EUTECH INSTRUMENTS alpha-pH 2000D User manual

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Instruction Manual
αlpha-pH2000D
pH and ORP Controller/Transmitter
68X216855 Rev 1 12/04

Preface
This manual serves to explain the use of the αlpha-pH2000D series pH/ORP controller/transmitter. The
manual functions in two ways, firstly as a step by step guide to help the user operate the instrument.
Secondly, it serves as a handy reference guide. This instruction manual is written to cover as many
anticipated applications of the αlpha-pH2000D pH/ORP controller/transmitter. If you have doubts in the
use of the instrument, please do not hesitate to contact the nearest Eutech Instruments Authorised
Distributor.
The information presented in this manual is subject to change without notice as improvements are
made, and does not represent a commitment on part of Eutech Instruments.
Eutech Instruments cannot accept any responsibility for damage or malfunction of the unit due to
improper use of the instrument.
Copyright ©2004 All rights reserved.
Eutech Instruments Pte Ltd.
Rev 1 12/04

Safety Information
The Controller/ Transmitter shall be installed and operated only in the manner specified in the
Instruction manual. Only skilled, trained or authorized person should carry out installation, setup and
operation of the instrument.
Before powering up the unit, make sure that power source it is connected to, is as specified in the top
label. Failure to do so may result in a permanent damage to the unit.
The unit has live and exposed parts inside. If it has to be opened, make sure that the power to the unit
is off and disconnected.
The unit is Fuse protected. In the event the fuse has to be replaced, use only those as specified in the
manual.
The degree of protection against electric shock will be achieved only by observance of the
corresponding installation rules.

TABLE OF CONTENTS
1INTRODUCTION....................................................................................................................................... 1
1.1 AT THE VERY BEGINNING...................................................................................................................... 1
1.2 INTENDED USE ...................................................................................................................................... 1
1.3 SAFETY INSTRUCTIONS ......................................................................................................................... 2
1.4 PUTTING OUT OF SERVICE /CORRECT DISPOSAL OF THE UNIT ............................................................... 2
2PRODUCT DESCRIPTION....................................................................................................................... 3
2.1 DESCRIPTION OF UNIT........................................................................................................................... 3
2.2 MEASUREMENT AND CONTROL SYSTEM................................................................................................ 4
2.3 UNIT OVERVIEW ................................................................................................................................... 5
2.3.1 Display Overview............................................................................................................................ 6
2.3.2 Key functions................................................................................................................................... 6
2.3.3 LED indicators................................................................................................................................ 7
2.3.4 Security codes.................................................................................................................................. 7
2.3.5 Menu overview................................................................................................................................ 8
3ASSEMBLY AND INSTALLATION........................................................................................................ 9
3.1 MOUNTING THE UNIT ............................................................................................................................ 9
3.2 CONNECTION DIAGRAM...................................................................................................................... 10
4NORMAL OPERATION.......................................................................................................................... 12
4.1 MEASUREMENT MODE ........................................................................................................................ 12
5CALIBRATION MODE........................................................................................................................... 13
5.1 ENTERING CALIBRATION MODE.......................................................................................................... 13
5.2 PHCALIBRATION................................................................................................................................14
5.3 ORP-MVCALIBRATION...................................................................................................................... 16
5.4 ORP -% CALIBRATION ....................................................................................................................... 16
5.5 VIEW ACTUAL ZERO AND SLOPE.......................................................................................................... 17
6SETUP MODE........................................................................................................................................... 18
6.1 ENTER SETUP MODE............................................................................................................................ 18
6.2 ELECTRODE OFFSET (OFS) SUB-FUNCTION ........................................................................................ 19
6.3 SETTING TEMPERATURE (SET °C°F) SUB-FUNCTION ........................................................................... 20
6.4 CONTROL RELAY A/RELAY B(SP1/SP2) SUB-FUNCTION ................................................................. 21
6.5 CONTROLLER (CNTR) SUB-FUNCTION ............................................................................................... 23
6.6 CURRENT OUTPUT 1SUB-FUNCTION................................................................................................... 26
6.7 CURRENT OUTPUT 2SUB-FUNCTION................................................................................................... 27
6.8 WASH RELAY (WASH) SUB-FUNCTION .............................................................................................. 28
6.9 CONFIGURATION (CNFG) SUB-FUNCTION .......................................................................................... 29
6.10 CALIBRATION (CAL) SUB-FUNCTION.................................................................................................. 30
7RELAY MODES ....................................................................................................................................... 31
7.1 VIEW RELAY SET POINTS..................................................................................................................... 31
7.2 MANUAL RELAY MODE ....................................................................................................................... 32
8TECHNICAL SPECIFICATIONS.......................................................................................................... 33
8.1 GENERAL SPECIFICATION ................................................................................................................... 33
8.2 SET-POINT AND CONTROL FUNCTION –RELAY 1&RELAY 2.............................................................. 33
8.3 WASH FUNCTION –WASH RELAY ...................................................................................................... 34
8.4 ALARM FUNCTION –ALARM RELAY .................................................................................................. 34
8.5 TRANSMITTER FUNCTION ................................................................................................................... 34
8.6 VOLTAGE OUTPUT &HOLD FUNCTION SWITCH ................................................................................. 34
8.7 DISPLAY ............................................................................................................................................. 35
8.8 POWER SUPPLY................................................................................................................................... 35
8.9 ELECTRICAL DATA AND CONNECTIONS .............................................................................................. 35

