Delta OHM HD25.2 User manual

Our instruments' quality level is the results of the product continuous development. This
can bring about differences between the information written in this manual and the
instrument that you have purchased. We cannot entirely exclude errors in the manual, for
which we apologize.
The data, figures and descriptions contained in this manual cannot be legally asserted. We
reserve the right to make changes and corrections without prior notice.
REV. 1.0
14th Nov. 2006
HD25.2

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HD25.2 - Turbidimeter
1. Connectors
2. ESC key: in the menu, cancels the current setting.
3. MEM key: stores the currently displayed screen.
4. Battery symbol: indicates the battery level. The symbol does not appear when the external
power supply is connected.
5. Line for symbols and comments.
6. Main display line.
7. ON-OFF key: turns the instrument on and off. When pressed together with the key, disables
the automatic turn off.
8. Measurement piece.
9. MENU key: allows access to and exit from the menu. When pressed together with the ENTER
key, starts the calibration procedure.
10. ENTER key: in the menu, confirms the current selection. When pressed together with the
MENU key, starts the calibration procedure.
11. MEAS key: performs the selected measurement. Use the arrows (and ) to choose the type
of measurement before pressing the MEAS key.
12. key: selects the type of measurement. When pressed together with the ON/OFF key, disables
the automatic turn off. In the menu, increases the current value.
13. Secondary display line.
14. key: selects the type of measurement. In the menu, decreases the current value.
15. PRINT key: prints the data on the current screen. It uses the serial communication port
RS232C or the USB 2.0 port.

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HD25.2 Connectors
16. Power supply input 12Vdc/1A for ∅5.5mm - 2.1mm connector.
17. USB2.0 connector - type B.
18. RS232C serial port, sub D 9-pole connector.

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INTRODUCTION
The HD25.2 is a laboratory, portable digital turbidimeter for drinking water, beverage, waste water
or process liquid measurements. It operates according to the nephelometric (90°) and ratiometric
measurement principles.
It is provided with three photo detectors and two LED light sources (white and infrared) constantly
monitored to ensure the response stability with time. The instrument performs measurements in
accordance with EPA 180.1, ISO-NEPH (ISO 7027), EBC and ASBC standards. The measurements
of the transmittance percentage for white and infrared light are also provided.
The initial factory calibration is based on the Formazine primary standard. For routine calibration a
set of stabilised secondary standards STCAL (Turbidity Calibration Standard) is available:
•STCAL 1 turbidity less than 0.05 NTU
•STCAL 2 equal to 8 NTU
•STCAL 3 equal to 80 NTU
•STCAL 4 equal to 800 NTU
User calibration is automatic on one, four or five points, according to the measurement variable.
A stabilized power supply of the sources and advanced electronics guarantee optimum instrument
performance over time.
The HD25.2 is a datalogger.It memorizes up to 999 samples. The measured data can be transferred
from the instrument connected to a PC via the RS232C serial port or the USB 2.0 port.
The RS232C serial port can be used for direct printing of the data using a 24 column printer.
The PRINT function allows printing of a label reporting an automatically increased progressive
number and all data concerning the sample under examination.
The DeltaLog11 dedicated software manages the instrument and the data processing through the
PC and the firmware update.
The use of the HD25.2 by multiple users is assisted by the “User Management” function that can,
according to the circumstances, lock or enable some instrument's advanced features by using a
password.
IP66 protection degree.

