancel the Hold measurement,
press the Hold key for 2 seconds, or
simply activate another
measurement.
HOLD
Hold Measurement
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ADVANCED MEASUREMENT
Applicable to
ACV
DCV
ACI
DCI
2/4W
Hz/P
TEMP
Background
Compare measurement checks and updates if the
measurement data stays between the upper (high) and
lower (low) limit specified.
1. Activate
Compare
measurement
Press the Shift key, then the Hold
(Comp) key.
/ EXITSHIFT
HOLD
COMP
2. High limit
setting
V
1st display
Shows the high limit value
2nd display
Indicates high limit setting
1. Use the Left/Right key to move
the cursor (flashing point)
between high/low setting, digits,
and decimal point.
HOLD TRIG
2. Change the parameter using the
Up/Down key.
3. Press the Enter key to confirm
editing and move to the low
limit setting.
AUTO
ENTER
Compare Measurement
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GDM-8261 User Manual
3. Low limit
setting
V
1st display
Shows the low limit value
2nd display
Indicates low limit setting
1. Use the Left/Right key to move
the cursor (flashing point)
between high/low setting, digits,
and decimal point.
HOLD TRIG
2. Change the parameter using the
Up/Down key.
3. Press the Enter key to confirm
editing. The compare
measurement starts right away.
AUTO
ENTER
4. Compare
measurement
appears
V
SAC
COMP
COMP
Indicates Compare mode
2nd display
Shows the compare measurement result:
Pass, High, or Low.
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ADVANCED MEASUREMENT
5. Result
High
If the 2nd display shows
High, the result is above
the High limit.
Digital I/O: FAIL Out (Pin 6) and
HIGH Limit FAIL Out (Pin 7) are
activated.
Low
If the 2nd display shows
Low, the result is below
the Low limit.
Digital I/O: FAIL Out (Pin 6) and LOW
Limit FAIL Out (Pin 8) are activated.
Pass
If the 2nd display shows
Pass, the result is staying
between the High and the
Low limit.
Digital I/O: PASS Out (Pin 5) is
activated.
Digital I/O
The Compare measurement result
comes out from the rear panel
Digital I/O terminal. For the
terminal details, see page 121.
Deactivate
Compare
measurement
To cancel the Compare
measurement, press the Shift key
followed by the Hold (Comp) key, or
simply activate another
measurement.
/ EXITSHIFT
HOLD
COMP
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GDM-8261 User Manual
Applicable to
ACV
DCV
ACI
DCI
2/4W
Hz/P
TEMP
Background
Math measurement runs four types of mathematical
operations, MX+B, 1/X, Percentage and Stats, based on
the other measurement results.
Math type
MX+B
Multiplies the reading (X) by the factor (M)
and adds/subtracts offset (B).
1/X
Inverse. Divides 1 by the reading (X).
Percentage
Runs the following equation.
(ReadingX – Reference)
x 100%
Reference
Stats
Performs standard deviation calculations
on measurement data.
1. Activate MX+B
Press the Shift key followed by the
2/4W (Math) key. The MX+B
setting appears.
/ EXITSHIFT
2/4W
MATH
2. Set the factor
(M)
1st display
Shows the factor (M)
2nd display
Indicates MX+B (The letter M flashes)
1. Use the Left/Right key to move
the cursor (flashing point)
between the factor, digits, and
decimal point.
HOLD TRIG
Math Measurement
Measure MX+B
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ADVANCED MEASUREMENT
2. Change the parameter using the
Up/Down key.
3. Press the Enter key to confirm
editing and move to offset
setting.
AUTO
ENTER
3. Set the offset
(B)
V
1st display
Shows the offset (B)
2nd display
Indicates MX+B (The letter B flashes)
1. Use the Left/Right key to move
the cursor (flashing point)
between the offset, digits and
decimal point.
HOLD TRIG
2. Change the parameter using the
Up/Down key.
3. Press the Enter key to confirm
the editing. The MX+B
measurement result appears.
AUTO
ENTER
4. View MX+B
SDC
V
AUTO
MATH
m
1st display
Shows the calculated result
2nd display
Indicates MX+B
MATH
Indicates Math operation
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GDM-8261 User Manual
1. Activate 1/X
Press the Shift key, the 2/4W (Math)
key, the Down key twice. The 1/X
setting appears.
