Hanna Instruments HI 24 Series User manual

1
HI 23 / HI 24 Series
Wall-mounted,
Microprocessor-based,
Conductivity and TDS
Process Controllers
Instruction Manual

32
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
© 2001 Hanna Instruments
All rights are reserved. Reproduction in whole or in part is prohibited without the written consent
of the copyright owner.
Dear Customer,
Thank you for choosing a Hanna Product.
This instruction manual refers to the following products:
HI 23211-αα
αα
αEC controller with dual setpoint, ON/OFF
control and analog output
HI 23212-αα
αα
αEC controller with dual setpoint, ON/OFF
control and RS 485 port
HI 23221-αα
αα
αEC controller with dual setpoint, ON/OFF
and PID control, and analog output
HI 23222-αα
αα
αEC controller with dual setpoint, ON/OFF
and PID control, and RS 485 port
HI 24211-αα
αα
αEC and TDS controller with dual setpoint,
ON/OFF control and analog output
HI 24212-αα
αα
αEC and TDS controller with dual setpoint,
ON/OFF control and RS 485 output
HI 24221-αα
αα
αEC and TDS controller with dual setpoint,
ON/OFF and PID control, and analog out-
put
HI 24222-αα
αα
αEC and TDS controller with dual setpoint,
ON/OFF and PID control, and RS 485 port
αα
αα
α = 1, for models with 115 Vac power supply
2, for models with 230 Vac power supply
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.
If you need additional technical information, do not hesitate
to e-mail us at [email protected]
These instruments are in compliance with the directives.

54
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 con-
ductivity dosage (COM, NO and NC contacts) and
1 output relay for alarm condition (COM, NO and NC
contacts).
PRELIMINARY EXAMINATION
Remove the instrument from the packing material and exam-
ine 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, ana-
log 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 net-
work.
This allows the control of any process where conductivity is
involved.
The figure below illustrates the connection possibilities of ad-
vanced Hanna controllers, such as HI 23 or HI 24.

76
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 se-
lecting 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
• 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 solu-
tions.
• 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 tem-
perature compensation of the measurements in long dis-
tance applications.
• Manual temperature setting when the temperature probe is
not inserted or the temperature exceeds the upper range.
• Last calibration data internally recorded (nonvolatile EE-
PROM 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 KΩmaximum load (optional);
- isolated 0-20 mA, 750 Ωmaximum load (optional);
- isolated 4-20 mA, 750 Ωmaximum load (optional);
- isolated 0-5 VDC, 1 KΩminimum load (optional);
- isolated 1-5 VDC, 1 KΩminimum load (optional);
- isolated 0-10 VDC, 1 KΩminimum 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).
• Calibration and Setup procedures allowed only through
an unlock password.

98
MECHANICAL DIMENSIONS
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.

1110
INSTALLATION
HI 23 and HI 24 series offer a multitude of possibilities,
from dual setpoints to ON/OFF or PID dosage, isolated out-
puts 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 tempera-
ture compensation of the measurements in long distance
applications.
See the below diagram for a recommended installation.
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.
CONDUCTIVITY
PROBE
* Note: actual TDS range for HI 24 series depends on TDS factor set.
SPECIFICATIONS
Range 0.0 to 199.9 µS/cm, 0 to 1999 µS/cm
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)*
0.00 to 10.00 ppt, 0.0 to 100.0 ppt (HI 24 series only)*
-10.0 to 100.0 °C
Resolution 0.1 µS/cm, 1 µS/cm, 0.01 mS/cm, 0.1 mS/cm
0.1 ppm, 1 ppm, 0.01 ppt, 0.1 ppt (HI 24 series only)
0.1 °C
Accuracy ±0.5 % full scale (EC and TDS)
(@20°C/68°F) ±0.5°C between 0 to 70°C, ±1°C outside
Temperature Automatic or manual, -10 to 100°C
Compensation with β adjustable from 0.00 to 10.00%/°C
Typical EMC Deviation ±2 % full scale (EC and TDS) / ±0.5 °C
Installation Category II
Probe 4-ring conductivity probe with built-in 3-wire Pt100
temperature sensor or conductivity probe + external Pt100
(see “Accessories” section)
Analog Input 4 - 20 mA
Analog Output 0-10 Vdc, 0-5 Vdc or 1-5 Vdc; 0-1mA, 0-20 mA or 4-20mA
RS485 baud rate 1200, 2400, 4800 and 9600
Power Supply 230 ±10% VAC or 115 ±10% VAC, 50/60 Hz
Power Consumption 15 VA
Over Current Protection 400 mA 250 V fast fuse
Relays 1, 2 and Contact outputs SPDT, 5A-250 VAC, 5A-30 VDC (resistive load)
Alarm Relay Fuse protected: 5A, 250V fuse
Environment 0-50 °C; RH max 85% non-condensing
Case Material Fiber-reinforced, self-extinguishing ABS
Protection IP 54
Dimensions 221 x 181 x 86 mm (8.7 x 7.1 x 3.4”)
Weight 1.6 kg (3.5 lb.)