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MEASUREMENT PRINCIPLE
The most known liquid analysis methods, like pH, conductivity or dissolved Oxygen measurements,
express quantitatively the parameters that determine the solution's chemical-physical state. Such
methods allow measuring the quantity of substances dissolved in the liquid, for example as ions.
The substances suspended in the liquids are not measured using these methods.
Suspensions are mainly formed by solid non soluble substances, like metal oxides, grease, algae and
micro organisms that do not influence the chemical characteristics of the liquid, but modify, even
visually, its physical characteristics. The most visible, even to a simple visual inspection, is
turbidity. It is an optical characteristic, that is, based on light propagation.
A light ray passing through a fluid is subject to the effects caused by the interaction between the ray
and the substances in the liquid. This interaction causes a deviation of the light ray, that is, a path
variation. The deviation is caused not only by mat particles, but also by the optical non-
homogeneity caused by particles that, despite being transparent, have a different refraction index
from that of the liquid.
Due to complex optical phenomena, a part of the light is diffused in different directions and,
consequently, the intensity of the ray moving in the original direction is reduced.
In the nephelometric method, the turbidity is calculated from the light detected by a photodiode
positioned at 90° compared to the emitted light direction.
Turbidity measurements are influenced by several factors, such as particle size, colour and form,
liquid colour, etc.
MEASUREMENT STANDARD
The following table shows the measurement methods supported by the instrument. It contains:
measurement standard, unit of measurement and, per each type of measurement, the relevant names
as appearing on the display.
Measurement
method
Unit of
Measurement
Measurement method
on display
Unit of measurement
on display
EPA 180.1 NTU EPA ntu
ISONEPH
(ISO7027)
FNU INPH FnU
EBC EBC EBC EbC
ASBC ASBC ASBC ASbC
WHITE %T --- WHTE% ---
IR %T --- IRT % ---

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KEYBOARD DESCRIPTION
ON-OFF key
The instrument is turned on and off using the ON/OFF key. The turning on starts a self test that
checks the instrument status.
In the following window you will enter the password identifying the user: press ENTER to access
as a non registered user (Anonymous). To access as a registered user (Administrator, User1, User2
or User3), enter the user code assigned by the administrator using the arrows and confirm with
ENTER (please see the details concerning user management on page 10).
Finally, the instrument is set for normal measurement.
+ 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 key pressed down when turning the instrument on: 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.
PRINT key
It sends the displayed data to the serial RS232C output or USB output. The ID is increased after
each new measurement (MEAS key). The ID is not increased by repeatedly pressing the PRINT
key: in this way it is possible to print multiple labels with the same ID.
See the details on page 22.
Before starting the communication via the RS232C serial port, set the baud rate. To do so, select
“System Parameters >> Communication Options >> Baud Rate” and select the maximum value
equal to 115200 baud by using the arrows and. Confirm by pressing ENTER.
The DeltaLog11 software for PC will automatically set the same baud rate value as the instrument
one during connection. If you are using a different program than DeltaLog11, be sure the baud
rate is the same for both the instrument and the PC: the communication will only work in this
way.
If the instrument is connected directly to a serial printer, set the recommended baud rate for the
printer.
The direct connection between instrument and printer via a USB connector is not allowed.

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MEM key
Stores the displayed data using the current unit of measurement. The following is also recorded:
measurement method (EBC, NTU, FTU,…), current date, ID and calibration date.
For the details see the chapter dedicated to recording on page 22.
ESC key
In the menu, this key cancels the current setting.
MENU key
To access and exit the menu (please see the menu description on page 8).
When pressed together with the ENTER key, starts the calibration procedure (please see the chapter
dedicated to calibration on page 12).
ENTER key
In the menu, the ENTER key confirms the current parameter.
When pressed together with the MENU key, starts the calibration procedure (please see the chapter
dedicated to calibration on page 12).
MEAS key
This key starts the measurement of turbidity using the currently displayed type of measurement.
Up Arrow
During normal operation selects the measurement variable; in the menu, increases the currently
displayed variable.
Down Arrow
During normal operation selects the measurement variable; in the menu, decreases the currently
displayed variable.

