CAMBRIDGE SENSOTEC Rapidox 1100E User manual

Rapidox 1100E Oxygen Analyser
Instruction Manual
Revision 3.8
Cambridge Sensotec Ltd.
Unit 29 Stephenson Road
St Ives
Cambs
PE27 3WJ
ENGLAND
Tel. [phone]
Fax [phone]
Mobile [phone]
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Cambridge Sensotec Rapidox 1100E Oxygen Analyser Instruction Manual
Declaration of Conformity
Manufacturer: Cambridge Sensotec Ltd.
Unit 29 Stephenson Road
St Ives
Cambs
PE27 3WJ, ENGLAND
Product Names: Rapidox portable oxygen gas analyser
Model Numbers: RX1100E
Conform to the following specifications:
EMC: EN 61326:1998 Electrical equipment for measurement,
control and laboratory use
Declaration: I declare that the above products conform to the applicable
requirements of the LVD Directive 73/23/EEC and the EMC Directive 89/336/EEC
and is CE marked accordingly.
Signature:
Name: Dr. Mark Swetnam
Title: Managing Director
Company: Cambridge Sensotec Limited
Date: 4th May 2009
WEEE Regulations 2006
Cambridge Sensotec takes its responsibilities under the WEEE
Regulations extremely seriously and has taken steps to be compliant in
line with our corporate and social responsibilities. In the UK,
Cambridge Sensotec has joined a registered compliance scheme
“WeeeCare” (WeeeCare registration number WEE/MP3538PZ/SCH).
UK users only: If you have purchased any electronic or electrical product from
Cambridge Sensotec since 2007 and would like to dispose of it correctly under the
WEEE scheme, please contact us and we will be happy to either arrange the
collection of the waste or have it returned to our offices for recycling. All our in-
house manufactured products are scheme compliant and carry the WEEE label
indicating that it is NOT allowed to be disposed of in a landfill site.

Cambridge Sensotec Rapidox 1100E Oxygen Analyser Instruction Manual
Contents
1Introduction .......................................................................................................... 1
2Features ................................................................................................................. 1
3Technical Specification........................................................................................ 2
4Precautions............................................................................................................ 2
5Warning ................................................................................................................. 2
6Rapidox Operating Instructions........................................................................... 3
6.1 Rapidox Analyser Menu System .................................................................. 4
6.2 Getting Started............................................................................................... 4
6.3 Display Behaviour ......................................................................................... 4
6.4 Pump Control................................................................................................. 5
6.5 Menu Access / Passwords ............................................................................. 5
6.6 Rapidox Calibration....................................................................................... 6
6.7 Alarms............................................................................................................ 8
6.8 Analogue Outputs.......................................................................................... 9
6.9 Setting the Display Units ............................................................................ 11
6.10 Setting the Display Options ........................................................................ 12
6.11 Internal Pressure Sensor ............................................................................. 12
6.12 Pressure Mode ............................................................................................. 12
6.13 Setting the Baud Rate .................................................................................. 13
6.14 Setting Date & Time..................................................................................... 13
6.15 Load Defaults ............................................................................................... 13
6.16 RS232 / RS485 Port...................................................................................... 14
6.16.1 RS232 Protocol ..................................................................................... 14
RS232................................................................................................................... 15
RS232................................................................................................................... 15
6.16.2 RS485 protocol ..................................................................................... 16
6.17 Sensor Lifetime and Replacing ................................................................... 16
6.18 Printing......................................................................................................... 16
7Rapidox Software Instructions........................................................................... 17
7.1 Software Installation ................................................................................... 17
7.2 Getting Started............................................................................................. 17
7.3 On-Screen Help ........................................................................................... 18
7.4 Configuration Page ...................................................................................... 18
7.5 Reconfiguring the Analyser ........................................................................ 19
7.5.1 Config 1 Screen ........................................................................................ 20
7.5.2 Config 2 Screen ........................................................................................ 21
7.5.3 Alarm Config Screen................................................................................ 22
7.6 On-Screen LCD ............................................................................................ 23
7.7 Remote Calibrating ...................................................................................... 23
7.8 Calibration Error Messages ......................................................................... 25
7.9 Software Utilities......................................................................................... 27
7.9.1 Setting Analyser Date and Time ............................................................. 27
7.9.2 Check for Updates.................................................................................... 27
7.9.3 Image Grabber .......................................................................................... 27
8Rapidox Data-Logging Software ......................................................................... 27
8.1 Introduction ................................................................................................. 27
8.2 Setting up the Data Logger.......................................................................... 28

