Thank you for purchasing a Omega DFG35 digital force gauge,
designed for tension and compression force testing applications from
0.12 lb to 500 lb (0.5 N to 2,500 N) full scale. The DFG35 is an essential
component of a force testing system, typically also comprising a test
stand, grips, and data collection software.
With proper usage, we are confident that you will get many years of
great service with this product. Omega force gauges are ruggedly built
for many years of service in laboratory and industrial environments.
This User’s Guide provides setup, safety, and operation instructions.
Dimensions and specifications are also provided. For additional
information or answers to your questions, please do not hesitate to
contact us. Our technical support and engineering teams are eager to
assist you.
Before use, each person who is to use the DFG35 force gauge
should be fully trained in appropriate operation and safety
procedures.
1 12-1049 12-1049 12-1049 Carrying Case
1 08-1022 08-1022 08-1022 AC adapter body with US, EU, or UK prong
1 08-1026 08-1026 08-1026 Battery (inside the gauge)
1 G1024 G1024 G1031 Extension rod
1 G1026 G1026 G1033 Cone
1 G1025 G1025 G1032 Chisel
1 G1027 G1027 G1034 V-groove
1 G1029 G1029 G1036 Flat
1 G1028 G1038 G1035 Hook
1 N/A G1039 G1037 Coupling
1 - Certificate of calibration
1 09-1165 USB cable
1 - Resource CD (USB driver, user’s guide)
1.2 Safety / Proper Usage
DFG35-20
DFG35-50 –
DFG35-100
DFG35-200 –
DFG35-500
Description
Caution!
Note the force gauge’s capacity before use and ensure that the capaci ty is not exceeded.
Producing a force greater than 150% of the gauge’s capacity can damage the internal load cell. An
overload can occur whether the gauge is powered on or off.
Typical materials able to be tested include many manufactured items, such as springs, electronic
components, fasteners, caps, films, mechanical assemblies, and many others. Items that should not be
used with the gauge include potentially flammable substances or products, items that can shatter in an
unsafe manner, and any other components that can present an exceedingly hazardous situation when
acted upon by a force.
The following safety checks and procedures should be performed before and during o peration:
1. Never operate the gauge if there is any visible damage to the AC adapter or the gauge itself.
2. Ensure that the gauge is kept away from water or any other electrically conductive liquids at all
times.
3. The gauge should be serviced by a trained technician only. AC power must be disconne cted and
the gauge must be powered off before the housing is opened.
4. Always consider the characteristics of the sample being tested before initiating a test. A risk
assessment should be carried out beforehand to ensure that all safety measures have been
addressed and implemented.
5. Wear eye and face protection when testing, especially when testing brittle samples that have the
potential to shatter under force. Be aware of the dangers posed by potential energy that can
accumulate in the sample during testing. Extra bodily protection should be worn if a destructive
failure of a test sample is possible.
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DFG35 Digital Force Gauges User’s Guide
6. In certain applications, such as the testing of brittle samples that can shatter, or other applications
that could lead to a hazardous situation, it is strongly recommended that a machine guarding
system be employed to protect the operator and others in the vicinity from shards or debris.
7. When the gauge is not in use, ensure that the power is turned off.
2 POWER
The gauge is powered either by an 8.4V NiMH rechargeable battery or by an AC adapter. Since these
batteries are subject to self discharge, it may be necessary to recharge the unit after a prolonged period
of storage. Plug the accompanying charger into the AC outlet and insert the charger plug into the
receptacle on the gauge (refer to the illustration below). The battery will fully charge in approximately 8
hours.
USB connector
Power input jack
Caution!
Do not use chargers or batteries other than supplied or instrument damage may occur.
If the AC adapter is plugged in, an icon appears in the lower left corner of the display, as follows:
If the AC adapter is not plugged in, battery power drainage is denoted in a five-step process:
1. When battery life is greater than 75%, the following indicator is present:
2. When battery life is between 50% and 75%, the following indicator is present:
3. When battery life is between 25% and 50%, the following indicator is present:
4. When battery life is less than 25%, the following indicator is present:
5. When battery life drops to approximately 2%, the indicator from step 4 will be flashing.
Several minutes after (timing depends on usage and whether the backli ght is turned on or
off), a message will appear, “BATTERY VOLTAGE TOO LOW. POWERING OFF”. A 4-tone
audio indicator will sound and the gauge will power off.
