WIKA CTH7000 Operating Manual

Download

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.

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) = 0.001C (one milli-degree Celsius) iii. 1 milli-degree C = 0.001 C = 1mC = 1mK = 1.8mF iv. 1 milli-degree F = 0.001F = 1mF = 0.56mK = 0.56mC 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 0C)

RTD (Resistance Temperature Device)

vii. Abbreviations for thermistor thermometers include -

therm

ASL operating instructions, model CTH7000 1

CTH7000 Operating Instructions

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

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

4 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

This page is intentionally left blank.

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

Key

Function



Menu display



Backlight



Up arrow



Down arrow



Left arrow



Right arrow



Clear (view statistics)



Enter

A/B

A/B channel select

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.

CTH7000 Operating Instructions

This page is intentionally left blank.

8 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

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

CTH7000 Operating Instructions

PRT or thermistor

Figure 3.4.2 4-Wire Passive probe PRT/thermistor input

10 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Battery pack removed

Battery charger input

connector

USB communications

connector

3.5 Battery Pack

Figure 3.5 - Base of the CTH7000 showing the battery back removed

The instrument operates from battery power. The battery pack is replaceable. A low battery

indication is shown on the LCD when the battery needs recharging; the instrument also

audibly indicates a low battery condition. The battery may be d when attached to the

instruments.

3.5.1 Removing and replacing the battery pack

To remove the battery pack, press the latching tab and slide the battery pack backwards.

See figure 3.6 for details.

ASL operating instructions, model CTH7000 11

Figure 3.6 – Removing and replacing the battery pack

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.

Warning

Take care not to short the battery packs’ contacts with any metal object when the pack is not connected to the instrument.

Warning

Take care not trap any part of your hand when closing the battery compartment.

Warning

Never cover the battery pack or charger during use.

To replace the battery pack, place the pack in position before sliding home. See figure 3.6

for details. Check that the battery pack is securely in position before using the instrument.

3.5.2 Battery charger

Please observe the following warnings (repeated from the front of the manual).

The batteries are located in a removable pack located on the base of the instrument.

The battery pack contains two NiMHi cells (in series) and a charger control circuit. The

battery pack must only be charged using the unit supplied.

The battery pack has a socket on its side that accepts the charger’s connector. A LED

(viewable through an aperture on the top-rear of the pack) indicates the charger status –

see figure 3.7.

12 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Note

Disconnect the charger when not charging the battery

pack.

Note

Performance may degrade if the batteries are charged during use.

Charge indication

LED aperture

The battery charger is provided with various interchangeable mains connectors; select the

one that you require - see the charger PSU pack for details.

3.5.2.1 Charging the battery pack

The CTH7000 battery pack may be charged during instrument use, when the instrument is off,

or when the pack is detached from the CTH7000.

Please follow the instructions below to ensure that the battery pack is fully charged (LED

charge status is shown in the table below) –

 Turn off power to the adapter before plugging it into the side of the battery pack.

Figure 3.7 – Charge indication LED

 Switch on the power adapter (6 Vdc), ensuring the LED flashes orange.

 Leave the battery pack to fully charge. An overnight charge of about 10 hours (for a

flat battery with the CTH7000 off6) will ensure that the pack is fully charged (the

Allow 5 minutes before use if the batteries are completely flat.

ASL operating instructions, model CTH7000 13

CTH7000 Operating Instructions

Status LED

LED

indication

Description

Slow orange flash (1 s)

Trickle charge

Fast orange flash (0.2 s)

Fast charge

Solid green

Charged (trickle charge enabled)

Slow red flash (1 s)

Low battery temperature (trickle charge enabled)

Solid red

PSU voltage too high8

Fast red flash (0.2 s)

Hardware error9

actual time depends on the initial battery state)7. Charge time will increase if the

CTH7000 is used during this period.

 Turn off and remove the power adapter after charging is complete.

The meaning of the various LED indications is shown on below –

Charge times may increase at higher ambient temperatures.

The PSU input voltage must be less than10 volts (6 volts PSU supplied).

Refer to customer services.

14 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Note

Communication via an USB cable connected to a PC may cause the CTH7000 to be noisy.