8.10 MECHANICAL SPECIFICATIONS........................................................................................................... 35
8.11 ELECTROMAGNETIC COMPLIANCE (EMC) SPECIFICATIONS ............................................................... 35
8.12 ENVIRONMENTAL CONDITIONS........................................................................................................... 35
9ACCESSORIES......................................................................................................................................... 36
9.1 REPLACEMENT UNIT........................................................................................................................... 36
9.2 ASSEMBLY ACCESSORIES ................................................................................................................... 36
10 GENERAL INFORMATION................................................................................................................... 37
10.1 WARRANTY ........................................................................................................................................ 37
10.2 PACKAGING /SCOPE OF DELIVERY...................................................................................................... 37
10.3 RETURN OF GOODS.............................................................................................................................. 37
10.4 GUIDELINES FOR RETURNING UNIT FOR REPAIR .................................................................................. 37
10.5 MAINTENANCE AND CLEANING .......................................................................................................... 37
11 APPENDICES ........................................................................................................................................... 38
11.1 APPENDIX 1–UNIT FUSE AND JUMPER SETTINGS................................................................................ 38
11.2 APPENDIX 2–PHBUFFER VALUES AT VARIOUS TEMPERATURES ........................................................ 39
11.3 APPENDIX 3–SIMPLE EXPLANATION ON THE FUNCTION OF HYSTERESIS ............................................ 40
11.4 APPENDIX 4–GENERAL INSTRUCTIONS CONCERNING CONTROLLER SETTING ................................... 41
11.4.1 Control characteristic of Controllers used as limit value switch ............................................. 41
11.4.2 Control characteristic of P-Controllers as proportional controller......................................... 41
11.4.3 Control characteristic of PI-Controllers as proportional integral controller.......................... 41
11.4.4 Control signal of Pulse length Controllers............................................................................... 42
11.4.5 Control signal of Pulse Frequency Controllers........................................................................ 43
11.5 APPENDIX 5–ABBREVIATIONS USED IN MENU DISPLAYS ................................................................... 44

Instruction Manual αlpha-pH2000D
- 1 -
1INTRODUCTION
1.1 At the very beginning
We thank you for having purchased the αlpha pH 2000D pH/ORP Controller.
The construction of the pH/ORP Controller employs leading edge technology and complies
with safety regulations currently in force. Notwithstanding this, improper use could lead to
hazards for the user or a third-party, and/or adverse effects on the plant or other equipment.
Therefore, the operating instructions must be read and understood by the persons involved
before work is started with the pH/ORP Transmitter.
This instruction manual identifies safety instructions and additional information by means of
the following symbols:
This symbol draws attention to safety instructions and warnings of
potential danger which, if neglected, could result in injury to persons
and/or damage to property.
This symbol identifies additional information and instructions which, if
neglected, could lead to inefficient operation and possible loss of
production.
The instruction manual must always be stored close at hand, in a place accessible to all
people working with the pH/ORP Controller.
If you have questions, which are not or insufficiently answered in this instruction manual,
please contact your authorized supplier. They will be glad to assist you.
1.2 Intended use
The αlpha pH 2000D pH/ORP Controllers are intended solely for pH or ORP and temperature
measurement, as described in this instruction manual.
Any other use, or use not mentioned here, that is incompatible with the technical specifications
is deemed inappropriate. The operator is solely responsible for any damage arising from such
use.
Other prerequisites for appropriate use include:
–observing the instructions, notes and requirements set out in this instruction manual.
–observing all local safety regulations concerning safety at work.
–observing all information and warnings in the documentation dealing with the products
used together with the transmitter (housings, sensors, etc.).
–observing the prescribed environmental and operational conditions.