The gauge can be configured to automatically power off following a period of inactivity. Refer to the Other Settings section for details.
If battery replacement is necessary, the battery may be accessed by separating the two halves of the
gauge. Refer to the Mechanical Setup section for details.
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DFG35 Digital Force Gauges User’s Guide
3 SETUP
3.1 Mechanical setup
3.1.1 Loading shaft orientation
In order to accommodate a variety of testing requirements, the orientation of the loading shaft may be set
up in either of the two positions shown below. In order to change the loading shaft orientation, loosen the
two captive screws on the back side of the housing, separate the two housing halves, rotate one half 180
degrees, and reassemble. Exercise care when reassembling the two halves of the housing, ensuring that
internal wires do not interfere.
Load cell shaft up Load cell shaft down
3.1.2 Mounting to a plate
Although the gauge may be used by hand, proper mounting is important if attached to a fixture or test
stand. The round steel insert with a hole in the back of the housing is provided to withstand the load
during a test. A mating dowel pin should be used (see illustration below). There are four threaded holes
located near the corners of the housing. These holes are designed to accommodate screws in order to
hold the gauge in place. The screws must not be used for load bearing purposes. Failure to use a dowel
pin properly can result in a hazardous situation.
3.1.3 Mounting attachments to the gauge
The force gauge’s threaded loading shaft is designed to accommodate common grips and attachments
with female mounting holes. To mount a grip, gently thread it onto the shaft. Other mounting adapters are
also available to prevent rotation. Ensure that the grip or fixture is positioned to ensure axial load with
respect to the loading shaft of the force gauge. When using a grip, ensure that it secures the sample in
such a way that it is prevented from slipping out during a test, preventing a potential safety risk to the
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DFG35 Digital Force Gauges User’s Guide
g
y
operator and others in the vicinity. If using a grip or fixture from a supplier other than Omega, ensure that
it is constructed of suitably rugged materials and components.
Do not use jam nuts or tools to tighten grips or attachments onto the shaft. Finger-tighten only. Antirotation mounting adapters are available.
3.2 Installing the USB driver
If communicating via USB, install the USB driver provided on the Resource CD. Installation instructions
may also be found on the CD or may be downloaded from www.mark-10.com.
Caution!
Install the USB driver before physically connecting the gauge to a PC with the USB cable.
Further instructions for configuring and using the gauge’s outputs are provided in the Communications
and Outputs section.
4 HOME SCREEN AND CONTROLS
4.1 Home Screen
1
9
8
2
3
7
No. Name Description
1 Tension /
compression
indicator
2 Peaks The maximum measured compression and tension readings. These readings
3 Primary reading The current displayed force reading. See Operating Modes section for
- indicates a compression (push) direction
- indicates a tension (pull) direction
These indicators are used throu
are reset b
details.
pressing ZERO or by powering the gauge off and on.
hout the display and menu.
5 6
4
6
DFG35 Digital Force Gauges User’s Guide
y
g
r
y
y
(UP)
y
(
4 Load bar Analog indicator to help identify when an overload condition is imminent. The
bar increases either to the right or to the left from the midpoint of the graph.
Increasing to the right indicates compression load, increasing to the left
indicates tension load. If set points are enabled, triangular markers are
displayed for visual convenience. This indicator reflects the actual load, which
may not correspond to the primary reading (depends on operating mode).
The ZERO key does not reset the load bar. See Operating Modes section for
details.
5 Units The current measurement unit. Abbreviations are as follows:
lbF – Pound-force
kgF – Kilogram-force
gF – Gram-force
N – Newton
Note: not all gauge capacities measure in all the above units. Refer to the
capacit
/ resolution table in the Specifications section for details.
6 Mode The current measurement mode. Abbreviations are as follows:
RT – Real Time
PC – Peak Compression
PT – Peak Tension
Modes section for details about each of these modes
7 Battery / AC
adapter indicato
8 High / low limit
indicators
See Operatin
Either the AC adapter icon or battery power icon will be shown, depending on
power conditions. Refer to the Power section for details.
