WIKA CTH7000 Operating Manual
Pressure and temperature
measurement
Manual
Hand-held thermometer CTH7000
Version 1.1, 03/14
CTH7000 Operating Instructions
Contents
CONVENTIONS USED IN THIS MANUAL ............................................................................................................. III
Structure of manual ................................................................................................................................................. iii
Terminology ............................................................................................................................................................... iii
Warnings and Notices ............................................................................................................................................. iii
IMPORTANT SAFETY INFORMATION ................................................................................................................. IV
IMPORTANT BATTERY CHARGER SAFETY INFORMATION ................................................................................ VI
IMPORTANT PROBE SAFETY INFORMATION .................................................................................................... VII
IMPORTANT DISPOSAL INFORMATION .......................................................................................................... VIII
European Union ...................................................................................................................................................... viii
Outside the European Union ................................................................................................................................ viii
1.0 INTRODUCTION ...................................................................................................................................... 1
1.1 Overview ...................................................................................................................................................... 1
1.2 Definitions and Terminology ..................................................................................................................... 1
1.3 Principles of measurement ....................................................................................................................... 2
2. SETTING UP THE CTH7000 ........................................................................................................................... 4
2.1 Safety information ...................................................................................................................................... 4
2.2 Unpacking the instrument ......................................................................................................................... 4
3. ABOUT THE CTH7000................................................................................................................................... 6
3.1 The Front Panel ............................................................................................................................................ 6
3.2 About the display screen .......................................................................................................................... 6
3.3 The Keypad .................................................................................................................................................. 6
3.3.1 Keypad overview ............................................................................................................................. 7
3.4 CTH7000 thermometer inputs ................................................................................................................... 9
3.5 Battery Pack .............................................................................................................................................. 11
3.5.1 Removing and replacing the battery pack ............................................................................... 11
3.5.2 Battery charger ............................................................................................................................... 12
3.5.3 Name plate(s) ................................................................................................................................. 15
3.5.4 USB Communication interface connector.................................................................................. 15
4. OPERATING THE CTH7000 ........................................................................................................................ 17
4.1 Instrument operating modes .................................................................................................................. 17
4.1.1 Measurement Mode ...................................................................................................................... 17
4.1.2 Menu Mode ( key) ....................................................................................................................... 18
4.1.3 Other menu options ....................................................................................................................... 21
4.1.4 Setting up Temperature measurement ....................................................................................... 34
4.1.5 Smart Probe review ........................................................................................................................ 34
5. INSTRUMENT MEASUREMENT RANGE ...................................................................................................... 36
5.1 Instrument measurement working range............................................................................................. 36
ASL operating instructions, model CTH7000 i
CTH7000 Operating Instructions
5.2 Measurement Ranges ............................................................................................................................. 36
6. SMART PROBES ......................................................................................................................................... 38
6.1 About Smart Probes ................................................................................................................................. 38
6.2 How Smart Probes Work .......................................................................................................................... 38
6.3 Smart Probe Data Security ..................................................................................................................... 38
6.4 Smart Probe Calibration Supervisor ...................................................................................................... 38
6.5 Smart Probe Working Range Monitor ................................................................................................... 38
6.6 Smart Probe Errors .................................................................................................................................... 38
7. CALIBRATING THE CTH7000 ..................................................................................................................... 39
7.1 CTH7000 Instrument calibration ............................................................................................................. 39
7.2 Equipment ................................................................................................................................................. 39
7.3 Calibration procedure ............................................................................................................................ 39
8. COMMUNICATIONS INTERFACE .............................................................................................................. 41
8.1 Introduction ............................................................................................................................................... 41
8.2 USB Command syntax ............................................................................................................................. 41
8.2.1 Command terminators (CR) or (CR)(LF) ...................................................................................... 41
8.2.2 Command details .......................................................................................................................... 42
8.2.3 Example log output ........................................................................................................................ 44
9. SPECIFICATION ......................................................................................................................................... 46
9.1 Resistance thermometer measurement .............................................................................................. 46
9.2 Display ........................................................................................................................................................ 47
9.3 Functions .................................................................................................................................................... 47
9.4 Supply ......................................................................................................................................................... 47
9.5 Environmental ........................................................................................................................................... 47
9.6 Dimensions and weight ........................................................................................................................... 47
9.7 CE conformity ........................................................................................................................................... 47
10. CLEANING AND MAINTENANCE ......................................................................................................... 49
10.1 Cleaning .................................................................................................................................................... 49
11. SERVICE AND WARRANTY ................................................................................................................... 51
11.1 Technical Support .................................................................................................................................... 51
12. APPENDIX A .......................................................................................................................................... 52
12.1 USB device driver ...................................................................................................................................... 52
12.2 USB device driver installation ................................................................................................................. 52
ii ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
Conventions used in this manual
Structure of manual
The manual is divided into sections. Each section deals with a specific topic or related
topics. Sections are displayed in a regular, bold typeface, for example - 1.0 Introduction.
