ISO-9001 CERTIFIED MANUFACTURER
GOOD WILL INSTRUMENT CO., LTD.
GDM-8255A/8251A 5 ½ Dual Display Digital Multimeter
New Product Announcement
GOOD WILL INSTRUMENT is announcing the next generation’s
digital multimeter, GDM-8255A / 8251A, to the global market.
GDM-8255A/8251A portable precision multi-meters engage with 5
½ , dual-display, 0.012% DCV accuracy and 2w/4w measurement.
The VFD display technology provides the excellent observation of
contrast and brightness.
GDM-8255A / 8251A carry an extensive list of measurement
items - ACV, DCV, ACA, DCA, R, Hz, Continuity beeper, Diode
GDM-8255A（199999 Counts）
GDM-8251A（120000 Counts）
test and Temperature. The dual-display measurement items
include ACV + Hz, DCV + dBm, ACV + dBm, DCV + ACV ripple
and
dBm. Advanced measurement functions, such as Max/Min, Hold, Relative value and Compare, are suitable
for multiplicity of applications such as production testing, research and field verification. The USB, RS-232C
and 9-pin digital I/O interface are included as standard features, which enable its remote controlling and data
capturing for ATE applications.
Fast Measurement Speed / Transfer Rate
GDM-8255A / 8251A offer selectable measurement speed rate under different modes. The speed rates allow
users to maximize the measurement efficiency while maintaining sufficient accuracy. At the fast mode, the
instrument delivers 60 readings/sec (see table below), adequately meeting today’s speed demand. Besides,
the display could be turned off by pressing OUTPUT ON/OFF button at anytime. By doing so, the operation
loading could be reduced and entire running speed could be increased since the unit has been remote
controlled and not showing the display.
Mode
Resolution
Measurement Speed Transfer Speed
Fast
Medium
Slow
3 ½ digits
4 ½ digits
5 ½ digits
60 readings/second
30 readings/second
10 readings/second
Typical 17mS
Typical 34mS
Typical 100mS
Various Measuring Functions
GDM-8255A / 8251A provide 9 major measuring functions such as DCV/ACV, DCI/ACI, 2w/4w Resistance,
Diode, Frequency, Continuity test and Temperature. The 0.012% DC voltage accuracy provides user the best
measuring precision at the DC voltage applications. In addition, there are several advanced measuring
functions such as Max, Min, dB, dBm, REL/REL#, Hold, Compare and Math functions to enhance the
serviceability of measuring results.
GDM-8200A Series NPI Announcement(USA)
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2/ 4 Wire Resistance Measurement
GDM-8255A / 8251A offer two methods for resistance measurement.
2-wire resistance measurement is the most common and simplest
connection method, typically used in the impedance greater than 1k.
4-wire resistance measurement is required for accurate low
impedance measurement. Once the 4-wire measurement is applied,
the test lead resistance and contact resistance will be reduced
automatically.
Combinational Dual Measurement Function
GDM-8255A / 8251A offer varieties of dual display
combinations with main measurement function which allows
GDM-8255A / 8251A to measure two properties of input
signals. The dual measuring function will save customers
measurement time when dealing with applications requiring
multiple parameters simultaneously.
Multiple Standard Interfaces
GDM-8255A / 8251A provide the standard multiple interfaces for PC connection: RS232C and USB device
port. Unlike the common RS232 transfer speed, the GDM-8255A / 8251A even raises the baud rate up to
115200 which would be 12 times faster. It would make the command or data flow faster and smoother.
Besides, it is not necessary to expend the fabrication in order to communicate with a PC. It would certainly
reduce the user cost.
In addition, the digital I/O terminal
outputs the result of comparison
measurements to control external
devices for ATE applications. By
providing an independent VCC for the
terminal, the digital I/O outputs can also be used as power source for TTL or CMOS logics.
Free PC Software – Remote Control & Data Capture
For a convenient remote control and a long data capture, the
GDM-8255A / 8251A accompanies free software, DMM-Viewer. This
software allows users to remotely control the GDM-8255A / 8251A
without entering extra commands. Besides, the software interface
and even the measurement method resemble those of GDM-8255A /
8251A front panel, thus guaranteeing safe operation and shortened
training and program development time.
GDM-8200A Series NPI Announcement(USA)
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For data capturing through a PC, the software allows users to
observe measuring result before saving it as a file for further study.
In addition, the saved data could be reloaded for converting into a
graph.
With the DMM-Viewer PC software, the user operation of
GDM-8255A / 8251A can be much more effective.
Buffer Store / Recall Function
GDM-8255A / 8251A provide an internal buffer for storing up to 10,000 counts of measuring data, and it
allows users to recall the test records for observation or analyzing the maximum, minimum, or average
values after the internal processing is completed.
Key Features

