Extech Instruments DT40M User manual

USER MANUAL
Laser Distance Meter
MODELS DT40M, DT60M, and DT100M

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Contents
Introduction ..........................................................................................3
Safety Instructions .................................................................................3
Descriptions...........................................................................................4
Measurement Preparation ......................................................................6
Programming Menu ...............................................................................8
Distance Measurements .........................................................................8
Area Measurements .............................................................................10
Volume Measurements.........................................................................12
Indirect Measurements (Pythagorean) ...................................................13
Stakeout Function ................................................................................16
20-point Datalogger .............................................................................17
Maintenance .......................................................................................18
Display Error Codes ..............................................................................20
Specifications.......................................................................................20

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Introduction
Thank you for selecting the Extech Laser Distance Meter. This meter
measures distance up to 40m (131.2’) for DT40M, 60m (197’) for
DT60M, or 100m (328.1’) for DT100M and calculates Area, Volume,
and Indirect readings using the Pythagorean Theorem (a2+b2=c2). It
also includes a laser pointer and a stakeout feature. Please visit
www.extech.com for the latest version of this User Guide, Product
Updates, and Customer Support.
Safety Instructions
This meter has been designed for safe use, but must
be operated with caution.
Laser classification (Class 2)
The meter produces a visible Class 2 laser beam from
the top of the instrument.
WARNING: Do not directly view or point the laser at an eye. Do not
look directly into the beam using an optical aid such as binoculars. This
can create a hazard. Low power visible lasers do not normally present a
hazard, but may present some potential for hazard if viewed directly for
extended periods of time.
Please read all safety instructions carefully before using this
instrument
Do not use this device in flammable or explosive environments
Do not use this device near aircraft or medical equipment
Do not use this device near strong electro-magnetic interference
Do not aim the meter directly into sunlight
Do not dis-assemble or modify the instrument
Do not store in areas of high temperature/humidity
Remove the batteries when storing the instrument for long periods

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Descriptions
Meter
1. LCD display area
2. Keypad
3. Level
4. Laser Pointer
5. Sensor Beam
Note: Battery compartment on back of meter
Display Description
1. Length measurement mode
2. Battery status
3. Datalogger icon and memory location (1~20)
4. Signal strength icons
5. Laser pointer default
mode
6. Edge Reference (from top
or bottom of meter)
7. Indirect measurements:
Single Pythagorean,
Double Pythagorean, and
Double Pythagorean
(partial height)
8. Stakeout mode
9. Area/Volume mode
10. Primary/summary display line
11. Auxiliary Display lines 1 (top), 2, and 3
12. Units of measure

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Keypad Description
Short press: Power ON
Short press: Laser ON (can be set to default ON)
Short press: Single distance measurement
Long press: Continuous measurement mode
Short press: Datalogger mode (press CLR to exit)
Long press: Open program menu
Short press: Clear display; Long press: Power OFF
Short press: Area/Volume mode
Long press to 1st beep: Stakeout mode
Indirect measurements
Press 1x: Single Pythagorean mode
Press 2x: Double Pythagorean mode
Press 3x: Double Pythagorean (partial height)
Add / Subtract keys
Short press: Measurement edge selection
Long press: Backlight ON/OFF
Short press: Select unit of measure

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Measurement Preparation
Measurement Considerations
1. For best results, choose a target that is flat, hard and smooth
2. Use a section of cardboard or similar material if the target
size needs to be increased
3. For distance measurements, this device performs best
indoors. If used outdoors, the range will be limited
depending on intensity of light and other environmental
factors.
4. Replace the battery if the battery icon flashes on the display
5. The meter will not measure through glass, liquid, or
Styrofoam
6. Inaccurate measurements may result from low battery,
measured distance exceeding specified range, and irregular
shaped objects near the target.
Range considerations
The range is limited to 40m (131.2’), 60m (197’), or 100m
(328.1’) depending on model. At night or dusk, if the target is in
shadow, the measuring range without target plate is increased.
Use a target plate to increase the range during daylight or if the
target has poor reflection properties. In unfavorable conditions
such as intense sunlight, poor reflective surfaces, or high
temperatures, distance readings over 10m (33’) can increase by
±0.15mm/m (±0.0018in/ft.).
Target surfaces
Measurement errors can occur when measuring toward colorless
liquids (e.g. water), dust free glass, Styrofoam or similar semi-

