Hanna Instruments HI 23 User Manual

HI 23 / HI 24 Series

Wall-mounted,
Microprocessor-based,
Conductivity and TDS
Process Controllers

Instruction Manual

1

Dear Customer,
Thank you for choosing a Hanna Product.
This instruction manual refers to the following products:

HI 23211 EC controller with dual setpoint, ON/OFF

control and analog output

HI 23212 EC controller with dual setpoint, ON/OFF

control and RS 485 port

HI 23221 EC controller with dual setpoint, ON/OFF

and PID control, and analog output

HI 23222 EC controller with dual setpoint, ON/OFF

and PID control, and RS 485 port

HI 24211 EC and TDS controller with dual setpoint,

ON/OFF control and analog output

HI 24212 EC and TDS controller with dual setpoint,

ON/OFF control and RS 485 output

HI 24221 EC and TDS controller with dual setpoint,

ON/OFF and PID control, and analog out­put

HI 24222 EC and TDS controller with dual setpoint,

ON/OFF and PID control, and RS 485 port

Please read this instruction manual carefully before using the
instrument. It will provide you with the necessary information
for the correct use of the instrument, as well as a precise idea
of its versatility.

These instruments are in compliance with the directives.

© 2001 Hanna Instruments

All rights are reserved. Reproduction in whole or in part is prohibited without the written
consent of the copyright owner, Hanna Instruments Inc., 584 Park East Drive, Woon­socket, Rhode Island, 02895, USA.

2

TABLE OF CONTENTS

PRELIMINARY EXAMINATION ............................................4

GENERAL DESCRIPTION ................................................. 4

MAIN FEATURES OF DIFFERENT MODELS .........................5

FUNCTIONAL DESCRIPTION ............................................7

MECHANICAL DIMENSIONS ............................................9

SPECIFICATIONS .......................................................... 10

INSTALLATION ..............................................................11

SETUP MODE .............................................................. 14

CONTROL MODE ........................................................ 21

IDLE MODE ................................................................. 29

ANALOG OUTPUT ....................................................... 30

CALIBRATION ...............................................................32

LAST CALIBRATION DATA ............................................... 40

FAULT CONDITIONS AND SELFTEST PROCEDURES ...........41

EXTERNAL FUNCTIONS .................................................45

RS 485 COMMUNICATION ............................................46

STARTUP ......................................................................53

EC VALUES AT VARIOUS TEMPERATURES ..........................54

EC / TDS PROBE MAINTENANCE ................................... 55

ACCESSORIES ..............................................................56

WARRANTY ................................................................. 58

CE DECLARATION OF CONFORMITY .............................59

3

PRELIMINARY EXAMINATION

Remove the instrument from the packing material and exam­ine it carefully to make sure that no damage has occurred
during shipping. If there is any noticeable damage, notify
your Dealer or the nearest Hanna Customer Service Center
immediately.

Note Save all packing materials until you are sure that the instru-

ment functions correctly. Any damaged or defective items
must be returned in their original packing materials together
with the supplied accessories.

GENERAL DESCRIPTION

HI 23 and HI 24 series are real time microprocessor-based
EC or TDS controllers. They provide accurate measurements,
flexible ON/OFF or proportional control capabilities, ana­log input and output, dual setpoint and alarm signal.

The system is composed of a case inside which the signal
conversion circuitry, the microprocessor circuitry and the
output power drivers are contained.

GREAT FLEXIBILITY

The HI 23 and HI 24 controller series offer a great flexibility
with the possibility to connect a large variety of peripherals,
such as pumps, valves, relays and other control devices.
Each output can be fully programmed. The input can be
from a conductivity probe or from a 4-20mA transmitter. A
programmable analog output can be used for monitoring or
other purposes.

The controller also has the capability to communicate with a
computer via RS485 bus and to be part of an RS485 net­work.

This allows the control of any process where conductivity is
involved.

The figure below illustrates the connection possibilities of ad­vanced Hanna controllers, such as HI 23 or HI 24.

4

MAIN FEATURES OF DIFFERENT MODELS

• Display: large LCD with 4 ½ 13 mm digits and 3 ½ 7.7 mm
digits.

• LEDs: four LEDs are provided for signaling the energizing
of relays 1 and 2 (yellow LEDs) and alarm relay (a green
and a red LED).

• Relays: 2 output relays for low conductivity or high con­ductivity dosage (COM, NO and NC contacts) and
1 output relay for alarm condition (COM, NO and NC
contacts).

5

• Calibration and Setup procedures allowed only through
an unlock password.

• Calibration: 2 points with Hanna EC and TDS calibration
solutions.

• Four different EC working ranges (0 to 199.9µS; 0 to
1999µS; 0 to 19.99mS; 0 to 199.9mS).

• Four different TDS working ranges (0 to 100.0ppm; 0 to
1000ppm; 0 to 10.00ppt; 0 to 100.0ppt) for HI 24 series.

• Possibility to switch to TDS measurements with conversion
factor from 0.00 to 1.00 (HI 24 series).

• Temperature compensation of the HANNA standard solu­tions.

• Temperature compensation of the EC and TDS reading with
temperature coefficient ß selectable from 0 to 10%/°C.

• Use of a 3-wire Pt 100 temperature sensor to compensate
for the cable resistance and have a precise automatic tem­perature compensation of the measurements in long dis­tance applications.

• Manual temperature setting when the temperature probe is
not inserted or the temperature exceeds the upper range.

• Last calibration data internally recorded (nonvolatile EE­PROM memory): calibration date and time, cell constant,
calibration solution values.

• Input: 4-ring EC/TDS probe with cell constant 2.0 ± 10%,
or 4-20mA analog input from a transmitter.

• Analog output (HI 23xy1 and HI 24xy1)

- isolated 0-1 mA, 10 KΩ maximum load (optional);

- isolated 0-20 mA, 750 Ω maximum load (optional);

- isolated 4-20 mA, 750 Ω maximum load (optional);

- isolated 0-5 VDC, 1 KΩ minimum load (optional);

- isolated 1-5 VDC, 1 KΩ minimum load (optional);

- isolated 0-10 VDC, 1 KΩ minimum load (optional).

• Real time clock.

• Serial comunication via RS485 with the possibilities to set
the working parameters and to read the displayed data (HI
23xy2 and HI 24xy2).

6

FUNCTIONAL DESCRIPTION

1. Liquid Crystal Display

2. CAL DATA key last calibration data viewing (enters and exits)

3. LCD key exits from setup and reverts back to normal mode (in idle
or control phases with the measurement on the display).
During EC/TDS calibration, it alternates EC/TDS buffer
value and current cell constant on the display. In HI 24
series, it switches between EC and TDS reading

4. CAL key initiates and exits calibration mode

5. SETUP key enters setup mode

6.  key moves to the next digit/letter (circular solution) when se­lecting a parameter. Same as  key during last calibration
data viewing mode

7.  key increases the blinking digit/letter by one when selecting a
parameter. Advances forward while in last calibration
data viewing mode. Increases the temperature setting
when temperature probe is not inserted

8. CFM key confirms current choice (and skips to the next item)

9.  key decreases the blinking digit/letter by one when selecting
a parameter. Reverts backward while in last calibration
data viewing mode. Decreases the temperature setting
when temperature probe is not inserted

10. LEDs

7

1. RS 485 communications terminal (HI 23xy2 and HI 24xy2
models only)

2. Analog Output terminal (HI 23xy1 and HI 24xy1 models only)

3. Pt 100 Temperature Sensor terminal

4. Power supply output for external transmitter

5. 4-20 mA input from external transmitter

6. Main Power Supply

7. Alarm Terminal

8. Contact 1 - First Dosing Terminal

9. Contact 2 - Second Dosing Terminal

10. EC/TDS probe connector

11. Hold terminal

12. Timer terminal

Unplug the meter before any electrical connection.

Note The connections of terminals 1 to 5 are numbered from 1 to 15

from top to bottom and the connections of terminals 11 and 12
are numbered from 16 to 19 from top to bottom.