Correspond to the programmed set points. Indicator definitions are as follows:
– the displayed value is greater than the upper force limit
– the displayed value is between the limits
– the displayed value is less than the lower force limit
9 Set points The programmed force limits. Typically used for pass/fail type testing. 1, 2, or
no indicators may be present, depending on the configuration shown in the
Set Points menu item.
4.2 Controls
Primary
Label Primar
Powers the gauge on and off. Press
Function
briefly to power on, press and hold
to power off. Active only when the
home screen is displa
ed.
ZERO Zeroes the primary reading and
peaks.
Secondary
Label Secondary Function
ENTER Various uses, as described in the
following sections.
Navigates up through the menu and
sub-menus .
MENU Enters the main menu. ESCAPE Reverts one step backwards through
.
MODE Toggles between measurement
modes.
DATA Transmits the current reading to an
external device, via the USB port.
the menu hierarch
DOWN)
Navigates down through the menu
and sub-menus.
DIRECTION Reverses the display during
calibration, and toggles between
tension and compression directions
while configuring set points and other
menu items.
Note: Measurement units are configured through the menu. Refer to Section 6 for details.
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DFG35 Digital Force Gauges User’s Guide
4.3 Menu navigation basics
Most of the gauge’s various functions and parameters are configured through the main men u. To access
the menu press MENU. Use the UP and DOWN keys to scroll through the items. The cu rrent selection is
denoted with clear text over a dark background. Press ENTER to select a menu item, then use UP and
DOWN again to scroll through the sub-menus. Press ENTER again to select the sub-menu item.
For parameters that may be either selected or deselected, press ENTER to toggle between selecting and
deselecting. An asterisk (*) to the left of the parameter label is used to indicate when the parameter has
been selected.
For parameters requiring the input of a numerical value, use the UP and DOWN keys to increment or
decrement the value. Press and hold either key to auto-increment at a gradually increasing rate. When
the desired value has been reached, press ENTER to save the change and revert back to the sub-menu
item, or press ESCAPE to revert back to the sub-menu item without saving. Press ESCAPE to revert one
step back in the menu hierarchy until back into normal operating mode.
Refer to the following sections for details about setting up particular functions and parameters.
5 OPERATING MODES
Caution!
In any operating mode, if the capacity of the instrument has been exceeded by more than 110%,
the display will show “OVER” to indicate an overload. A continuous audible tone will be sounded
(if beeps are enabled) until the MENU key has been pressed or the load has been reduced to a
safe level.
Three operating modes are possible with DFG35 gauges. To cycle between the modes, press MODE
while in the home screen.
5.1 Real time (RT)
The primary reading corresponds to the live measured reading.
5.2 Peak Compression (PC)
The primary reading corresponds to the peak compression reading obse rved. If the actu al force
decreases from the peak value, the peak will still be retained in the primary reading area of the display.
Pressing ZERO will reset the value.
5.3 Peak Tension (PT)
Same as Peak Compression, but for tension readings.
6 CHANGING THE UNITS
DFG35 gauges display one of three measurement units. To change the unit, select Units from the menu.
The display will appear as follows:
UNITS
* lbF
kgF
gF
N
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DFG35 Digital Force Gauges User’s Guide
The gauge will always power on with the unit selected.
7 DIGITAL FILTERS
Digital filters are provided to help smooth out the readings in situations where there is m echanical
interference in the work area or test sample. These filters utilize the moving average technique in which
consecutive readings are pushed through a buffer and the displayed reading is the average of the buffer
contents. By varying the length of the buffer, a variable smoothing effect can be achieved. The selection
of 1 will disable the filter since the average of a single value is the value itself.
To access digital filter settings, select Filters from the menu. The display will appear as follows:
DIGITAL FILTERS
(1 = Fastest)
Current Reading 8
Displayed Reading
1024
Two filters are available:
Current Reading – Applies to the peak capture rate of the instrument.
Displayed Reading – Applies to the primary reading on the display.
Available settings: 1,2,4,8,16,32,64,128,256,512,1024. It is recommended to keep the current reading
filter at its lowest value for best performance, and the displayed reading filter at its highest value for best
stability.