/ EXITSHIFT
2/4W
MATH
2. View 1/X
Press the Enter key to view the 1/X
measurement result.
AUTO
ENTER
SAC
V
SAUTO
MATH
1st display
Shows the 1/X value
2nd display
Indicates 1/X
MATH
Indicates Math operation
1. Activate
Percentage
Press the Shift key, the 2/4W (Math)
key, the Up key twice. The Reference
setting appears. The Percentage is
calculated as:
[Reading−Reference]/Reference x
100%.
/ EXITSHIFT
2/4W
MATH
2. Set the
reference number
1st display
Shows the reference number
2nd display
Indicates Percentage setting
Measure 1/X
Measure Percentage
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ADVANCED MEASUREMENT
1. Use the Left/Right key to move
the cursor (flashing point)
between the digits and decimal
point.
HOLD TRIG
2. Change the parameter using the
Up/Down key.
3. Press the Enter key to confirm
editing.
AUTO
ENTER
3. View
Percentage
SDC
V
AUTO
MATH
1st display
Shows the calculated result
2nd display
Indicates the Percentage measurement
MATH
Indicates Math operation
Background
The Analyze Stats menu allows you to make statistical
calculations on a continuous or user-defined number of
measurement counts. The measurements supported
include, Maximum, Minimum, Average and Standard
deviation.
Number of
counts
User Defined
2~100,000 counts
Continuous
9,999,999 count
1. Activate
Statistics
Press the Shift key, the 2/4W (Math)
key, the Up key. The Analyze Stats
setting menu appears.
/ EXITSHIFT
2/4W
MATH
Statistics Calculations
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GDM-8261 User Manual
2. Set Count
Press the Enter key to set the
number of measurements (counts)
that will be used for the Stats
function. The Count menu appears.
AUTO
ENTER
1st display
Shows the count number as continuous
2nd display
Indicates the count setting
2a.Continuous
count
1. To set the count to Continuous
and to start measurement, press
Enter when CONTINU is
displayed on the 1st display.
2. Measurement starts
automatically.
AUTO
ENTER
2b. User-defined
count
1. To set a user-defined count
number, press the Left key
followed by Up when
CONTINU is displayed on the
screen. The Count setting menu
will appear.
HOLD
1st display
Shows the count number (2~100,000)
2nd display
Indicates the count setting
2. Use the Left/Right key to move
the flashing point (cursor), and
use the Up/Down key to change
the count number.
HOLD TRIG
3. Press the Enter key to confirm
editing and to start
measurement.
AUTO
ENTER
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ADVANCED MEASUREMENT
3. View Data
SDC AUTO
MATH
1st display
Shows the current count
number/measurement
2nd display
Indicates the count measurement mode.
MATH
Indicates Math operation
Press the 2nd key to cycle through
the different statistical data
measurements.
2ND
COUNT
Indicates the current measurement
count
MIN
Indicates the minimum data value
MAX
Indicates the maximum data value
AVG
Indicates the mean (average) value
STDEV
Indicates the standard deviation of the
data
Stop/Restart
Measuring
Press the SHIFT key and the
OUPUT key to stop or restart
measuring.
/ EXITSHIFT
ON/OFF
S:
Indicates the measurement has started
P:
Indicates the measurement has stopped
Exit
Press the SHIFT key and the 2/4W
key to exit.
/ EXITSHIFT
2/4W
MATH
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GDM-8261 User Manual
ACV
DCV
ACI
DCI
AUTO
RATE
MX/MN
FILTER
2ND
MENU
Refresh Rate
Refresh Rate Setting .............................................. 75
View Serial Number ............................................... 75
Trigger
Manual/Automatic Triggering ................................ 76
Use External Trigger ............................................... 76
Set Trigger Delay .................................................... 78
Digital Filter
Overview ................................................................ 79
Filter Setting .......................................................... 80
Display
Display Light Setting .............................................. 81
Display On/Off Setting (+ key lock) ....................... 82
Measurement
Configuration
Settings
D-Shift Settings...................................................... 82
Input Resistance Setting ........................................ 83
AC Bandwidth Setting ............................................ 84
Current Input Port Auto-Detect Setting ................. 86
ADC Settings
Auto-Zeroing .......................................................... 87
Auto-Gain .............................................................. 89
ADC Speed Setting ................................................. 90
Frequency/
Period settings
Input Port Selection ............................................... 91
Gate Time Setting .................................................. 92
Identification
Settings
Changing the Identification String ......................... 94
SYSTEM/DISPLAY
CONFIGURATION
74
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SYSTEM/DISPLAY CONFIGURATION
Background
Refresh rate defines how frequently the GDM-8261
captures and updates the measurement data. A faster
refresh rate yields a lower accuracy and resolution. Slower
refresh rates yield a higher accuracy and resolution.