8

MECHANICAL DIMENSIONS

9

SPECIFICATIONS

Ranges 0.0 to 199.9 µS/cm, 0 to 1999 µS/cm

0.00 to 10.00 ppt, 0.0 to 100.0 ppt (HI 24* series only)

Resolution 0.1 µS/cm, 1 µS/cm

Accuracy ±0.5 % full scale (EC and TDS)

(@20°C/68°F) ±0.5°C between 0 to 70°C, ±1°C outside

Temperature Compensation Automatic from -10 to 100°C or manual with

Typical EMC Deviation ±2 % full scale (EC and TDS)

Installation Category II
Probe HI 7639D 4-ring EC/TDS probe (K=2) with built-in

Analog Input 4 - 20 mA
Analog Output 0-10VDC, 0-5VDC or 1-5VDC (HI 23xy1 and HI 24xy1)

RS485 baud rate 1200, 2400, 4800 and 9600 (HI 23xy2 and HI 24xy2)
Power Supply 230 ±10% VAC or 115 ±10% VAC, 50/60 Hz
Power Consumption 15 VA
Over Current Protection 200 mA 250V FAST FUSE
Relays 1, 2 and Electromechanical relay SPDT contact outputs,

Alarm Relay 5A-250 VAC, 5A - 30 VDC (resistive load)

Environment 0-50 °C; max 95% R.H. non-condensing
Enclosure 189 x 228 x 102 mm (7.4 x 9 x 4”)
Case Material Fiber-reinforced, self-extinguishing ABS
Weight approximately 1.6 kg (3.5 lb.)

0.00 to 19.99 mS/cm, 0.0 to 199.9 mS/cm

0.0 to 100.0 ppm, 0 to 1000 ppm (HI 24* series only)

-10.0 to 100.0 °C

0.01 mS/cm, 0.1 mS/cm

0.1 ppm, 1 ppm (HI 24 series only)

0.01 ppt, 0.1 ppt (HI 24 series only)

0.1 °C

Temperature Coefficient from 0.00 to 10.00%/°C

±0.5 °C

3-wire Pt100 temperature sensor and 5 m cable
HI3012D + HI5001/5 (external temperature sensor)

0-20mA or 4-20mA, 0-1mA (HI 23xy1 and HI 24xy1)

Fuse protected: 5A, 250V FUSE

10

* Note: actual TDS range for HI 24 series depends on TDS factor set.

INSTALLATION

HI 23 and HI 24 series offer a multitude of possibilities,
from dual setpoints to ON/OFF or PID dosage, isolated out­puts with user-selectable zoom, recorder outputs in mA and
volts.

Use the 3-wire Pt 100 temperature sensor to compensate for
the cable resistance and have a precise automatic tempera­ture compensation of the measurements in long distance
applications.

See the below diagram for a recommended installation.

CONDUCTIVITY

PROBE

Note All external cables to be connected to the right panel should

end with cable lugs.
Use wires with cable lugs when connecting to the strip con-

tacts.

Always disconnect the power cord when wiring the controller.

11

• Power Supply: Connect a 3-wire power
cable to the terminal strip, while paying
attention to the correct line (L), earth (PE)
and neutral (N) terminal connections.

Power: 230VAC - 50 mA.

Line Contact: 200mA fuse inside.
PE leakage current 1 mA; this contact must be con-

nected to ground.

• Conductivity input: the default input is from conductivity
probe. Connect the EC probe to the terminals #10 on
page 8. HI7639D is a conductivity probe with built-in tem­perature sensor.

• Pt 100 Terminals (to be used only if the EC probe is
without Pt 100): connect to these contacts (#3 on page 8)
the Pt 100 temperature sensor for automatic temperature
compensation of measurement. Follow the below diagram
for connecting a 3-wire Pt 100 sensor as HI5001/5:

Color Pin #
GRAY 8
BROWN 9
YELLOW 10

12

If using a different Pt 100, separated from the conductivity
probe, connect the cable shield to pin 11, and the other
wires as explained below.

In the case of a 2-wire sensor connect
the Pt 100 to pins 8 and 10, and short
pins 9 and 10 with a jumper wire.

If the Pt 100 has more than 2 wires, con­nect the two wires of one end to pins 9
and 10 (pin 9 is an auxiliary input to
compensate for the cable resistance) and
one wire from the other end to pin 8.
Leave the fourth wire unconnected, if
present.

Note If the meter does not detect the temperature probe, it will

switch automatically to manual temperature compensation
with the temperature adjustable through the up and down
arrow keys. The “°C” symbol will blink on the LCD.

Note All external cables to be connected to the right panel should

end with cable lugs.

• Analog output: In the models where it
is available, connect an external recorder
with a 2-wire cable to these terminals
(#2 on page 8) paying attention to the
correct polarity. A wide variety of output
signals, either in V or in mA, is avail­able to fit most standards. Terminal 5 is the voltage output,
terminal 6 is the analog output common and terminal 7 is
the current output.

• Contact 1 and 2: Connect the dosing
devices to these terminals (#8 and #9
on page 8) in order to activate and de­activate them according to the selected
control parameters.

• mA Input: to switch to mA input signal
from a conductivity transmitter (e.g.
HI8936 or HI98143 series) see the setup
procedure (code 6).

13

SETUP MODE

Connect the two signal wires from the transmitter to terminals
#5 on page 8, paying attention to the correct polarity. Termi­nal 14 is the positive input and terminal 15 is the negative
input.

An unregulated 10 ÷ 30 VDC - 50 mA max.
power supply output (#4 on page 8) is pro­vided to power the transmitter, if needed. Pin
12 is the positive voltage terminal and pin 13
is the negative voltage terminal.

Once the installation is completed, select the appropriate
working range, the reference temperature (20 or 25°C) and
perform conductivity or TDS calibration as described in this
instruction manual. Set the control parameters according
to the process of interest.

The Setup Mode allows the user to set all needed character­istics of the meter.

The setup mode is entered by pressing SETUP
and entering the password when the device
is in idle or control mode.

14

Generally speaking, if the password is not inserted the user
can only view the setup parameters (except for password)
without modifying them (and the device remains in control
mode). An exception is certain setup items, or flags, which
can activate special tasks when set and confirmed.

To each setup parameter (or setup item) is assigned a two­digit setup code which is entered and displayed on the
secondary LCD.

The setup codes can be selected
after password and CFM are
pressed. When CFM is pressed,
the current setup item is saved
on EEPROM and the following
item is displayed. Whenever
LCD is pressed, the device reverts back to control mode. The
same is true when CFM is pressed on the last setup item.

The possible transitions in setup mode are the following:

ENTERING THE PASSWORD

• Press SETUP to enter the setup mode. The LCD will display
“0000” on the upper part and “PAS” on the lower. The first
digit of the upper part of the LCD will blink.

• Enter the first value of the password by the  or  keys.

• Then confirm the displayed digit with  and move to the
next one.

• When the whole password has been inserted, press CFM
to confirm it.

15

Note The default password is set at “0000”.

• The LCD will display “SET” on the up­per part and “c.00” on the lower, al­lowing the user to edit setup param­eters (see table below).

• Using the arrow keys as for the above password proce­dure, enter the code of the parameter to set, e.g. 41.

• Confirm the code by pressing CFM and the default or the
previously memorized value will be displayed with the
first digit blinking.

Note When the password is not inserted or a wrong password is

confirmed, the display will only show the previously memo­rized value, without blinking (read only mode). In this case,
the value cannot be set. Press LCD and start again.

16

• Enter the desired value using the arrow keys and then press
CFM.

• After confirmation, the selected parameter is
displayed. The user can scroll through the
parameters by pressing CFM.

• In order to directly set another param­eter, press SETUP again and enter the
code or scroll to it by pressing CFM.