GDM-8255A : 199999 Counts Display

GDM-8251A : 120000 Counts Display

VFD, Two Colors Display

Selectable Measurement Rate

Auto/Manual Ranging

True RMS (AC, AC+DC)

2/4 Wire Resistance Measurement

Temperature Measurement

Frequency Measurement

Max./Min., REL, dBm, Compare, Math, Store, Recall, dB

Standard USB device, RS232, Digital I/O Interface
Compare Specification
Colored mark indicates best performance.
“X” stands for “no such function” or “function not available”.
Features
Dual Display Measurements
Counts Resolution
Meas. Rate
True rms
DCV Accuracy
Measurement Functions
DCV
ACV
GDM-8200A Series NPI Announcement(USA)
GDM-8255A
Fluke 8808A
Agilent 34405A
●
199999
10/30/60 (S/M/F)
●
199999
2.5/20/100 (S/M/F)
●
120000
----
●
●
●
0.012%
0.015%
0.025%
9
100mV ~ 1000V
In 5 ranges
100mV ~ 750V
In 5 ranges.
9
200mV ~ 1000V
In 5 ranges
200mV ~ 750V
In 5 ranges
10
100mV ~ 1000V
In 5 ranges
100mV ~ 750V
In 5 ranges.
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10mA ~ 10A
In 4 ranges
10mA ~ 10A
In 4 ranges
100 ~ 100M
In 7 ranges
Up to 800kHz
200uA ~ 10A
In 6 ranges
20mA ~ 10A
In 4 ranges
200 ~ 100M
In 7 ranges
Up to 1MHz
10mA ~ 10A
In 4 ranges
10mA ~ 10A
In 3 ranges
100 ~ 100M
In 7 ranges
Up to 300kHz
Temperature
●
●
●
Continuity Test
●
●
●
Diode Test
●
●
Capacitance
X
X
Math Functions
●
●
●
1nF ~ 10,000uF
In 7 ranges
●
Compare Mode
●
●
●
2w / 4w
2 x 4w / 4w
2w
Interface (Standard)
RS232/USB Device
RS232
USB Device
Digital I/O (Standard)
●
X
X
Free Charge
●
X
●
Data Storage & Recall
●
X
●
Graphical User Interface
●
X
X
DCI
ACI
Resistance
Frequency
Resistance Meas. Method
PC Software
Target Markets and Associated Features
R&D

5 ½ digits resolution and 0.012% DCV accuracy for product development.

Various functions(ACV, DCV, ACA, DCA, R, Hz, Continuity beeper, Diode test, REL… ) and 2/4 wire
resistance, relative and comparing measurement: suitable for wide range of applications

Multiple standard interfaces and free PC software for data recording and improved productivity.
Quality Assurance Verification

ACV, DCV, ACA, DCA, R, Hz, Continuity beeper, Diode test, REL… various functions for wide
range of applications

The built-in function of 10,000 set measurement record can store the historical measuring data that
enables the ability of data recall for purposes of observation and analysis with the Maximum,
Minimum, and Average values.

Multiple standard interfaces and free PC software for data record of product reliability.
Education

High 5 ½ digits resolution and measurement 0.012% DCV accuracy for research.

Multiple standard interfaces and free PC software for data recording experiment.
GDM-8200A Series NPI Announcement(USA)
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Maintain & Repair

Dual display function can deal with application requiring multiple parameters simultaneously.

High 5 ½ digits resolution and measurement 0.012% DCV accuracy for circuit debug.
ATE System

Fast transfer rate with RS232 / USB and Digital I/O multiple standard interfaces plus free PC
Software for remote applications
Key Dates for Product Announcement
1. Order Queue Open (Middle of May)
2. Distributor Announcement (Middle of May)
3. Global Market Announcement (Middle of May)
4. Demo Units Shipped to Distributors (End of May)
5. Mass Quantity Order Fulfillment (Middle of June)
Service Policy
1. 1 year warranty
2. Service Support
The service instructions in the Service Manual will help distributors repair defective units promptly.
Should the board replacement is necessary to fix the defective unit, the board swapping service
support is provided by Good Will Instrument to facilitate the repair jobs done at the distributor’s site.
3. GW Instek continuingly provides the after-sales support through its website. The most up-to-date
version of service manual and Marcom material of GDM-8255A/ 8251A will be posted on the distributor
zone of GW Instek Website at http://www.gwinstek.com.tw.
GDM-8255A Outlook
GDM-8200A Series NPI Announcement(USA)
GDM-8251A Outlook
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Specifications
General
All specifications are ensured only under a single display.
At least 30 minutes of warm-up time is required before applying these specifications.
Make sure the power ground is connected.
Type
Digit
Fast (F)
3 ½ Digit
Medium (M)
4 ½ Digit
Slow (S)
5 ½ Digit
Ambient Temperature 0°C ~ 40°C, Relative Humidity < 75%
(For full accuracy: 18°C ~ 28°C)
< 0.15 x applicable accuracy per degree (C°) (for 0°C ~ 18°C and 28°C ~ 40°C)
Ambient Temperature −10°C ~ 70°C
Relative Humidity: 0°C ~ 35°C < 75%, 35°C ~ 50°C < 50%
AC 100–240V ± 10%, 50–60Hz
265(W) x 107(H) x 350(D) mm
Approx. 2.6kg without option