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MENU DESCRIPTION
To access to the menu press the MENU key: the first item will display. Press ENTER to go to the
following items. To modify the item displayed, use the arrow keys (and ). The current value is
confirmed by pressing the ENTER key and the display moves on to the next parameter. If pressing
ESC the setting is cancelled.
To exit the menu, press the MENU key at any time.
The menu items are listed in this order:
1. BAUD_RATE RS232: indicates the frequency used for the serial RS232 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
20).
2. SMPL ID – MEA = RST (Sample ID – press MEAS to reset). The measured sample ID
(Sample ID) is an automatically increased progressive number associated to the MEAS
function: to each new sample obtained using the MEAS key is associated an ID number
shown in the printout and in the downloaded data together with date, time and measured
value. This number is assigned to each measurement and is increased, from the previous
number, only when the measurement is printed or logged. It does not change if the same
measurement is printed more than once: in this way it is possible to print multiple labels,
concerning an unique measurement, with the same identification code.
To set the value of the first sample, select the menu item “SMPL ID –MEA = RST, set the
desired number using the arrows and confirm with ENTER. To reset the ID value, select the
menu item “SMPL ID –MEA = RST, press the MEAS key and confirm with ENTER.
3. DISP_LAY LOG (“Display stored data”): the message is scrolled in the comment line. By
using the arrows and the data stored with the MEM key are displayed. Per each datum
memory location m001, m002, …, measured value and ID code are shown.
4. CONFIRM DUMP ALL MEA? (“Confirm full memory data dump?”). This command allows
sending all the data contained in the instrument’s memory to the PC. Select YES using the
arrow and press ENTER to download all the data. Select NO (default) and confirm with
ENTER to go to the next step without downloading the data.
5. CONFIRM ERAS ALL MEA? (“Confirm full memory erase?”). This command allows
clearing all the data contained in the instrument’s memory. Use the arrow to select
“YES” and confirm with ENTER. To go to the next step without erasing, select NO and
confirm with ENTER.
6. LAST CAL m/d h/m (Last calibration date month/day hour/minutes) reports the date of the
last calibration made by the user. This item cannot be modified.
7. ACTUAL USER (Current user): displays the currently registered user (see the chapter “User
Management” on page 10). This item cannot be modified.
8. CAL EXP TOTA DAY (Calibration validity number of days): sets the calibration validity
number of days. When the validity period has expired, upon turning on the “CAL
EXPIRED” blinking message appears; the calibration data are still used. The “Expired
calibration” message is indicated in the printout. Enter “Number of days” = 0 to disable this
feature. This parameter can be changed only by an user registered as "Administrator" (see
the chapter “User Management” on page 10).

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Note: the day is counted at midnight: by entering 1, at midnight of the same day, the
calibration is considered expired.
9. CAL RESIDUAL DAY (Days to calibration expiration): displays the number of days to the
calibration expiration. This item cannot be modified.
10. MEM ON PRNT (Recording upon printing): if this function is enabled, each time the PRINT
key is pressed, the measurement is also recorded in the instrument internal memory. To
enable it, select YES and confirm with ENTER.
11. AUTO LOG IN (Automatic login): if this function is enabled, upon turning on the instrument
does not require the input of the password and uses the last registered user. To enable this
feature, select YES and confirm with ENTER.
12. YEAR: to set the current year. Use the arrows to modify this parameter and confirm using
ENTER.
13. MNTH (month): to set the current month. Use the arrows to modify this parameter and
confirm using ENTER.
14. DAY: to set the current day. Use the arrows to modify this parameter and confirm using
ENTER.
15. HOUR: to set the current hour. Use the arrows to modify this parameter and confirm using
ENTER.
16. MIN – MEA = ZERO SEC (Minutes – Press MEAS to clear the seconds): to set the current
minutes. In order to correctly synchronize the minute, it is possible to reset the seconds by
pressing the MEAS key. Use the arrows to set the current minute plus one, and as soon as
that minute is reached press MEAS: this synchronizes the time to the second. Press ENTER
to go onto the next item.

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USER MANAGEMENT
Upon turning on the instrument, the user must identify himself or herself by entering a password:
each password is associated to a registered user indicated in the printing and recording operations.
The available users are: administrator, user_1, user_2, user_3 and anonymous user. The
Administrator is enabled to use all of the instrument functions and assigns the password to the other
users. The anonymous user does not need a password.
If you wish the instrument to request the user selection upon turning on, disable the menu item
AUTO LOG IN (=OFF): in this case, upon turning on the instrument requires a password.
If AUTO LOG IN is enabled (=ON), upon turning on the instrument does not require the input of
the password and uses the last registered user.
To access as an anonymous user, just confirm the “00000” password prompted by the instrument by
pressing ENTER, without changing anything.
When the instrument comes out of the factory, the passwords associated to the registered users are
the following:
User Factory password
Administrator 00123
User_1 00456
User_2 00789
User_3 00012
Upon turning on the instrument, after the automatic test, you are requested to enter a password:
“ENTER LOG_IN CODE”. Use the arrows to enter the password and confirm with ENTER.
All password creation, modification and update operations are managed by the DeltaLog11
software through the PC.
To modify a password you need to access the instrument as an administrator. Connect the
instrument to the PC and use the function “MODIFY PASSWORD” in the DeltaLog11 software:
you can assign a new password to one of the users or to the administrator.
Please note that the password identifies the type of user and not vice versa, for example, the
number 00456 identifies the user as User_1 and the number 00012 as User_3. Upon turning on you
are not requested to choose a user but only to enter a numeric code.