Consider this trade-off when selecting the refresh rate.
The refresh rate settings are individually set for all
measurement modes except for ACV/ACI
measurements. ACV/ACI use the same refresh rate
settings.
Display/Range
A
SAC
S
6 ½ digits
M 5 ½ digits
F 4 ½ digits
Refresh rate
selection
Press the Shift key followed by the
AUTO (Rate) key. The refresh rate
indicator switches to the next rate
setting.
/ EXITSHIFT
AUTO
RATE
Refresh Rate
S→M→F→S
Background
View the serial number using the System menu.
Panel operation
1. Press the Shift key, the 2nd
(Menu) key, followed by the
down key. Then press the left
key repeatedly until the S/N
menu appears.
/ EXITSHIFT
2ND
MENU
HOLD
Refresh Rate Setting
View Serial Number
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GDM-8261 User Manual
2. Press the Down key. The serial
number is shown on the display.
1st display
Shows 2 characters (AA~ZZ).
2nd display
Shows 6 numbers (000000~99999).
3. Press the Enter key or the Exit
key to go back to the previous
display.
AUTO
ENTER
or
/ EXITSHIFT
Automatic
triggering
(default)
The GDM-8261 triggers according to the refresh rate.
See the previous page for refresh rate setting details.
Manual
triggering
Press the Trig key to trigger
measurement manually. See below
for details.
TRIG
Background
The GDM-8261 uses the internal trigger by default, for
example to count the frequency and the period. Using an
external trigger allows customized triggering conditions.
Signal
connection
Connect the external trigger signal to the Digital I/O
port located on the rear panel.
Trigger Setting
Manual/Automatic Triggering
Use External Trigger
76
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SYSTEM/DISPLAY CONFIGURATION
DB-9, female
Digital I/O pin
assignment
6
FAIL Out
7 8 9
1
2 3 4 5
High Limit FAIL Out
VCC Out
NC
PASS Out
External Trigger In
EOM Out
LOW Limit FAIL Out
Digital (chassis) Ground
1. Activate
external trigger
Press the Shift key followed by the
Trig (Int/Ext) key. The EXT
indicator appears on the display.
EXT
/ EXITSHIFT
TRIG
INT/EXT
2. Start trigger
Press the Trig key to start triggering
manually. The indicator turns
On.
Vm
SAUTOAC
TRIG
Reading indicator
The reading indicator does not flash before triggering
(can be on or off). After triggering, the indicator flashes
according to the external signal trigger timing.
Exit external
trigger
Press the Shift key followed by the
Trig key. The EXT indicator
disappears and the trigger goes back
to internal mode.
/ EXITSHIFT
TRIG
INT/EXT
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GDM-8261 User Manual
Background
Trigger delay defines the time delay between triggering
and measurement start. The default is set at 10ms.
Panel operation
1. Press the Shift key, the 2nd
(Menu) key, the Right key, the
Down key. The delay menu
appears.
/ EXITSHIFT
2ND
MENU
TRIG
2. Press the Down key. The delay
setting appears.
3. Move the flashing point (cursor)
using the Left/Right key.
Change the value using the
Up/Down key.
HOLD TRIG
4. Press the Enter key to confirm
editing and press the Exit key.
The display goes back to
previous mode.
AUTO
ENTER
/ EXITSHIFT
Range
0 ~ 9999ms, 1ms resolution
Set Trigger Delay
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SYSTEM/DISPLAY CONFIGURATION
Filter basics
The GDM-8261’s internal digital filter converts the
analog input signal into digital format before passing it to
internal circuits for processing. The filter affects the
amount of noise included in the measurement result.