Note
Resolution
Operation Environment
Temperature Coefficient
Storage Environment
Power Source
Dimension
Weight
Reading rates (readings/sec)
Function
Rate
DCV
DCI
ACV
ACI
2/4WΩ (10M/100MΩ )
2/4WΩ (others)
ACV+DCV
ACI+DCI
Diode
S
10
10
1
1
1
3
0.3
0.3
30
M
30
30
5
5
1.5
5
0.6
0.6
30
F
60
60
20
20
2
8
1.1
1.1
60
DC Voltage
Note
Rate
S
M
F

Max. Input: 1000V DC or Peak on all range
Range
Resolution
100.000mV
1.00000V
10.0000V
100.000V
1000.00V
100.00mV
1.0000V
10.000V
100.00V
1000.0V
100.0mV
1.000V
10.00V
100.0V
1000V
1µV
10µV
100µV
1mV
10mV
10µV
100µV
1mV
10mV
100mV
100µV
1mV
10V
100mV
1V
GDM-8200A Series NPI Announcement(USA)
Full Scale
(8251A)
120.000mV
1.20000V
12.0000V
120.000V
1000.00V
120.00mV
1.2000V
12.000V
120.00V
1000.0V
120.0mV
1.200V
12.00V
120.0V
1000V
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Full Scale
(8255A)
199.999mV
1.99999V
19.9999V
199.999V
1000.00V
199.99mV
1.9999V
19.999V
199.99V
1000.0V
199.9mV
1.999V
19.99V
199.9V
1000V
Accuracy
(reading%+digits)
0.012%+8
0.012%+5
0.012%+5
0.012%+5
0.012%+5
0.012%+5
0.012%+5
0.012%+5
0.012%+5
0.012%+5
0.012%+2
0.012%+2
0.012%+2
0.012%+2
0.012%+2
6/20/2008
ISO-9001 CERTIFIED MANUFACTURER
GOOD WILL INSTRUMENT CO., LTD.
AC Voltage
Note
Rate
S
M
F
Rate


Specifications are for sine wave input > 5% of range
(*) Input > 450V only for 30sec, < 200V for 20 ~ 45Hz
Resolution
100.000mV
1.00000V
10.0000V
100.000V
750.00V(*)
100.00mV
1.0000V
10.000V
100.00V
750.0V(*)
100.0mV
1.000V
10.00V
100.0V
750V(*)
Range
1µV
10µV
100µV
1mV
10mV
10µV
100µV
1mV
10mV
100mV
100µV
1mV
10V
100mV
1V
100.000mV
1.00000V
10.0000V
100.000V
750.00V(*)
100.00mV
1.0000V
10.000V
100.00V
750.0V(*)
100.0mV
1.000V
10.00V
100.0V
750V(*)
S
M
F
Full Scale
(GDM-8251A)
120.000mV
1.20000V
12.0000V
120.000V
750.00V
120.00mV
1.2000V
12.000V
120.00V
750.0V
120.0mV
1.200V
12.00V
120.0V
750V
Accuracy (reading%+digits)
45~10kHz
10k~30kHz
0.2% + 100
1.5% + 300
0.2% + 100
1% + 100
0.2% + 100
1% + 100
0.2% + 100
1% + 100
0.2% + 100
1% + 100
0.2% + 40
1.5% + 80
0.2% + 40
1% + 40
0.2% + 40
1% + 40
0.2% + 40
1% + 40
0.2% + 40
1% + 40
0.2% + 5
1.5% + 10
0.2% + 5
1% + 5
0.2% + 5
1% + 5
0.2% + 5
1% + 5
0.2% + 5
1% + 5
Range
20~45Hz
1% + 100
1% + 100
1% + 100
1% + 100
1% + 100
—
—
—
—
—
—
—
—
—
—
Full Scale
(GDM-8255A)
199.999mV
1.99999V
19.9999V
199.999V
750.00V
199.99mV
1.9999V
19.999V
199.99V
750.0V
199.9mV
1.999V
19.99V
199.9V
750V
30k~100kHz
5% + 300
3% + 200
3% + 200
3% + 200
3% + 200
5% + 120
3% + 80
3% + 80
3% + 80
3% + 80
5% + 15
3% + 10
3% + 10
3% + 10
3% + 10
DC Current
Note
Rate
S
M
mA range protected with a 100mA fuse
10A range protected with a 12A, 600V fuse
10A only for 30 seconds
Full Scale
Range
Resolution
(GDM-8251A)
10.0000mA
0.1µA
12.0000mA
100.000mA
1µA
120.000mA
1.0000A
100µA
1.9999A
10.0000A
100µA
10.0000A
10.000mA
1µA
12.000mA
100.00mA
10µA
120.00mA
1.000A
1mA
1.999A
10.000A
1mA
10.000A



