Delta OHM HD2108.1 User manual



Operating manual
Thermocouple thermometers
HD2108.1 – HD2108.2
HD2128.1 – HD2128.2
www.deltaohm.com
Companies / Brands of GHM
English
Keep for future reference.

HD2108/HD2128 - 2 - V2.3
CONTENTS
INTRODUCTION..................................................................................................................................................... 3
KEYBOARD AND MENU DESCRIPTION ............................................................................................................ 8
THE PROBES..........................................................................................................................................................14
TEMPERATURE MEASUREMENT ...............................................................................................................................14
Calibration of the temperature probe on line with the instrument........................................................................14
WARNINGS AND OPERATING INSTRUCTIONS ..............................................................................................16
INSTRUMENT SIGNALS AND FAULTS..............................................................................................................17
LOW BATTERY WARNING AND BATTERY REPLACEMENT.......................................................................19
INSTRUMENT STORAGE.....................................................................................................................................20
SERIAL INTERFACE AND USB ...........................................................................................................................21
STORING AND TRANSFERRING DATA TO A PERSONAL COMPUTER......................................................23
THE LOGGING FUNCTION -ONLY FOR HD2108.2 AND HD2128.2..............................................................................23
CLEARING THE MEMORY -ONLY FOR HD2108.2 AND HD2128.2 ..............................................................................23
THE PRINT FUNCTION ...........................................................................................................................................24
CONNECTION TO A PC........................................................................................................................................25
CONNECTION TO THE RS232C SERIAL PORT OF THE INSTRUMENT .............................................................................25
CONNECTION TO THE USB 2.0 PORT OF THE INSTRUMENT -ONLY FOR HD2108.2 AND HD2128.2..............................25
NOTES ABOUT WORKING AND OPERATIVE SAFETY..................................................................................26
INSTRUMENT TECHNICAL CHARACTERISTICS...........................................................................................27
ORDER CODES ......................................................................................................................................................30

HD2108/HD2128 - 3 - V2.3
INTRODUCTION
The HD2108.1 and HD2108.2 with one input and the HD2128.1 and HD2128.2 with two inputs
are portable instruments with a large LCD display. They measure the temperature using immersion,
penetration or air contact probes. The sensor may be a thermocouple of type K, J, T, N, R, S, B or
E.
The HD2108.2 and HD2128.2 instruments are dataloggers. The HD2108.2 memorizes up to 76,000
samples, the HD2128.2 up to 38,000 pairs of values. These data can be transferred from the
instrument connected to a PC via the RS232C serial port or USB 2.0 port. The logging interval,
printing, and baud rate can be configured using the menu.
All the models are fitted with an RS232C serial port and can transfer the acquired measurements in
real time to a PC or to a portable printer.
The Max, Min and Avg function calculate the maximum, minimum or average values.
Other functions include: the relative measurement REL, the HOLD function, and the automatic
turning off that can also be disabled. The HD2128.1 and HD2128.2 calculate the A-B difference of
the temperatures captured by the two input channels.
The instruments have IP66 protection degree.
This manual describes the HD2108.1, HD2108.2, HD2128.1 and HD2128.2 models: if not
otherwise specified, the description is intended to be applicable to all models.
The table below illustrates all existing differences between the various models.
HD2108.1 HD2108.2 HD2128.1 HD2128.2
TC Inputs: 1 1 2 2
Storage capacity
--- 76,000 samples --- 38,000
temperature pairs
PC interface RS232C RS232C + USB2.0 RS232C RS232C + USB2.0
Datalogger NO YES NO YES
A-B function NO NO YES YES

HD2108/HD2128 - 4 - V2.3
HD2108.1 and HD2108.2
Thermocouple Thermometers with one input