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MEASUREMENT PROCESS
The following steps outline how to carry out a turbidity measurement.
•The cell must be accurately cleaned with distilled water and a non aggressive detergent.
Before measurement check that the cell is clean and that no fingerprints are present.
•Pour the liquid under examination in the cell: in order to perform a correct measurement, the
liquid must reach at least the white position indicator.
•Wait until the liquid reaches the environment temperature.
•Make sure that no air bubbles are trapped in the liquid.
•Close the cell with the cap, wipe any possible dirt trace using the supplied cloth.
•Holding the cell by the cap, insert it in the measurement compartment.
•Screw the measurement compartment cap on, to avoid any external lights distorting the
measurement.
•Select the desired unit of measurement using the arrows (and ).
•Press MEAS to start the measurement: after a few seconds the result is shown on the display.
Now the measurement result can be (see the chapter on page 22):
•recorded in the instrument internal memory by pressing MEM,
•printed using a printer connected to the RS232C serial port,
•sent to a PC connected to the RS232C serial port or the USB 2.0 port.
Comply with the following precautions to increase the measurement accuracy, particularly with low
turbidity measurements:
•Align the cell reference notch with that on the measurement compartment.
•Do not leave the measurement compartment open without the cap when the instrument is not
in use.
•Do not insert wet cells in the measurement compartment.
•Do not use cells with imperfections, scratches, …
•Apply a light layer of silicon oil to hide possible glass imperfections using the supplied cloth.
•Remove any fingerprint on the glass: insert and extract the cell holding it by the cap.
•Before filling the cell, rinse it using the same liquid being measured.

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CALIBRATION
HD25.2 has 6 different turbidity measurement methods: EPA 180.1, ISO NEPH according to norm
ISO7027, EBC, ASBC, percentage of white light transmitted (WHITE %T) and percentage of
infrared light transmitted (IR %T).
As some quantities are directly correlated to each other, it is only necessary to calibrate one to get
the others calibrated too: e.g. by calibrating the EPA180.1 measurement scale also the ASBC scale
will be calibrated.
The table shows the measurement methods divided by calibration group, and the relevant standard
to be used.
Measurement
method STCAL… EPA 180.1
ASBC
ISONEPH
EBC WHITE %T IR %T
Calibration
Standard (*)
…1
…2
…3
…4
0 NTU
8 NTU
80 NTU
800 NTU
0 NTU
8 NTU
80 NTU
800 NTU
0 NTU 0 NTU
(*) By “0 NTU” is meant a liquid having a very low turbidity, less than 0.05 NTU.
As you can see, a total of four calibration procedures is needed: the EPA180.1 and ASBC scales,
the ISONEPH and EBC scales require four calibration standard, WHITE %T and IR %T only need
the 0 NTU standard.
The HD25.2 must be calibrated before using it for the first time, and when a check using the
calibration standards detects an error exceeding ±10%.
To carry out the calibration you should have the standard solutions outlined in the previous table.
Calibration of the EPA 180.1 and ASBC scales
The following steps are performed to calibrate the EPA180.1 and ASBC scales.
1. Select the EPA180.1 measurement method using the arrows. If the ASBC measurement is
selected, the instrument changes it automatically in EPA180.1 by entering calibration function;
at the end of the calibration it comes back to the ASBC measurement.
2. Press simultaneously MENU and ENTER to start the calibration procedure.
3. The “H2O_INSERT” message appears: insert the standard cell STCAL 1 equal to 0 NTU in the
measurement compartment and screw the cap.
4. Press ENTER: the MEAS message is shown in the comment line. After a few seconds the “UP
DOWN TO CHNG VAL” message appears and the next standard will be STCAL 2 equal to 8
NTU.
5. Insert the standard cell STCAL 2 equal to 8 NTU. If the turbidity value is slightly different from
8, correct it using the arrows.
6. Press ENTER to continue. The MEAS message is shown in the comment line. After a few
seconds the “UP DOWN TO CHNG VAL” message appears and the next standard will be
STCAL 3 equal to 80 NTU.
7. Insert the standard cell STCAL 3 equal to 80 NTU. If the turbidity value is slightly different
from 80, correct it using the arrows.