Instruction Manual αlpha-pH2000D
- 2 -
1.3 Safety instructions
- The αlpha pH 2000D should be installed and operated only by personnel familiar
with the transmitter and who are qualified for such work.
- A defective controller must neither be installed nor put into service.
- The αlpha pH 2000D must only be operated under the specified operating
conditions (see section 8).
- The αlpha pH 2000D must not be repaired by the customer.
- The αlpha pH 2000D must only be opened to replace the unit fuse. This work must
be carried out only by personnel familiar with the transmitter and who are
qualified for such work. Make sure the mains cable is separated from the power
supply before opening the unit.
- No modifications to the αlpha pH 2000D are allowed. The manufacturer/supplier
accepts no responsibility for damage caused by unauthorized modifications. The
risk is borne entirely by the user.
1.4 Putting out of service / Correct disposal of the unit
Putting out of service
•First disconnect the unit from the mains, then undo all electrical connections.
•Remove the unit from the wall / panel.
Correct disposal of the unit
When the transmitter is finally taken out of service, observe the local environmental
regulations for correct disposal or send the transmitter to your local distributor, they will take
care of proper disposal.

Instruction Manual αlpha-pH2000D
- 3 -
2PRODUCT DESCRIPTION
2.1 Description of unit
The αlpha pH 2000D is used for measuring pH and temperature values. The pH values can be
measured using industrial differential & combination pH sensors. The temperature values can
be measured using 2-wire / 3-wire NTC300 thermistor. The transmitter is available in a wall
mounting enclosure. The controller / transmitter can be used for applications such as water
treatment and monitoring, galvanic-decontamination, chemical processing, food processing,
clean or wastewater control and neutralization processes.
This transmitter has many user-friendly and safety features which include:
•Push-button for calibration and sensor offset adjustment from the keypad.
•Built-in non-volatile memory to ensure that calibration and other information are not
erased if power supply fails.
•Menu-driven program that simplifies set-up.
•Automatic temperature compensation (ATC).
•Manual temperature compensation setting without the ATC probe, with independent
setting for calibration and process temperature.
•Two galvanically isolated current outputs 0/4...20mA.
•Two switching contacts as set-point relays.
•0 to 2000 seconds time delay adjustment on all relays – minimizes false alarms.
•Separately adjustable high and low set-point hysteresis (dead bands) prevent chattering
of relays around the set points.
•Three control modes: limit controller, P controller and PI controller (P/PI controller as
pulse length or pulse frequency).
•Large dual display LCD for easy reading with clear multiple annunciators, alarm status,
operational and error messages.
•Separate alarm relay alerting you to set point limits exceeded for a certain time and if the
NTC300 thermistor wires are broken or disconnected during the ATC function.
•Wash relay.
•Hold function to freeze output current (0/4...20mA) and release control relays.
•LED indicators signal control activities to visually monitor transmitter status from a
distance.
•Protection against electromagnetic interference.
•Back lit and UV light protected LC display.

Instruction Manual αlpha-pH2000D
- 4 -
2.2 Measurement and control system
A typical measurement system consists of:
•A pH/ORP process controller
•A pH/ORP combination electrode with integrated or separate temperature sensor NTC300
thermistor.
•An appropriate pH or ORP measurement cable
•An immersion, flow or process assembly with or without a potential matching pin (PMP)
•A final control element such as pump or valve
•A chart recorder
Power Mains
(80 - 250 VAC)
0/4 - 20 mA
Measurement Cable
Housing and
Sensors
Chart Recorder
αlpha pH 2000D Transmitter