SETUP CODES

The following table lists the setup codes along with the descrip­tion of the specific setup items, their valid values and whether
password is required to view that item (“PW” column):

Code Valid Values Default PW

00 Factory ID 0 to 9999 0000 no

01 Process ID 0 to 99 00 no

02 Control enable/disable 0: C.M. disabled 0 no

1: C.M. enabled

03 Range 1: 0.0-199.9 µS (or 100.0 ppm) 4 no

(depends on model) 2: 0-1999 µS (or 1000 ppm)

3: 0.00-19.99 mS (or 10.00 ppt)
4: 0.0-199.9 mS (or 100.0 ppt)

04 Reference Temperature 20°C or 25°C 25°C no

05 Temperature Coefficient 0.00 to 10.00 %/°C 2.00 no

06 Input Selection 0: conductivity probe 0 no

1: 4-20 mA input signal

07 Temperature ATC: Automatic ATC no

compensation User: Manual

08 TDS Factor 0.00 to 1.00 0.50 no

11 Relay 1 mode 0: disabled 0 no

(M1) 1: ON-OFF high setpoint

2: ON-OFF low setpoint
3: PID, high setpoint
4: PID, low setpoint

12 Relay 1 setpoint (S1) 0.5 to 99.5% full scale 25% f.s. no

13 Relay 1 hysteresis (H1) 0 to 5% f.s. 1% f.s. no

14 Relay 1 deviation (D1) 0.5 to 10% f.s. 1% f.s. no

15 Relay 1 reset time 0.1 to 999.9 minutes 999.9 no

16 Relay 1 rate time 0.0 to 999.9 minutes 0.0 no

17

Code Valid Values Default PW

21 Relay 2 mode (M2) same as relay 1 0 no

22 Relay 2 setpoint (S2) 0.5 to 99.5% full scale 75% f.s. no

23 Relay 2 hysteresis (H2) 0 to 5% f.s. 1% f.s. no

24 Relay 2 deviation (D2) 0.5 to 10% f.s. 1% f.s. no

25 Relay 2 reset time 0.1 to 999.9 minutes 999.9 no

26 Relay 2 rate time 0.0 to 999.9 minutes 0.0 no

30 Alarm relay 0.5 to 99.5% full scale 95% f.s. no
High Alarm (HA) HA-HysULA+Hys,Hys=1.5%f.s.,HAUS1 or HAUS2

31 Alarm relay 0.5 to 99.5% full scale 5% f.s. no
Low Alarm (LA) LA+HysTHA-Hys,Hys=1.5%f.s.,LATS1 or LATS2

32 Proportional control 1 to 30 min 5 no

mode period

33 Maximum relay ON time 1 to 10 min 10 no

(after which an alarm mode is entered)

34 Alarm mask time 00:00 to 30:00 00:00 no

40 Analog output selection 0: 0-1mA 2 no

1: 0-20 mA
2: 4-20 mA
3: 0-5 VDC
4: 1-5 VDC
5: 0-10 VDC

18

41 Analog output 0 to 100% full scale 0 no
lower limit (O_VARMIN) (O_VARMIN T O_VARMAX - 5% f.s.)

42 Analog output 0 to 100% full scale 100% f.s. no
upper limit (O_VARMAX) (O_VARMIN T O_VARMAX - 5% f.s.)

60 Current day 01 to 31 from RTC no
61 Current month 01 to 12 from RTC no
62 Current year 1998 to 9999 from RTC no
63 Current time 00:00 to 23:59 from RTC no

Code Valid Values Default PW

71 Baud rate 1200, 2400, 4800, 9600 4800 yes
72 Cleaning timer 0 to 19999 days 0 no
73 Initial cleaning day 01 to 31 01 no
74 Initial cleaning month 01 to 12 01 no
75 Initial cleaning year 1998 to 9999 1998 no
76 Initial cleaning time 00:00 to 23:59 00:00 no
77 Cleaning ON interval 0 to 19999 minutes 0 no
90 Display selftest 0: off 0 yes

1: on

91 Keyboard selftest 0: off 0 yes

1: on

92 EEPROM selftest 0: off 0 yes

1: on

93 Relays and LEDs selftest 0: off 0 yes

1: on

94 Watchdog selftest 0: off 0 yes

1: on

99 Unlock password 0000 to 9999 0000 yes

Note The process controller automatically checks to ensure that

the entered data matches other related variables. If a wrong
configuration is entered, “ERROR” blinks on the LCD to
prompt the user. The correct configurations are the follow­ing:

If M1=/ 0 then S1THA, S1ULA;
If M2=/ 0 then S2THA, S2ULA;

If M1= 1 then S1-H1ULA;

If M1= 2 then S1+H1THA;
If M1= 3 then S1+D1THA;
If M1= 4 then S1-D1ULA;

19

If M2= 1 then S2-H2ULA;
If M2= 2 then S2+H2THA;
If M2= 3 then S2+D2THA;
If M2= 4 then S2-D2ULA;
If M1= 1 and M2 = 2

then S1-H1US2+H2, S2ULA, HAUS1;
If M1 = 2 and M2 = 1

then S2-H2US1+H1, S1ULA, HAUS2;
If M1 = 3 and M2 = 2

then S1US2+H2, S2ULA, HAUS1+D1;
If M1 = 2 and M2 = 3

then S1+H1TS2, S1ULA, HAUS2+D2;
If M1 = 4 and M2 = 1

then S1TS2–H2, S1–D1ULA, HAUS2;
If M1 = 1 and M2 = 4

then S1–H1US2, S2–D2ULA, HAUS1;
If M1 = 3 and M2 = 4

then S1US2, S2–D2ULA, HAUS1+D1;
If M1 = 4 and M2 = 3

then S2US1, S1–D1ULA, HAUS2+D2;
where the minimum deviation (D1 or D2) is 0.5% of the maxi-

mum range value.

20

Note Some setup codes are available depending on the model.
Note When a wrong setup value is confirmed

or a wrong setup code is selected, the con­troller does not skip to the next setup item
but remains in the current item displaying
a flashing “ERROR” indicator until the pa­rameter value is changed by the user.

Note In some circumstances, the user cannot succeed in setting a

parameter to a desired value if the related parameters are not
changed beforehand; e.g. to set a EC high setpoint to 10.0
mS the high alarm must be set to a value greater than 10.0
mS first.

CONTROL MODE

The control mode is the normal operational mode for these
meters. During control mode the meter fulfills the following
main tasks:

• converts information from EC/TDS and temperature in-

• control relays and generates the analog outputs as de-

In the HI 24 series it is possible to switch between EC and
TDS reading pressing “LCD”. The TDS value is obtained mul­tiplying the EC measurement by the TDS factor set through
setup. The HI 23 series displays EC only.

The status of the meter is shown by the LEDs.

puts to digital values;

termined by the setup configuration, displays alarm
condition;

STATUS LEDs

Control Alarm Green LED Contacts LED (yellow) Red LED

OFF ---- ON OFF ON

ON OFF ON ON or OFF OFF

ON ON OFF ON or OFF Blinking

RELAY MODES

The meter exits control mode by pressing SETUP or CAL and
confirming the password. Note
that this command generates
a temporary exit. To deactivate
the control mode definitively,
set CONTROL ENABLE to “0”
(item # 02).

Once enabled, the relays 1 and 2 can be used in four differ­ent modes):

1) ON/OFF, high setpoint (low conductivity dosage);

2) ON/OFF, low setpoint (high conductivity dosage);

3) PID, low setpoint (low conductivity dosage, if available);

4) PID, high setpoint (high conductivity dosage, if available).

21

An upper boundary is imposed for dosage time when relays
are energized continuously, i.e. when relay works in ON/
OFF mode or also in PID mode but in the latter case only if
the relay is always ON. This parameter can be set through
the setup procedure. When the maximum boundary is
reached, an alarm is generated; the device stays in alarm
condition until relay is de-energized.

ON/OFF CONTROL MODE

Either for mode 1 or 2 (high or low
conductivity dosage) the user has to
define the following values through
setup:

• relay setpoint (µS/mS/ppm value);

• relay hysteresis (µS/mS/ppm value).

Connect your device to the COM and NO (Normally Open)
or NC (Normally Closed) terminals.

The ON relay state occurs when relay is energized (NO
and COM connected, NC and COM disconnected).

The OFF relay state occurs when relay is de-energized (NO
and COM disconnected, NC and COM connected).

The following graphs show relay states along with EC mea­sured value (similar graph can be derived for TDS control).

As shown below, a high setpoint relay is activated when the
measured EC exceeds the setpoint and is deactivated when it
is below the setpoint value minus hysteresis.

22

ON

OFF

Setpoint

Hysteresis

ECSetpoint –

Such a behavior is suitable to control a high conductivity
dosing pump.
A low setpoint relay as can be seen from the following graphs
is energized when the EC value is below the setpoint and is

de-energized when the EC value is above the setpoint plus
the hysteresis.