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8. Press ENTER to continue. The MEAS message is shown in the comment line. After a few
seconds the “UP DOWN TO CHNG VAL” message appears and the next standard will be
STCAL 4 equal to 800 NTU.
9. Insert the standard cell STCAL 4 equal to 800 NTU. If the turbidity value is slightly different
from 800, correct it using the arrows.
10. Press ENTER to continue. The MEAS message is shown in the comment line. After a few
seconds the “CAL END” message appears to indicate the procedure was successful.
Calibration of the ISONEPH and EBC scales
The following steps are performed to calibrate the ISONEPH and EBC scales.
1. Select the ISONEPH or EBC measurement method using the arrows. If the EBC measurement
is selected, the instrument changes it automatically in ISONEPH by entering calibration
function; at the end of the calibration it comes back to the EBC measurement.
2. Press simultaneously MENU and ENTER to start the calibration procedure.
3. The “H2O_INSERT” message appears: insert the standard cell STCAL 1 equal to 0 NTU in the
measurement compartment and screw the cap.
4. Press ENTER: the MEAS message is shown in the comment line. After a few seconds the “UP
DOWN TO CHNG VAL” message appears and the next standard will be STCAL 2 equal to 8
NTU.
5. Insert the standard cell STCAL 2 equal to 8 NTU. If the turbidity value is slightly different from
8, correct it using the arrows.
6. Press ENTER to continue. The MEAS message is shown in the comment line. After a few
seconds the “UP DOWN TO CHNG VAL” message appears and the next standard will be
STCAL 3 equal to 80 NTU.
7. Insert the standard cell STCAL 3 equal to 80 NTU. If the turbidity value is slightly different
from 80, correct it using the arrows.
8. Press ENTER to continue. The MEAS message is shown in the comment line. After a few
seconds the “UP DOWN TO CHNG VAL” message appears and the next standard will be
STCAL 4 equal to 800 NTU.
9. Insert the standard cell STCAL 4 equal to 800 NTU. If the turbidity value is slightly different
from 800, correct it using the arrows.
10. Press ENTER to continue. The MEAS message is shown in the comment line. After a few
seconds the “CAL END” message appears to indicate the procedure was successful.
Calibration of the WHITE %T scale
The following steps are performed to calibrate the WHITE %T scale.
1. Select the WHITE %T measurement method using the arrows.
2. Press simultaneously MENU and ENTER to start the calibration procedure.
3. The “H2O_INSERT” message appears: insert the standard cell STCAL 1 equal to 0 NTU in the
measurement compartment and screw the cap.
4. Press ENTER: the MEAS message is shown in the comment line. After a few seconds the “CAL
END” message appears to indicate the procedure was successful.

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Calibration of the IR %T scale
The following steps are performed to calibrate the IR %T scale.
1. Select the IR %T measurement method using the arrows.
2. Press simultaneously MENU and ENTER to start the calibration procedure.
3. The “H2O_INSERT” message appears: insert the standard cell STCAL 1 equal to 0 NTU in the
measurement compartment and screw the cap.
4. Press ENTER: the MEAS message is shown in the comment line. After a few seconds the “CAL
END” message appears to indicate the procedure was successful.
NOTES:
•If an error is made during calibration, the ERR blinking message appears. It is possible to
repeat the current point by entering the correct standard and pressing ENTER.
•Press ESC to quit the calibration without making changes before carrying out the last step.
•The instrument quits the calibration procedure without making changes if you do not use
the keyboard for at least 2 minutes.
DAILY CHECK
It is better to check daily if the instrument is calibrated, before doing the measurements. Perform a
measurement using the standard STCAL 1 and a second measurement using the standard solution
that is closest to the values being measured. If the measurement error for the 0 NTU is greater than
0.1 NTU and/or the error of the second standard is higher than ±10%, you need to do a new
calibration.