Sections are sub-divided into sub-headings, for example - 1.1 Features. These may also be
subdivided.
Terminology
The terms Precision thermometer, thermometer, CTH7000 and instrument are used
interchangeably in this manual.
Warnings and Notices
These appear in the body of the text, clearly displayed with a box surrounding the text.
The first word within the box displays the type - Warning or Note.
A Warning (double box) is designed to draw attention to an aspect that may cause
danger to the user or damage to the instrument. A Note (single box) is used to bring
special attention to something important requiring action or avoidance.
Copyright © 2013 ASL. All rights reserved.
Information in this document is subject to change without notice.
Reproduction or modification of the whole or any part of this document (in any form) without ASLs’ written
permission is forbidden (except for internal use by an authorised dealer or agent). Customers may make copies
for internal use only.
Whilst efforts have been made to ensure the accuracy of information presented here, ASL can assume no
responsibility for the accuracy of any information presented or the consequences of acting on this information.
ASL also disclaims any representation that the contents are current. However, ASL would be grateful for any
comments on the layout, accuracy or contents of this manual.
ASL shall not be liable for problems or damages arising from the use (or misuse) of items, servicing, equipment,
procedures or options supplied by other companies.
ASL. 4 Gatton Park Business Centre, Wells Place, Merstham, Redhill, RH1 3LG, U.K.
Phone: +44 (0) 1737 644 008. Fax: +44 (0) 1737 644 403. email info@aslltd.co.uk
ASL operating instructions, model CTH7000 iii
CTH7000 Operating Instructions
Warning
The protection provided by the instrument may be impaired if the
equipment is not used in the manner specified.
Only replace items or components with an approved or
equivalent spare part. All spare and consumable parts are
available from ASL.
Warning
The instrument is NOT designed to be used in a potentially
explosive atmosphere or medical environment.
Warning
Do NOT open the case. There are no user serviceable parts inside.
Important safety information
Read and understand the user instruction manual before attempting to use the instrument.
The CTH7000 is a handheld, battery operated, thermometer. It must not be used for any other
purpose.
Do NOT use the instrument near water or in damp conditions
Do NOT clean the instrument with solvents
Do NOT insert objects into openings
Do NOT place the instrument, battery-pack or charger onto a hot or cold surface
Do NOT place any weight on top of the instrument, battery-pack or charger
Do ensure air can freely circulate around the battery compartment during charging
Do use the correct USB lead supplied
iv ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
Warning
Inspect cables and probes regularly, ensuring that their insulation
is not damaged
Warning
The instrument and batteries must be disposed of in accordance
with local regulations.
Warning
The instrument is sensitive to radiated noise and care must be
taken to ensure a clean mains supply and controlled EM
environment.
General warning symbol. This indicates that a
hazardous condition or general danger may exist.
You must read the relevant sections in the User
Manual before using the instrument.
Refer to manual symbol. When you see this symbol
on the instrument it means that there is more
information relating to this in the User Manual.
ASL operating instructions, model CTH7000 v
CTH7000 Operating Instructions
Warning
Only use the battery charger supplied. Use of any
other charger will invalidate the warranty and may
lead to the danger of overheating and to permanent
instrument damage.
The battery charger supplied must NOT be used with
other equipment.
Warning
Do NOT cover the battery charger, battery pack or
instrument during charging or use.
Ensure air is free to circulate around these items during
charging.
Warning
Do NOT short the contacts on the battery
compartment with any metallic object.
Important battery charger safety information
The battery charger and battery pack are supplied for use with the CTH7000.
vi ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
Warning
Because of the nature of the instrument, probes can
be excessively HOT or COLD during use. Take suitable
precautionary measures when handling probes.
Take care that you (and other people working in the
same area) do not come into contact with the
metallic probe or the insulating sheath near the
probe, which will also be hot/cold.
Precautions apply both during use or when moving
the probe from one position to another.
Warning
Probes may be immersed in various chemicals during
use. Some of these chemicals may be dangerous or
harmful (even when the probe is cold).