ASL can accept no responsibility for any performance degradation when connected to a PC.

3.5.3 Name plate(s)

The instrument rating plate shows the instruments maximum power consumption and

instrument serial number.

The label on the battery charger shows its operating voltage, current and frequency.

The label on the battery charger shows its operating voltage, current and pack’s serial

number.

3.5.4 USB Communication interface connector

The USB connector is fitted as standard (see figure 3.1). Communication requires the

installation of the USB driver on a PC. See the separate information supplied on the CD. A

standard USB cable is supplied with the CTH7000.

The instrument can be used with ASL’s ULOG program (supplied on the CD) or simply used to

transmit ASCII data, which may be recorded using a simple terminal program.

ASL operating instructions, model CTH7000 15

CTH7000 Operating Instructions

This page is intentionally left blank.

16 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

ChA s:CTH7000-1234 PRT4 Bat

22.479 oC

ITS-90 10:24:33

Smart probe serial number

Current reading with units displayed

Time of day

Reading units

Low battery indication

Channel (ChA) using a

4 wire sensor (PRT4)

Probe conversion

4. Operating the CTH7000

4.1 Instrument operating modes

The instrument has two operating modes -

 Measurement Mode which displays the measurement readings and status information  Menu Mode which lets you select and alter the instrument operation and its settings

4.1.1 Measurement Mode

In Measurement Mode, the LCD displays the current reading (temperature or resistance), the

unit symbol, the channel and type of sensor selected (and conversion method); the time of

day is also shown10. This is the normal operating display for the CTH7000. The display will look

similar to the one shown below -

This display will always reflect the operation of the instrument, showing the current reading

and settings. Readings are updated at the normal conversion rate of one every two seconds.

ASL operating instructions, model CTH7000 17

The time will be replaced by ‘Logging’ or ‘Remote’ when these modes are selected

CTH7000 Operating Instructions

SMP Probe Info

SMP Coefficients

Units

Channel A

Channel B Logging Statistics Settings System

Units

Channel A Channel B Logging Statistics Settings System

Current menu highlighted

4.1.2 Menu Mode ( key)

In menu mode, the LCD displays the various options available to control CTH7000 operation.

Press the Menu key (  ) to select the menu screen.

The reverse-video background indicates the menu that will be selected should the Enter key (

 ) be pressed (Units selection in the example above). Further menu options will follow once

the Enter key has been pressed.

Press the Up (  ) and Down (  ) keys to move through the options. Pressing an up/down key

will move the reverse video selection one line up or down one line11. Once the selection is

corrrect, press the Enter key. So, for example, to change channel A options, press the Down

key (  ) once to obtain the following display -

Now press the Enter key (  ) to select this option. The following screen will appear (when a

Smart probe is connected to channel A). The display will be different for a passive probe –

Press the Down key (  ) once to obtain –

The selection line will wrap round from top to bottom (or bottom to top) on repeated arrow presses.

18 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

SMP Probe Info

SMP Coefficients

ChA(s) CVD R0 +1.00000e+02 A +3.90830e-03 B -5.77500e- 03

Read Only Up/Down Move Clear Exit

Now that this menu has been highlighted, press the Enter key (  ) once to obtain –

In this example, pressing the Up or Down key will display more of the Smart probes’

coefficients.

Pressing the Clear key (  ) will return the display to the previous menu. Press the Clear key (

 ) once more to return to Measurement mode. Pressing the Enter key (  ) will return the

CTH7000 immediately to Measurement Mode (generally applies to all lower level menu

options).

No changes can be made in this example. When changes are made, all settings are stored

and retained when power is removed.

Refer to the sections on Smart Probes for more details.

4.1.2.1 Selecting the thermometer input channel and differential mode (A/B key)

The channel Select key ( A/B ) is used to change between channels and also to select the

differential mode ( A – B ). The channel selection order is –

A missing probe will be indicated on the display by a series of dashed lines.