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BATTERY REPLACEMENT
The HD25.2 is supplied by three 1.5V, AA batteries or by external power supply (12Vdc/1A).
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 wish to continue using the instrument, remove the flat batteries and supply it using the
external power supply. Data stored on memory are maintained even without power supply.
If the battery charge level is insufficient, and the external power supply is not connected, 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 or use the
external power supply, in order to turn the instrument back on.
The battery symbol turns off when the external power supply is connected.
To replace the batteries, switch the instrument off and unscrew the two screws on the battery cover
counter clockwise. Put the new batteries in making sure the polarity is correct. After replacing the
batteries, close again the cover and fasten the two screws clockwise.
After replacing the batteries, the date, time and baud rate must be set again. To go to the next
item press ENTER; to return to measurement mode, press MENU.
In order to avoid losing the menu settings, before removing the batteries, connect the external
power supply.

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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 the Use of Batteries
•Batteries should be removed when the instrument is not used for an extended time.
•Flat batteries must be replaced immediately.
•Avoid loss of liquid from batteries.
•Use waterproof and good-quality batteries, if possible alkaline. 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.
•During storage avoid locations 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: do not use any incompatible solvent for cleaning.

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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 indication Explanation
ERR This appears during calibration if a wrong standard is inserted.
OVER
Measurement overflow: this appears when the measurement value
exceeds the expected measurement range, or when the instrument has
not been calibrated on that scale.
MEM
FULL
Memory full; the instrument cannot store further data, the memory
space is full.
SYS
ERR
#
Instrument management program error. Contact the instrument's
supplier and communicate the numeric code # reported by the display.
CAL
EXPIRED
This calibration has expired: the calibration validity number of days,
set in the menu item “CAL EXP TOTA DAY”, has been exceeded.
ALREADY
MEM
The measurement was already stored.
COVR
VIAL
This appears if the measuring chamber lid was left open.
ERR1 This appears when an user who is not an administrator tries to modify,
from the menu, the calibration validity interval.
OVL_R90
UFL_R90
OFL_R0
UFL_R0
OVF_MON
When the instrument detect a functioning anomaly, these items are
displayed: contact the instrument supplier and specify which kind of
error is displayed.

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SERIAL INTERFACE AND USB
The HD25.2 is fitted with an electrically isolated RS-232C serial interface, and an USB 2.0
interface. The instrument can be connected using a serial cable with sub D 9-pole female connectors
(code 9CPRS232) and a cable with USB2.0 connectors (code CP22).
The USB connection requires the previous installation of a driver contained in the DeltaLog11 CD-
Rom. Install the driver before connecting the USB cable to the PC (please see the details on
page 20).
Standard parameters of the instrument serial transmission are:
•Baud rate 38400 baud
•Parity None
•N. bit 8
•Stop bit 1
•Protocol Xon/Xoff
It is possible to change the RS232C serial port baud rate by setting the "Baud Rate" parameter in the
menu (please see page 8). The possible values are: 38400, 19200, 9600, 4800, 2400 e 1200. The
other transmission parameters are fixed.
The USB 2.0 connection does not require the setting of parameters.
The selection of the port (serial or USB) is carried out directly by the instrument: if the USB
port is connected to a PC, the RS232 serial port is automatically disabled.
The instruments are provided with a complete set of commands and data queries to be sent via the
PC.
All the commands transferred to the instrument must have the following structure:
XY CR+LF where: XY is the command code and CR+LF is the Carriage Return (ASCII 0D) +
Line Feed (ASCII 0A).
COMMAND ACTION RESPONSE NOTES
AA Model request HD25-2
Turbidimeter
AG Firmware version Firmware 1.00.100
AH Firmware date Firm.Date=2006/01/09
AS Serial number Ser.Number=12345678
AU User identification Operator = Administrator
Operator = User_1
Operator = User_2
Operator = User_3
Operator = Anonymous
DA Input date-time &/? DA0501010F2615 hexadecimal.
IT REJECTS ANY INCORRECT
DATE
FA Clock date request &050101002431 Hexadecimal
FD Instrument calibration request &0501010F2615 Hexadecimal
K1 Current measurement print Increases ID

