Extech Instruments SDL550 User manual

User's Guide
Moisture Content Meter
Plus Dew Point, Wet Bulb, and Thermocouple Temperature functions
SD Card real-time datalogger
Model SDL550
%RH
Moisture Content
Meter
SDL550

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Moisture Content
Meter
SDL550
Introduction
Congratulations on your purchase of the Extech SDL550 Moisture Content Meter. This meter
displays and stores Moisture Content readings, Air Temperature, Dew Point Temperature, and Wet
Bulb Temperature. Logged data readings are stored on an SD card for transfer to a PC. In addition,
an RS232 port allows data streaming to a PC. This meter is shipped fully tested and calibrated and,
with proper use, will provide years of reliable service.
Safety
International Safety Symbols
This symbol, adjacent to another symbol or terminal, indicates the user must refer to the
manual for further information.
Meter Description
1. Thermocouple Temperature Probe input jack
2. Moisture Sensor input jack
3. Primary LCD Display digits
4. Unit of Measure for Primary Display
5. HOLD and Backlight key
6. MAX-MIN key
7. SET and Clock key
8. PC interface jack
9. Reset button
10. Power Adaptor jack
11. SD card slot
12. ENTER and LOG key
13. Down arrow ▼/ FUNCTION key
14. Up arrow ▲key
15. Power ON-OFF key
16. Secondary LCD Display digits with unit of measure
Notes: Items 8, 9, and 10 are located behind the snap-off compartment cover on meter’s right side.
Battery compartment, tilt stand, and tripod mount are locatedon the rearof the instrument

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Moisture Probe Description
1. Probe Handle
2. Probe connecting cable
3. Probe-to-meter input plug
4. Probe collar (probe sensor unscrews from here to access filter)
5. Moisture Sensor penetrating tip
6. Sensor port openings
7. Protective cap (slides off of sensor tip)
Basic Operation
Power ON-OFF
•Power the meter by pressing and holding the power button for at least 1.5 seconds.
•Press and hold the power button for at least 1.5 seconds to power OFF the meter.
•This meter is powered by six (6) 1.5VDC ‘AA’ batteries or by optional AC adaptor.
Display Backlight
To turn the display backlight ON or OFF, press and hold the backlight button for at least 1.5
seconds. The meter will beep when switching the backlight ON or OFF unless the beeper is
disabled.
Moisture Content Sensor
The supplied Moisture Content sensor connects to the meter via the DIN jack at the top right of the
meter. Note that the utility end of the sensor is located beneath the protective cap; use great caution
when removing the cap and when handling the sensor as the sensor head is extremely sharp. The
sensor uses an internal filter and when the filter becomes soiled or defective the readings take
longer to stabilize. Contact Extech for replacement filters.
Temperature (Thermocouple) Sensor
A type J or K thermocouple (optional) can be connected to the meter via the thermocouple input
jack at the top left of the meter for measuring air temperature. Note that the temperature range of
the meter extends up to 1300
°
C (2372
°
F), however thermocouple ranges vary greatly; be sure to
select a thermocouple rated for the expected temperature measurement ranges.