HD2108/HD2128 - 5 - V2.3
HD2108.1 and HD2108.2
1. Input for thermocouple, standard mignon connector.
2. External auxiliary power supply connector input.
3. Battery symbol: displays the battery charge level.
4. Function indicators.
5. Secondary display line.
6. HOLD/key: freezes the measurement during normal operation; in the menu, increases the
current value.
7. FUNC/ENTER key: displays the maximum (MAX), the minimum (MIN) and the average
(AVG) of current measurements. In the menu, confirms the current selection.
When pressed together with the UNIT/UserCal key, starts the calibration procedure for the
probe connected to the instrument.
8. REL/key: enables the relative measurement (displays the difference between the current
value and the logged value when the key is pressed); in the menu, decreases the current value.
9. SERIAL key (for HD2108.1) or SERIAL/ERASE LOG (for HD2108.2): starts and ends data
transfer to the serial/USB communication port. In the menu, clears the data contained in the
instrument's memory.
10. LOG/DUMP LOG key (for HD2108.2): during normal operation, starts and ends the saving of
the data in the internal memory; in the menu, starts the data transfer from the instrument's
memory to the PC.
11. Mini-USB type B connector for USB 2.0 (only HD2108.2). For the connection to PC (with
cable CP23).
12. MENU key: allows access to and exit from the menu.
13. TC SEL/ESC key: in measurement mode, selects the type of thermocouple K, J, T, N, R, S, B
and E. In the menu cancels the operation in progress without making changes.
14. UNIT/USER CAL key: during normal operation, selects the unit of measurement for the
temperature between °C, °F or °K; displays the voltage generated by the probe ("mV") or the
voltage in mV equivalent to the read temperature, and indicated at 0°C ("mV*C"). When
pressed together with the FUNC key, starts the calibration procedure for the probe connected to
the instrument.
15. ON-OFF/AUTO-OFF key: turns the instrument on and off; when pressed together with the
HOLD key, disables the automatic turn off.
16. MAX, MIN and AVG symbols.
17. Main display line.
18. Line for symbols and comments.
19. 8-pole MiniDin connector for RS232C. For the connection to PC (with cable HD2110CSNM or
C206) or printer (with cable HD2110CSNM).

HD2108/HD2128 - 6 - V2.3
HD2128.1 and HD2128.2
Thermocouple Thermometers with two inputs

HD2108/HD2128 - 7 - V2.3
HD2128.1 and HD2128.2
1. Input for 2 thermocouples, standard mignon connectors (the upper one is input "A", the lower
one input "B").
2. External auxiliary power supply connector input.
3. Battery symbol: displays the battery charge level.
4. Function indicators.
5. Secondary display line (temperature measured at input B).
6. HOLD/key: freezes the measurement during normal operation; in the menu, increases the
current value.
7. FUNC/ENTER key: displays the maximum (MAX), the minimum (MIN) and the average
(AVG) of current measurements. In the menu, confirms the current selection.
When pressed together with the UNIT/UserCal key, starts the calibration procedure for the
probe connected to the instrument.
8. REL/key: enables the relative measurement (displays the difference between the current
value and the logged value when the key is pressed); in the menu, decreases the current value.
9. SERIAL key (for HD2128.1) or SERIAL/ERASE LOG (for HD2128.2): starts and ends data
transfer to the serial communication port. In the menu, clears the data contained in the
instrument's memory.
10. A-B key for HD2128.1: displays the difference of the two inputs A and B.
LOG/DUMP LOG key (for HD2128.2): during normal operation, starts and ends the saving of
the data in the internal memory; in the menu, starts the data transfer from the instrument's
memory to the PC.
11. Mini-USB type B connector for USB 2.0 (only HD2128.2). For the connection to PC (with
cable CP23).
12. MENU key for HD2128.1: allows access to and exit from the menu.
A-B/MENU key for HD2128.2: displays the difference of the two inputs A and B. When
pressed together with the FUNC/ENTER key, allows access to and exit from the menu.
13. TC SEL/ESC key: in measurement mode, selects the type of thermocouple K, J, T, N, R, S, B
and E. In the menu cancels the operation in progress without making changes.
14. UNIT/USER CAL key: during normal operation, selects the unit of measurement for the
temperature between °C, °F or °K; displays the voltage generated by the probe ("mV") or the
voltage in mV equivalent to the read temperature, and indicated at 0°C ("mV*C"). When
pressed together with the FUNC key, starts the calibration procedure for the probe connected to
the instrument.
15. ON-OFF/AUTO-OFF key: turns the instrument on and off; when pressed together with the
HOLD key, disables the automatic turn off.
16. MAX, MIN and AVG symbols.
17. Main display line (temperature measured at input A).
18. Line for symbols and comments.
19. 8-pole MiniDin connector for RS232C. For the connection to PC (with cable HD2110CSNM or
C206) or printer (with cable HD2110CSNM).