Always assume that the probe has been used this way
and DO NOT touch the probe without suitable
protective clothing.
Important Probe safety information
Care must be taken with probes used with the instrument. The following safety information
must be observed.
Do NOT lift the CTH7000 by any of the leads
Do ensure that long probe-leads are kept away from areas where people could trip
over them or become tangled in them
Do ensure the probe-leads are kept in good condition
ASL operating instructions, model CTH7000 vii
CTH7000 Operating Instructions
European Union
This symbol means that the product to be disposed of
should not be mixed with commercial or general
household waste. Used products must be treated
separately in accordance with legislation that requires
the proper treatment, recovery and recycling of the
product.
If you wish to discard the product, then please contact
your dealer, supplier or representative who will advise the
correct procedure for disposal.
Disposing of the product correctly will help to save
valuable resources and prevent environmental damage.
Outside the European Union
The symbol only applies within the European Union. If you
need to discard the product, then please contact your
dealer, supplier or the local authorities and ask for the
correct method of disposal.
Important disposal information
If you are responsible for disposal, then please note that this product may contain
materials that are regulated in their disposal due to environmental considerations. The
presence of these materials is consistent with global regulations applicable at the time
this product was placed on the market.
viii ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
1.0 Introduction
1.1 Overview
The CTH7000 Precision Handheld Thermometer is a high precision instrument designed for
laboratory, commercial and industrial temperature measurement and calibration
applications.
Features include:
Two input channels
A large graphic LCD display for excellent viewing of temperature measurement
values and instrument settings
USB communication interface as standard for automated monitoring and calibration
applications
Calibration against traceable external standards
The CTH7000 will operate with all 4-wire Pt100 (100 ohm) Platinum Resistance Thermometers
(PRTs) and with virtually all thermistors.
Temperature measurement units are user-selectable and can display C, F, K and .
Overall system accuracy will depend on the sensor quality and calibration - see the
specification section.
1.2 Definitions and Terminology
i. 0°C = 273.15 K
ii. 1 mK (milli-Kelvin) = 0.001C (one milli-degree Celsius)
iii. 1 milli-degree C = 0.001 C = 1mC = 1mK = 1.8mF
iv. 1 milli-degree F = 0.001F = 1mF = 0.56mK = 0.56mC
v. Alpha, or , is the temperature coefficient, or temperature sensitivity, of the platinum
wire used in PRTs. In general, the greater the alpha value, the better the PRT
thermometer measurement reproducibility, stability and performance
vi. Abbreviations for platinum resistance thermometers include -
PRT (Platinum Resistance Thermometer)
Pt100 (PRT with nominally 100 resistance at 0C)
RTD (Resistance Temperature Device)
vii. Abbreviations for thermistor thermometers include -
therm
ASL operating instructions, model CTH7000 1
CTH7000 Operating Instructions
s
t
st
V
V
RR
Note
For non-Smart probes, always check that the
coefficients are correctly set for the probe being used.
Failure to do so, may lead to incorrect measurements.
viii. System accuracy refers to the overall, combined accuracy of the CTH7000 and
thermometer.
1.3 Principles of measurement
The CTH7000 measures the voltage (Vt) developed across the unknown sensor resistance (Rt)
and the voltage (Vs) across a stable internal reference resistance (Rs). The voltages are
proportional to the resistances so the thermometer resistance is derived from –
This technique achieves immunity from slow moving time and temperature drifts in the
electronics, as it is not affected by voltage measurement gain variations or current source
fluctuations.
In the same way that AC resistance measurement eliminates thermal EMFs, switched DC
achieves a similar advantage. Switched DC works by reversing the current flow on alternate
measurement cycles and taking the average value, thereby cancelling any thermal EMF
offsets from the measurement.
For PRTs, the relationship between resistance and temperature varies slightly from one PRT to
another. Therefore, no matter how accurately the CTH7000 measures the PRT resistance, if
the relationship between resistance and temperature for a particular PRT is not known,
accurate temperature measurement is not possible. For thermistors, the relationship depends
totally on the thermistor type and specifications.
The CTH7000 uses PRT and thermistor calibration data to overcome this problem and
calculates the result from temperature conversion functions stored in either the sensors
‘SMART’ connector or the CTH7000’s internal non-volatile memory. This method enables the
CTH7000 to convert resistance to temperature, uniquely for each sensor used.