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Selecting Meter Functions
The SDL550 can measure Moisture Content (%RH), Dew Point Temperature (
°
C/
°
F), Wet Bulb
Temperature (
°
C/
°
F), and Thermocouple Temperature (
°
C/
°
F). Press and hold the FUNCTION button
for 1.5 seconds to begin scrolling through the functions. Release the FUNCTION button when the
desired function is displayed. Refer to the table below.
Functions Primary display Secondary display Unit of measure
Moisture Content Relative Humidity rh briefly displayed then the
Moisture Probe Temperature RH% and
o
C or
o
F
Dew Point Temperature* dp display icon
°
C or
°
F
Wet Bulb Temperature* _et display icon
°
C or
°
F
Air Temperature Thermocouple Temperature tp briefly displayed
°
C or
°
F
Measurements
Moisture Content Measurements
1. Connect the Moisture probe to the jack at the top of the meter on the right
2. Switch the meter ON by pressing and holding the power button for 1.5 seconds
3. Press and hold the FUNCTION button to select the Moisture Content mode. When the Moisture
Content mode is selected, the display icon rh is briefly shown
4. Carefully remove the protective cap from the moisture probe. The probe tip is extremely sharp,
use caution
5. Insert the probe tip into the material under test far enough to cover the sensor’s openings
6. The meter will now display moisture content in %RH on the primary (upper) LCD digits
7. The secondary (lower) LCD digits will show the temperature measured by the moisture probe’s
built-in temperature sensor. Use the Setup mode to change the temperature units of measure
8. Note that the probe uses a built-in filter. When the filter needs replacing (becomes soiled or
defective), the measurement readings require a longer stabilization time. Please contact Extech
for replacement filters
Dew Point and Wet Bulb Temperature Measurements
1. Connect the Moisture probe to the jack at the top of the meter on the right
2. Switch the meter ON by pressing and holding the power button for 1.5 seconds
3. Press and hold the FUNCTION button to select the Wet Bulb or the Dew Point mode. When the
Dew Point mode is selected, the display icon dp is shown on the secondary display area. When
the Wet Bulb mode is selected, the display icon _et is shown on the secondary display area.
4. Carefully remove the protective cap from the moisture probe. The probe tip is extremely sharp,
use caution
5. Insert the probe tip into the material under test far enough to cover the sensor’s openings
6. The meter will now display the Dew Point Temperature or Wet Bulb Temperature on the primary
(upper) LCD digits. Use the Setup mode to change the temperature units of measure

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Thermocouple Temperature Measurements
1. Note that the temperature range of the meter extends up to 1300
o
C (2372
o
F), however
thermocouple sensor ranges vary greatly; be sure to select a thermocouple rated for the
expected temperature measurement ranges.
2. Connect a Thermocouple Temperature sensor (not supplied) to the jack at the top of the meter
on the left
3. Switch the meter ON by pressing and holding the power button for 1.5 seconds
4. Press and hold the FUNCTION button to select the Thermocouple Temperature mode. When
the Thermocouple Temperature mode is selected, the display icon tp is briefly shown. The
thermocouple type (J or K) will be shown on the left side of the LCD. Use the Setup mode to
change the thermocouple type
5. Hold the thermocouple sensor tip in the air to be measured
6. The meter will now display thermocouple temperature on the primary (upper) LCD digits. Use
the Setup mode to change the temperature units of measure
Data Hold
To freeze a displayed reading on the LCD, momentarily press the HOLD button (the HOLD icon will
appear above the reading). To exit the Data Hold mode, press the HOLD button again.
Max-Min Reading Record
For a given measurement session, this meter can record the highest (MAX) and the lowest (MIN)
readings for later recall.
1. Press the MAX-MIN button momentarily to access this mode of operation (REC icon appears)
2. The meter is now recording the MAX and MIN readings.
3. Press the MAX-MIN button again to view the current MAX readings (MAX icon appears). The
readings on the display are now the highest readings encountered since the REC icon was
switched on (when the MAX-MIN button was first pressed).
4. Press the MAX-MIN button again to view the current MIN readings (MIN icon appears). The
readings on the display are now the lowest readings encountered since the REC icon was
switched on (when the MAX-MIN button was first pressed).
5. To exit the MAX-MIN mode, press and hold the MAX-MIN button for at least 1.5 seconds. The
meter will beep, the REC-MAX-MIN icons will switch off, the MAX-MIN memory will clear, and
the meter will return to the normal operating mode.