Cambridge Sensotec Rapidox 1100E Oxygen Analyser Instruction Manual
8.3 Running the Data Logger............................................................................. 29
8.4 Auto Date Stamped Files............................................................................. 29
8.5 Live Time Graphing Screen ........................................................................ 30
8.6 Main Graph Window................................................................................... 31
8.7 Plot Colours.................................................................................................. 31
8.8 Graph Titles and Labels .............................................................................. 32
8.9 Plot Co-ordinates ......................................................................................... 32
8.10 Last data point ............................................................................................. 32
8.11 Using the Cursor.......................................................................................... 32
8.12Zooming ....................................................................................................... 33
8.13 Y-Axis Graph Units ..................................................................................... 33
8.14 Oxygen Scale ............................................................................................... 33
8.15Second Y Axis.............................................................................................. 33
8.16 Loading an Old Run .................................................................................... 33
8.17 Printing Graphs............................................................................................ 34
8.18 Data Logging in the Background................................................................. 34
8.19 Pausing the Data Logging ............................................................................ 34
8.20 Changing the Data Logging Parameters Mid-run....................................... 34
8.21 Working with Spreadsheets ........................................................................ 35
8.22 Disaster Recovery ........................................................................................ 35
8.23 Diagnostics................................................................................................... 35
9Troubleshooting.................................................................................................. 37
10 Warranty.............................................................................................................. 38
10.1 Conditions of Warranty:.............................................................................. 38

Cambridge Sensotec Rapidox 1100E Oxygen Analyser Instruction Manual
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1Introduction
The Rapidox 1100E oxygen analyser gives accurate oxygen analysis over the
oxygen range 0 to 100% O2 with a resolution of 0.01%. The analyser provides
continuous on-line oxygen analysis, with a typical response time of less than 20
seconds for a 90% response to a step change in gas compositions.
The Rapidox 1100E is a fully integrated unit complete with a powerful diaphragm
pump to provide gas sampling at up to approximately 1.5 litres per minute.
The sensor head is located inside the analyser and comprises a long-life
electrochemical sensor. An internally mounted pressure sensor compensates for
any fluctuations in pressure caused by differing flow conditions.
The analyser is packed with features including programmable alarm circuits,
programmable analogue outputs, easy calibration (user selectable gases), RS232
communications and complete communications / data-logging software.
2Features
Continuous gas sampling via powerful internally located pump.
Fast measurement response (typically 20 seconds for a 90% response).
Wide measurement range available (0 to 100% O2).
High accuracy maintained throughout the measurement range. Accuracy ±
1% of the full scale.
Easy calibration procedure requiring any two gas mixtures (ordinary room air
is usually one).
Low maintenance, sensor life expectancy typically 3-5 years.
Large back-lit LCD display (16 x 2 characters).
RS232, 0-10V and 4-20mA current loop outputs (both fully programmable).
Fully programmable alarm circuits.
Full data-logging software accessed via RS232 connection to a PC (RS485
available on request).
PIN code protected menu access.
Printer and transport Peli-case options.

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3Technical Specification
Property
Specification
Supply Voltage
90-260VAC, 50/60Hz
Power consumption
10W max
Analyser dimensions
250mm X 263mm X 150mm
Weight
3.5 kg
Display
16 ×2 character (9mm) back lit LCD
Warm up time
5 minutes at 20°C
Normal operating temperature
5-35°C
Operating pressure range
800 to 1200mbar absolute
Absolute maximum pressure range
500 to 1500mbar absolute
Range of measurement
0-100% O2in steps of 0.01%
Accuracy
±1% of the full scale
Outputs: O2& pressure
0-10V (user-programmable) into minimum
5kΩ
O2& pressure
4-20mA current loop (user-programmable)
into maximum 500Ω
Programmable alarms
Relay circuits – fully user-programmable
All data and parameters
RS232 (or RS485) - data streamed on
demand
Sample Pump
Mains type diaphragm vacuum pump
(variable flow) with on/off switch on rear
panel.
Flow Rate
Typically 0-1.5 L.min-1 in 10 steps
Max. gas temperature on input
50°C
Calibration
Requires 2 user-selectable gas
compositions (air is default plus another)
Table 1: Technical specification
4Precautions
Make sure you read and understand these instructions and keep them safe for later
use. The unit should not be exposed to extreme temperatures < -5°C or > 50°C.
Normal operating temperature is 5-35°C. Avoid direct sunlight. Do not use liquid
cleaners, aerosols or solvents to clean the case. Use a damp cloth for cleaning. Do
not use this equipment near water. Avoid touching the LCD display as this may
cause permanent damage. Make sure the rear ventilation slots and the fan on the
rear panel are free of obstruction. There are no user serviceable parts in this unit.
Do not attempt to repair yourself. Refer all servicing to qualified Cambridge
Sensotec personnel.
5Warning
This unit is NOT designed for use in life support situations. No responsibility can
be held for injury or loss of life caused by inappropriate use of this equipment.