GDM-8200A Series NPI Announcement(USA)
7 OF 10
Full Scale
(GDM-8255A)
19.9999mA
199.999mA
1.9999A
10.0000A
19.999mA
199.99mA
1.999A
10.000A
Accuracy
(reading%+ digits)
0.05%+15
0.05%+5
0.2%+5
0.2%+5
0.1%+6
0.1%+3
0.2%+3
0.2%+3
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ISO-9001 CERTIFIED MANUFACTURER
GOOD WILL INSTRUMENT CO., LTD.
10.00mA
100.0mA
1.00A
10.00A
F
10µA
100µA
10mA
10mA
12.00mA
120.0mA
1.99A
10.00A
19.99mA
199.9mA
1.99A
10.00A
0.1%+2
0.1%+2
0.2%+2
0.2%+2
AC Current
Note
Rate
S
M
F
mA range protected with a 100mA fuse
10A range protected with a 12A, 600V fuse
*10A range specification is verified for < 5kHz
Full Scale
Range
Resolution
(GDM-8251A)
10.0000mA
0.1µA
12.0000mA
100.000mA
1µA
120.000mA
1.0000A
100µA
1.9999A
10.0000A
100µA
10.0000A
10.000mA
1µA
12.000mA
100.00mA
10µA
120.00mA
1.000A
1mA
1.999A
10.000A
1mA
10.000A
10.00mA
10µA
12.00mA
100.0mA
100µA
120.0mA
1.00A
10mA
1.99A
10.00A
10mA
10.00A



Accuracy (reading%+digits)
Rate
Range
10.0000mA
100.000mA
S
1.00000A
10.0000A
10.000mA
100.00mA
M
1.0000A
10.000A
10.00mA
100.0mA
F
1.000A
10.00A
20 ~ 50Hz
1.5% + 100
1.5% + 100
—
—
—
—
—
—
—
—
—
—
Full Scale
(GDM-8255A)
19.9999mA
199.999mA
1.9999A
10.0000A
19.999mA
199.99mA
1.999A
10.000A
19.99mA
199.9mA
1.99A
10.00A
50 ~ 10kHz
0.5% + 100
0.5% + 100
1% + 100
1% + 100*
0.5% + 40
0.5% + 12
—
—
0.5% + 5
0.5% + 2
—
—
10k ~ 20kHz
2% + 200
2% + 200
—
—
2% + 80
2% + 30
—
—
2% + 10
2% + 5
—
—
Full Scale
(GDM-8255A)
199.999Ω
1.99999kΩ
19.9999kΩ
199.999kΩ
1.99999MΩ
19.9999MΩ
199.999MΩ
Accuracy
(reading%+digits)
0.1% + 8*
0.08% + 5*
0.06% + 5*
0.06% + 5
0.06% + 5
0.3% + 5
3.0% + 8
2W Resistance
Note