HD2108/HD2128 - 8 - V2.3
KEYBOARD AND MENU DESCRIPTION
Foreword
In some versions, the instrument keyboard is composed of single-function keys and double-function
keys such as the ON-OFF/Auto-OFF.
In the double-keys, the function in the upper part is the “main function”, while the one in the bottom
part is the “secondary function”. When the instrument is in standard measurement mode, the main
function is active. In the menu or in conjunction with the FUNC key, the secondary function is
enabled.
The pressing of a key is accompanied by a short confirmation beep: a longer beep sounds if the
wrong key is pressed.
The HD2128.1 and HD2128.2 models measure two temperatures: The upper connector is input "A",
and the corresponding temperature is displayed in the main line. The lower connector is input "B",
and the corresponding temperature is displayed in the secondary line.
Each key specific function is described in detail below.
ON-OFF/Auto-OFF key
The instrument is turned on and off using the ON/OFF key. The turning on enables all display
segments for a few seconds, and then the type of calibration enabled (CAL FACT = factory
calibration; CAL USER = user calibration). The instrument is then ready for normal measurement.
MIN
cm
min s
2
3
m
µ
m
k
>>> >>>
If no probe is connected to one of the input connectors, the BURN message appears in the
corresponding line.
+
Automatic turning off
The instrument has an AutoPowerOff function that automatically turns the instrument off after about
8 minutes if no key is pressed during the intervening time. The AutoPowerOff function can be
disabled by holding the HOLD key pressed down during the turning on phase: the battery symbol
will blink to remind the user that the instrument can only be turned off by pressing the <ON/OFF>
key.
The automatic turning off function is disabled when external power is used. On the other
hand, it cannot be disabled when the batteries are discharged.

HD2108/HD2128 - 9 - V2.3
FUNC/ENTER key
It enables the display and logging of the maximum (MAX), minimum (MIN) and average (AVG)
value of the measurements captured by the probe connected to the instrument, updating them with
the acquisition of new samples. The acquisition frequency is once a second.
In the models with two inputs, the HD2128.1 and HD2128.2, on activation of the key the two
display lines represent the MAX, MIN or AVG values for both inputs. In the models with one
input, the HD2108.1 and HD2108.2, the display shows the current temperature in the main line
and the maximum, minimum or average temperature in the secondary line.
The MAX, MIN and AVG measurements remain in the memory until the instrument is on, even
after exiting the calculation function. To reset the previous values and restart with a new
measurement session, press FUNC until the message “FUNC CLR” appears, then use the arrows to
select YES and confirm using ENTER.
Attention: the data captured using the Record function cannot be transferred to the PC.
HOLD/key
It increases the current parameter when used in the menu; when used in measurement mode, it
freezes the measurement in progress, and upon application of pressure on the key, the message
HOLD appears in the upper side of the display. To return to the current measurement, press the key
again.
Upon turning on the instrument, the AutoPowerOff function can be disabled by holding the MENU
key down (please see the ON-OFF key description).
UNIT/UserCAL key
During measurement allows selection of the unit of measurement for the input temperature. By
repeatedly pressing the function key, the different units of measurement are displayed in sequence:
1. °C Celsius degrees
2. °F Fahrenheit degrees
3. °K Kelvin degrees
4. mV voltage in mV generated by the probe (hot junction)
5. mV*C voltage in mV equivalent to the read temperature indicated at 0°C.
Represents the voltage signal reported by the table illustrating the thermocouple.
This setting changes the information displayed and the immediate print of data (SERIAL key). The
data recorded using the LOG function (HD2108.2 and HD2128.2) and sent to the printer or
PC through the serial port using the SERIAL function, keep the chosen unit of measurement
and display it.