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6Rapidox Operating Instructions
Figure 1: Rapidox 1100E front panel. Numbers are referred to in the text.
Figure 2: Rapidox 1100E rear panel. Numbers are referred to in the text.
1
2
3
4
5
6
7
8
9
10

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6.1 Rapidox Analyser Menu System
All of the user-programmable functions are accessed via a menu system which is
controlled using the front panel Keypad (2). To access the menu press the ENT
button and to escape and return to the operating screen press ESC at any time.
The menu system flow chart is shown in Appendix 1 at the back of the manual.
6.2 Getting Started
Ensure that the Rapidox analyser is located away from extreme heat and dirt
environments. Plug the unit in to a suitable supply (noting the information on the
serial sticker and using the power cable supplied) using the rear power socket (8).
Make sure that the cooling fan (9) is not obstructed during operation.
Turn the unit on using the red power switch on the front (5). The LCD (1) will
display the firmware version and then begin taking measurements. The LCD
display will show the oxygen reading and the pressure. The symbol AL1 or AL2
may appear to the bottom right of the LCD if the alarm system is enabled and an
alarm condition applies.
Push the gas sample tube (6mm OD/4mm ID) onto the GAS IN (3) connector and
fit the retaining collar hand tight. Repeat for the GAS OUT (4) connector should
an outlet tube be required. The pump will draw gas at a flow rate depending on
the value set either in the software or from the menu. The default setting is one
hundred percent.
Allow five minutes for the box to stabilise fully. This allows the components of
the analyser to reach a stable working temperature. During this warm-up period it
is common for the baseline oxygen to drift by a small amount, which may be
corrected by re-calibrating.
6.3 Display Behaviour
Once at temperature the LCD display will show the oxygen reading (in percent or
ppm) on line 1 and the pressure (in mbar, bar, kPa, torr or psi) on line 2. The
symbol AL1 or AL2 may also appear in the bottom right of the LCD if the alarm
system is enabled and an alarm condition applies. The oxygen sensor reading
may flash, show U/Range or O/Range when its limits are reached, and error
messages will be displayed if there is a fault with the sensor. See Table 2 for more
details:

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Oxygen Sensor Display Possibilities
O2Reading > 200%
Display shows “O/Range”
O2Reading > 0% and < 200%
Display shows the normal oxygen reading in % or ppm
O2Reading <0%
Display shows “U/Range”
O
2
sensor signal has dropped below 70% of its factory
output
Display shows “Replace Sensor Soon”
O
2
sensor signal has dropped below 65% of its factory
output
Display shows “Sensor Must be Replaced”
O
2
Sensor is OK the pressure sensor is out of range
and automatic pressure correction is on.
O2Reading is flashing
O
2
Sensor has failed completely or become
disconnected
Display shows “No sensor or sensor Fault”
O
2
Sensor is OK but the pressure sensor is faulty and
the auto pressure correction mode is selected
Display shows “Fault” flashing.
Pressure Sensor Possibilities
Pressure Reading is >2000mbar absolute
Display shows “O/Range Press.”
Pressure Reading is >-1000mbar and <2000mbar
absolute
Display shows the normal pressure reading in mbar, bar,
kPa, torr or psi
Pressure Reading is <-1000mbar absolute
Display shows “U/Range Press.”
Pressure sensor has failed completely or become
disconnected
Display shows “Fault Press.” With the word “Fault” flashing
Table 2: Different display possibilities depending on the sensor reading.
6.4 Pump Control
The flow rate of gas drawn into the analyser can be controlled using the menu
option 9 “Set Pump Flow”. The unit is supplied with the flow rate set to OFF. If
you wish to change the flow rate press ENT and select menu option 9. Use the UP
& DOWN arrows to change the value from OFF to 100% in 10% increments. 100%
equates to approximately 1.2 litres per minute. Once you have selected the
desired flow rate, press ENT to confirm your selection. If you do not press ENT,
the pump will revert to the previous rate when the unit exits the menu system.
Alternatively the pump can be switched on or off using the switch (10) on the rear
panel. When using the unit with a pressurised (flowing) gas source the pump can
be left switched off.
6.5 Menu Access / Passwords
The analyser has an option to set a password that will restrict access to the menus.
The password menu is disabled by default in the factory. If you wish to password
protect the analyser press ENT and scroll down to the PASSWORD option (Menu
option 9). Pressing ENT again will ask you for the default password which is
“0000”. Enter this using the UP and DOWN arrows. Once the password has been
entered successfully you can chose between ENABLE and DISABLE in the menu
using the UP and DOWN keys.
The other option is to RESET the password to a new value. The password must be
4 digits long and can be any combination of numbers from 0000-9999. Make sure
that the new password is noted down!
If the password function has been enabled then in the future each time the menu
system is accessed then the password prompt will display. After the correct