ASL operating instructions, model CTH7000 19

Channel A  Channel B  Channel (A – B)  Channel A

CTH7000 Operating Instructions

ChA s:CTH7000-1234 PRT4

0.009

( 022.048) oC

Offset 10:24:33

Zero offset value

Absolute value (flashing)

Zero mode indication

alternates with the conversion

C hA * 22.048

-C hB 22.090

-0.042

CVD 11:53:08

Probe conversion for

current channel

Individual channels

Differential mode

indicator

In differential mode (when both channel A and channel B have probes connected), the

screen will look similar to the following example. The asterisk next to the ChA and ChB

legends will alternate as readings are updated.

The probe conversion indicator (bottom-left) displays the conversion method for the current

reading (and so will alternate if the two channels have different conversion methods).

4.1.2.2 Selecting relative temperature measurement (0 key)

The instrument displays a reading value relative to a fixed offset in Zero (or relative) mode.

Press the Zero ( 0 ) key to select this mode.

In Zero mode, the instrument stores the last reading (at the time of Zero key press) to subtract

from all subsequent readings. It continues doing this until it is either cancelled by pressing the

Zero key again or until power is removed.

Zero mode may be used on differential measurements (A – B). In this case, the difference is

set to zero at the time the key is pressed and the absolute value in the example above, is

replaced by the absolute difference value.

To cancel the relative measurement mode, press the Zero ( 0 ) key again. Zero mode is

cancelled when power is turned off.

20 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Note

When the CTH7000 is battery operated, using the

backlight will dramatically reduce battery life (by about 30% if used continually at full-brightness).

ChA s:CTH7000-1234 PRT4

22.479 oC

Hold 10:24:33

Hold mode indication

alternates with the conversion

4.1.2.3 Selecting run/hold mode ()

Instrument measurements stop completely when Hold mode is active. This is indicated on the

bottom-left of the display where Hold mode indication alternates with the current conversion

method, providing a flashing indication. Hold mode may be used when the CTH7000 is in

differential mode.

Press the Hold () key to alternate between run and hold modes. Hold mode is cancelled

when power is turned off.

4.1.2.4 Backlight key ()

Press the Backlight key () to illuminate the display. Once on, the backlight will go

automatically off after about 10 seconds; alternatively, press the key again to turn it off.

The brightness level can be set on the Settings menu (see later section). Reducing the

brighness value will increase battery life when the backlight is used.

4.1.3 Other menu options

This section describes the other options available through menu selection. Generally, these

options are set once and then altered rarely. The set-up is stored in non-volatile memory and

recalled when power is reapplied.

In the following sections, the top level menu is shown, followed by the sub-menu(s) that it

selects.

ASL operating instructions, model CTH7000 21

CTH7000 Operating Instructions

Units

Channel A Channel B Logging Statistics Settings System

Celcius

Fahrenheit Kelvin Ohms

Units

Channel A

Channel B Logging Statistics Settings System

Probe Type

Temp Conv Coefficients

4.1.3.1 Selecting Units

Press the Menu key (  ) to change the measurement units. The Units menu will be

highlighted. Press the Enter key once to reach the Units selection menu.

Select the units required with the Up/Down keys and then press the Enter key. Units of Celsius

(°C), Fahrenheit (°F), Kelvin (K) or Resistance () can be selected; the current units are shown

on the Measurement Menu screen. Changing units will automatically clear any statistics. The

current measurement units are retained when power is removed.

Having selected the new units, press the Menu key to return to Measurement Mode.

4.1.3.2 Channel options menu (Channel A or Channel B)

Operation of channel A and channel B is identical; Press the Enter key to select the sub-menu

–

a) Probe type

The sub-menu is used to select the type of probe attached. There are two completely

different probe types - either PRT or Thermistor. This probe selection sub-menu is used

to set these options.

22 ASL operating instructions, model CTH7000

Alternatively, the Up () and Down () keys can be used to change the displayed units

CTH7000 Operating Instructions

PRT 4 wire

NTC Thermistor

DIN

CVD

ITS - 90

Passcode = 0000

Left/Rt selects Up/Down changes Enter OK

The currently selected sensor type is always shown at the top left of the measurement

screen (see the example shown in section 4.1.1).

Channel A is always used for the PRT probe and channel B is always used for the

Thermistor probe.