8 SET POINT INDICATORS
8.1 General Information
Set points are useful for tolerance checking (pass/fail). Two limits, high and low, are specified and stored
in the non-volatile memory of the instrument and the primary reading is compared to these limits.
8.2 Configuration
To configure set points, select Set Points from the menu. The screen will appear as follows:
SET POINTS
Upper Disabled
* Upper Enabled
5.00
Lower Disabled
* Lower Enabled
3.50
Either one, two, or none of the set points may be enabled. To toggle between the tension and
compression directions, press the DIRECTION key.
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DFG35 Digital Force Gauges User’s Guide
If two set points have been enabled, they are displayed in the upper left corner of the display. If only one
set point has been enabled, the word “OFF” will appear in place of the value. If no set points have been
enabled, the upper left corner of the display will be blank.
When set points are enabled, the following indicators are shown to the left of the primary reading:
– the displayed value is greater than the upper
force limit (NO GO HIGH)
– the displayed value is between the limits (GO)
– the displayed value is less than the lower force
limit (NO GO LOW)
Note: Set point indicators reference the displayed reading,
not necessarily the current live load.
9 COMMUNICATIONS AND OUTPUTS
Communication with DFG35 force gauges is achieved through the micro USB port locate d along the left
side of the housing, as shown in the illustration in the Power section. Communication is possible only
when the gauge is in the main operating screen (i.e. not in a menu or configuration area).
The current reading is transmitted from the gauge when the DATA key is pressed. For continuous output,
the gauge also responds to the ASCII command ‘?’ (no quotes), terminated with a Carriage Return
character or with a Carriage Return/Line Feed combination. The gauge’s responses are always
terminated with a Carriage Return/Line Feed. Any detected errors are reported back by means of error
code *10 (illegal command).
9.1 Communication Settings
To set up communication settings, select USB Settings from the menu. The screen appears as follows:
USB SETTINGS
+ Baud Rate
+ Data Format
Communication settings are permanently set to the following:
Data Bits: 8
Stop Bits: 1
Parity: None
Other settings are configured as follows:
9.1.1 Baud Rate
Select the baud rate as required for the application. It must be set to the same value as the receiving
device.
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DFG35 Digital Force Gauges User’s Guide
y
y
y
9.1.2 Data Format
Select the desired data format. The screen appears as follows:
DATA FORMAT
* Numeric + Units
Numeric Only
Invert Polarity
Omit Polarity
Selection Description
Numeric + Units Output format includes the value and unit of measure. Compression values have
positive polarit
Numeric Only Output format includes the value only. Polarity same as above.
Invert Polarity Compression values have negative polarity, tension values have positive polarity.
Ma
Omit Polarity Both directions are formatted with positive polarity. May be selected in addition to
the Numeric + Units / Numeric Onl
Individual data points may be transmitted by pressing DATA.
, tension values have negative polarity.
be selected in addition to the Numeric + Units / Numeric Only selection.
selection.
10 CALIBRATION
10.1 Initial Physical Setup
The gauge should be mounted vertically to a test stand or fixture rugged enough to withstand a load
equal to the full capacity of the instrument. Certified deadweights or master load cells should be used,
along with appropriate mounting brackets and fixtures. Caution should be taken while handling such
equipment.
10.2 Calibration Procedure
1. Select Calibration from the menu. The display will appear as follows:
CALIBRATION
To invert the
display, press the
DIRECTION button,
then press ENTER.
2. Press DIRECTION to invert the display, if desired. ENTER to continue. The display will appear as
follows:
CALIBRATION
Enter # cal points
(1 to 10)
Compression:
5
Tension:
5
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DFG35 Digital Force Gauges User’s Guide
The gauge can be calibrated at up to 10 points in each direction. Enter the number of calibration
points for each direction (compression and tension). At least one point must be selected for each
direction.
Note: To achieve the accuracy specification of ±0.3%, it is recommended to calibrate the gauge
at 5 or more even increments in both the tension and compression directions. For example, a
gauge with capacity of 10 lbF should be calibrated at 2, 4, 6, 8, and 10 lb loads in each direction.