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password is entered then the full menu will be accessible. You can make as many
changes as you want to the options and only press ESC once you have finished.
Pressing ESC takes you out of the password protected area and you will have to re-
enter the password to go back in again.
If the password has been forgotten please contact Cambridge Sensotec who will
advise you on how to recover it.
6.6 Rapidox Calibration
Once the unit is stable it may be necessary to calibrate the sensor. If a new sensor
is fitted this will also require recalibration. Full calibration is a simple procedure
requiring only two gases (one of which is normally air – 20.95%). For best
accuracy the second gas should ideally be 0% oxygen (e.g., pure N2). The two gas
values are user-selectable and can be changed by using the front keypad (2) or the
communications software described in section 7, and the calibration values can be
stored on file for later use.
Care must be taken to calibrate the analyser so that, whenever possible, the range
of measurement lies between the two calibration points. For example, if you are
working at 1% but have calibrated the analyser between 21% and 100% then the
analyser may be inaccurate at 1%. You should instead calibrate using pure
nitrogen (0%) and 21% to be sure of good accuracy. The procedure is as follows:
1) Bearing in mind the points made above, decide which two gases you are
going to use for calibration. If you are constantly working at a particular
range of compositions then it would be wise to obtain small cylinders of
calibration gas with analysis certificates. Cambridge Sensotec can supply
these. Press the ENT button on the front panel keypad (2) to access the
menu system. Using the UP and DOWN arrow buttons scroll to menu
option 1 “Calibrate” and press ENT again to enter the calibration menu.
The analyser will ask you if a new sensor has been fitted with the prompt
“NEW SENSOR?”The default answer is NO unless you have just replaced
the sensor and in this case use the UP or DOWN key to change to YES.
Selecting YES allows the machine to store the unique profile of the new
sensor so it can advise you when the sensor is ready to be replaced. Use the
UP and DOWN arrows to select “O2High” or “O2Low” and press ENT to
proceed. The top line of the display shows the current calibration gas
stored and the bottom line of the display shows the prompts. If the gas
value is not what you require you can edit the value (in ppm scientific
notation) using the up and down and right arrows on the keypad. The
cursor flashes underneath the digit to edit. For example 20.95% should be
entered as 2.095E+05ppm. Note that you cannot go backwards to edit a
digit to the left of the cursor. Instead keep pressing the RIGHT button and
the cursor will wrap around back to the beginning. Alternatively press ESC
to start again. Press ENT when you are ready to proceed.
2) The sensor needs to be exposed to the first calibration gas (e.g., air) or from