Use the Down key (twice) to select the thermistor probe on channel B. When the

menu is entered again, the thermistor line will be highlighted.

Selection of PRTs is more involved since the conversion method has to be set at the

same time as the probe is changed. Selecting one of the PRT menus will display the

passcode screen –

b) Conversion method

Use the Up/Down arrow keys to increment or decrement the passcode. Use the Enter

key once the correct passcode has been set; this procedure helps to prevent

inadvertent changes. The default passcode setting13 is 4300.

This screen will only appear once the correct passcode has been entered. This screen

shows that the CVD conversion method is currently selected. Use the Up and Down

keys to highlight the required conversion method and then use the Enter key to select

it.

This can be changed using the Settings menu; keep careful note of the new value if changed. A lost

ASL operating instructions, model CTH7000 23

password can be retrieved, but you will need to contact ASL directly for further information.

CTH7000 Operating Instructions

Note

Smart probes use their own internal calibration data.

The instrument coefficients are ignored when a Smart

probe is attached.

For PRTs, the instrument provides three standard algorithms for converting resistance

to temperature. The choice of algorithm will depend on the type of PRT and its

calibration –

 DIN (1992) - used for un-calibrated industrial PRTs with 0.00385 ‘alpha’

value, to provide a conversion of resistance to temperature in

accordance with BS EN60751 (ITS 90) standard

 CVD coefficients - Callendar van Dusen used for calibrated industrial or

low alpha PRT’s of 0.00385

 ITS-90 coefficients - used for calibrated high alpha PRT’s of values

0.003926 to 0.003928

The choice of conversion method and the relevant coefficients are set from this

menu.

For Thermistors, the instrument provides one standard algorithm for converting

resistance to temperature –

 Steinhart and Hart

c) Probe coefficients

Both PRT and Thermistor probes must be correctly calibrated to produce their most

accurate performance. The CTH7000 can store calibration data for each of the two

channels; this information is only required when passive probes are being used. When

Smart probes are used, the calibration data is stored in the probe and the coefficients

held in the CTH7000 are not required or used.

When passive probes are used, correct entry of the parameter values is absolutely

critical to obtain accurate readings. For this reason, the coefficients menu is passcode

protected. The passcode screen (below) will appear once the Coefficients menu has

been selected. Use the Up and Down arrow keys to increment or decrement the

passcode value.

24 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Probe Type Temp Conv

Coefficients

Passcode = 0000

Left/Rt selects Up/Down changes Enter OK

CHA ITS90

Rtp +1.00000 e+02

A +3.90830e-03 B -5.77500e - 07

Up/Down move Enter edit Clear exit

EDIT Rtp +1.00000 e+02 A +3.90830e-03 B -5.77500e - 07

Left/Rt selects Enter changes Clear saves

Use the Enter key once the correct passcode has been set; this procedure

helps to prevent inadvertent changes. The default passcode setting14 is 4300.

The coefficient edit screen will appear once the correct passcode has been

entered. In this example, the edit screen for CVD coefficients is shown; the first digit

of the R0 coefficient will be highlighted (in this case the ‘1’). This is the current cursor

position. Use the Up and Down keys to change the value under the cursor. Once this

value is correct, use the Left and Right keys to select the next digit to set. Use the

Enter key once the complete coefficient has been edited correctly; alternatively use

the Clear key to move on to the next coefficient15. The coefficients will be set to the

value shown when the Enter key is pressed.

Once the first coefficient has been edited, the screen will scroll (if more than three

coefficients are required). Note that DIN coefficients cannot be edited.

Follow a similar procedure for entry of NTC thermistor coefficients.

4.1.3.3 Data logging menu

The CTH7000 can log data. Logging status is always shown at the bottom right-hand of the

measurement screen (see section 4.1.1).

This can be changed using the Settings menu; keep careful note of the new value if changed. A lost

password can be retrieved, but you will need to contact ASL directly for further information.

Use the Clear key repeatedly to exit without changing any of the coefficients.