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COMMAND ACTION RESPONSE NOTES
KX Start measurement &
LDxxxx Send sample
no. xxxx+1
Dump or ? Xxxx from 1 to 1000
LE Clear memory &
LN No. of next memory location
request
Next avail. Memory =0001
MR Type of measurement reading &n n = see MW command
MW0..5 Type of measurement selection 0 = EPA 180
1 = ISO NEPH
2 = EBC
3 = ASBC
4 = WHITE %
5 = IR %
P0 Ping & lock keys &
P1 Ping & unlock keys &
RH Shows the calibration
validity number of days
RI Sample ID= 00000001
RL Print&mem = 0 0 = free print,
1 = print & store,
(see the MEM ON PRNT
command in the menu)
RP Battery voltage reading &nnn Nnn = hundredths of Volt
SH Calibration status reading calibration status = valid
calibration status = expired!
T3Do35 User calibration reset, return to
factory calibration
&
T4Do35nnnnn
xxxxx
Enable user to change its
password
&/? Nnnnn = current administrator
password
Xxxxx = user password being
changed
WI Enter sample identification
number
&/?
00000000 ... 00019999
WL Choice of print-memory
connection mode
&/? 0 = free print,
1 = print and forced storing
WUnnnnn Set new password of user
previously selected with
command T4Do35
&/?
Command characters are exclusively upper case characters. Once a correct command is entered, the
instrument responds with "&"; when any wrong combination of characters is entered, the instrument
responds with "?". The instrument response strings end with the sending of the “|”+CR+LF
command (| + Carriage Return + Line Feed). Before sending commands to the instrument via the
serial port, locking the keyboard to avoid functioning conflicts is recommended: use the P0
command. When complete, restore the keyboard with the P1 command.

- -
20
CONNECTION TO A PC
There are two ports for connecting the instrument to the PC:
RS232C serial port with null modem cable code 9CPRS232. The cable has two sub D 9-pole
female connectors.
USB 2.0 port with the cable code CP22. The cable has a USB type A connector for PC
connection and a USB type B connector for connection to the instrument.
The instruments are supplied with the DeltaLog11 software that manages the PC connection, data
transfer, and printing operations of the captured or logged measurements.
The DeltaLog11 software is complete with "On-line Help" (also in PDF format) describing its
characteristics and functions.
The instruments are also compatible with the HyperTerminal communication program supplied
with the Windows operating systems (from Windows 98 to Windows XP).
CONNECTION TO THE RS232C SERIAL PORT
1. The measuring instrument has to be switched off.
2. Using the Delta Ohm 9CPRS232 cable, connect the measurement instrument to the first free
serial port (COM) of the PC.
3. Turn on the instrument and set the baud rate to 38400 (MENU >> “Baud Rate” >> select 38400
using the arrows >> confirm with ENTER). The parameter remains in the memory.
4. Launch the DeltaLog11 application and press CONNECT. Wait for the connection to occur and
follow the indications on the screen. For a description of the DeltaLog11 application, please refer
to its On-line Help.
CONNECTION TO THE USB 2.0 PORT
The USB connection requires the installation of the drivers. They are contained in the
DeltaLog11 CD-Rom.
Proceed as follows:
1. Do not connect the instrument to the USB port until you are expressly requested to do it.
2. Insert the DeltaLog11 CD-Rom and select the "Install/Remove USB driver" item.
3. The application checks the presence of the drivers on the PC: the installation starts if they are
not present; if they are already installed, the drivers are removed by pressing the key.
4. The installation wizard prompts the software user license: to proceed, the software usage
terms must be accepted - click on YES.
5. On the next page the folder where the drivers will be installed is indicated: confirm without
modifying.
6. Complete the installation by clicking on Finish. Wait few seconds until the DeltaLog11 page
appears.
7. Close DeltaLog11.