ON

OFF

Setpoint

Setpoint +
Hysteresis

The low setpoint relay may be used to control a low conduc­tivity dosing pump.

P.I.D. CONTROL MODE (HI 23x2z and HI 24x2z models only)

PID control is designed to eliminate the cycling associated
with ON/OFF control in a rapid and steady way by means
of the combination of the proportional, integral and de­rivative control methods.

With the proportional function, the duration of the activated
control is proportional to the error value (Duty Cycle Con­trol Mode): as the measurement approaches setpoint, the
ON period diminishes.

The following graph describes the EC/TDS process control­ler behavior. Similar graph may apply to the controller.

t

0

t0+T

t0+2T

c

c

During proportional control the process controller calculates
the relay activation time at certain moments t0, t0+Tc, t0+2T
etc. The ON interval (the shaded areas) is then dependent
on the error amplitude.

With the integral function (default), the controller will reach a
more stable output around the setpoint providing a more
accurate control than with the ON/OFF or proportional
action only.

t0+3T

EC

c

c

23

The derivative function (rate action) compensates for rapid
changes in the system reducing undershoot and overshoot
of the EC or TDS value.

During PID control, the ON interval is dependent not only on
the error amplitude but even on the previous measurements.

Definitely PID control provides more accurate and stable
control than ON/OFF controllers and it is best suitable in
system with fast response, quickly reacting to changes due
to addition of low or high conductivity solution.

An example of how the response overshoot can be improved
with a proper rate action setting is depicted in the following
graphic.

EC

RATE ACTION COMPENSATES FOR RAPID CHANGES t

PID TRANSFER FUNCTION

The transfer function of a PID control is as follows:

with Ti = Kp/Ki, Td = Kd/Kp,

where the first term represents the proportional action, the

24

Kp + Ki/s + s Kd = Kp(1 + 1/(s Ti) +s Td)

second is the integrative action and the third is the deriva­tive action.

Proportional action can be set by means of the Proportional
Band (PB). Proportional Band is expressed in percentage of
the input range and is related to Kp according to the follow­ing:

100%

Controller

output

Kp = 100/PB.
The proportional action is set through the setup procedure

as “Deviation” in percent of full scale of the selected range.
Each setpoint has a selectable deviation: D1 for setpoint1

and D2 for setpoint2.
Two further parameters must be provided for both setpoints:

Ti = Kp/Ki, reset time, measured in minutes
Td = Kd/Kp, rate time, measured in minutes.

Ti1 and Td1 will be the reset time and rate time for setpoint1,
while Ti2 and Td2 will be the reset time and the rate time
for setpoint2.

TUNING A PID CONTROLLER

The proportional, integrative, derivative terms must be tuned,
i.e. adjusted to a particular process. Since the process vari­ables are not typically known, a “trial and error” tuning
procedure must be applied to get the best possible control
for the particular process. The target is to achieve a fast
response time and a small overshoot.

Many tuning procedures are available and can be applied
to the EC/TDS controllers. A simple and profitable proce­dure is reported in this manual and can be used in almost
all applications.

0

Proportional Band

Error

25

The user can vary five different parameters, i.e. the setpoint
(S1 or S2), the deviation (D1 or D2), the reset time, the rate
time and the proportional control mode period Tc (from 1
to 30 minutes).

Note User can disable the derivative and/or integrative action

(for P or PI controllers) by setting Td = 0 and/or Ti = MAX
(Ti) respectively through the setup procedure.

SIMPLE TUNING PROCEDURE

The following procedure uses a graphical technique of ana­lyzing a process response curve to a step input.

1. Starting from a solution with an EC or TDS value quite
different from the dosed liquid, turn on the dosing device
at its maximum capacity without the controller in the loop
(open loop process). Note the starting time.

2. After some delay (T0) the EC or TDS starts to vary. After
more delay, the EC or TDS will reach a maximum rate of
change (slope). Note the time that this maximum slope
occurs and the EC or TDS value at which it occurs. Note
the maximum slope in EC or TDS per minute. Turn the
system power off.

26

3. On the chart draw a tangent to the maximum slope point until
intersection with the horizontal line corresponding to the initial
EC or TDS value. Read the system time delay Tx on the time
axis.

ALARM RELAY

4. The deviation, Ti and Td can be calculated from the following:

• Deviation = Tx * max. slope (EC/TDS)

• Ti = Tx / 0.4 (minutes)

• Td = Tx * 0.4 (minutes).

5. Set the above parameters and restart the system with the
controller in the loop. If the response has too much over­shoot or is oscillating, then the system can be fine-tuned
slightly increasing or decreasing the PID parameters one
at a time.

Note Connecting an external device (e.g. chart recorder) to the

controller, the procedure is easier and doesn’t need to hand
plot the process variable (EC or TDS).

The alarm relay functions in the following manner:
During alarm condition, the relay is de-energized. When

not in alarm condition, the relay is energized.

FS•C = NO (Normally Open)

Energized Relay

COM

FS•O = NC (Normally Closed)

De-energized Relay

Example: High alarm set at 1400 µS

Low alarm set at 600 µS

An hysteresis will eliminate the possibility of continuous se­quences ‘energizing/de-energizing’ the alarm relay when
the measured value is close to the alarm setpoint. The alarm
hysteresis amplitude is 1.5% of full scale.

27

Moreover the alarm signal is generated only after a user
selectable time period (alarm mask) has elapsed since the
controlled value has overtaken one alarm threshold. This
additional feature will avoid fake or temporary alarm con­ditions.

Note If the power supply is interrupted, the relay is de-energized as

if in alarm condition to alert the operator.
In addition to the user-selectable alarm relays, all EC/TDS

controllers are equipped with the Fail Safe alarm feature.
The Fail Safe feature protects the process against critical

errors arising from power interruptions, surges and human
errors. This sophisticated yet easy-to-use system resolves
these predicaments on two fronts: hardware and software.
To eliminate problems of blackout and line failure, the alarm
function operates in a “Normally Closed” state and hence
alarm is triggered if the wires are tripped, or when the power
is down.

This is an important feature since with most meters the alarm
terminals close only when an abnormal situation arises, how­ever, due to line interruption, no alarm is sounded, causing
extensive damage. On the other hand, soft­ware is employed to set off the alarm in
abnormal circumstances, for example, if the
dosing terminals are closed for too long. In
both cases, the red LED will also blink pro­viding a visual warning signal.

The Fail Safe mode is accomplished by connecting the ex­ternal alarm circuit between the FS•C (Normally Open)
and the COM terminals. This way, an alarm will warn the
user when EC exceeds the alarm thresholds, during power
down and in the case of a broken wire between the process
meter and the external alarm circuit.

28

Note In order to have the Fail Safe feature activated, an external

power supply has to be connected to the alarm device.

CONTROL THROUGH ANALOG OUTPUT

Models HI 23xy1 and HI 24xy1 have a proportional ana­log output signal (selectable among 0-1mA, 0-20mA,
4-20mA, 0-5VDC, 1-5VDC and 0-10VDC) at the analog
output terminals.

With this signal, the actual output level amplitude is varied,
rather than the proportion of ON and OFF times (duty cycle
control). A device with analog input (e.g. a pump with a 4­20 mA input) can be connected to these terminals.

IDLE MODE

IDLE mode is entered through setup code 2.
During idle mode the device performs the same tasks as when

it is in control mode except for the relays. The alarm relay is
activated (no alarm condition), the control relays are not
activated while the analog output remains activated.

When the instrument is in idle mode the red and green status
LEDs are on.

Idle mode is useful to disable control actions when the exter­nal devices are not installed or when the user detects unusual
circumstances.

29

Control actions are stopped as soon as the
user presses SETUP and enters the pass­word.

In order to reactivate the control mode, use
code 02 of setup (see “Setup” section). Oth­erwise, the meter remains in idle mode.

ANALOG OUTPUT

Models HI 23xy1 and HI 24xy1 are provided with the ana­log output feature.

The output is galvanic separated and can be a voltage or a
current.

Pin 5 is the voltage output, pin 6 is the
analog output common and pin 7 is the
current output.

With the recorder, simply connect the
common port to the common output
and the second port to the current out­put or voltage output (depending on
which parameter is being used) as de­picted aside.

30

The type (voltage or current) and the range of the output
analog signal is selectable through the jumpers on the board.