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Setup Mode
Basic settings at a glance
To view the current configuration of the meter with regard to time, date, and datalogging sampling
rate press the SET button momentarily. The meter will now display the configuration in quick
succession. If the information is missed on the first try, simply press the SET button again until all of
the information is noted.
Accessing the Setup mode
1. Press and hold the SET button for at least 1.5 seconds to access the Setup menu.
2. Press the SET button momentarily to step through the available parameters. The parameter
type is shown on the bottom of the LCD and the current selection for that type is shown above it.
3. When a parameter is displayed that is to be changed, use the arrow keys to change the setting.
Press the ENTER button to confirm a change.
4. Press and hold the SET button for at least 1.5 seconds to exit the Setup mode. Note that the
meter automatically switches out of the Setup mode if no key is pressed within 7 seconds.
5. The available Setup parameters are listed below. Additional detailed information is provided
below this list:
dAtE Set the clock (Year/Month/Date; Hours/Minutes/Seconds)
SP-t Set the datalogger sampling rate (0 to 3600 Seconds)
PoFF Automatic power-off management (Enable or disable the auto-power off function)
bEEP Set the beeper sound ON/OFF
dEC Set the numerical format; USA (decimal: 20.00) or European (comma: 20,00)
SdF Format the SD memory card
t-CF Select the temperature unit of measure (degrees C orF)
tYPE Select the thermocouple type (J or K)
Setting the Clock Time
1. Access the dAtE parameter.
2. Use the arrow keys to change a value
3. Use the ENTER button to step through the selections
4. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode (or
simply wait 7 seconds for the meter to automatically switch to the normal operating mode).
5. The clock will keep accurate time even when the meter is switched off. However, if the battery
expires the clock will have to be reset after fresh batteries are installed.

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Setting the Datalogger Sampling Time (Rate)
1. Access the SP-t parameter.
2. Use the arrow buttons to select the desired sampling rate. The available settings are: 0, 1, 2, 5,
10, 30, 60, 120, 300, 600, 1800, and 3600 seconds.
3. Pressthe ENTERbuttontoconfirmtheentry.
4. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode.
Enabling/Disabling the Auto Power OFF Feature
1. Access the PoFF parameter.
2. Use the arrow buttons to select ON or OFF. With the Auto Power OFF feature enabled, the
meter will automatically switch OFF after 10 minutes of inactivity.
3. Press ENTER to confirm setting.
4. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode.
Set the Beeper Sound ON or OFF
1. Access the bEEP parameter.
2. Use the arrow buttons to select ON or OFF.
3. Press ENTER to confirm setting.
4. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode.
Numerical Format (comma or decimal)
European and USA numerical formats differ. The meter defaults to USA mode where a decimal
point is used to separate units from tenths, i.e. 20.00; The European format uses a comma, i.e.
20,00 to separate units from tenths. To change this setting:
1. Access the dEC parameter.
2. Use the arrow buttons to select USA or EUro.
3. Press ENTER to confirm setting.
4. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode.
SD Card FORMATTING
1. Access the Sd-F parameter.
2. Use the arrow buttons to select YES to format the card (select NO to abort). Note that all data
on the card will be lost if formatting is attempted.
3. Press ENTER to confirm selection.
4. Press ENTER again to re-confirm.
5. The meter will automatically return to the normal operating mode when formatting is complete.
If not, press and hold SET button for at least 1.5 seconds to exit to the normal operation mode.
Set the Temperature Units of Measure (°C or °F)
1. Access the t-CF parameter.
2. Use the arrow buttons to select °C or °F. Press ENTER to confirm setting.
3. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode.

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Set the Thermocouple Type
1. Access the tYPE parameter.
2. Use the arrow buttons to select the desired sensor type (Jor K)
3. Press ENTER to confirm setting.
4. Press and hold the SET button for at least 1.5 seconds to exit to the normal operation mode (or
simply wait 7 seconds for the meter to automatically switch to the normal operating mode).
Datalogging
Types of Data Recording
•Manual Datalogging: Manually log up to 99 readings onto an SD card via push-button press.
•Automatic Datalogging: Automatically log data onto an SD memory card where the number of
data points is limited only by the card size. Readings are logged at a rate specified by the user.
SD Card Information
•Insert an SD card (from 1G size up to 16G) into the SD card slot at the bottom of the meter. The
card must be inserted with the front of the card (label side) facing toward the rear of the meter.
•If the SD card is being used for the first time it is recommended that the card be formatted and
the logger’s clock set to allow for accurate date/time stamping during datalogging sessions.
Refer to the Setup Mode section for SD card formatting and time/date setting instructions.
•European and USA numerical formats differ. The data on the SD card can be formatted for
either format. The meter defaults to USA mode where a decimal point is used to separate units
from tenths, i.e. 20.00. The European format uses a comma, i.e. 20,00. To change this setting,
refer to the Setup Mode section.
Manual Datalogging
In the manual mode the user presses the LOG button to manually log a reading onto the SD card.
1. Set the sampling rate to ‘0’ seconds as described in the Setup Mode section.
2. Press and hold the LOG button for at least 1.5 seconds and the secondary display area will
show p-n(n= memory position number 1-99).
3. Momentarily press the LOG button to store a reading. The REC icon will flash each time a data
point is stored.
4. Use the ▲and ▼buttons to select one of the 99 data memory positions in which to record.
5. To exit the manual datalogging mode, press and hold the LOG button for at least 1.5 seconds.