Instruction Manual αlpha-pH2000D
- 5 -
2.3 Unit overview
Wall mounting version

Instruction Manual αlpha-pH2000D
- 6 -
2.3.1 Display Overview
The LC display shows two alpha-numerical fields for parameters and measured values as well
as various mode and status indicators.
MEAS
SETUP
CAL
HOLD
O
C
pH
A
TC
mV
pH %
READY
ERR
O
F
Mode indicators:
MEAS: measurement mode
SETUP: Set-up mode
CAL: Calibration mode
Status indicator:
READY: Visible after successful calibration
HOLD: Unit in “HOLD” mode
ATC: Visible in ATC (Automatic Temperature
Compensation) mode. Not visible in the Manual
Temperature Compensation mode. “ATC”
flashes if the temperature probe is faulty in its
ATC mode
ERR: Error indicator
S: Visible in symmetrical measurement mode
2.3.2 Key functions
Key Description
Enter Calibration mode (requires access code)
Enter Set-up mode (requires access code)
Access sub functions (parameters) within a function group of Set-up mode
Confirm (store) set-up parameters and numerical values
Start/Confirm calibration in Calibration mode.
Select function group in the Set-up mode.
Set parameters and numerical values (if key is pressed continuously, the setting speed
increases).
Control the relays in MANUAL relay operation.
Returns to “Measurement mode” when both keys are pressed simultaneously.
Display limit values for SP1 and SP2 and settings for wash contact in AUTO relay
operation.
Toggle between RELAY A, RELAY B or Wash relay in MANUAL relay operation
Switch from AUTO to MANUAL relay operation (requires access code)

Instruction Manual αlpha-pH2000D
- 7 -
2.3.3 LED indicators
Relay indicators
If REL key is pressed the LED (A, B or W) indicates to which Relay (A, B or
Wash) the displayed limit values refer.
Relay mode indicators
Auto LED lights if relay operation is set to automatic mode. Manu LED lights
if relay operation is set to manual mode.
Relay status indicators
This LED lights if limit value is exceeded or the ATC probe fails.
This LED lights green if measured value is within the limit for Relay A or
lights red if measured value exceeds limit.
This LED lights green if measured value is within the limit for Relay B or
lights red if measured value exceeds limit.
This LED lights if cleaning cycle is on.
2.3.4 Security codes
The access to Calibration mode, Setup mode and Manual relay operation mode is protected
with security codes. The security codes are set at the factory and cannot be changed by the
user. The following security codes are used:
Security code Mode Description
000 View only mode to view actual settings
11 Calibration mode to start calibration
22 Setup mode to configure parameters
22 Manual relay operation to switch relay operation mode from
automatic to manual

Instruction Manual αlpha-pH2000D
- 8 -
2.3.5 Menu overview
CCD “000” = Check calibration parameters (View only mode)
CCD “11” = Calibration mode
SCD “000” = Check setup parameters (View only mode)
SCD “22” = Setup mode
MEAS
SETUP
SETUP
SETUP
SETUP
SETUP
SETUP
SETUP
SETUP
SETUP
HOLD
HOLD
HOLD
HOLD
HOLD
HOLD
HOLD
HOLD
HOLD
°C
Temperature settings
see section 6.3
Relay A (set point 1) settings
see section 6.4
Relay B (set point 2) settings
see section 6.4
Controller settings
see section 6.5
Current output 1 settings
see section 6.6
Current output 2 settings
see section 6.7
Wash contact settings
see section 6.8
Calibration
see section 5
CAL
ENTER
ENT
ENT
ENTER
ENTER
ENT
ENT
ENT
ENT
ENT
ENT
ENT
ENT
ENT
ENT
SETUP
HOLD Unit settings
see section 6.9
ENT
1
2
Offset setting
see section 6.2
P
H
OFS

Instruction Manual αlpha-pH2000D
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3ASSEMBLY AND INSTALLATION
3.1 Mounting the unit
Wall mounting version
Unit:
MM [INCH]
approx. 14 [.55]
39 [1.54]
144 [5.67]
144 [5.67]
78 [3.07]
Pg13.5 (3 pcs.)
111.50 [4.39]
27.5 [1.08]
24 [.94]
57.8[2.28]
For P
g
13.5 cable
g
lands
Holes for wall
mounting (2X)
21.5 [.85]
6 [.24]
66.5 [2.62]
80 [3.15]
90 [3.54]
90 [3.54]
Holes for post
mounting (4X)
Red Plugs for wall
mounting holes
enclosure (2X)
175 [6.88]
175 [6.88]
138 [5.43]
138 [5.43]
Cut-out mountin
g
plates for post mountin
g
84 [3.30] 29 [1.14]
1-22 [0.03 - 0.87]
Threaded rod for panel mountin
g
Max.80
Seal gasket
Transmitter housing for wall mounting: protection class IP 65