1312
If the Pt 100 has more than 2 wires, con-
nect 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 avail-
able 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 de-
activate 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).
• 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 tem-
perature 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
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.

1514
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.
Connect the two signal wires from the transmitter to terminals
#5 on page 8, paying attention to the correct polarity. Termi-
nal 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 pro-
vided 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.
SETUP MODE
The Setup Mode allows the user to set all needed character-
istics of the meter.
The setup mode is entered by pressing SETUP
and entering the password when the device
is in idle or control mode.
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 two-
digit setup code which is entered and displayed on the
secondary LCD.

1716
SETUP CODES
The following table lists the setup codes along with the descrip-
tion 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
Note The default password is set at “0000”.
• The LCD will display “SET” on the up-
per part and “c.00” on the lower, al-
lowing the user to edit setup param-
eters (see table below).
• Using the arrow keys as for the above password proce-
dure, 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 memo-
rized value, without blinking (read only mode). In this case,
the value cannot be set. Press LCD and start again.
• 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 param-
eter, press SETUP again and enter the
code or scroll to it by pressing CFM.

1918
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 follow-
ing:
If M1=/ 0 then S1HA, S1LA;
If M2=/ 0 then S2HA, S2LA;
If M1= 1 then S1-H1LA;
If M1= 2 then S1+H1HA;
If M1= 3 then S1+D1HA;
If M1= 4 then S1-D1LA;
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-HysLA+Hys,Hys=1.5%f.s.,HAS1 or HAS2
31 Alarm relay 0.5 to 99.5% full scale 5% f.s. no
Low Alarm (LA) LA+HysHA-Hys,Hys=1.5%f.s.,LAS1 or LAS2
32 Proportionalcontrol 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
41 Analog output 0 to 100% full scale 0 no
lower limit (O_VARMIN) (O_VARMIN O_VARMAX - 5% f.s.)
42 Analog output 0 to 100% full scale 100% f.s. no
upper limit (O_VARMAX) (O_VARMIN O_VARMAX - 5% f.s.)
60 Current day 01 to 31 from RTC no
61 Current month 01 to 12 fromRTC no
62 Current year 1998 to 9999 from RTC no
63 Current time 00:00 to 23:59 fromRTC no

2120
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-
puts to digital values;
• control relays and generates the analog outputs as de-
termined by the setup configuration, displays alarm
condition;
In the HI 24 series it is possible to switch between EC and
TDS reading pressing “LCD”. The TDS value is obtained mul-
tiplying 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.
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
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).
RELAY MODES
Once enabled, the relays 1 and 2 can be used in four differ-
ent 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).
If M2= 1 then S2-H2LA;
If M2= 2 then S2+H2HA;
If M2= 3 then S2+D2HA;
If M2= 4 then S2-D2LA;
If M1= 1 and M2 = 2
then S1-H1S2+H2, S2LA, HAS1;
If M1 = 2 and M2 = 1
then S2-H2S1+H1, S1LA, HAS2;
If M1 = 3 and M2 = 2
then S1S2+H2, S2LA, HAS1+D1;
If M1 = 2 and M2 = 3
then S1+H1S2, S1LA, HAS2+D2;
If M1 = 4 and M2 = 1
then S1S2–H2, S1–D1LA, HAS2;
If M1 = 1 and M2 = 4
then S1–H1S2, S2–D2LA, HAS1;
If M1 = 3 and M2 = 4
then S1S2, S2–D2LA, HAS1+D1;
If M1 = 4 and M2 = 3
then S2S1, S1–D1LA, HAS2+D2;
where the minimum deviation (D1 or D2) is 0.5% of the maxi-
mum range value.
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 con-
troller does not skip to the next setup item
but remains in the current item displaying
a flashing “ERROR” indicator until the pa-
rameter 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.