ASL operating instructions, model CTH7000 25

CTH7000 Operating Instructions

Logging Channel A Channel B

Logging

Statistics Settings System

Stop

Review

Logging Channel A Channel B

Logging

Statistics Settings System

Start

Setup Review Clear

Data can be logged at regular intervals (the interval is set when Setup selected), reviewed

and logging can be turned on and off.

Press the Enter key to select the sub-menu used to set the various logging options.

Note that there are a finite number of data points that can be stored, so eventually, any old

results will be overwritten as the selected log will eventually wrap-round – i.e. the oldest

reading will be overwritten first16.

Use the Start menu item to begin logging.

Select Clear to clear the log and return to the main menu.

Selecting Stop (see below) will halt logging. Logging can be restarted using the Start menu

item (logging will then continue after the last point previously logged).

Only two menu options will be available when the instrument is logging.

After approximately 8000 points when continuously logging; starting and stopping the log will decrease this

number points available.

26 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Logging Channel A Channel B

Logging

Statistics Settings System

Start

Setup

Review Clear

10 – 18 April 0 22:27 A 120.000F 22:29 A 120.000F 22:31 A 120.000F 22:33 A 120.000F 22:35 A 120.000F 22:37 A 120.000F

Dn Next Pg

Use the down key to select the next page

Hour of reading &

Reading and units

Minutes/seconds and

channel

Current page

History Setup

MM:SS Intvl: 00:00:02

a) Review

Results similar to the following example will appear once the Review key has been

pressed.; exact details will vary with the instrument setup. The example shows channel

A results logged at 2 second intervals.

Use the Down key to scroll through the logged readings a page at a time.

Press the Clear key (  ) to return to the main menu screenu.

b) Setup

Use the setup menu to set the logging interval. Either select the required interval with

ASL operating instructions, model CTH7000 27

the Enter key or use the Clear key to return to the measurement menu.

The interval can be set anywhere between 1 second and 59 minutes 59 seconds (a

logging interval of 2 seconds is shown in the example). Selecting an interval of 00:00

will log data as fast as possible; select an interval that best matches your

requirements. Logging with a larger data intervals effectively increases the total

period for which data can be logged.

CTH7000 Operating Instructions

Units Channel A Channel B Logging

Statistics

Settings System

Exit

Clear

ChA Mn 23.456 Mx 23.559 Mean 23.405 Std dev 0.010 Total 10

Logging will stop when the power is turned off.

4.1.3.4 Statistics menu

The CTH7000 provides statistics on the data it is collecting. Press the Enter key to select the

statistics sub-menu.

Statistical information is calculated continuously from the moment statistics are cleared (see

sub-menu). Changing any parameter that affects the calculation (e.g. units) will

automatically clear and restart calculation.

The Exit option is used to return to the Measurement Menu after viewing statistics.

Alternatively, press the Clear key (  ) to return to Measurement Menu without clearing

statistics.

The minimum, maximum, mean, standard deviation and total number of readings are

displayed on this screen17. Select Clear to immediately clear and restart the statistical

calculations.

28 ASL operating instructions, model CTH7000

The maximum and minimum values are also displayed continuously on the measurement menu screen.

CTH7000 Operating Instructions

Units Channel A Channel B Logging Statistics

Settings

System

Brightness

Timeouts Time & Date ADC Mode

Brightness Timeouts Time & Date

ADC Mode

50 & 60 Hz Reject

50 Hz Reject 60 Hz Reject

Brightness

Timeouts Time & Date ADC Mode

Set Brightness Use Up/Down Keys Any key to Exit

4.1.3.5 Settings menu

Several operational parameters can be changed in the Settings menu. Press the Enter key to

select the Settings sub-menu. Foe example, to change the ADC mode (50/60 Hz) setting -

CTH7000 has been set to 50 Hz & 60 Hz reject (rejection filter) by default. Select 50 Hz or 60 Hz,

depending on the operational mains frequency in your area. This can provide better noise

rejection. See the menu screen shown below.

a) Brightness

Selecting this option allows the brightness of the LCD backlight to be adjusted. Use

the Enter key once you are happy with the backlight intensity. Use the Clear key to

exit without altering the set value.