Filter type
The digital filter averages a specific number of input
signal samples to generate one reading. The filter type
defines the averaging method. The following diagrams
highlight the differences between the Moving and
Repeating filter using 4 samples per reading.
Moving
(default)
The Moving filter takes in one new
sample and discards the oldest sample
per reading. This is the default behavior
when the digital filter is not specified,
and is recommended for most
applications except for the optional
scanner operation (page 101).
1Sample #
1st reading Sample 1 - 4
2nd reading Sample 2 - 5
32 4 5 6 7 8 9 10 11 12
3rd reading Sample 3 - 6
Repeating
The Repeating filter renews a whole
group of samples per reading. This
method is recommended when using
the optional scanner (page 101).
1Sample #
1st reading
Sample 1 - 4
2nd reading
Sample 5 - 8
32 4 5 6 7 8 9 10 11 12
3rd reading
Sample 9 - 12
Digital Filter Setting
Overview
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GDM-8261 User Manual
Filter count
Filter count defines the number of samples to be
averaged per reading. More samples offer low noise but
long delay. Less samples offer high noise but short delay.
Range
2 ~ 100
Turn on Filter
1. Press the Shift key followed by
the MX/MN (Filter) key.
/ EXITSHIFT
MX/MN
FILTER
1st display
Shows the filter count
2nd display
Shows the filter type (flashing)
2. Select the filter type using the
Up/Down key.
3. Move the cursor to filter count
using the Left/Right key.
Change the value using the
Up/Down key.
HOLD TRIG
4. Press the Enter key to confirm
editing. The Filter indicator
appears on the display.
AUTO
ENTER
Vm
SDC
FILT
FILT
Indicates manual Filter setting
Filter Setting
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SYSTEM/DISPLAY CONFIGURATION
Turn off Filter
Press the Shift key followed by the
MX/MN (Filter) key. The Filter
indicator will disappear from the
display.
/ EXITSHIFT
MX/MN
FILTER
Background
The display light setting adjusts the brightness of the
display reading. Use light 3 or more (brighter) when
working indoor; use light 2 or 1 (darker) when working
outdoor under the sun.
Level
5 (brightest) ~ 1 (darkest), default = 3
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. The system
menu appears.
/ EXITSHIFT
2ND
MENU
2. Press the Down key, then the
Right key twice. The light menu
appears.
TRIG
TRIG
3. Press the Down key. The light
level setting appears.
1st display
Shows the current display light level
Display Setting
Display Light Setting
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GDM-8261 User Manual
4. Select the level using the
Up/Down key.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Background
The display can be turned off when not used for a long
time. Note that when this function is used, the panel keys
are also locked except for the Output On/Off key. The
display is turned on by default. The display needs to be
switched off when using the fastest measurement speed
(2400rdg/sec). See page 90 for details.
Panel operation
1. Press the Output On/Off key
once. The display will be turned
off and the panel keys become
locked.
ON/OFF
2. To on the display and enable the
panel keys, press the Output
On/Off key again.
ON/OFF
Background
The D-Shift setting automatically shifts the decimal point
depending on the measurement. If D-Shift is turned off,
the measured readings will be displayed at the full 6
2
1
digits with a fixed decimal place. The D-Shift setting is on
by default.
D-Shift
On, Off (default, On)
Panel operation
1. Press the Shift key, the 2nd
(Menu) key followed by the
Right key. The MEAS menu
appears.
/ EXITSHIFT
2ND
MENU
TRIG
Display On/Off Setting (+ key lock)
Measurement Configuration Settings
D-Shift Settings
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SYSTEM/DISPLAY CONFIGURATION
2. Press the down key, followed by
the right key twice to enter the
D-SHIFT menu.
TRIG
TRIG
3. Press the Down key. The
D-Shift setting appears.
1st display
Shows the D-Shift setting
4. Select the setting using the
Up/Down keys.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Background
The 0.1V and 1V DC voltage ranges can be set to an
input resistance of 10MΩ or 10GΩ. This setting is only
applicable for DC Voltage only.
Input
Resistance
10MΩ, 10GΩ (default = 10M)
Panel operation
1. Press the Shift key, the 2nd
(Menu) key followed by the
Right key. The MEAS menu
appears.
