GW Instek GOM-804 User manual

D.C. Milli-Ohm Meter
GOM-804 & GOM-805
USER MANUAL
GW INSTEK PART NO. 82OM-80500EA1
ISO-9001 CERTIFIED MANUFACTURER

This manual contains proprietary information, which is protected by
copyright. All rights are reserved. No part of this manual may be
photocopied, reproduced or translated to another language without
prior written consent of the 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.

Table of Contents
3
Table of Contents
SAFETY INSTRUCTIONS ....................................................5
Safety Symbols ....................................................5
Safety Guidelines ................................................6
GETTING STARTED ............................................................9
GOM-804/805 Characteristics........................... 10
Key Features ...................................................... 13
Model Lineup .................................................... 14
Front Panel Overview ........................................ 15
TFT-LCD Overview ............................................ 19
Rear Panel Overview ......................................... 21
Set Up ............................................................... 23
MEASUREMENT...............................................................27
Resistance Measurement .................................. 29
Compare Function............................................. 41
Binning Function............................................... 46
Temperature Measurement ............................... 50
Temperature Compensation .............................. 52
Temperature Conversion ................................... 56
Measurement Settings ...................................... 60
System Settings ................................................ 69
HANDLER/SCAN INTERFACE ..........................................77
Handler Overview ............................................. 78
Pin Definitions for the Handler Interface .......... 80
Scan Overview................................................... 82
Configure Interface ........................................... 90
SAVE/RECALL...................................................................99
COMMAND OVERVIEW .................................................102
Command Syntax ............................................ 102
Command List................................................. 105

GOM-804 & GOM-805 User Manual
4
General Commands......................................... 108
Compare Commands....................................... 112
Binning Commands......................................... 117
Temperature Compensate Commands ............ 122
Temperature Conversion Commands .............. 123
Temperature Commands ................................. 125
Scan Commands ............................................. 126
Source Commands .......................................... 131
Meas. Setup Commands ................................. 132
System Commands.......................................... 137
Memory Commands ........................................ 141
Status Commands ........................................... 143
IEEE 488.2 Common Commands..................... 144
Status system .................................................. 147
FAQ ................................................................................148
APPENDIX ......................................................................149
Function Selection Combinations ................... 150
Temperature Measurement ............................. 151
Specifications .................................................. 154
Dimensions ..................................................... 158
Declaration of Conformity ............................... 159
INDEX ............................................................................160

SAFETY INSTRUCTIONS
5
SAFETY INSTRUCTIONS
This chapter contains important safety instructions that you must follow
when operating the GOM-804/805 or when keeping it in storage. Read the
following before any operation to insure your safety and to keep the
GOM-804/805 in the best possible condition.
Safety Symbols
These safety symbols may appear in this manual or on the GOM-804/805.
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 instrument or to other properties.
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.

GOM-804 & GOM-805 User Manual
6
Safety Guidelines
General Guideline
CAUTION
Do not place any heavy objects on the instrument.
Avoid severe impact or rough handling that leads to
damaging the instrument.
Do not discharge static electricity to the instrument.
Use only mating connectors, not bare wires, for the
terminals.
Do not disassemble the instrument unless you are
qualified as service personnel.
(Note) EN 61010-1:2010 specifies the measurement categories and
their requirements as follows. The GOM-804/805 doesn’t fall
under category II, III or IV.
Measurement category IV is for measurements performed at the
source of low-voltage installation.
Measurement category III is for measurements performed in the
building installation.
Measurement category II is for measurements performed on the
circuits directly connected to the low voltage installation.
Power Supply
WARNING
AC Input voltage: 100 - 240 V AC, 50 - 60Hz, 25VA
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.
Cleaning the
GOM-804/805
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
instrument.
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 Range: 0~35°C, Relative Humidity:
<80%RH; >35°C, Relative Humidity: <70%RH
Altitude: < 2000m
Operating Environment: 0°C to 40°C (operation)
Pollution Degree 2

SAFETY INSTRUCTIONS
7
(Note) EN 61010-1:2010 specifies the pollution degrees and their
requirements as follows. The GOM-804/805 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
Storage Conditions: −10°C to 70°C
Temperature Range: 0~35°C, Relative Humidity:
<90%RH; >35°C, Relative Humidity: < 80%RH
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.