ASL operating instructions, model CTH7000 29

CTH7000 Operating Instructions

Note

When the CTH7000 is battery operated, using the

backlight will dramatically reduce battery life. The current used increases as the backlight intensity rises.

Brightness Timeouts

Time & Date

ADC Mode

2005:Aug:20 12:23:38

Left/Rt selects Up/Down changes Clr/Enter exits

Brightness

Timeouts

Time & Date ADC Mode

No Timeout

5 Minutes 15 Minute 30 Minutes 1 Hour 4 Hours 8 Hours

b) Timeouts

The CTH7000 can be set to timeout after a preset period (to save battery life); by default the

timeout is off. Selecting this option allows the various timeout values to be set. Use the Up

and Down keys to select the required timeout and then press the Enter key to select it (or use

the Clear key to return to the Measurement Menu).

c) Time/Date menu

The CTH7000 contains a real-time clock18. The Time/Date menu is used to set the clock.

The menu keys are used to change the settings. Use the Up and Down keys to alter the value

under the reverse-video cursor. Once the correct value is set, use the Right and Left keys to

move to the next field. Use the Clear key to exit without changing the values. The Enter key

will set the clock to the new values.

It is important to set the clock correctly when using data logging.

d) ADC mode

See the example at the start of this section.

30 ASL operating instructions, model CTH7000

The clock battery is contained internally; the battery pack is not used for the real time clock.

CTH7000 Operating Instructions

Units Channel A Channel B Logging Statistics Settings

System

Change Passcode

Calibration Factory Defaults Diagnostics

Change Passcode

Calibration Factory Defaults Diagnostics

Old code = 0000

Left/Rt selects Up/Down changes

Enter OK

Current = 4300

Any key to exit

4.1.3.6 System menu

The settings menu allows the remainder of the instrument parameters to be set.

a) Change Passcode

Selecting this option allows the CTH7000 passcode to be set to another value19. The current

passcode has to be entered before it can be altered. The passcode screen will always show

the value ‘0000’ when it is first displayed; use the Up and Down keys to change this to the

current passcode value. Press Enter when the current passcode is correct. The new value can

then be set. In the example below, the passcode is ‘4300’.

Set to 4300 by default

ASL operating instructions, model CTH7000 31

CTH7000 Operating Instructions

Note

Selecting this option will overwrite the instrument calibration data. Do not attempt to do this unless you have the correct equipment, environment and suitably trained personnel.

Note

Specialised equipment is required to proceed further with this procedure.

Change Passcode

Calibration

Factory Defaults Diagnostics

Do Calibration

Edit Resistors Edit Calibration Reset Cal

b) Instrument calibration

Selecting this option allows the CTH7000 to be calibrated; this option will overwrite and

replace the exiting calibration data. The correct equipment, environment and accurately

calibrated resistors are required. For this reason, a passcode (9900) has to be entered first –

32 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Note

Selecting this option will overwrite all instrument calibration data and settings. Do not attempt to do this unless you have the correct equipment, environment and suitably trained personnel.

Change Passcode Calibration

Factory Defaults

Diagnostics

Passcode = 0000

Left/Rt selects Up/Down changes Enter OK

Clear coeff’s Restore factory

defaults?

Enter if yes

Clear for no

Factory defaults

The instrument parameters can be set to the factory defaults. Selecting this option will

overwrite any exiting calibration data. For this reason, a passcode (9900) must be entered

(see below) -

c) Diagnostics

Not available for use.

ASL operating instructions, model CTH7000 33

CTH7000 Operating Instructions

Note

The CTH7000 may take up to 5 seconds to recognise and acquire data from the Smart Probe after switch-on before displaying a measurement.

4.1.4 Setting up Temperature measurement

To enable accurate resistance to temperature conversion to be carried out by the

instrument, PRT or characterisation data is required for both –

 temperature conversion algorithm, and  temperature conversion algorithm coefficients

For Thermistors, characterisation data is only required for –

 temperature conversion algorithm coefficients

The data can be stored in either a Smart probe or the instruments’ internal non-volatile

memory, each thermometer input channel stores one set of PRT/Thermistor characterisation

data. See the relevant section above for details on entering the data.