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Automatic Datalogging
In automatic datalogging mode the meter takes and stores a reading at a user-specified sampling
rate onto an SD memory card. The meter defaults to a sampling rate of two seconds. To change the
sampling rate, refer to the Setup Mode section (the sampling rate cannot be ‘0’ for automatic
datalogging):
1. Select the sampling rate in the Setup Mode to a value other than zero.
2. Press and hold the LOG button for at least 1.5 seconds. The meter will flash the REC icon at the
selected sampling rate indicating that readings are now being automatically recorded to the SD
card. The LOG display icon will appear on the secondary (lower) LCD display digits.
3. If a card is not inserted, the meter will display "Sd","-E-" If a card is defective, the meter will
display " ScAn "," Sd ".
4. Pause the datalogger by pressing the LOG button momentarily. The REC icon will stop flashing
and the sample rate will display for a short time. To resume logging simply press the LOG
button again momentarily.
5. To terminate the datalogging session press and hold the LOG button for at least 1.5 seconds.
6. When an SD card is used for the first time a folder is created on the card and named HTB01. Up
to 99 spreadsheet documents (each with 30,000 readings) can be stored in this folder.
7. When datalogging begins a new spreadsheet document named HTB01001.xls is created on the
SD card in the HTB01 folder. The data recorded will be placed in the HTB01001.xls document
until 30,000 readings are reached.
8. If the measurement session exceeds 30,000 readings, a new document will be created
(HTB01002.xls) where another 30,000 readings can be stored. This method continues for up to
99 documents, after which another folder is created (HTB02) where another 99 spreadsheet
documents can be stored. This process continues in this same fashion with folders HTB03
through HTB10 (last allowable folder).
SD Data Card to PC Data Transfer
1. Complete a datalogging session as detailed in above in the previous sections. Hint: For the first
few tests, simply record a small amount of test data. This is to ensure that the datalogging
process is well understood before committing to critical, large scale datalogging.
2. With the meter switched OFF, remove the SD Card.
3. Plug the SD Card directly into a PC SD card reader. If the PC does not have an SD card slot,
use an SD card adaptor (available at most outlets where computer accessories are sold).
4. Power the PC and run a spreadsheet software program. Open the saved documents in the
spreadsheet software program (see example spreadsheet data screen below).
Spreadsheet data example

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RS-232/USB PC Interface
The optional 407001A software kit (software and cable) allows streaming of data to a PC via
the RS232 Output jack.
AC Power Adaptor
This meter is normally powered by six (6) 1.5V ‘AA’ batteries. An optional 9V power adaptor is
available. When the adaptor is used, the meter is permanently powered and the power button will
be disabled.
System Reset
If the meter’s keys become inoperable or if the display freezes the Reset button can be used to
reset the instrument.
1. Use a paper clip or similar item to momentarily press the reset button located on the lower right
side of the instrument under the snap-off compartment cover.
2. After pressing the Reset button, switch the instrument ON by pressing and holding the POWER
key for at least 1.5 seconds. If using the power adaptor unplug the adaptor and then plug it back
in again to power the meter.
Battery Replacement and Disposal
When the low battery icon appears on the LCD, the batteries must be replaced. Several hours of
accurate readings are still possible in this condition; however batteries should be replaced as soon
as possible:
1. Remove the two (2) Phillips screws from the rear of the meter (directly above the top of the tilt
stand).
2. Remove and safely place the battery compartment and screws where they will not be damaged
or lost.
3. Replace the six (6) 1.5V ‘AA’ batteries observing polarity.
4. Replace the battery compartment cover with the two (2) Phillips screws.
All EU users are legally bound by the battery ordinance to return all used batteries to
collection points in your community or wherever batteries / accumulators are sold!
Disposal in the household garbage is prohibited!