Analog output options are as follows:

0-5 VDC; 1-5 VDC

0-10 VDC (default)

0-20 mA; 4-20 mA (default)

0-1 mA

Choice between different ranges with the same configura­tion (for example 0-20 mA and 4-20 mA) is achieved via
software by entering the setup mode and selecting code 40
(see Setup Mode section for exact procedure).

Factory default is 0-20 mA, 4-20 mA for the current output
and 0-10 VDC for the voltage output.

In any case, contact the nearest Hanna Customer Service
Center for changing of the default configuration.

By default the minimum and maximum values of analog
output correspond to the minimum and maximum of the
selected range of the meter. For example, for a controller with
a selected 0 to 1999 µS range and analog output of 4-20
mA, the default values are 0 and 1999 µS corresponding to
4 and 20 mA, respectively.

These values can be changed by the user to have the analog
output matching a different EC or TDS range, for example,
4 mA = 30 mS and 20 mA = 50 mS.

To change the default values, the setup mode must be en­tered. Setup codes for changing the analog output minimum
and maximum are 41 or 42, respectively. For the exact pro­cedure, refer to the setup mode section in the manual.

Note The analog output is factory calibrated through software. The

user may also perform the calibration procedure as explained
in the following. It is recommended to perform the output
calibration at least once a year.

Note Analog output resolution is 1.5‰ f.s. with 0.5% f.s. accu-

racy.

Note The analog output is “frozen” when entering the setup or

calibration mode (after password confirmation).

31

CALIBRATION

The controller is factory calibrated for temperature as well as
for the analog input and outputs.

The user should periodically calibrate the instrument for EC
or TDS. For greatest accuracy, it is recommended that the
instrument is calibrated frequently.

Before beginning normal operation, it is recommended to
standardize the probe with the Hanna calibration solution
close to the expected sample value and inside the selected
range.

EC AND TDS CALIBRATION

The calibration points for EC and TDS are as follows:

The user should select the appropriate range to calibrate (setup
code 03). Calibration must be performed for each range used.

The temperature probe should also be connected to the pro­cess meter (when using a different temperature probe). The
meters are equipped with a stability indicator. The user is also
guided with indications on the display during the calibration
procedure.

Initial Preparation

Pour a small quantity of the calibration solution (e.g. 1413 µS/
cm) into a beaker. If possible, use a plastic beaker to mini­mize any EMC interference.

For accurate calibration use two beakers containing the same
solution, the first one for rinsing the probe, the second one
for calibration. By doing this, contamination between the so­lutions is minimized.

Range Calibration point(s)

0.0÷199.9 µS/cm 84.0 µS/cm
0÷1999 µS/cm 1413 µS/cm

0.00÷19.99 mS/cm 5.00 - 12.88 mS/cm

0.0÷199.9 mS/cm 80.0 - 111.8 mS/cm

0.0÷100.0 ppm 42.0 ppm
0÷1000 ppm 800 ppm

0.00÷10.00 ppt 6.44 ppt

0.0÷100.0 ppt 55.9 ppt

32

Offset Calibration

Note If the wrong password is entered the system reverts back to

Cell constant calibration

To obtain accurate readings, use the calibration solution in
the selected range and closer to the values to be mea­sured.

• To perform the EC or TDS calibration en­ter the calibration mode, by pressing CAL
and entering the password.

• After the correct password is entered,
the control actions stop and the pri­mary LCD will display the first EC or
TDS calibration value, with the "CAL"
indicator blinking. The secondary LCD
displays the temperature.

normal operation, displaying EC or TDS values.

• 0 is the default value for the 1st calibra­tion point. Dry the conductivity probe
and leave it in air.

• Only when the reading is stable the "CAL"
indicator will stop flashing (after about
30 seconds) and the "CFM" indicator
will start blinking.

• Press CFM to confirm the calibration point;
the primary LCD will display the second
expected buffer value.

If the zero calibration cannot be performed,

"ERROR" will blink.

• Select the solution value on
the primary display by press­ing  or  if the selected
range has two possibilities
(e.g. 5.000 and 12.880
mS).

• Immerse the EC/TDS probe with the temperature sensor in
the selected solution. The level of solution must be higher
than the holes of the EC/TDS probe sleeve. Tap the EC/
TDS probe repeatedly on the bottom of the beaker and stir
to ensure that no air bubbles are trapped inside the sleeve.

33

• When the reading is stable, "CAL" will stop
flashing (after about 30 seconds) and
"CFM" indicator will blink.

• Press CFM to confirm the calibration
point; if the reading is close to the selected
solution, the meter stores the reading.

If the reading is not close to the selected
solution, "ERROR" will blink.

A 2-point calibration is always suggested. However the EC/
TDS calibration can also be performed at 1 point. To cali­brate offset only, just press CAL after confirmation (with CFM)
of the zero reading; the meter will return to normal opera­tional mode. To have the cell constant calibrated first, press
the up or down arrow keys after entering the calibration pro­cedure to skip to the next possible calibration buffer. In this
case, after confirmation of the cell constant, the meter will
ask for the offset calibration displaying zero on the LCD; press
CAL to exit or calibrate the offset, if desired.

Note The EC or TDS calibration value shown is referenced at 25°C

even if the reference temperature of 20°C has been selected.

Note During calibration, press LCD to display the cell constant

value on the primary display. Press LCD again to return to
calibration buffer visualization.

Note To interrupt the calibration procedure press CAL to exit to

normal operational mode.

34

Note If the process meter has never been calibrated or an EE-

PROM reset has occurred, the meter continues to perform
measurements. However, the user is informed of an EC or
TDS calibration requirement by a blinking “CAL” indication
(see “Startup” section).

Note The device must be calibrated within the temperature range

specified for the EC or TDS calibration solution.

CELL CONSTANT DIRECT SELECTION

Whenever the EC/TDS probe cell constant is known, it is
possible to directly calibrate the meter using that value.

• Press CAL to enter calibration mode. The LCD will show 0.

• Press LCD to display the current cell constant on the pri­mary LCD (factory default value is 2.000 cm-1).

• Press SETUP key.

• Using ,  and , enter the probe cell constant (the
value must be between 1.333 and 4.000 cm-1) and con­firm by pressing CFM.

Note If the entered cell constant value is invalid, the “ERROR” indi-

cator appear on the LCD.

Note Press SETUP before CFM to exit without changing the cell

constant.

CALIBRATION BUFFER DIRECT SELECTION

This feature allows to set a user-defined calibration point,
in order to perform calibration at a point different from the
memorized standards.

• Press CAL to enter calibration mode. The LCD will show 0.

• Press SETUP key.

• Using ,  and , enter the desired buffer value and
confirm by pressing CFM.

35

Note Press SETUP before CFM to exit without changes.
Note It is suggested to calibrate the offset before entering the cali-

bration buffer direct selection.

TEMPERATURE CALIBRATION

The controller is factory calibrated for temperature. However,
the user may also perform a one point temperature calibra­tion. This procedure is to calibrate the offset only; the slope
will remain as factory calibrated.

• Prepare a beaker containing a solution at a given tem­perature inside the range of the meter.

• Use a Checktemp or a calibrated thermometer with a
resolution of 0.1° as a reference thermometer.

• Immerse the temperature probe in the beaker as close to
the Checktemp as possible.

• Press and hold first CFM and
then CAL to enter the tem­perature calibration mode.

• Execute the password proce­dure.

• Select code 1 via the arrow keys for temperature calibra­tion and confirm with CFM.

• CAL will blink on the LCD. The measured
temperature will be displayed on both the
primary and secondary LCD.

• Use the arrow keys to set on the secondary LCD the tem­perature read by the reference thermometer.

• When the reading has stabilized at a value near the cali­bration point, CAL will stop blinking and an intermittent
CFM will prompt the user to confirm the calibration.

• If the reading stabilizes at a reading significantly variant
from the first setpoint, an intermittent ERROR will prompt
the user to check the beaker or bath.

36

Calibration procedure may be interrupted by pressing CAL
again at any time. If the calibration procedure is stopped
this way, or if the controller is switched off before the last
step, no calibration data is stored in nonvolatile memory (EE­PROM).