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permeable surfaces. Aiming at high gloss surfaces may deflect
the laser beam and lead to measurement errors. For non-
reflective and dark surfaces, the measuring time may increase.
Preparing for Measurements
1. Press the MEAS key to switch the meter ON.
2. You can elect either to have the Laser always ON or to have
the laser turn ON only when the MEAS key is pressed. Go to
the Programming Menu section of this manual for details.
3. The unit automatically switches OFF after three (3) minutes
of inactivity. Long press CLR to switch the unit OFF manually.
4. Press CLR to cancel the last action performed or clear the last
data displayed on the screen.
5. Press UNIT to change the unit of measure (ft = feet, in =
inches, m = meters.
6. Long press to turn the backlight on or off.
7. Short press the reference key to select the top edge or
bottom edge reference. See diagram below.
In the Top mode (2), the displayed reading will represent
the distance from the top of the meter to the target.
In the Bottom mode (1), the
displayed reading will
represent the distance from
the bottom of the meter to
the target. This is the
default mode.

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Programming Menu
1. Long press to open the programming menu
2. Use the MEAS button to step through the options
3. Use the (+) and (-) keys to make changes
4. Use the MEAS button to exit the menu
5. See table below for the program options
1
ON: OFF:
For distance measurements: Set Laser to
default ON/OFF. Use + key to select.
2
For all other measurements: Set Laser to
default ON/OFF. Use + key to select.
3
CAL. 0
Use +/- keys to offset display by ±7mm
4
bP. on/oFF
Use +/- keys to set beeper default ON/OFF
5
bL. On/oFF
Use +/-keys to set backlight default
ON/OFF
6
od. On/oFF
Unused mode
Distance Measurements
Single Distance Measurements
1. Momentarily press the MEASURE key to switch the meter ON;
Dashes (- - -) will appear on the display.
2. If the Laser point is already ON, go directly to step 3 below. If
the Laser point is not ON, press MEASURE to switch it ON.
3. Aim the meter and short press MEASURE to take a reading.
4. You can elect either to have the Laser always ON or to turn ON
only when MEASURE is pressed. Go to the Programming Menu
section of this manual for details.

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5. The reading will remain on the display until it is cleared with
the CLR key (short press) or until the meter is powered OFF.
Continuous Distance Measurements (with MAX-MIN)
This mode of operation is useful for determining the shortest
and longest distances from a given point. The meter can be
moved to various targets while the primary display (bottom)
updates with each new measurement. The MIN and MAX values
are displayed dynamically in auxiliary displays above the primary
display.
1. Press the MEASURE key to switch the meter ON.
2. Press and hold MEASURE for 3 seconds to begin a continuous
measurement session. The laser pointer will stay ON in
continuous mode.
3. The meter will beep with each new automatic measurement
update (approx. every one half second).
4. The MIN reading will be indicated (example below, left) and
will update each time a lower reading (< displayed MIN
reading) is encountered.
5. The MAX reading (example below, right) will be indicated and
will update each time a higher reading is encountered.
6. The actual reading will be indicated on the primary display.

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7. To stop measuring, short press MEASURE. Use the CLR key to
delete measurement displays.
8. Note that the meter exits to the normal mode of operation
after approx. 100 measurements in continuous mode.
Adding / Subtracting Distance Measurements
To display the sum or difference of two distance measurements:
1. Press the MEASURE key to switch the meter ON. Press
MEASURE to turn Laser ON, if it is not already ON.
2. Press MEASURE to take the first reading. The reading appears
on the primary display line (bottom).
3. Press the plus (+) or minus (-) key. The first reading will move
to auxiliary display line 2.
4. The plus or minus sign will appear on auxiliary display line 3.
5. Press MEASURE to turn Laser ON, if it is not already ON.
6. Press MEASURE to take the second reading. The second
reading appears on auxiliary display line 3.
7. Read the sum or difference of the two readings on the
primary display line.
8. Press CLR to cancel the last step or press MEASURE to move
the result (now shown in the primary display) to auxiliary
display line 2, for additional adding/subtracting work.
9. Press CLR to exit this mode or turn the meter OFF.
Area Measurements
Area Calculations
Computing the area of a room:
1. Press the MEASURE key to turn the meter ON.