4.1.4.1 Temperature measurement with Smart probe (s)

If a Smart probe is detected on a selected input channel, the PRT calibration data is loaded

directly from the Smart probe. Smart probe data always takes precedence over the internal

CTH7000 coefficient data (but does not overwrite the instrument data).

4.1.4.2 Instrument calibration

This is not usually a customer option; refer to separate documentation.

4.1.4.3 Firmware Version

The firmware version is shown at the bottom of the LCD when the instrument is first powered.

4.1.5 Smart Probe review

The Smart probe data can be reviewed, but not changed on the CTH7000. The Smart probe

data contains the following information -

Version Smart probe data format

Lock Password protection state

00 = Smart probe data locked can not be changed from the instrument

01 = Smart probe data unlocked can be changed from the instrument

34 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

Cal type Selected method of resistance to temperature conversion algorithm to use,

DIN, ITS90, CvD or Steinhart and Hart (for thermistors)

Cal date Date of the Smart probe calibration

Due date Date the Smart probe calibration is next due

Source Company that carried out the Smart probe calibration

Serial Number Serial number of the Smart probe

Max since cal Maximum recorded temperature the Smart probe has been exposed to since

it was last calibrated (units are in resistance)

Min since cal Minimum recorded temperature the Smart probe has been exposed to since it

was last calibrated (units are in resistance)

Max ever Maximum recorded temperature the Smart probe has been exposed to during

its

working life (units are in resistance)

Min ever Minimum recorded temperature the Smart probe has been exposed to during

its working life (units are in resistance)

ASL operating instructions, model CTH7000 35

CTH7000 Operating Instructions

Measurement Units

Thermistor

Conversio

Under

Range

Over Range

Units

Resistance

None

400,000

ohms

Temperature

S & H

Thermistor dependent

C/F/K

Measurement Units

PRT

Conversio

Under

Range

Over Range

Units

Resistance

None 0 410

ohms

Temperature

Din90

-201

+851

C/F/K

CvD

-201

+850

C/F/K

ITS90

-201

+963

C/F/K

ChA Mn - - PRT4 Mx - OVF

---------

CVD Log off

No reading

No reading available

Reading overflow

5. Instrument Measurement Range

5.1 Instrument measurement working range

The instrument can detect the following conditions Open Circuit Probe20, Over Range

measurement and Under Range measurement. These conditions are shown by a line of

dashes ‘----------‘ on the LCD display.

5.2 Measurement Ranges

Because of the potentially high resistances of thermistors, it may not be possible to determine the difference

36 ASL operating instructions, model CTH7000

between connected and disconnected probes for these sensors.

CTH7000 Operating Instructions

This page is intentionally left blank.

ASL operating instructions, model CTH7000 37

CTH7000 Operating Instructions

6. Smart Probes

6.1 About Smart Probes

Smart probes are similar to passive probes except for one key advantage - all the probe

details, calibration data and probe history are stored within the probe itself and not within

the measurement instrument.

Smart probes can be moved freely from channel to channel or from instrument to instrument

without the need to manually enter any data into the instrument.

6.2 How Smart Probes Work

Each Smart probe if fitted with a small non-volatile memory device; this device is transparent

during normal temperature measurement.

The probe is interrogated before a measurement cycle and the probe data is read into the

instrument for use in the measurement process.

6.3 Smart Probe Data Security

To maintain a high level of data security, the Smart probe has a built in data-lock. If the data-

lock is set, the Smart probe data cannot be modified.

6.4 Smart Probe Calibration Supervisor

To assist in maintaining valid calibration, the instrument checks the Smart probe calibration

date and compares it with the instruments current date. If the Smart probe date is found to

have expired, the instrument will warn the operator ‘Probe is out of calibration’.

6.5 Smart Probe Working Range Monitor

The Smart probe working range monitor is used to monitor a Smart probes working range and

to notify a user if it is used outside its specified range.

6.6 Smart Probe Errors

Smart probe errors should never occur. They take the form – “Error 0xNN”, where NN is the

error code. Please refer to ASL Technical Services if this error is seen.