HD2108/HD2128 - 10 - V2.3
+
Calibration of the probe and selection of the type of calibration
Simultaneous pressure on the UNIT/UserCal and FUNC/Enter keys starts the calibration procedure
of the temperature probe connected to the instrument. Please see the paragraph dedicated to
calibration on page 14.
To select the type of calibration (USER=user or FACT= factory) press the UNIT/UserCal and
FUNC/Enter keys together, then use the arrows to select the desired item, and confirm using
ENTER.
TC SEL/ESC key
In measurement mode, it selects the type of thermocouple K, J, T, N, R, S, B and E. The selected
thermocouple is shown in quotation marks in the upper line.
In the menu, the key clears or cancels the active function (ESC).
REL/key
In measurement mode, it displays the difference between the current value and that measured on
pressing the key. The REL message appears on the display; press the key again to return to the
current measurement.
When used in the menu, it decreases the current variable value.
A-B key - only for HD2128.1
It displays the difference of the temperatures measured by the probes connected to the inputs A and
B, and indicates ERR if one of the probes is in error (not connected, faulty or overrange). To end
the function, press the key again.
A-B/MENU key - only for HD2128.2
In measurement mode, it displays in the secondary line the difference of the temperatures measured
by the probes connected to the inputs A and B, and indicates ERR if one of the probes is in error
(not connected, faulty or overrange). To end the function, press the key again.
To access the instrument menu, press simultaneously the A-B/Menu and FUNC/Enter keys. Please
see the description illustrated below.

HD2108/HD2128 - 11 - V2.3
MENU Key
The first menu item is accessed by initially pressing on the MENU key (A-B/Menu + FUNC/Enter
in the HD2128.2 model); press ENTER to go to the following items. To modify the item displayed,
use the arrow keys (and ). By pressing the ENTER key, the current value is confirmed and the
display moves on to the next parameter. By pressing the FUNC key, the setting is cancelled.
To exit the menu, press the MENU key at any time.
The menu items are listed in this order:
1) Management of memorized data (only HD2108.2 and HD2128.2): the message
“>>>_LOG_DUMP_or_ERAS” (Transfer data or erase) is scrolled in the comment line.
The center figure reports the number of free memory pages (FREE). All memory data are
permanently erased by pressing SERIAL/EraseLOG. By pressing LOG/DumpLOG, the data
transfer of the logged data on the serial port is started: the “BAUD-RATE” must have
previously been set to the maximum value (please see the menu items described below and
the paragraph "STORING AND TRANSFERRING DATA TO A PERSONAL
COMPUTER" on page 23).
2) Print and log interval: sets the interval in seconds between two loggings or data transfers
to the serial port. The interval can be set at 0, 1s, 5s, 10s, 15s, 30s, 60s (1min), 120s (2min),
300s (5min), 600s (10min), 900s (15min), 1200s (20min), 1800s (30min) and 3600s (1hour).
If the value 0 is set, SERIAL works on command: the sending of data to the serial port
is performed each time the key is pressed. Recording (LOG) is performed with one
second intervals even if the interval is set to 0. With an interval from 1 to 3600s, continuous
data transfer is started when the SERIAL key is pressed. To end the recording (LOG) and
continuous data transfer operations (SERIAL with an interval greater than 0), press the
same key again.
3) Sleep_Mode_LOG (Automatic turning off during recording) (only HD2108.2 and
HD2128.2): this function controls the instrument's automatic turning off during logging,
occurring between the capture of a sample and the next one. When the interval is lower than
60 seconds, the instrument will always remain on. With intervals greater than or equal to 60
seconds, it is possible to turn off the instrument between loggings: it will turn on at the
moment of sampling and will turn off immediately afterwards, thus increasing the battery
life. Using the arrows select YES and confirm using ENTER in order to enable the
automatic turning off, select NO and confirm to disable it and keep the instrument on
continuously.
Note: even if Sleep_Mode_LOG=YES is selected, the instrument does not turn off for less
than one minute intervals.
4) YEAR: to set the current year. Use the arrows to modify this parameter and confirm using
ENTER.
5) MNTH (month): to set the current month. Use the arrows to modify this parameter and
confirm using ENTER.
6) DAY: to set the current day. Use the arrows to modify this parameter and confirm using
ENTER.
7) HOUR: to set the current hour. Use the arrows to modify this parameter and confirm using
ENTER.