3. To escape the Calibration menu at any time, press ESCAPE. The display will appear as follows:
CALIBRATION
NOT COMPLETE
Cancel
Exit w/o saving
Selecting “CANCEL” will revert back to the Calibration setup. Selecting “EXIT W/O SAVING” will
return to the menu without saving changes.
4. After the number of calibration points has been entered, press ENTER. The display will appear as
follows:
CALIBRATION
OFFSET
Place force gauge
horizontally, then
press ZERO.
5. Place the force gauge horizontally on a level surface free from vibration, then press ZERO. The
gauge will calculate offsets, and the display will appear as follows:
CALIBRATION
OFFSET
Please wait…
CALIBRATION
OFFSET
Sensor passed
Analog passed
CALIBRATION
OFFSET
Sensor failed
Analog failed
If failed:
6. The following screen appears after the offsets have been calculated:
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DFG35 Digital Force Gauges User’s Guide
CALIBRATION
COMPRESSION
Attach necessary
weight fixtures,
then press ENTER.
Attach weight fixtures (brackets, hooks, etc), as required. Do not yet attach any weights or apply
any calibration loads. Then press ENTER.
7. The display will appear as follows:
CALIBRATION
COMPRESSION
Optionally exercise
sensor, then press
ENTER.
Optionally exercise the load cell shaft several times (at full scale, if possible), then press ENTER.
8. The display will appear as follows:
CALIBRATION
COMPRESSION
Gain adjust
Apply full scale load
10.00 lbF +/-20%,
then press ENTER.
Apply a weight equal to the full scale of the instrument, and then press ENTER.
9. After displaying “PLEASE WAIT…” the display will appear as follows:
CALIBRATION
COMPRESSION
Ensure no load,
then press ZERO.
Remove the load applied in Step 8, leave the fixtures in place, then press ZERO.
10. The display will appear as follows:
CALIBRATION
COMPRESSION
Apply load
1 OF 5
Enter load:
2.00 lbF
Press ENTER.
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DFG35 Digital Force Gauges User’s Guide
Use the UP and DOWN keys to adjust the load value as required. The load values default to even
increments, as indicated by the previously entered number of data points (even increments are
recommended for best results). For example, if a 50 lbF capacity gauge is calibrated, and 5 data
points were selected, the load values will default to 10, 20, 30, 40, and 50 lb. Apply the
calibration load. Then press ENTER.
Repeat the above step for the number of data points selected.
11. After all the compression calibration points have been completed, the display will appear as
follows:
CALIBRATION
COMPRESSION COMPLETE
Reverse direction
for tension.
Attach necessary
weight fixtures,
then press ENTER.
Press ENTER.
12. The display will appear as follows:
CALIBRATION
To invert the
display, press the
DIRECTION button,
then press ENTER
Reverse the orientation of the load cell shaft by rotating the gauge 180 degrees. Press
DIRECTION to invert the display. Then attach weight fixtures. The following screens will step
through the same procedure as with the compression direction. Proceed in the same manner.
13. At the completion of the tension calibration, the display will appear as follows:
CALIBRATION
COMPLETE
Save & exit
Exit w/o saving
To save the calibration information, select “SAVE & EXIT”. To exit without saving the data select
“EXIT W/O SAVING”.
14. Any errors are reported by the following screens:
14
DFG35 Digital Force Gauges User’s Guide
CALIBRATION
Units must be kgF.
Please try again
Press ENTER.
Displayed at the start of calibration if a disallowed unit is selected.
CALIBRATION
Load not stable.
Please try again.
Ensure that the load is not swinging, oscillating, or vibrating in any manner. Then try again.
CALIBRATION
COMPRESSION
Load too low.
Please try again.
The calibration weight does not match the set value.
CALIBRATION
TENSION
Load too close
to previous.
Please try again.
The entered calibration point is too close to the previous point.