It is very important, therefore, that a sensor without a ‘SMART’ connector is used on a properly
configured input channel and that the probes’ coefficients are correctly entered into the
instrument.
2 ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
System accuracy is a combination of the CTH7000 accuracy in measuring sensor resistance
and the calibration uncertainty placed on PRTs and thermistors by the calibrating laboratory.
ASL operating instructions, model CTH7000 3
CTH7000 Operating Instructions
1
2. Setting up the CTH7000
2.1 Safety information
Please read the safety information section before attempting to operate the
CTH7000.
2.2 Unpacking the instrument
When you unpack the CTH7000 thermometer, check that the following items are present
before using the instrument1 -
CTH7000 precision thermometer
Battery charger
Operator’s handbook on CD
Calibration certificate
USB lead
Please contact the ASL Technical Services Group immediately if any of these items are
missing or damaged.
Please retain the packaging. In case of return, servicing or calibration, use the original
packaging. Failure to do so may invalidate the warranty and/or incur additional costs
outside the warranty period. Please contact your agent, dealer or supplier when the original
packaging is unavailable.
Thermometer probes (if ordered), will be supplied separately
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ASL operating instructions, model CTH7000 5
CTH7000 Operating Instructions
USB
Keypad
LCD display
Inputs at rear
3. About the CTH7000
This section will introduce you to the features and functions of the CTH7000 Precision Thermometer.
Each of the features is explained in turn. Once the CTH7000 has been set-up to your particular
requirements, all the commonly used functions are available using single key-strokes.
3.1 The Front Panel
Figure 3.1- Front panel
3.2 About the display screen
The large graphic LCD screen is your direct link to the instrument, presenting you with the
measurement results and information or menus to set and control the instrument.
The LCD screen is designed for reflective-viewing under normal ambient lighting; a backlight
is provided for use when ambient conditions are darker.
3.3 The Keypad
The CTH7000 keypad is shown below. The keys are used to select the various menu options.
Generally, no more than two menu levels are used. A few (infrequently used options) require
three menu levels. Operation is simple once you are familiar with instrument.
6 ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
2
3
4
Key
Function
Menu display
Backlight
Up arrow
Down arrow
Left arrow
Right arrow
Clear (view statistics)
Enter
A/B
A/B channel select
0
Zero (offset) reading
Hold reading
Power on/off
It may help to have the instrument to hand when reading through these sections.
Refer to section 4 for a detailed description of how to use the keys to operate the instrument
Figure 3.3 – CTH7000 Keypad
3.3.1 Keypad overview
The red Power ( ) key turns power on and off2 to the CTH7000.
The CTH7000 uses a menu system. The Menu ( ) key is located at the top right of keypad.
Use the Menu key to access to the less frequently used CTH7000 functions. The four Arrow (
) keys are used to navigate through the menus3; the Enter ( ) and Clear ( ) keys
are used to act on the menu selections4.
The Backlight () key located at the top left of the keypad provides LCD illumination when
the ambient light-level is too low for normal viewing.
The A/B key is used to select one of the two channels or the difference (A – B)
The Zero ( 0 ) key is used to provide relative (offset) readings.
The Hold ( ) key is used to freeze the current reading.
ASL operating instructions, model CTH7000 7
The CTH7000 may also be set to power-off after a preset period.
The Up () and Down () keys can be used to change the displayed units
The Clear ( ) key is also used to view CTH7000 statistics; press once to select the statistics page. Press any
key to return.
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8 ASL operating instructions, model CTH7000
CTH7000 Operating Instructions
5
Channel B (blue)
Channel A (red)
PRT or thermistor
3.4 CTH7000 thermometer inputs
There are two input channels; two 5 pin DIN input-sockets are located at the rear of the
instrument. These are designed to take either PRT or thermistor probes. Channel A is colour-
coded red. Channel B is colour-coded blue.
Figure 3.4 - Rear panel
Either channel can accept either Smart or Passive probes; any combination of probes can
be use together. Smart probes (described in section 6.0) contain their own calibration
information and communicate this to the CTH7000 as soon as they are used. Passive probes
do not contain calibration information and the CTH7000 must be set-up with the calibration
information for each probe used (and each time the probe is changed).
Probe connection information for both PRTs and thermistors5 is shown below (viewed looking
towards the sockets) -
Figure 3.4.1 4-Wire SMART probe (SMP) PRT/thermistor input
Two wire PRTs/thermistors must have pins1 & 2 connected together and also pins 4 & 5 connected together.
ASL operating instructions, model CTH7000 9
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