HD2108/HD2128 - 12 - V2.3
8) MIN (minutes): to set the current minutes. In order to correctly synchronize the minute, it is
possible to reset the seconds by pressing the UNIT key. Use the arrows to set the minutes,
press the UNIT key to confirm: this synchronizes the time to the second. Press ENTER to go
onto the next item.
9) BAUD_RATE: indicates the frequency used for the serial communication with the PC.
Values from 1200 to 38400 baud. Use the arrows to modify this parameter and confirm
using ENTER. The communication between instrument and PC (or serial port printer)
only works if the instrument and PC baud rates are the same. If the USB connection is
used this parameter value is automatically set (please see the details on page 23).
LOG/DumpLOG key - only HD2108.2 and HD2128.2
In measurement mode, this function starts and stops the logging of a data block to be saved in the
instrument's internal memory. The data logging frequency is set in the "Print and log interval"
menu parameter. The data logged between a start and subsequent stop represent a block.
When the logging function is on, the LOG indication is displayed, the battery symbol blinks and a
beep is issued each time a logging occurs; the battery symbol does not appear when using an
external power supply.
To end the logging, press LOG.
The HD2108.2 and HD2128.2 can turn off during logging between one capture and the next: the
function is controlled by the Sleep_Mode_LOG parameter. When the logging interval is less than
one minute, the logging instrument remains on; with an interval of at least one minute, it turns off
between one capture and the next if the parameter Sleep_Mode_LOG=YES.
>>>
Dump LOG - only HD2108.2
When the LOG key is pressed after the MENU key, the transfer of the logged data on the serial port
is started.
Please see the paragraph dedicated to data transfer on page 23.
[ + ]>>> Dump LOG - only HD2128.2
To start the transfer of the data contained in the instrument internal memory via the serial port, press
simultaneously the FUNC/Enter and A-B/Menu keys, and then the LOG/DumpLOG key.
Please see the paragraph dedicated to data transfer on page 23.

HD2108/HD2128 - 13 - V2.3
SERIAL key - only HD2108.1 and HD2128.1
SERIAL/EraseLOG key - only HD2108.2 and HD2128.2
In measurement mode, this function starts and stops the data transfer to the RS232C serial output.
According to the settings entered in the Print and log interval menu item, a single sample can be
printed if Print and log interval=0 or a continuous indefinite printing of the measured data can be
set up if Print and log interval=1…3600.
The printing operation is accompanied by the display of the RS232 symbol and the blinking of the
battery symbol; when using an external power supply the battery symbol does not appear.
Press SERIAL to end the continuous printing.
Before starting the printing with SERIAL, set the baud rate. To do so, select the Baud Rate menu
item and select the maximum value equal to 38400 baud by using the arrows. Confirm by pressing
ENTER.
The DeltaLog9 software for PC will automatically set the baud rate value during connection. If you
are using a different program than DeltaLog9, be sure the baud rate is the same for both the
instrument and the PC: the communication will only work in this way.
>>>
Erase memory - only HD2108.2
When pressed after the MENU key, the SERIAL/ERASE LOG key permanently erases all the data
contained in the instrument's memory.
[ + ]>>> Erase memory - only HD2128.2
Press simultaneously the FUNC/Enter and A-B/Menu keys, and then the SERIAL/ERASE LOG
key, to permanently erase the data contained in the HD2128.2's memory.