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a cylinder of known composition. For accurate calibration it is important to
allow sufficient time to flush the sensor properly. Wait for the top line of
the display (1) to become stable. To complete the calibration press and
hold the ENT button for two seconds. During this time you will see a bar
graph progress across the lower display. The analyser will then recalibrate
and display “O2Calibrated” and then return to normal run mode. The
display will now correctly read the value of the first calibration gas. Note
that if the ENT button is released before two seconds have elapsed, the
recalibration will be aborted and when the analyser eventually returns to
run mode it will use the existing calibration.
3) Note that the analyser should ideally be calibrated at normal ambient
pressure and at the temperature at which it will be used. If the pressure
correction mode is set to AUTO then it is still possible to perform an
accurate calibration at pressures other than ambient. If the gas temperature
is significantly different from the ambient temperature, allow the gas to
flow for sufficient time for the sensor temperature to stabilise fully before
calibrating.
4) The analyser predicts the correct signal from the sensor during calibration
and if this is outside the range of expected values then the display will flash
and display “G?” to warn you that either the cal gas flowing over the sensor
is different to the value you have programmed OR the sensor may be old
and approaching the end of its life. Check before proceeding!
5) To calibrate using the second calibration gas, repeat the procedure from 2
but this time press ENT followed by the UP or DOWN button to scroll
through to the “O2Low” screen. Flush the sensor chamber with the second
calibration gas allowing several minutes for the new gas to flush through.
Wait for the display to become stable before pressing the ENT button for
two seconds. The analyser will then recalibrate and display “O2Calibrated”
and then return to normal run mode. The display will now correctly read
the value of the calibration gas.
6) The analyser is now correctly calibrated and will read accurately between
these two calibration points. Note that this procedure can also be
performed remotely using the software described in section 8.
7) If at any time, you encounter difficulties and wish to restore the machine to
its factory set calibration, use the configuration software provided and load
the original factory settings (described in section 6.15 below). Each
machine is provided with a unique file that contains the factory settings.
This is located on the CD-ROM provided and is copied onto your PC during
the installation process.
8) Note that the two calibration points are independent of each other so you
can calibrate the analyser in any order you desire. However please note
that ‘O2High’ must always be greater than ‘O2Low’. Typically the factory
settings are ‘O2High’ = 20.95% and ‘O2Low’ = 0%.

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NB You must always perform a FULL calibration to achieve good accuracy.
6.7 Alarms
The Rapidox is fitted with two independent and fully programmable alarm relay
outputs, which can be programmed to be either normally open (N/O - closes on
alarm) or normally closed (N/C - opens on alarm). You have the option of
assigning each alarm to the oxygen or internal pressure sensors, as well as
enabling the alarm relay circuits, enabling an audible buzzer and enabling a visual
warning on the screen.
The alarms can be programmed by the user via the keypad (2) on the front panel
or using the software provided.To change the alarm settings scroll down the
menu to no. 2 “Set Alarms” and press ENT. Now use the UP & DOWN arrows to
select “Alarm 1” or “Alarm 2” and press ENT. The next screen shows the message
“Assign To:”. Use the UP and DOWN arrows to select O2, or Pressure depending
on which measurement you want the alarm to work with, and press ENT to
proceed. The default is O2.
The next settings configure the behaviour of the alarm. Use the UP & DOWN
arrows to select ON or OFF for the following parameters:
1. OUTPUTS: This enables the rear panel relay outputs when ON is selected
2. AUDIBLE: This enables or disables the audible buzzer inside the unit
which will sound in an alarm condition
3. VISIBLE: This enables or disables warning messages on the LCD screen on
the front of the Rapidox. During an alarm condition either “AL1” or “AL2”
(or a combination of both) will flash at the bottom right hand corner of the
display
4. POLARITY: This determines whether you are setting a rising or falling
alarm. Use the arrows to change the direction of the alarm to up or down.
A rising alarm means that the alarm will be silent at values below the set-
point but as soon as the value rises above the set-point the alarm will be
triggered
5. SETPOINT: The current alarm set-point is displayed in scientific notation
with a flashing cursor under the first digit. Use the UP & DOWN arrows to
change the digit and the RIGHT arrow to progress until the correct value is
displayed. When done, press ENT to proceed to the next setting
6. CONTACTS: The relay outputs can be set to either normally open (N/O) or
normally closed (N/C). The factory default is N/O, meaning the contacts
will close when an alarm condition occurs. Press ENT to save all the above
settings for the selected alarm.

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Alarm 2 can be set in exactly the same way as described above and both alarm
circuits are completely independent of each other. Note that you must programme
all the parameters for each alarm for the settings to be saved. The bottom line of
the LCD will display “Alarm x set” (where ‘x’ is the selected alarm channel) to
confirm that the settings have been saved.
The alarm circuit relays are accessed via the terminal block on the rear panel and
are clearly labelled. Alarm 1 is assigned to the terminals labelled “Alarm High”
and Alarm 2 is assigned to the terminals labelled “Alarm Low”. The relay circuit
is rated at 24V 0.5amps maximum.
The alarm limits for oxygen are set to a minimum of -1% and a maximum of
200%. Under certain conditions (e.g. the sensor becomes disconnected) the
Rapidox will set the alarm channel to OFF to prevent false alarms, and the relay
contacts for the affected channel will go to the programmed N/O or N/C setting.
For more information please refer to Table 3 in section 6.8 below.
6.8 Analogue Outputs
The standard industrial analogue outputs (0-10V and 4-20mA) for both oxygen
and pressure are accessible via the terminal block (6) on the rear panel. Note that
the ranges of the 0-10V and 4-20mA are tied together so changing one alters the
other. In the case of oxygen, the outputs are factory set to provide a linear
response in the range 0-100% that will cover most applications. However the
lower and upper values are fully user-programmable using the keypad (2) or the
software provided (section 7). A more details description is given below:
The linear oxygen output mode setting produces an output that is scaled linearly
between 0 and 10V (or 4 and 20mA). So, for example, if the scale is set 0V = 0%
O2and 10V = 100% O2then 5V would indicate an oxygen reading of 50% O2.
The scaling of this example is shown in the following plot, from which other
intermediate values can also be read.