GOM-804 & GOM-805 User Manual
8
Power cord for the United Kingdom
When using the instrument 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:
Green/ Yellow:
Earth
Blue:
Neutral
Brown:
Live (Phase)
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 0.75mm2should 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.

GETTING STARTED
9
GETTING STARTED
This chapter describes the GOM-804/805 in a nutshell, including its main
features as well as its front and rear panels. After going through the panel
overview, follow the Power-up sequence before attempting to use the
instrument.
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.
Characteristics
GOM-804/805 Characteristics ................................10
Key Features ...........................................................13
Model Lineup .........................................................14
Panel Overview
Front Panel Overview .............................................15
TFT-LCD Overview..................................................19
Rear Panel Overview...............................................21
Setup
Tilt Stand................................................................23
Power Up................................................................24
4 Wire Kelvin Connection .......................................25
Zeroing (Relative Function)....................................26

GOM-804 & GOM-805 User Manual
10
GOM-804/805 Characteristics
GOM-804 and GOM-805 are modern high precision programmable DC
Milli-ohm meters suitable for low resistance measurements of switches, relays,
connectors, PCB tracks and a variety of other devices. The meters feature a
color TFT-LCD screen with easy-to-read measurement results. With the
easy-to-use features, superior performance and automatic test interfaces, these
meters are dependable instruments for resistance measurements.
Easy to Use
Features
Each test function on the GOM-804/805 can be easily
activated by pressing a single front panel key. All the
settings and measurement results are displayed and set on
the TFT-LCD panel at the same time making each
function naturally intuitive to use.
Each primary and secondary measurement result is
displayed prominently on the display along with any
corresponding settings. For sequential measurement
results, such as those from the scan or binning function,
are tabulated in an intuitive and easy-to-read format.
In addition, the meters can recall previously used settings
upon startup, allowing the meter to be ready the next
time it used in a matter of moments. The meters can also
save or recall up to 20 sets of function settings.
Performance
The GOM-804/805 has nine selectable measurement
ranges from 50mΩ to 5MΩ, a constant current source of
1uA to 1A, an accuracy of up to 0.05%, a 1uΩ resolution
and performs measurements using four wire Kelvin
connections for accurate, consistent measurements.
The ability to choose between high accuracy
measurements at 10 samples/sec (full scale at 50000
counts) or high speed measurements at 60 samples/sec
(full scale at 50000 counts), allows the GOM-804/805 the
flexibility to fulfill a number of different measurement
roles.

GETTING STARTED
11
Advanced
Temperature
Measurements
The GOM-804/805 has a number of advanced
temperature functions that can be used with the optional
temperature probe, PT-100.
The temperature compensation function can extrapolate
what the resistance of a DUT will be at a desired
temperature, if the temperature coefficient of the DUT
and the resistance of the DUT at ambient temperature
are known.
The temperature conversion function can be used to
extrapolate what the temperature rise of a DUT will be at
specified resistance if the initial resistance, initial
temperature and the constant for the DUT are known.
Drive Signals
The GOM-805 can select a number of different drive
signals to suit a number of different measurement
scenarios, for example the Pulse setting can be used to
cancel the effects of thermoelectric EMF on the
measurement results.
Dry Circuit
Testing
Dry circuit testing allows the GOM-805 to measure the
contact resistance of switches and connectors according
to the DIN IEC 512 and ASTM B539 standards. The
open circuit voltage will not exceed 20mV in this mode
to prevent the oxidization layer on metal switches and
connector points from breakdown. GOM-805 only.
Automatic
Testing
For automatic testing The GOM-804/805 has a handler
interface designed for automatic testing. The handler
interface outputs the status of PASS, FAIL, HI, LO,
READY and EOT signals and inputs a trigger control
signal. Automatic testing is used with the binning,
compare and scan functions.
For computer control applications, RS-232 and USB are
standard remote interfaces, with GPIB as standard only
for the GOM-805 and GOM-804G.