HD2108/HD2128 - 14 - V2.3
THE PROBES
The instrument works with thermocouple probes of type K, J, T, N, R, S, B or E. The selection is
done using the TC SEL key.
The contacts of the thermocouple probe connector are polarized. They must be inserted on the
standard mignon socket located on the instrument in the correct direction. These probes are usually
marked with a + and – sign: These symbols must coincide with the corresponding symbols located
on the instrument's rubber protection.
The user can choose the unit of measurement for display, printing and logging among the allowed
ones: °C, °F or °K. Moreover, the voltage in mV generated by the probe (hot junction) or the
voltage in mV equivalent to the read temperature, and indicated at 0°C, can be displayed.
The HD2128.1 and HD2128.2 models have two inputs: the upper one is input "A", and the
corresponding temperature is displayed in the main line. The lower one is input "B", and the
corresponding temperature is displayed in the secondary line.
If two probes are used, they must be the same type of thermocouple.
TEMPERATURE MEASUREMENT
In all versions the thermocouple hot junction is housed in the end part of the probe.
The response time for the measurement of the temperature in air is greatly reduced if the air is
moving. If the air is still, stir the probe. The response times are longer than those for liquid
measurements.
The temperature measurement by immersion is carried out by inserting the probe in the liquid in
which the measurement has to be performed; the hot junction is housed in the end part of the probe.
In the temperature measurement by penetration the probe tip must be inserted in the material, the
hot junction is housed in the end part of the probe. When measuring the temperature on frozen
blocks it is convenient to use a mechanical tool to bore a cavity in which to insert the tip probe.
In order to perform a correct contact measurement, the measurement surface must be even and
smooth, and the probe must be perpendicular to the measurement plane. A contact measurement is
hard to perform due to various factors: the operator must be experienced in handling the probe and
consider all the factors influencing it.
So as to obtain the correct measurement, the insertion of a drop of oil or heat-conductive
paste is useful (do not use water or solvents). This method also improves the response time.
Calibration of the temperature probe on line with the instrument
To calibrate the probes correctly, a knowledge of and abiding by the physical phenomena on which
the measurement is based is fundamental: this is the reason why it is recommended to abide by what
is reported below carefully, and only to perform new calibrations if technically proficient and using
the suitable equipment.
The instrument is provided with the FACT (factory) calibration only. The user is also able to
perform a USER calibration of instrument+probe. The calibration information is saved in the
instrument memory and not in the probe. The same correction is applied to any probe connected to

HD2108/HD2128 - 15 - V2.3
the input: it is therefore implied that the USER calibration should only be used with a precise probe:
the one used during calibration and no other probe.
To pass from the user to the factory calibration and back again, press the UNIT/UserCal and
FUNC/ENTER keys together, then use the arrows to select the type of calibration, and confirm
using ENTER.
Calibration sequence - instrument on line with the probe(s):
The calibration can be carried out on one or two points that should differ by at least 10°C and be
included in the probe functioning range.
Insert the probe into a thermostatic bath, the temperature of which is precisely known from a
reading taken on a sample reference thermometer. Wait for the measurement to stabilize.
Press simultaneously the UNIT/UserCal and FUNC/ENTER keys, using the arrows select the
USER calibration, and confirm with UNIT/UserCal.
In the HD2128.2 model, use the arrows to select the input to which the probe being calibrated is
connected, choosing the upper connector A or the lower one B: confirm with ENTER.
Use the arrows to select 1 (first calibration point) and confirm using ENTER. The message “UP
DOWN 1st MEAS" is scrolled in the comment line. The instrument display shows the measured
temperature: use the arrows to correct the indicated value until it coincides with the value measured
by the sample reference thermometer.
Confirm by pressing ENTER.
To exit the procedure without performing the second point, select 0 and press ENTER.
To calibrate the second point, select the point 2 using the arrows and press ENTER.
The message “UP DOWN 2nd MEAS" is scrolled in the comment line.
Move the probe to the second thermostatic bath and wait for the measurement to stabilize. The
instrument display shows the measured temperature: use the arrows to correct the indicated value
until it coincides with the value measured by the sample reference thermometer.
Confirm by pressing ENTER.
The procedure is now complete.