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DFG35 Digital Force Gauges User’s Guide
11 OTHER SETTINGS
11.1 Automatic Shutoff
The gauge may be configured to automatically power off following a period of inactivity while on battery
power. Inactivity is defined as the absence of any key presses or load changes of 100 counts or less. To
access these settings, select Automatic Shutoff from the menu. The display will appear as follows:
AUTOMATIC SHUTOFF
* Disabled
Enabled
Set Minutes
5
Select Disabled to disable automatic shutoff. Select Enabled to enable it. The length of time of inactivity
is programmed in minutes via the Set Minutes parameter. Available settings: 5-30, in 5 minute
increments.
Note: If the AC adapter is plugged in, the gauge will ignore these settings and remain powered on until
the POWER key is pressed.
11.2 Backlight
Several initial settings are available, upon powering on the gauge. To access these settings, select
Backlight from the menu. The display will appear as follows:
BACKLIGHT
Off
On
* Auto
Set Minutes
1
Select Off for the backlight to be off upon powering on the gauge.
Select On for the backlight to be on upon powering on the gauge.
Select Auto for the backlight to be on upon powering gauge, but will shut off after a period of inactivity (as
defined in the Automatic Shutoff sub-section). The backlight will turn on again when activity resumes.
The length of time of inactivity is programmed in minutes via the Set Minutes parameter. Available
settings: 1-10, in 1 minute increments.
Note: If the AC adapter is plugged in, the gauge will ignore these settings and keep the backlight on.
Selecting the On or Off setting in the Backlight menu will manually turn the backlight on or off as if the
Backlight key were pressed.
11.3 LCD Contrast
The contrast of the display may be adjusted. Select LCD Contrast from the menu. The screen will appear
as follows:
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DFG35 Digital Force Gauges User’s Guide
LCD CONTRAST
Set Contrast
10
Press ENTER to modify the contrast. Select a value from 0 to 25, 25 producing the most contrast.
11.4 Tones
Audible tones can be enabled for all key presses and alerts, such as overload, set point value reached,
etc. The Set Point alert can be configured to be either a momentary tone or a continuous tone (until the
load is restored to a value between the set points). To configure the functions for which audibl e tones will
apply, select Tones from the menu. The screen will appear as follows:
TONES
Keys
* Alerts
Set Points
* Momentary
Continuous
11.5 Initial Mode
This section is used to configure the initial mode upon powering on the gauge. To access this para m eter,
select Initial Mode from the menu. The screen will appear as follows:
INITIAL MODE
* Real Time
Peak Compression
Peak Tension
The default value is Real Time.
11.6 Information / Welcome Screen
The following screen is displayed at power up and can be accessed at any time by selecting Information
from the menu:
Digital Force Gauge
Series DFG35
Model No: DFG35-50
Serial No: 1234567
Version: 1.0
www.omega.com
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DFG35 Digital Force Gauges User’s Guide
r
A
A
12 SPECIFICATIONS
12.1 General
Accuracy: ±0.3% of full scale
Sampling rate: 2,000 Hz
Power:
Battery life:
Measurement units:
USB output:
Safe overload:
Weight (gauge only):
Included accessories:
Environmental
requirements:
Warranty:
12.2 Factory Settings
Paramete
Set points
Upper Disabled (defaults to 80% of full scale, compression, when enabled)
Lower Disabled (defaults to 40% of full scale, compression, when enabled)
Filters
Current 8
Displayed 1024
Backlight
Minutes 1
USB Output
Baud Rate 9,600
Data Format Numeric + units
utomatic Shutoff Enabled
Minutes 5
Tones
Keys Enabled
Alerts Enabled
Set Points Momentary
Initial Mode Real Time
Units lbF
AC or rechargeable battery. Low battery indicator appears when battery level is low, and
gauge powers off automatically when power reaches critical stage.
Backlight on:
Backlight off:
lbF, gF, kgF, N (depending on model)
Fully configurable up to 115,200 baud
150% of full scale (display shows “OVER” at 110% and above)
DFG35-0.12 – DFG35-100:
DFG35-200 – DFG35-500:
Carrying case, chisel, cone, V-groove, hook, flat, extension rod, AC adapter, battery, USB
cable, resource CD (USB driver and user’s guide), NIST-traceable certificate of calibration
40 - 100°F, max. 96% humidity, non-condensating
3 years (see individual statement for further details)
up to 7 hours of continuous use
up to 24 hours of continuous use