GOM-804 & GOM-805 User Manual
12
Applications
Production testing for contact resistance of switches,
relays, connectors, cables and printed circuit boards
and other low resistance devices.
Component testing of resistors, motors, fuses and
heating elements.
Incoming inspection and quality assurance testing.
Conductivity evaluation for product design.

GETTING STARTED
13
Key Features
50,000 counts
Measurement Range: 50mΩ~5MΩ
Accuracy of up to 0.05%
Compare function
Binning function
Manual or Auto-ranging
Continuous or Triggered measurement modes
Temperature measurement, temperature
compensation and temperature conversion
Four-wire Kelvin measurement method
Selectable power-on settings
Diode test
Alarm settings for function-specific PASS/FAIL test
results
Sampling rate: 10 or 60 sampling/sec
Standard interfaces:
USB/RS232/Scan/Handler/GPIB(GOM-805,
GOM-804G)
Save/Recall settings: 20 memory sets
External I/O logic function

GOM-804 & GOM-805 User Manual
14
Model Lineup
Feature / Model
GOM-804
GOM-804G*
GOM-805
Ohm Measurement
✔
✔
✔
Compare Function
✔
✔
✔
Diode Measurement
✔
✔
✔
Temp. Compensation
✔
✔
✔
Temp. Conversion
✔
✔
✔
Temp Measurement
✔
✔
✔
Dry Circuit
✘
✘
✔
Drive Selection
✘
✘
✔
Binning Function
✘
✘
✔
Interface
GPIB Interface
✘
✔
✔
RS-232 Interface
✔
✔
✔
USB Device Interface
✔
✔
✔
Handler/EXT IO/Scan
Interface
✔
✔
✔
Temperature Sensor
Interface
✔
✔
✔
* The GOM-804G is simply the GOM-804 with the factory-installed
GPIB option. Please note that the GPIB option cannot be
user-installed on the GOM-804. The option must be ordered prior to
purchase.

GETTING STARTED
15
Front Panel Overview
SOURCE SENSE POWER SENSE SOURCE
Rx
DC Milliohm Meter
G O M - 8 0 5
Ohm Compare Binning
TEMP
TCONVTC
Speed REL RT
Trigger
DryScan
Display Diode Drive
ESC
GND
GUARD
Enter
Local Range
ESC key
GND
terminal
Function keyLCD display
Power key
Arrow keys,
Enter keys
GUARD
terminal
Sense+, Source+Sense-, Source-
Power Switch
SOURCE SENSE POWER SENSE SOURCE
Rx
DC Milliohm Meter
G O M - 8 0 5
Ohm Compare Binning
TEMP
TCONVTC
Speed REL RT
Trigger
DryScan
Display Diode Drive
ESC
GND
GUARD
Enter
Local Range
Turns On or Off the main
power. For details about the power up
sequence, see page 24.
Measurement Terminals
Source, Sense
Terminals
Rx
SOURCE SENSE SENSE SOURCE
Sense +and Sense -terminals.
Current source terminals: Source + and
Source -.
CAUTION
When measuring components
with polarity, connect Source+
to the positive potential and
connect Source- to the negative
potential of the component.
WARNING
Discharge any DUT before
measurement to avoid
damaging the GOM-804/805.

GOM-804 & GOM-805 User Manual
16
GND Terminal
GND
Connect the GND (ground) terminal to
the earth ground.
GUARD Terminal
GUARD
The GUARD terminal has the same
potential as earth, but cannot be
substituted for it. Connect the GUARD
terminal to the cable shield layer of the
test leads to help reduce noise.
Function Keys
Ohm
The Ohm key activates the resistance
measurement function.
Compare
The Compare key activates the
comparator function.
Binning
The Binning key activates the binning
function to grade the DUTs into eight
bins according to the tolerance settings.
GOM-805 only.
TC
The TC key activates the TC
(temperature compensation) function
which calculates the resistance of a
DUT at a specified temperature given
the resistance of the DUT at the
ambient temperature and the
temperature coefficient of the DUT is
known.
TCONV
The TCONV (Temperature
Conversion) function calculates the
temperature of a DUT given an initial
temperature, initial resistance, measured
resistance and a constant (inferred zero
resistance temperature) for the DUT.
TEMP
The TEMP key activates the
temperature measurement function.