HD2108/HD2128 - 16 - V2.3
WARNINGS AND OPERATING INSTRUCTIONS
1. Do not expose the probes to gases or liquids that could corrode the material of the probe. Clean
the probe carefully after each measurement.
2. Do not bend the probe connectors or force them upward or downward.
3. Comply with the correct polarity of the probe.
4. Do not bend or force the contacts when inserting the probe connector into the instrument.
5. Do not bend, deform or drop the probes, as this could cause irreparable damage.
6. Always select the most suitable probe for your application.
7. In general, do not use temperature probes in presence of corrosive gases or liquids; the probe
external container is made of AISI 316 or INCONEL stainless steel, while the contact probe
container is made from AISI 316 or INCONEL stainless steel plus silver. Avoid contact
between the probe surface and any sticky surface or substance that could corrode or damage it.
8. To obtain reliable temperature measurements, temperature variations that are too rapid must be
avoided.
9. Temperature probes for surface measurements (contact probes) must be held perpendicular
against the surface. Apply oil or heat-conductive paste between the surface and the probe in
order to improve contact and reduce reading time. Whatever you do, do not use water or solvent
for this purpose. A contact measurement is always very hard to perform. It has high levels of
uncertainty and depends on the ability of the operator.
10. Temperature measurements on non-metal surfaces usually require a great deal of time due to the
low heat conductivity of non-metal materials.
11. The sensor is not insulated from its external casing; be very careful not to come into contact
with live parts (above 48V). This could be extremely dangerous for the instrument as
well as for the operator, who could be electrocuted.
12. Avoid taking measurements in presence of high frequency sources, microwave ovens or large
magnetic fields; results may not be very reliable.
13. The instrument is water resistant and IP66, but should not be immersed in water. Protect the
connectors from water by closing them well using their caps. The probe connectors must be
fitted with sealing gaskets. Should the instrument fall into the water, check for any water
infiltration. Gently handle the instrument in such a way as to prevent any water infiltration from
the connectors' side.

HD2108/HD2128 - 17 - V2.3
INSTRUMENT SIGNALS AND FAULTS
The following table lists all error indications and information displayed by the instrument and
supplied to the user in different operating situations:
Display indications Explanation
ERR
This message appears when a wrong function is called: for example,
should the A-B key be pressed or the AVG function be enabled when
one of the two probes is not connected.
OVER
or
UNDR
Measurement overflow: indicates that the probe is measuring a value
exceeding the measuring range.
BURN The probe is disconnected or faulty.
LOG
MEM
FULL
Memory full; the instrument cannot store further data, the memory
space is exhausted.
SYS
ERR
#
Instrument management program error. Contact the instrument's
supplier and communicate the numeric code # reported by the display.
CAL
LOST
Program error: it appears after turning on for a few seconds. Contact
the instrument's supplier.
CAL
FACT Factory calibration.
CAL
USER User calibration.
BATT TOO LOW
CHNG NOW
Indication of insufficient battery charge appearing on turning on. The
instrument issues a long beep and turns off. Replace the batteries.