Instruction Manual αlpha-pH2000D
- 10 -
3.2 Connection Diagram
Caution: Ensure electrical mains are disconnected before proceeding.
Connections for wall mounting version
1
L
2
N
Current
15
Current
13
OP2
14 16
OP1
17
3456
22
HOLD
18 19 2120 23 24 25
78 9 10 11
2926 2827 30 31 32 33
12
-5V
TEMP
SENS TEMP pH
REFpH
MEAS
Fuse: 250V 315 mA,
Time Delay
L
112
24
Current
N
OP2
13
Current
14
2
15 16
OP1
17
3
21
HOLD
18 19 20
4
22 23 28
5
25
6 7
26 27
8
-5V
TEMP
31
TEMP
SENS
29
9
30
10
pH
REF
11
32 33
pH
MEAS
250V, 315 mA,
Time Delay
1. AC mains live wire 18. 12V output Power supply
2. AC mains neutral wire 19. Hold Function
3. AC mains protective earth wire 20. Hold Function
4. Relay A (SP 1) 21. Earth ground
5. Relay A (SP 1) 22. no connection
6. Relay B (SP 2) 23. no connection
7. Relay B (SP 2) 24. no connection
8. Wash relay 25. no connection
9. Wash relay 26. Shield (drain wire)
10. Alarm relay (NC) 27. -5V to differential pH sensor (White wire)
11. Alarm relay common 28. Temperature ground (black wire)
12. Alarm relay (NO) 29. Temperature Sense (Yellow wire)
13. 4-20 mA temperature output, +ve terminal 30. Temperature Input (Yellow wire)
14. 4-20 mA temperature output, -ve terminal (Internally connected by jumper to terminal 29)
15. 4-20 mA pH/ORP output, +ve terminal 31. No connection
16. 4-20 mA pH/ORP output, -ve terminal 32. pH input, Reference (Green wire)
17. 12V output ground 33. pH input, Measure (Red wire)
IMPORTANT: The Alarm relay functions as an “Active Low” device i.e. it switches OFF
under Alarm condition. Therefore the Alarm display device should be connected to the
‘NC’ contacts of the relay (10 & 11).
-5V

Instruction Manual αlpha-pH2000D
- 11 -
NOTE:
a) Switch or circuit breaker shall be included in the building installation.
b) It shall be in close proximity to the equipment and within easy reach of the
operator.
c) It shall be marked as the disconnecting device for the equipment.

Instruction Manual αlpha-pH2000D
- 12 -
4NORMAL OPERATION
4.1 Measurement mode
When the controller/transmitter is powered on, the display first shows all segments briefly,
after which the controller/transmitter automatically enters into the Measurement mode.
Please note: To guarantee accurate readings, the measuring system (transmitter
and sensor) must be calibrated.
pH
MEAS
O
C
The mode indicator “MEAS” at the top of the display indicates that the transmitter is in
Measurement mode. The upper alpha-numerical display shows the measured pH or ORP
value, while the lower display shows the temperature value if the controller is set for pH
measurement, or “ORP” if it is set for ORP measurement.
The annunciators “pH”, “mV” or “%” at the upper right side of the display indicate the current
measurement mode setting whether the controlling is set for pH, mV or ORP % measurement.
From Measurement mode you can access Calibration mode and Setup mode by pressing
the CAL key or ENT key followed by the corresponding security code. For detailed information
refer to section 5 “Calibration mode” or section 6 “Setup mode”, respectively.
By pressing the REL key in Measurement mode you can view the actual relay set points. By
pressing the MODE key followed by the corresponding security code in Measurement mode
you can switch relay operation mode from automatic to manual.
For detailed information refer to section 7 “Relay Modes”.