2322
The low setpoint relay may be used to control a low conduc-
tivity 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 de-
rivative control methods.
With the proportional function, the duration of the activated
control is proportional to the error value (Duty Cycle Con-
trol Mode): as the measurement approaches setpoint, the
ON period diminishes.
The following graph describes the EC/TDS process control-
ler behavior. Similar graph may apply to the controller.
ON
OFF
EC
Setpoint +
Hysteresis
Setpoint
t0t0+Tct0+2Tct0+3Tc
During proportional control the process controller calculates
the relay activation time at certain moments t0, t0+Tc, t0+2Tc
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.
de-energized when the EC value is above the setpoint plus
the hysteresis.
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 mea-
sured 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.
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
ON
OFF
Setpoint EC
Setpoint –
Hysteresis

2524
second is the integrative action and the third is the deriva-
tive 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 follow-
ing:
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 vari-
ables 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 proce-
dure is reported in this manual and can be used in almost
all applications.
Error
100%
0
Proportional Band
Controller
output
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.
PID TRANSFER FUNCTION
The transfer function of a PID control is as follows:
Kp + Ki/s + s Kd = Kp(1 + 1/(s Ti) +s Td)
with Ti = Kp/Ki, Td = Kd/Kp,
where the first term represents the proportional action, the
EC
RATE ACTION COMPENSATES FOR RAPID CHANGES t

2726
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 over-
shoot 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).
ALARM RELAY
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.
Example: High alarm set at 1400 µS
Low alarm set at 600 µS
An hysteresis will eliminate the possibility of continuous se-
quences ‘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.
FS•O = NC (Normally Closed)
De-energized Relay
COM
FS•C = NO (Normally Open)
Energized Relay
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 ana-
lyzing 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.
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.

2928
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 ana-
log 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 4-
20 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 exter-
nal devices are not installed or when the user detects unusual
circumstances.
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 con-
ditions.
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, how-
ever, due to line interruption, no alarm is sounded, causing
extensive damage. On the other hand, soft-
ware 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 pro-
viding a visual warning signal.
The Fail Safe mode is accomplished by connecting the ex-
ternal 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.

3130
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 configura-
tion (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 en-
tered. Setup codes for changing the analog output minimum
and maximum are 41 or 42, respectively. For the exact pro-
cedure, 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).
Control actions are stopped as soon as the
user presses SETUP and enters the pass-
word.
In order to reactivate the control mode, use
code 02 of setup (see “Setup” section). Oth-
erwise, the meter remains in idle mode.
ANALOG OUTPUT
Models HI 23xy1 and HI 24xy1 are provided with the ana-
log 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 out-
put or voltage output (depending on
which parameter is being used) as de-
picted aside.

3332
To obtain accurate readings, use the calibration solution in
the selected range and closer to the values to be mea-
sured.
Offset Calibration
• To perform the EC or TDS calibration en-
ter the calibration mode, by pressing CAL
and entering the password.
• After the correct password is entered,
the control actions stop and the pri-
mary LCD will display the first EC or
TDS calibration value, with the "CAL"
indicator blinking. The secondary LCD
displays the temperature.
Note If the wrong password is entered the system reverts back to
normal operation, displaying EC or TDS values.
• 0 is the default value for the 1st calibra-
tion 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.
Cell constant calibration
• Select the solution value on
the primary display by press-
ing 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.
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:
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
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 pro-
cess 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 mini-
mize 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 so-
lutions is minimized.

3534
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 pri-
mary 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 con-
firm 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.
• 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 cali-
brate offset only, just press CAL after confirmation (with CFM)
of the zero reading; the meter will return to normal opera-
tional mode. To have the cell constant calibrated first, press
the up or down arrow keys after entering the calibration pro-
cedure 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.
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.

3736
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 (EE-
PROM).
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 proce-
dure.
• Select code 0 via the arrow
keys for analog input calibra-
tion 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 inter-
mittent ERROR will prompt the user to
check the input.
• If everything is satisfactory the secondary
LCD will display “20” for the second cali-
bration 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.
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 calibra-
tion. This procedure is to calibrate the offset only; the slope
will remain as factory calibrated.
• Prepare a beaker containing a solution at a given tem-
perature 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 tem-
perature calibration mode.
• Execute the password proce-
dure.
• Select code 1 via the arrow keys for temperature calibra-
tion 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 tem-
perature read by the reference thermometer.
• When the reading has stabilized at a value near the cali-
bration 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.

3938
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 cor-
respond 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.
• Press CFM to confirm. The meter will return to normal op-
erational 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 (EE-
PROM).
ANALOG OUTPUT CALIBRATION
In the models where the analog output is available, this fea-
ture 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 be-
ing calibrated).
• Press and hold in sequence CFM first, then and then
• Execute the password procedure.
• The primary display will show the selected parameter blink-
ing. 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).