38 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

7. Calibrating the CTH7000

7.1 CTH7000 Instrument calibration

The dc bridge measurement technique used in the CTH7000 is inherently very stable and

linear. However some small drift of the internal reference resistor may occur with time,

making periodic re-calibration advisable.

7.2 Equipment

Temperature controlled environment at +20°C ±2°C.

Set of stable, calibrated (1ppm) resistors (3 ranges, 6 resistors).

7.3 Calibration procedure

See separate documentation.

ASL operating instructions, model CTH7000 39

CTH7000 Operating Instructions

This page is intentionally left blank.

40 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

8. Communications Interface

8.1 Introduction

The CTH7000 is fitted with USB communication interface as standard. The connected PC must have the correct USB driver installed. Please refer to the installation CD and the ULOG help system (ULOG version 3.3 onwards).

The USB PC interface will be installed as a virtual COM driver. The communication protocol is -

Bits per second 9600

Data bits 8

Stop bits 1

Parity none

Flow control none

An interval of 1ms to 2 ms should be allowed between transmitted characters.

8.2 USB Command syntax

The programming command language is based on the SCPI command format. Commands

are case insensitive.

Commands consist of one or more command words with each command word separated

by a colon (:) or a question mark (?). For commands requiring a response, a white space

character is used to separate the command parameter from the command words (e.g.

UNIT:TEMP <units>).

A response to a command returns a list of parameters (<parameter>) with each parameter

separated by a comma (,). The last parameter will be followed by a command terminator

carriage return (CR).

: (colon) Separates command words

? (question mark) Command requires a response

, (comma) Separates parameters list

Unrecognized commands will return ERR CMD after the CR character.

8.2.1 Command terminators (CR) or (CR)(LF)

ASL operating instructions, model CTH7000 41

CTH7000 Operating Instructions

All commands sent to the instrument must be terminated with a carriage return (CR)

character. A carriage return/line feed pair (CR)(LF) can also be sent to terminate a message;

the (LF) is ignored.

8.2.2 Command details

A list of the commands follow -

8.2.2.1 SYSTEM:REMOTE

Command SYSTEM:REMOTE

Return None

Function Places the CTH7000 in remote mode for USB control. CTH7000 indicates remote

on the instrument display. Disables the instrument front panel keys (excluding

backlight and power keys).

8.2.2.2 SYSTEM:LOCAL

Command SYSTEM: LOCAL

Return None

Function Returns the instrument to local mode. Removes the remote indication from the

8.2.2.3 *IDN?

Command *IDN?

Return <manufacturer>,<model no>,<serial no>,<firmware version>,<date>

Parameters <manufacture> ASL

instrument display. Enables the instrument front panel keys.

<model no> CTH7000

<serial no> Serial number of the instrument.

<firmware version> Current firmware version

<date> date.

Function Reads the instrument’s identification code consisting of the manufacturers

name, instrument model number, instrument serial number, firmware version

and date.

42 ASL operating instructions, model CTH7000

CTH7000 Operating Instructions

NB: If the serial number is not entered, the instrument will return 00000

8.2.2.4 MEASURE:CHANNEL? <channel>

Command MEASURE:CHANNEL? <channel>

Parameters <channel> 1 to 2 single channel measurement

<channel> - differential measurement mode

<measurement> last measurement value.

<units> currently selected units.

Return <channel>,<measurement>,<units>

Function Responds when a measurement is available.

8.2.2.5 UNIT:TEMP? <units>

Command UNIT:TEMP <units>

Parameters <units>

C or CEL Degrees celcius

F or FAR Degrees fahrenheit

K Degrees kelvin

R Resistance

Return None

Function Sets the temperature units.

8.2.2.6 LOG:DUMP 1

Command LOG:DUMP 1

Return <date>,<time>,<units>,<measurement CH1>,<measurement

CH2>,<differential>

Function Downloads the complete CTH7000 data log.

ASL operating instructions, model CTH7000 43

CTH7000 Operating Instructions

Log

Date

Time

UNITS

CH1

CH2

DIFF

05-May-06

13:09:26 C 5.172

……………

05-May-06

13:20:04 C 5.172

05-May-06

13:20:06 C 5.173

05-May-06