/ EXITSHIFT
2ND
MENU
TRIG
Input Resistance Setting
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GDM-8261 User Manual
2. Press the down key followed by
the right key three times. The
Input Resistance menu appears.
TRIG
TRIG
TRIG
3. Press the Down key. The input
resistance setting appears.
1st display
Shows the input resistance setting
4. Select the setting using the
Up/Down keys.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Background
Sets the AC Bandwidth (filter) setting for AC
measurements. The Slow, Medium, Fast (S, M, F) rate
settings are directly tied to the AC bandwidth settings.
Rate
Digits
Input Frequency
Readings/s
S
6 ½
3 Hz – 300 kHz
1.2
(sec/reading)
M
5 ½
20 Hz – 300 kHz (default)
3.38
F
4 ½
200 Hz – 300 kHz
30
AC Bandwidth Setting
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SYSTEM/DISPLAY CONFIGURATION
Panel operation
1. Press the Shift key, the 2nd
(Menu) key followed by the
Right key. The MEAS menu
appears.
/ EXITSHIFT
2ND
MENU
TRIG
2. Press the down key followed by
the left key twice. The AC
Bandwidth menu appears.
HOLD
HOLD
3. Press the Down key. The input
bandwidth setting appears.
1st display
Shows the bandwidth setting
4. Select the setting using the
Up/Down keys.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
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GDM-8261 User Manual
Background
The Current Input Port Auto-Detect setting will allow
the DMM to detect whether current is applied to the 1A
or 10A input ports and enables it to set the correct range
when Auto range is on.
The Current detect feature works by activating the input
port only when a certain Detect Threshold is reached and
deactivating the input port when the input current dips
below a certain Reset Threshold.
Detect
threshold
Reset
threshold
Input
current
Activate
port
Deactivate
port
I-DET
On, Off (default = Off)
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. The system
menu appears.
/ EXITSHIFT
2ND
MENU
2. Press the Right key, then the
down key. Press the left key. The
Current detect menu appears.
TRIG
HOLD
Current Input Port Auto-Detect Setting
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SYSTEM/DISPLAY CONFIGURATION
3. Press the Down key. The input
current detect setting appears.
1st display
Shows the current detect setting
4. Select the setting using the
Up/Down keys.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Background
The Auto Zeroing (A-Zero) function can be used in
resistance, TC, RTD, DCV and DCI measurements.
Auto zeroing is used to prevent measurements from
drifting by taking offset measurements.
Setting
Off, On (default=On)
Theory
The combined offset from the input buffer, A/D driver
and ADC is called the total offset. Due to temperature
variations inside the GDM-8261, the offsets for the
Buffer, A/D driver and ADC vary over time, and thus
the total offset will also vary over time.
Auto Zero deducts this total offset from the measured
signal to obtain a more accurate reading. If Auto Zero is
turned off, this total offset will not be deducted from the
measured signal.
Auto zero works in the following manner:
Internally, the DMM will periodically short the Buffer’s
Hi and Lo input to obtain a total offset. The frequency at
which the offset is obtained depends on the sample rate.
ADC Setting
Auto-Zeroing
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GDM-8261 User Manual
The diagram below shows how the total offset is
obtained.
Buffer
Hi
Total offset
A/D
Driver
ADC
Lo
ADC
offset
A/D Driver
offset
Buffer
offset
Input Hi
Terminal
Input Lo
Terminal
Applicable
Measurement
Mode, Rate and
Speed settings
Mode
Rate
Accuracy Speed
Quick Speed
DCV,
DCI,
4W/2W
S
M
F
TC, RTD
(No Speed setting)
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. Press the
right key twice. The ADC
setting menu appears.
/ EXITSHIFT
2ND
MENU
TRIG
TRIG
2. Press the Down key twice. The
A-Zero setting appears.
1st display
Shows A-Zero setting
3. Select the setting using the
Up/Down key.
4. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
88
Page 89
Auto-Gain
Background
The Auto-Gain (A-GAIN) setting performs auto gain
correction of the internal amplifiers.