ANALOG INPUT CALIBRATION

The analog input is already factory calibrated. However, the
user may also perform a 2-point calibration at 4 and 20 mA.
It is sufficient to perform the calibration on one range only.

• Connect a mA simulator (e.g. HI931002) to the analog
input of the controller (#5 at page 7)

• Press and hold first CFM and then CAL to enter the analog
input calibration mode.

• Execute the password proce­dure.

• Select code 0 via the arrow
keys for analog input calibra­tion and confirm with CFM. CAL will blink on the LCD.

• The secondary LCD will display “4” for the first calibration
point. The primary LCD will display the
conductivity reading.

• Set the mA simulator to 4 mA and wait
for the reading to stabilize, CAL will stop
blinking and an intermittent CFM will prompt the user to
confirm the calibration.

• If the reading stabilizes at a reading significantly variant
from the first calibration point, an inter­mittent ERROR will prompt the user to
check the input.

• If everything is satisfactory the secondary
LCD will display “20” for the second cali­bration point.

• Set the mA simulator to 20 mA and wait for the reading to
stabilize, CAL will stop blinking and an intermittent CFM
will prompt the user to confirm the calibration.

37

• Press CFM to confirm. The meter will return to normal op­erational mode.

Calibration procedure may be interrupted by pressing CAL
again at any time. If the calibration procedure is stopped
this way, or if the controller is switched off before the last
step, no calibration data is stored in nonvolatile memory (EE­PROM).

ANALOG OUTPUT CALIBRATION

In the models where the analog output is available, this fea­ture is factory calibrated through software. The user may also
perform these calibration procedures.

Note It is recommended to perform the output calibration at least

once a year. Calibration should only be performed after 10
minutes from power up.

• With a multimeter or an HI 931002
connect the common port to the
ground output and the second port to
the current output or voltage output
(depending on which parameter is be­ing calibrated).

• Press and hold in sequence CFM first, then  and then

38

• Execute the password procedure.

• The primary display will show the selected parameter blink­ing. Use the  to select the code (0-5 see chart below) for
the desired parameter displayed on the secondary display
(e.g. 4-20 mA).

OUTPUT CALIBRATION CALIBRATION CALIBRATION

TYPE CODE POINT 1 POINT 2

0-1 mA 0 0 mA 1 mA

0-20 mA 1 0 mA 20 mA

4-20 mA 2 4 mA 20 mA

0-5 VDC 3 0 VDC 5 VDC

1-5 VDC 4 1 VDC 5 VDC

0-10 VDC 5 0 VDC 10 VDC

• Press CFM to confirm the selected parameter that will stop
blinking on the primary display. The secondary display shows
the HI 931002 or multimeter input value as lower limit of
the interval.

• Use the  or  to make the HI
931002 or multimeter output cor­respond to the meter’s value
shown on the secondary display
(e.g. 4).

• Wait for approximately 30 seconds (until the reading of the
calibrator is stable).

• Press CFM to confirm. The meter will switch to the second
calibration point. Repeat the above procedure.

• After the desired readings are obtained, press CFM and
the meter will skip back to normal operational mode.

39

Note When adjusting values using the  or  keys it is important

to allow for sufficient response time (up to 30 seconds)
The table below lists the values of output codes along with

the calibration point values (which are the analog output
minimum and the analog output maximum) as indicated
on the display.

The secondary display indicates the current calibration point
value, while the primary display indicates the current cali­bration type.

LAST CALIBRATION DATA

The meter can display the following last calibration data:

• Date

• Time

• Cell constant

While displaying these data, the controller remains in con­trol mode. The data are related to the selected range only.

The procedure below indicates the flow. Displaying of the
items follows the above sequence.

• To begin the cycle press CAL DATA. The last calibration
date will appear on the primary LCD as DD.MM format,
while the secondary display will show the year.

If the meter has never been calibrated or an EEPROM
reset has occurred, no calibration data are shown when
CAL DATA is pressed. The “no CAL” message will blink
for a few seconds, then the meter skips back to normal
mode.

40

• Press  or  to cycle through the data forward or back-
wards respectively.

Note In any moment, by pressing LCD or CAL DATA the meter will

return to the regular operating display.

• Press  or  to view the time of last calibration. The sec-
ondary display will show "HOU".

• Press  or  again to view the cell con-
stant at the time of the last calibration.
The secondary display will show "CEL".

• Press  or  again to return to the first CAL DATA display
(date) at the time of last calibration.

FAULT CONDITIONS AND SELFTEST PROCEDURES

The fault conditions below may be detected by the software:

• EEPROM data error;

• I2C internal bus failure;

• date lost;

• code dead loop.

EEPROM data error can be detected through EEPROM test proce­dure at startup or when explicitly requested using setup menu.

When an EEPROM error is detected, to the user is given the
option to perform a reset of EEPROM.

Note When an EEPROM reset has been performed

the calibration data are reset to default (every
range). An intermittent CAL will blink on the
display to advise the user of this status.

41

DISPLAY SELFTEST

A I2C failure is detected when the I2C transmission is not
acknowledged or a bus fault occurs for more than a certain
number of attempts (this can be due, for example, to dam­age sustained by one of the ICs connected to I2C bus).

If so, the controller stops any tasks and displays a perpetual
sliding message “Serial bus error” (i.e. this is a fatal error).

If an invalid date is read from RTC, it is initialized back to the
default date and time (01/01/98 - 00:00).

You can use special setup codes, perform selftest procedures
for LCD, keyboard, EEPROM, relays and LEDs, watchdog.
The operation of these functions is outlined in the setup sec­tion. The selftest procedures are described in detail in the
following subsections.

The display selftest procedure consists of lighting up all of the
display segments together. The Display test is announced by
a scrolling "Display test" message.

The segments are lit for a few seconds and then switched
off The segments are lit for a few seconds and then switched

KEYBOARD SELFTEST

42

off before exiting the selftest procedure.

The keyboard selftest procedure begins with the message “But­ton test, press LCD, CAL and SETUP together to escape”. The
LCD will then show only a colon.

As soon as one or more keys are pressed, the appropriate
segments out of 88:88 corresponding to the pressed keys,
will light up on the screen. The correspondence is given
below:

For example, if UP and CAL are pressed together the LCD
will look like this:

The colon is a useful indicator for the correct position
squares.

Note A maximum of two keys may be pressed simultaneously to

be properly recognized.
To exit the keyboard test procedure press LCD, CAL and

SETUP simultaneously.

43

EEPROM SELFTEST

The EEPROM selftest procedure involves verifying the stored
EEPROM checksum. If the checksum is correct the “Stored
data good” message will be shown for a few seconds be­fore exiting selftest procedure.

If not, the message “Stored data error - Press  to reset
stored data or  to ignore”.

If  is pressed the EEPROM selftest procedure terminates
with no other action. Otherwise, EEPROM is reset with de-

fault values from ROM as when a device with a virgin EE­PROM is switched on.

During EEPROM reset a blinking message
“Set” is shown on primary LCD; the sec­ondary LCD displays “MEM”.

At the end of this operation all the param­eters are reset to their default values. The
calibrated cell constant is also reset. For
this reason the "CAL" flag blinks until the
EC/TDS calibration is performed.

RELAYS AND LEDS

Note Relays and LEDs test has to be carried out with the relay

44

Relays and LEDs selftests are executed as follows:
First all of the relays and LEDs are switched off, then they are

switched on one at a time for a few seconds and cyclically.
User can interrupt the otherwise endless cycle pressing any
key, as indicated by the scrolling message.

contacts disconnected from external plant devices.

WATCHDOG

When a dead loop condition is detected a reset is auto­matically invoked.

The effectiveness of watchdog capability can be tested
through one of the special setup items. This test consists of
executing a dummy dead loop that causes watchdog reset
signal to be generated.

EXTERNAL FUNCTIONS

HOLD FUNCTION

This function allows to perform the mainte­nance procedures. When the relevant digital
insulated input (terminals #11 on page 8) is
on, the analog output is frozen at its last value
and the control and alarm relays are dis­abled. The “Hld” indication is displayed on the secondary
LCD when the function is active. A 5 to 24 VDC voltage
can be applied to this input.

While in hold state, it is possible to display
the temperature reading on the secondary
LCD pressing the right arrow key. Only when
the key is released, the secondary LCD re­turns automatically after a few seconds to
the “Hld” indication.