GETTING STARTED
17
Speed
The Speed key toggles between 10
samples per second and 60 samples per
second (Slow rate and Fast rate).
REL
The REL key is used to perform a zero
adjustment to the test leads or a DUT.
RT
The RT key is used to display the
real-time (not averaged) measured
resistance value.
Scan
The Scan key is used to turn on the
Scan function.
Dry
The Dry key is used to turn on the dry
circuit measurement mode which allows
the GOM-805 to measure the contact
resistance of switches and connectors
according to DIN IEC 512 and ASTM
B539 standards. GOM-805 only.
Trigger
When in the internal trigger mode,
pressing the Trigger key will turn on the
external trigger mode. When in the
external trigger mode, pressing the
Trigger key will perform a manual
trigger.
A long press of the Trigger key when in
external trigger mode will reset the
trigger mode back to the internal trigger
mode.
Display
The Display key toggles between the
standard display mode and the
simplified display mode (sans menus
and display icons).
Local
The LOCAL key will switch the
milliohm meter between local and
remote mode.
Diode
The Diode key is used to turn on the
Diode measurement function.

GOM-804 & GOM-805 User Manual
18
Drive
+
Enter
The Drive key in conjunction with the
up/down arrow keys is used to select
the measuring signal: DC+, DC-, Pulse,
PWM, Zero. In particular, the Zero
setting can be used as a +/-10mV DC
voltmeter to measure the EMF of
passive components. See page 33 for
details. GOM-805 only. The drive signal
is fixed to DC+ on the GOM-804.
Range
Long pressing the Range key will
activate the auto ranging mode.
Range
+
Enter
The Range key in conjunction with the
up/down arrow keys is used to select
the resistance measurement range.
When in auto ranging mode, pressing
the Range key will activate the manual
ranging mode.
ESC
The ESC key cancels the current setting
and returns the cursor to its default
location or returns to the previous
menu, depending on the circumstances.
Arrow Keys,
Enter Key
Enter
The arrow keys and Enter key are
used to edit parameters, to navigate
the menu system and to select
parameter ranges.

GETTING STARTED
19
TFT-LCD Overview
Drive signal
RangeFunction mode
Function
mode
settings
Trigger mode
Main
measurement
display
Secondary menus
REL value Memory
number
Function control
indicators
Average value Dry circuit
Rate Remote mode
Remote error
Function Control
Indicators
The function control indicators show all the currently
active settings for the selected function mode:
Func
Currently selected function mode
Range
The measurement range. Auto
indicates that auto ranging is
active
Trigger mode
Int/Ext
Rate
Slow/Fast
Drive:
DC+, DC-, Pulse, PWM, Zero
Rel
Shows the relative (nominal)
reference value
Avg
Number of samples used for the
Average function.
Dry
Indicates that the dry circuit
function is active
Err
Indicates a remote command
error

GOM-804 & GOM-805 User Manual
20
RMT
Indicates that the unit is in
remote control mode
Mem No.
Indicates which memory setting
has been recalled
Main
Measurement
Display
Shows all measurement results for the selected function
mode.
Function Mode
Settings
Shows any function mode-specific settings.
Secondary
Menus
The secondary menus show global menus (Meas. Setup),
System, Memory) as well as function-specific secondary
menus.
Meas. Setup
Goes to the global Measurement Setup
menu.
System
Goes to the global System menu
Memory
Allows you to save, recall and clear
memory settings.
View
Shows the all results for all the channels
when a scan has finished.
Clear
Clears the measurement results in the
Binning function when the display
mode is set to Count.