Setting
Off, On (default=On)
Applicable
Measurement
Mode, Rate and
Speed settings
Mode
Rate
Accuracy Speed
Quick Speed
DCV,
DCI
S
M
F
TC
(No Speed setting)
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. Press the
right key twice to choose the
SET ADC menu.
/ EXITSHIFT
2ND
MENU
TRIG
TRIG
2. Press the Down key and then
the Left key to choose A-GAIN.
Press the Down key. The
A-GAIN setting appears.
HOLD
1st display
Shows A-Zero setting
3. Select the setting using the
Up/Down key.
4. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
SYSTEM/DISPLAY CONFIGURATION
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GDM-8261 User Manual
Background
The analog to digital converters have a Quick and
Accurate Speed setting. The ADC Speed settings only
apply to DCV, DCI or 2/4W resistance measurements.
The ADC Speed settings can only be set if DCV, DCI or
2/4W mode is active.
Setting
Quick, Accurate (default=Accurate)
Speed/Rate
Settings
The Speed settings depend on the operating mode and
the rate settings.
Readings/s
Function
Rate
Digits
Accurate
Quick
DCV, DCI, 2/4W
(100Ω
~100MΩ)
S
6 ½
5
30
M
5 ½
60
600
F
4 ½
240
2400*
Note
*To achieve the fastest measurement speed (2400), the
DMM must have the following settings set:
1. System Delay time set to 0ms (see page 78)
2. Display turned off (see page 82).
3. Auto Zero turned off (see page 87).
4. Auto Gain turned off (see page 89).
Panel operation
1. Ensure a DC related
measurement function is
selected.
DCV page 27
DCI page 32
2/4W page 33
2. Press the Shift key followed by
the 2nd (Menu) key. Press the
right key twice. The SET ADC
menu appears.
/ EXITSHIFT
2ND
MENU
TRIG
TRIG
ADC Speed Setting
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SYSTEM/DISPLAY CONFIGURATION
3. Press the Down key, the right
key and then the down key. The
Speed settings menu appears.
TRIG
1st display
Shows the Speed setting
4. Use the Up/Down keys to
select either ACCUR or
QUICK.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Background
The INJACK settings set which input port is used for
frequency or period measurements.
Setting
VOLT, 1A, 10A
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. Press the
right key three times. The
Frequency/Period menu
appears.
/ EXITSHIFT
2ND
MENU
TRIG
TRIG
TRIG
Frequency / Period Settings
Input Port Selection
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GDM-8261 User Manual
2. Press the Down key twice. The
INJACK setting appears.
1st display
Indicates which input port is assigned
as the input port.
3. Select the input using the
Up/Down key.
4. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Background
The gate time settings determine the accuracy of the
frequency and period measurements. The gate time
settings are the equivalent to the Fast, Medium and Slow
rate settings.
Setting
10ms, 100ms, 1000ms
Rate Settings
The gate time settings are analogous to the rate settings.
Function
Digits
Rate
Readings/s
Gate time
Frequency,
Period
6 ½
Slow
1
1000ms
5 ½
Med.
10
100ms
4 ½
Fast
100
10ms
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. Press the
right key three times. The Hz/P
menu appears.
/ EXITSHIFT
2ND
MENU
TRIG
TRIG
TRIG
Gate Time Setting
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SYSTEM/DISPLAY CONFIGURATION
2. Press the Down key, the right
key and then the down key. The
gate time settings menu appears.
TRIG
1st display
Shows the gate time setting
3. Select the gate time using the
Up/Down key.
4. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
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GDM-8261 User Manual
Background
The *IDN? query returns the manufacturer, model
number, serial number and system firmware version
number. When LANG is set to COMP, a user defined
manufacturer and model number is returned with the
*IDN? query. Please see the SYSTem:IDNStr command
on page 198 for details.
Setting
NORM, COMP
Panel operation
1. Press the Shift key followed by
the 2nd (Menu) key. The System
menu appears.
/ EXITSHIFT
2ND
MENU
2. Press the Down followed by the
Left key. The LANG menu
appears. Press the Down key to
enter the LANG menu.
HOLD
1st display
Indicates the LANG setting.
3. Select NORM or COMP using
the Up/Down key.
4. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Identification Settings
Changing the Identification String
94
Page 95
STORE/RECALL
DCI
STORE
ACI
RECALL
Store Measurement Record .................................... 96
Recall Measurement Record ................................... 97
Save Instrument Settings ....................................... 98
Recall Instrument Settings ..................................... 99
STORE/RECALL
The GDM-8261 can store and recall measurement
history (for up to 9999 counts) as well as the instrument
settings. For storing and recalling measurement results
using the Scanner, see page 101.
95
Page 96
GDM-8261 User Manual
Background
The GDM-8261 can log up to 9999 measurement results
(counts) which can be stored and recalled later for
analysis. Basic measurement statistics such as Maximum,
Minimum, Average value as well as Standard Deviation
are also recorded with the data.
Note: Previously recorded measurements will be
erased every time the store function is used or if
power is reset.
Data count
2 ~ 9999
Not applicable to
Store/recall measurement history is not applicable to the
Diode/Continuity tests
/
.
Store step
1. Press the Shift key followed by
the DCI (Store) key. The store
menu appears.
/ EXITSHIFT
DCI
STORE
2. Move the cursor using the
Left/Right key. Change the data
count using the Up/Down key.
HOLD TRIG
3. Press the Enter key to confirm
editing and to go back to the
previous display.
AUTO
ENTER
Vm
SDC
STO
STO
Indicates the measurement history is
stored
Store Measurement Record
96
Page 97
STORE/RECALL
Background
The GDM-8261 can recall previously recorded
measurement results for observation and analysis. The
Standard Deviation, Maximum Value, Minimum Value
and Average Value can also be viewed.
Not applicable to
Store/recall measurement history is not applicable to the
Diode/Continuity tests .
Recall stored
record
Press the Shift key, then the ACI
(Recall) key. The stored
measurement record appears.
/ EXITSHIFT
ACI
RECALL
V
RCL
1st display
Shows the stored measurement result
2nd display
Shows the reading count
RCL
Indicates the data has been recalled
View each
reading
Change the reading count using the
Up/Down key.
View Max/Min/
Average
Switch to the Standard
Deviation/Average/Maximum/
Minimum value of the recorded data
using the Right key. Use the left key
to go back.
HOLD TRIG
Recall Measurement Record
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GDM-8261 User Manual
Background
The GDM-8261 can save up to 5 instrument settings.
The settings can save the state, function, I/O and range.
Upon powering up, the current instrument setting is
displayed.
Parameter
Save (1-5), Del-All
Saved
Parameters
Main display parameters
2nd display parameters
Filter settings
Beep settings
I/O settings
System Delay Time
Backlight (Light) settings
Math settings
Auto-Zero settings
Auto-Gain settings
Scanner settings
Settings for each function
Continuity threshold
TCO settings
D-Shift
Bandwidth
Gate time
RTD settings
Input Resistance
Input Jack
I-DET
TX TERM
Set Instrument
Setting
1. Press the Shift key followed by
the 2nd (Menu) key. The
SYSTEM menu appears.
/ EXITSHIFT
2ND
MENU
2. Press the Down key followed by
the Right key three times. The
Save menu appears.
TRIG
TRIG
TRIG
3. Press the Down key to enter the
Save menu.
Save Instrument Settings
98
Page 99
STORE/RECALL
1st display
Shows the memory number
4. Select the memory number
using the Up/Down key or
select Del-All to delete the save
settings in memory.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
Note
The current instrument settings have been saved.
To enable the settings at power up, follow the
instructions in the next section.
Background
The Recall function enables saved settings or default
settings to be recalled at power up.
Parameter
Recall (0-5), 0 = recall default settings
Recall
Instrument
Setting
1. Press the Shift key followed by
the 2nd (Menu) key. The
SYSTEM menu appears.
/ EXITSHIFT
2ND
MENU
2. Press the Down key followed by
the Left key two times. The
Recall menu appears.
HOLD
HOLD
3. Press the Down key to enter the
Recall menu.
Recall Instrument Settings
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GDM-8261 User Manual
1st display
Shows the memory number
4. Select the memory number
using the Up/Down key.
5. Press the Enter key to confirm
your selection. Press the Exit
key to go back to the default
display.
AUTO
ENTER
/ EXITSHIFT
When the instrument is reset or upon the next
power up, the recalled settings will be enabled.
100
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