PRESETTABLE TIMER (CLEANING FUNCTION)

A timer is presettable by software to close a
digital insulated contact (terminals #12 on
page 8) after a user programmable time in­terval with a minimum interval of 1 day (e.g.
for probe cleaning function). The time inter­val is programmable in number of days through setup code

72.
This output is ON for the period set through setup code 77

(this period can be also changed when the output is ON).
The starting time of the cleaning timer can be set through

setup codes 73, 74, 75 and 76.

45

RS 485 COMMUNICATION

HI 23xy2 and HI 24xy2 are provided with an RS485 port.
RS485 standard is a digital transmission method that allows
long lines connections. Its differential transmission system
makes this standard suitable for data transmission in noisy
environments.

SPECIFICATIONS

The RS485 standard is implemented in EC process meter
controllers with the following characteristics:

Data rate: 1200, 2400, 4800 and 9600 bps

Communication: Bidirectional Half-Duplex

Line length: up to 1.2 Km typical with 24AWG cable

Loads: up to 32 typical.

Internal termination: none

CONNECTIONS

The connections for the 4-pin RS485 terminal
provided (#1 on page 8) are as follows:

46

The instrument has no internal line termination. To terminate
the line, an external resistor equal to the characteristic line
impedance (typically 120 ohm must be added at both ends
of the line.

Up to 32 units can be connected to the same RS485 line,
with a total line length of up to 1.2 Km using 24AWG cable.
To minimize electromagnetic interference, use shielded or
twisted pair cable to connect the units.

Each EC controller unit is identified by its process ID number
(setup item “01”).

The EC controller acts as a “slave” device: it only answers to
commands received from a “master” device (e.g. an indus­trial PC) connected to the line.

As additional feature, the controller is also
provided with two pins (5V and 0V) in or­der to apply the Fail Safe Open Line
protection method. To avoid erroneous
readings in Open-Line conditions, pull­up and pull-down resistors should be
connected as shown.

The Fail-Safe resistors are connected only to one unit in the
line, and their value depends on the application and char­acteristic impedance of the connection cable (typical between
15K and 50K).

The RS485 port is galvanic separated from measuring circuit
and power line. If both analog output and RS485 port are
present, they have the same ground.

SETTING THE SERIAL COMMUNICATION

The external connections for RS 485 communications are
accessible to the left panel (number 1) and the pins are as­signed as shown in figure.

Pin 1 is ground, pin 2 is signal line, pin 3 is the inverted
signal line and pin 4 is connected to +5V.

The network will be connected at pin 2 and 3 and cable
shield, if present, will be connected at pin 1

To set the communication parameters the following steps must
be performed:

• Enter the setup procedure by pressing the
SETUP key. After password procedure, enter
the parameter code 01.

47

Note In an RS 485 network, each device must have a different

RS485 PROTOCOL

• Using the arrow keys, set the
controller address. To exit setup,
press CFM key and then LCD key.

address.

• Select the desired baud rate with the up and down keys
and press the CFM key to store the new settings. Available
baud rates are: 1200, 2400, 4800 and 9600 Bps.

The PC software to communicate with the controllers is
HI92500. Please refer to this product specifications for fur­ther informations.

The commands sent to the controller must have the follow­ing format:

• 2-digit process ID number

• 3-character command name

• Parameters (variable length, may be null)

• End of command (always the CR character, Hex 0D)
A maximum time interval of 20 ms is allowed between two

consecutive characters of a command. It is possible to send
commands to change the controller settings or to simply
ask information on the controller status. Following is the
complete list of commands available:

Command Parameter Description

48

CAR null Request calibration data

GET NN Request setup item NN

K01 null Same as CFM+CAL keys

K02 null Same as LCD+CAL+SETUP keys

KCD null Same as CAL DATA key

KCF null Same as CFM key

KCL null Same as CAL key

KDS null Same as LCD key

KDW null Same as key

KRG null Same as key

KST null Same as SETUP key

KUP null Same as key

MDR null Request firmware code

ECR null Request EC reading (available in control or

idle mode only)

TDR null Request TDS reading (available in control

or idle mode only, for HI 24 series only)

RNG null Request measure Range (available in

control or idle mode only)

TMR null Request temperature reading

PWD NNNN Send the 4-digit password

SET NNPC1C2C3C4C5Set setup item NN to the PC1C2C3C4C5 value;

P=+ if the value is greater than 0, P=- if the value is less
than 0. C1 can be 0 or 1; only C2 C3 C4 C5 can be 0 to 9 or blank
(the command is not available if the controller is in setup
mode)

Note If the controller is not in control or idle mode and the tem-

perature reading is requested through the TMR command,
the controller answers with the last acquired reading when
it was in control or idle mode.

Following are examples of commands for setup items:

“03SET22+01200<CR>”

This command sets the setup item 22 (relay 2 set point) of a
EC controller, identified by the process ID number 03, to the
+12.00 mS value.

49

“01SET33+015••<CR>”

This command sets the setup item 33 (max. relay ON time) of
a controller, identified by the process ID number 01, to 15
minutes. The • character means blank.

Once the controller has received a command, it answers
with its 2-digit process ID number followed by:

• ACK (Hex 06)
If the controller recognizes the received command and per-

forms the requested task;

• STX (Hex 02), Data, ETX (Hex 03)
If the received command is a request of data;

• NAK (Hex 15)
If the received command is not recognized (e.g. The syntax

is wrong);

• CAN (Hex 18)
If the controller cannot answer the request (e.g. the pass-

word was not sent, the controller is in setup mode, the setup
item is not available in that model, etc.)

50

Note The controller answers to the GET command with the same

data format explained in the SET command.

Following are examples of answers:

“03<STX>+01200<ETX>”

The controller with process ID number 03 says that its cur­rent setpoint is +12.00mS.

“01<STX>UE24_21225<ETX>”

The controller with process ID number 01 says that it is a
HI24212 model with firmware release 2.5.

The time-out for the first character of the controller answer is
100 milliseconds.

The minim delay between the last received character and first
character of the answer is 15 ms.

When the controller answers to the ECR, TDR and TMR com­mands, the reading is sent as ASCII string followed by a
character indicating the control and alarm status of the
controller and info for controller setup modified.

This character can assume the following values:

• “A” control and alarm are ON;

• “B” control and alarm are ON and need update controller setup
(GET commands);

• “C” control is ON and alarm is OFF;

• “D” control is ON and alarm is OFF and need update control­ler setup (GET commands);

• “N” control and alarm are OFF;

• “M” control and alarm are OFF and need update controller
setup (GET commands);

For example, a possible answer to the TMR command is:

“03<STX>10.7C<ETX>”

meaning that the current temperature reading is 10.7°C,
the control action is active and no alarm condition is present
and controller setup is updated on PC.

51

“03<STX>10.7D<ETX>”

meaning that the current temperature reading is 10.7°C, the
control action is active and no alarm condition is present
and controller setup is modified (must update controller setup
for PC – GET commands for setup items).

If asking for the last calibration data and the controller was
never calibrated, it answers with “0”; e.g.

“01<STX>0<ETX>”.

If the controller was calibrated, it answers with “1” followed
by the calibration data. The Data field of the answer has
the following format:

1<Date><Time><Cell Constant>

• Date: DDMMYY (e.g. “170400” for April
17,2000)

• Time: HHMM (e.g. “1623” for 4:23 pm)

• Cell Constant: ASCII string (e.g. “1200”)

The items in the Data field are separated by blanks.

52

STARTUP

During the automatic startup the Real Time Clock (RTC) is
checked to see if a reset occurred since last software initial-

ization. In this case, the RTC is initialized with the default
date and time 01/01/1998 - 00:00. An EEPROM reset
does not affect the RTC settings.

The EEPROM is also checked to see if it is new. If this is the
case, the default values are copied from ROM and then the
device enters normal mode. Otherwise an EEPROM check­sum test is performed (the same is performed during EEPROM
selftest procedure).

If checksum is correct, normal mode is entered, otherwise the
user is asked whether the EEPROM should be reset.

If EEPROM reset is requested, default values from ROM are
stored into EEPROM as would happen with a new EEPROM.