HD2108/HD2128 - 18 - V2.3
The following table reports the indications provided by the instrument as they appear on the display,
together with their description.
Display indications Explanation
>>>
_
CAL
_
MODE >>> KEY
_
UNIT
FOR_NEW_USER CAL_ calibration mode >>> press UNIT to start a new user calibration
>>>
_
LOG
_
DUMP
_
or
_
ERAS transfer or erase data
1ST
_
MEAS UP DOWN correct the first point using the arrows /
2ND
_
MEAS UP DOW
N
correct the second point using the arrows /
BATT TOO LOW - CHNG NO
W
battery discharged - replace it immediatel
y
BAUDRATE >>
>
baud rate valu
e
CAL FACT factory calibration
CAL USER user calibration
COMM STO
P
p
rinting complete
COMM STRT
p
rinting starte
d
DAY
_
da
y
DUMP
_
END data transfer complete
DUMP
_
In
_
PROG >>
>
data transfer in progress
ERR error
FUNC CLR max, min and average values clearing
FUNC CLRD max, min and average values clearing
HOUR hour
LOG In PROG logging in progress
LOG MEM FULL memory full
LOG
_
CLRD memory data cleare
d
LOG
_
STO
P
logging complet
e
LOG
_
STRT logging starte
d
MIN >>> USE
_
UNIT
_
TO
_
ZERO SEC minutes >>> use the UNIT key to reset the seconds
MNTH month
OVER maximum limit exceede
d
PLS
_
EXIT >>> FUNC RES
_
FOR
_
FACT
ONLY please exit using ESC >>> function reserved to factory calibration
PRNT AND LOG INTV
p
rinting and logging intervals
PRNT INTV >>
>
p
rinting interval
SEL CHA
N
input channel selection
SEL MEAS 1/2 select the first/second calibration point
SLP
_
MODE
_
LOG turning off during recording mode
SYS ERR
#
p
rogram error number
#
UNDR minimum limit exceede
d
YEAR year

HD2108/HD2128 - 19 - V2.3
LOW BATTERY WARNING AND BATTERY REPLACEMENT
The battery symbol
on the display constantly shows the battery charge status. To the extent that batteries have
discharged, the symbol "empties". When the charge decreases still further it starts blinking…
In this case, batteries should be replaced as soon as possible.
If you continue to use it, the instrument can no longer ensure correct measurement. The memory
data are maintained.
If the battery charge level is insufficient, the following message appears when you turn the
instrument on:
BATT TOO LOW
CHNG NOW
The instrument issues a long beep and turns off. In this case, replace the batteries in order to
turn the instrument back on.
In order to avoid data loss, the logging session is ended, if the HD2108.2 and HD2128.2 are
logging and battery voltage falls below the minimum operating level.
The battery symbol turns off when the external power supply is connected.
To replace the batteries, switch the instrument off and unscrew the battery cover counter clockwise.
After replacing the batteries (4 1.5V alkaline batteries - type AA) screw the cover on clockwise.
After replacing the batteries, the date, time, baud rate, type of probe, printing interval, logging
parameters must be set again: in order to simplify the operation, on insertion of the new
batteries the instrument turns on automatically and requests these parameters in sequence.
To go to the next item press ENTER; to return to measurement mode, press MENU.

HD2108/HD2128 - 20 - V2.3
MALFUNCTIONING UPON TURNING ON AFTER BATTERY REPLACEMENT
After replacing the batteries, the instrument may not restart correctly; in this case, repeat the
operation. After disconnecting the batteries, wait a few minutes in order to allow circuit condensers
to discharge completely; then reinsert the batteries.
WARNING ABOUT BATTERY USE
•Batteries should be removed when the instrument is not used for an extended time.
•Flat batteries must be replaced immediately.
•Avoid batteries leaking.
•Always use good quality leakproof alkaline batteries. Sometimes on the market, it is
possible to find new batteries with an insufficient charge capacity.
INSTRUMENT STORAGE
Instrument storage conditions:
•Temperature: -25…+65°C.
•Humidity: less than 90%RH without condensation.
•Do not store the instrument in places where:
Humidity is high.
The instrument may be exposed to direct sunlight.
The instrument may be exposed to a source of high temperature.
The instrument may be exposed to strong vibrations.
The instrument may be exposed to steam, salt or any corrosive gas.
The instrument case is made of ABS plastic and the protections are rubber: do not use any
incompatible solvent for cleaning.