Instruction Manual αlpha-pH2000D
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5CALIBRATION MODE
You can access the Calibration mode directly from the Measurement mode by pressing the
CAL key and entering the Calibration security code “11”. Calibration mode may also be
accessed via the Setup mode (see section 6.1).
5.1 Entering Calibration mode
ENTERENTER
ENTERENTER ENTERENTER
ENTERENTER
MEAS
P
H
O
C
CAL
SETUP
HOLD
SETUP
HOLD
pH calibration
ORP-mV calibration
ORP-% calibration
see section 5.2
see section 5.3
see section 5.4
1. While in Measurement mode press the CAL key (direct access) or ENT key (access via Setup
mode).
2. If CAL key was pressed: The display prompts you to enter the calibration security code. Press
the ▲or ▼key to set the calibration security code to “11”, and then press the ENT key to
confirm the calibration security code.
3. If ENT key was pressed: The display prompts you to enter the security code. Press the ▲or
▼key to set the security code to “22”. Press the ENT key to confirm the security code, and
then press the ▲or ▼key to select the calibration sub-function.
If configured for pH control, the display shows “CAL PH”. If configured for ORP control, the
display shows “CAL ORP”. To start calibration, refer to the corresponding section (see
illustration above).
Note: to exit Calibration mode at any time press the ▲and ▼keys
simultaneously (escape). The transmitter returns to the Measurement mode and
the old calibration values remain active. The calibration security code automatically
resets from “11” to “000” after the transmitter returns to Measurement mode.
Note: The calibration is always carried out in the units (pH or mV or %) selected in
setup mode. The pH controller/transmitter allows a 1-point or 2-point calibration.

Instruction Manual αlpha-pH2000D
- 14 -
5.2 pH Calibration
If the unit of measure is in pH (default), then the calibration is also carried out in pH. This
transmitter features a one-point or two-point calibration for pH with five preset buffer sets.
Buffer values refer to 25 oC. A standard pH buffer solution that matches one of these values is
required to calibrate the instrument.
Two point calibration
SETUP
HOLD
P
H
CAL
HOLD
P
H
P
H
CAL
HOLD
P
H
P
H
CAL MEAS
P
H
O
C
atc
CAL
CAL
One point calibration
1. Enter Calibration mode as described in section 5.1. The display shows “CAL PH” (for pH
calibration).
Note: If the display reads “CAL ORP”, see section 6.9 for procedures on how to switch from ORP to
pH readings.
2. Press the ENT key to start calibration. The “CAL” indicator appears at the top of display and
the buffer indicator appears in the bottom corner of the display. The display shows the actual
pH reading (upper value) and the buffer value for zero point (lower value). For the offset
(zero point) calibration, there are two values to choose from. They are pH 7.00 or pH 6.86.
Using the ▲and▼keys, choose the value that matches with the buffer used.
3. Place the electrode in the first buffer solution. In ATC mode, you must also immerse the
temperature probe in the buffer solution.
4. You can conduct either a one-point or a two-point calibration: Press the ENT for two point
calibration or the CAL key for one point calibration. The electrode indicator and CAL indicator
both flash for a few seconds. The controller automatically adjusts the reading to match the
buffer value.
5. If one-point calibration was selected, the display will show the zero point in the lower section of
the display and the slope (default or using previous two-point calibration) in the upper section of
the display. Proceed to step 7 after zero point display. If two-point calibration was selected, the
lower section of the display will now show its next lower “pH” buffer. Use ▲and ▼keys to
select the second buffer from one of these preset value: - pH 1.68, pH 4.01, pH 9.00, pH 9.18
and pH 10.01. Remove the electrode from the first buffer, wash and then immerse it into the
second buffer. Press the ENT key, the electrode indicator and CAL indicator will flash for a few
seconds. The controller adjusts the reading to the second buffer.
6. After calibrating the second buffer value, the controller will automatically display the slope in the
upper and the zero point in the lower section of the display.
Note: You can also view the values for zero point and slope without calibration (see section 5.5 for
instruction). The zero point and slope are pre-determined after each calibration.
7. Press the ENT key to return to the Measurement mode.
Note: If you entered the Calibration mode from the Setup mode, the controller will return to the
setup menu.

Instruction Manual αlpha-pH2000D
- 15 -
Note: If there is a calibration error, the controller displays “CAL ERR”. If this happens,
push both ▲and ▼keys (escape) to restart the calibration beginning from Step 1.
Note: When calibrating with manual temperature compensation, the controller
automatically changes from the preset process temperature to the calibration
temperature. After leaving the Calibration mode, the controller switches back to
process temperature (for setting the calibration temperature and the process
temperature, see Section 6.3)