Note that EEPROM data is composed of setup data and
calibration data. As for the setup data, the calibration data
is assigned default values when an EEPROM reset occurs.
An uncalibrated meter can perform measurement, though
user is informed that EC or TDS calibration is needed by
means of a blinking “CAL”.

When the last calibration data is required, the “no CAL”
message is displayed if no calibration procedure was per­formed.

Unlike EC/TDS calibration, the user has no information on
calibration need for other ranges, other than the awareness
that EEPROM was reset.

After an EEPROM reset, all calibrations (input and output)
have to be performed in order to obtain correct measure­ments.

53

EC VALUES AT VARIOUS TEMPERATURES

Temperature has a significant effect on conductivity. Table
below shows EC values at various temperatures for the
Hanna calibration solutions.

TEMPERATURE EC VALUES (µS/cm)
°C °F HI7030 HI7031 HI7033 HI7034 HI7035 HI7039

HI8030 HI8031 HI8033 HI8034 HI8035 HI8039

0 32 7150 776 64 48300 65400 2760

5 41 8220 896 65 53500 74100 3180

10 50 9330 1020 67 59600 83200 3615

15 59 10480 1147 68 65400 92500 4063

16 60.8 10720 1173 70 67200 94400 4155

17 62.6 10950 1199 71 68500 96300 4245

18 64.4 11190 1225 73 69800 98200 4337

19 66.2 11430 1251 74 71300 100200 4429

20 68 11670 1278 76 72400 102100 4523

54

21 69.8 11910 1305 78 74000 104000 4617

22 71.6 12150 1332 79 75200 105900 4711

23 73.4 12390 1359 81 76500 107900 4805

24 75.2 12640 1386 82 78300 109800 4902

25 77 12880 1413 84 80000 111800 5000

26 78.8 13130 1440 86 81300 113800 5096

27 80.6 13370 1467 87 83000 115700 5190

28 82.4 13620 1494 89 84900 117700 5286

29 84.2 13870 1521 90 86300 119700 5383

30 86 14120 1548 92 88200 121800 5479

31 87.8 14370 1575 94 90000 123900 5575

EC / TDS PROBE MAINTENANCE

Probe can be compensated for normal contamination by a
process of recalibration. When calibration can no longer
be achieved, remove the conductivity probe from the sys­tem for maintenance.

PERIODIC MAINTENANCE

Inspect the probe and the cable. The cable used for the
connection to the controller must be intact and there must
be no points of broken insulation on the cable.

Connectors must be perfectly clean and dry.

CLEANING PROCEDURE

Rinse the probe with tap water. If a more thorough cleaning
is desired, remove the sleeve and clean the platinum sen­sors with a nonabrasive cloth or HI7061 cleaning solution.
Reinsert the sleeve in the same direction as before.

Recalibrate the instrument before reinserting the probe in
the system.

Note Always recalibrate the instrument when attaching a new

probe.

55

ACCESSORIES

CONDUCTIVITY & TDS CALIBRATION SOLUTIONS

HI 7030L 12880 µS/cm (µmho/cm), 460mL
HI 7030M 12880 µS/cm (µmho/cm), 230mL
HI 7031L 1413 µS/cm (µmho/cm), 460mL
HI 7031M 1413 µS/cm (µmho/cm), 230mL
HI 7033L 84 µS/cm (µmho/cm), 460 mL
HI 7033M 84 µS/cm (µmho/cm), 230 mL
HI 7034L 80000 µS/cm (µmho/cm), 460mL
HI 7034M 80000 µS/cm (µmho/cm), 230mL
HI 7035L 111800 µS/cm (µmho/cm), 460mL
HI 7035M 111800 µS/cm (µmho/cm), 230mL
HI 7039L 5000 µS/cm (µmho/cm), 460mL
HI 7039M 5000 µS/cm (µmho/cm), 230mL
HI 7032L 1382 ppm (mg/L), 460 mL
HI 7032M 1382 ppm (mg/L), 230 mL
HI 7036L 12.41 ppt (g/L), 460 mL
HI 7036M 12.41 ppt (g/L), 230 mL
HI 70038P 6.44 ppt (g/L), 25 mL sachet, 25 pcs.
HI 70080P 800 ppm (mg/L), 25 mL sachet, 25 pcs.
HI 7042 42 ppm (mg/L), 1 L
HI 7038 6.44 ppt (g/L), 1 L
HI 7037 800 ppm (mg/L), 1 L
HI 7055 55.9 ppt (g/L), 1 L

CONDUCTIVITY CALIBRATION SOLUTIONS IN FDA APPROVED BOTTLES

HI 8030L 12880 µS/cm (µmho/cm), 460 mL
HI 8031L 1413 µS/cm (µmho/cm), 460 mL
HI 8033L 84 µS/cm (µmho/cm), 460 mL
HI 8034L 80000 µS/cm (µmho/cm), 460 mL
HI 8035L 111800 µS/cm (µmho/cm), 460 mL
HI 8039L 5000 µS/cm (µmho/cm), 460 mL

56

ELECTRODE CLEANING SOLUTIONS

HI 7061M General Cleaning Sol., 230 mL
HI 7061L General Cleaning Sol., 460 mL

ELECTRODE CLEANING SOLUTIONS IN FDA APPROVED BOTTLES

HI 8061M General Cleaning Sol., 230 mL
HI 8061L General Cleaning Sol., 460 mL

OTHER ACCESSORIES

HI 3011D 4-ring EC/TDS probe with standard 1/2’’ external thread for

flow-thru mounting, DIN connector and 3 m (10’) cable

HI 3012D 4-ring EC/TDS probe with standard 1/2’’ external thread for

submersion applications, DIN connector and 3 m (10’) cable

HI 5001/5 Stainless steel Pt100 probe with standard 1/2’’ external threads

on both ends for in-line and immersion installation; 5 m
(16.5’) cable

HI 5002/5 Glass Pt 100 probe with 5 m (16.5’) cable
HI 7639D 4-ring EC/TDS probe with built-in 3-wire Pt100 temperature

sensor, DIN connector and 5 m shielded cable

HI 7640D Submersion/in-line conductivity probe with DIN connector
BL PUMPS Dosing Pumps with Flow Rate from 1.5 to 20 LPH
ChecktempC Stick Thermometer (range -50.0 to 150.0°C)
HI 8936A EC Transmitter (0.0 to 199.9 mS/cm)
HI 8936B EC Transmitter (0.00 to 19.99 mS/cm)
HI 8936C EC Transmitter (0 to 1999 µS/cm)
HI 8936D EC Transmitter (0.0 to199.9 µS/cm)
HI 98143 series EC Isolated Transmitter (0 to 10 mS/cm)
HI 931002 4-20 mA Simulator

57

WARRANTY

All Hanna Instruments meters are guaranteed for two
years against defects in workmanship and materials when

used for their intended purpose and maintained according
to instructions. The probes are guaranteed for a period
of six months. This warranty is limited to repair or replace­ment free of charge.

Damage due to accident, misuse, tampering or lack of pre­scribed maintenance are not covered.

If service is required, contact the dealer from whom you
purchased the instrument. If under warranty, report the model
number, date of purchase, serial number and the nature of
the failure. If the repair is not covered by the warranty, you
will be notified of the charges incurred. If the instrument is
to be returned to Hanna Instruments, first obtain a Returned
Goods Authorization number from the Customer Service
department and then send it with shipping costs prepaid.
When shipping any instrument, make sure it is properly pack­aged for complete protection.

Hanna Instruments reserves the right to modify the design,
construction and appearance of its products without ad­vance notice.

58

CE DECLARATION OF CONFORMITY

Recommendations for Users

Before using these products, make sure that they are entirely suitable for the
environment in which they are used.

Operation of these instruments in residential areas could cause unaccept­able interferences to radio and TV equipment.

To maintain the EMC performance of equipment, the recommended
cables noted in the user's manual must be used.

Any variation introduced by the user to the supplied equipment may
degrade the instruments' EMC performance.

To avoid electrical shock, do not use these instruments when voltage at the
measurement surface exceed 24VAC or 60VDC.

To avoid damage or burns, do not perform any measurement in microwave
ovens.

Unplug the instruments from power supply before the replacement of the
fuse.

External cables to be connected to the rear panel should be terminated with
cable lugs.

59

MANHI23

10/02

www.hannainst.com

60