Max. Input: 500V DC or 500V rms AC
*: Relative mode
Rate
Range
S
100.000Ω
1.00000kΩ
10.0000kΩ
100.000kΩ
1.00000MΩ
10.0000MΩ
100.000MΩ
GDM-8200A Series NPI Announcement(USA)
Full Scale
(GDM-8251A)
120.000Ω
1.20000kΩ
12.0000kΩ
120.000kΩ
1.20000MΩ
12.0000MΩ
120.000MΩ
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100.00Ω
1.0000kΩ
10.000kΩ
100.00kΩ
1.0000MΩ
10.000MΩ
100.00MΩ
100.0Ω
1.000kΩ
10.00kΩ
100.0kΩ
1.000MΩ
10.00MΩ
100.0MΩ
M
F
120.00Ω
1.2000kΩ
12.000kΩ
120.00kΩ
1.2000MΩ
12.000MΩ
120.00MΩ
120.0Ω
1.200kΩ
12.00kΩ
120.0kΩ
1.200MΩ
12.00MΩ
120.0MΩ
199.99Ω
1.9999kΩ
19.999kΩ
199.99kΩ
1.9999MΩ
19.999MΩ
199.99MΩ
199.9Ω
1.999kΩ
19.99kΩ
199.9kΩ
1.999MΩ
19.99MΩ
199.9MΩ
0.1% + 5*
0.08% + 3*
0.06% + 3
0.06% + 3
0.06% + 3
1.5% + 3
5.0% + 5
0.1% + 2*
0.08% + 2
0.06% + 2
0.06% + 2
0.06% + 2
1.5% + 2
5.0% + 2
4W Resistance
Note
Rate
S
M
F

Max. Input: 500V DC or 500V rms AC
Range
Full Scale
(GDM-8251A)
Full Scale
(GDM-8255A)
Accuracy
(reading%+digits)
100.000Ω
1.00000kΩ
10.0000kΩ
100.000kΩ
1.00000MΩ
10.0000MΩ
100.000MΩ
100.00Ω
1.0000kΩ
10.000kΩ
100.00kΩ
1.0000MΩ
10.000MΩ
100.00MΩ
100.0Ω
1.000kΩ
10.00kΩ
100.0kΩ
1.000MΩ
10.00MΩ
100.0MΩ
120.000Ω
1.20000kΩ
12.0000kΩ
120.000kΩ
1.20000MΩ
12.0000MΩ
120.000MΩ
120.00Ω
1.2000kΩ
12.000kΩ
120.00kΩ
1.2000MΩ
12.000MΩ
120.00MΩ
120.0Ω
1.200kΩ
12.00kΩ
120.0kΩ
1.200MΩ
12.00MΩ
120.0MΩ
199.999Ω
1.99999kΩ
19.9999kΩ
199.999kΩ
1.99999MΩ
19.9999MΩ
199.999MΩ
199.99Ω
1.9999kΩ
19.999kΩ
199.99kΩ
1.9999MΩ
19.999MΩ
199.99MΩ
199.9Ω
1.999kΩ
19.99kΩ
199.9kΩ
1.999MΩ
19.99MΩ
199.9MΩ
0.05% + 8
0.05% + 5
0.05% + 5
0.05% + 5
0.05% + 5
0.3% + 5
3.0% + 8
0.05% + 5
0.05% + 3
0.05% + 3
0.05% + 3
0.05% + 3
1.5% + 3
5.0% + 5
0.05% + 2
0.05% + 2
0.05% + 2
0.05% + 2
0.05% + 2
1.5% + 2
5.0% + 2
Diode/Continuity
Note
Item
Diode
Continuity

Max. Input: 500V DC or 500V rms AC
Range
2V, 0.5mA
1 ~ 1000Ω
GDM-8200A Series NPI Announcement(USA)
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Frequency

Note
Frequency
10Hz ~ 100kHz
100kHz ~ 600kHz
600kHz ~ 800kHz
Max. Input: 750V rms or 1000V peak
Sensitivity
0.1V
1V
2.5V
Accuracy (reading%+digits)
0.05% + 15
0.05% + 3
0.05% + 3
Temperature

Note
Sensor errors excluded from Temperature specification
Type
K
T
J
0.1°C (0 ~ 300°C)
Thermo Couple
Resolution
Measurement Range
0 ~ +300°C
0 ~ +300°C
0 ~ +300°C
Ordering information
GDM-8255A
5 1/2 ( 199999 counts ) Dual Display Digital Multimeter
GDM-8251A
5 1/2 ( 120000 counts ) Dual Display Digital Multimeter
Standard Accessories
Quick Start User manual x 1
Power cord x 1
Test lead GTL-117 x 1
Calibration key GDM-01 x 1
CD x 1 (including complete user manual, upgrade program and PC software – DMM-Viewer)
Optional Accessories
GTL-245
USB Cable
GTL-232
RS-232C Cable, 9-pin Female to 9-pin, null Modem
GTL-108A
4W Type Test lead
Should you have any questions on the GDM-8255A / 8251A announcement, please don’t hesitate to contact us
Sincerely Yours;
Marketing Department
Instek America Corp.
3661 Walnut Avenue Chino,
CA 91710, U.S.A.
Email: sales@instek.com
GDM-8200A Series NPI Announcement(USA)
10 OF 10
6/20/2008