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"Lin(ppm)"
Linear output mode
0
1.25
2.5
3.75
5
6.25
7.5
8.75
10
010 20 30 40 50 60 70 80 90 100
O
2
(%)
O
2
Volts output
4
6
8
10
12
14
16
18
20
O
2
mA output
Figure 3: Graph showing the linear output mode option for oxygen
The following general formulae can be used to calculate the oxygen from the
voltage or current outputs when set to the linear output mode:
Output type Formula for calculating oxygen from analogue output signal
0-10V O
2
= V
out
/ 10 * (O
2H
- O
2L
) + O
2L
4-20mA O2= (mAout – 4) / 16 * (O2H - O2L ) + O2L
Where: O2L = user setting of oxygen for 0V or 4mA output 1
O2H = user setting of oxygen for 10V or 20mA output 1
Vout = the measured voltage output in volts
mAout = the measured current output in mA
1O2, O2L and O2H must all be in the same units.
To modify the oxygen analogue output range scroll down the menu to no.3 “Set
Outputs” and press ENT. You can now edit the lower and upper values in exactly
the same manner as described in 6.6 for setting the cal gas values. Once
programmed the new values remain in the memory until they are edited again in
the future.
To select and modify the auxiliary outputs (pressure) scroll down to menu option
3 “Set Outputs” and pres ENT four times. Use the up and down arrow buttons to
program the pressure scale and press ENT.
During initial warm up of the Rapidox when the display reads the serial number
the output sent to the rear terminal for oxygen will stay at 2mA (1V) which is the
standby signal. If at any stage a sensor becomes disconnected internally, or the
signal exceeds the measurable range for that sensor, then the display will indicate
there is a fault and the outputs will change to 1mA (0.5V) which is the sensor fault
signal. This will recover as soon as the sensor is reconnected and the fault

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cleared. Additional current and voltage signals are provided by the analyser to
give an indication of various conditions and these are described in Table 3 below,
together with the status of the alarms during the condition:
O2Analogue Outputs
Description Explanation Alarms(3)
Current(1)
(4-20mA)
Voltage(2)
(0-10V)
1mA 0.5V Fault
There is a sensor fault on the oxygen
sensor, and/or the pressure mode is
set to automatic (pressure
compensation active) and the pressure
sensor has a fault condition.
De-activated
2mA
1V
Start up
The analyser is still initialising.
De-activated
2.5mA
1.25V
Sensor under range
The sensor reading is under range.
Active
3mA
1.5V
Sensor over range
The sensor reading is over range.
Active
3.5mA 1.75V Sensor operating out of
specification
The sensor reading is in range but the
pressure mode is set to automatic
(pressure compensation active) and
the pressure sensor is out of range.
Active
4 to 20mA 0 to 10V Normal operating output
The O
2
sensor and pressure sensor
are operating normally and readings
are in range.
Active
Pressure Analogue
Outputs
Description Explanation Alarms(3)
Current(1)
(4-20mA)
Voltage(2)
(0-10V)
1mA
0.5V
Fault
The pressure sensor has a fault.
De-activated
2mA
1V
Start up
The analyser is still initialising.
De-activated
2.5mA 1.25V Sensor under range
The pressure sensor reading is under
range.
Active
3mA 1.5V Sensor over range
The pressure sensor reading is over
range.
Active
4 to 20mA 0 to 10V Normal operating output
The pressure sensor is operating
normally and readings are in range.
Active
Table 3: Analogue output settings and alarm status for certain conditions
Notes:
1The current outputs are active self-powered outputs - they are not loop powered.
2The voltage (0 to10V) outputs produce non-zero voltages during start-up, fault and over/under range conditions - if
1V to 5V outputs are required, with these conditions indicated by corresponding voltages between 0V and 1V, the
current outputs can be used, with a 250 Ohm load resistor.
3Alarms are de-activated during start up initialisation, and when a fault condition occurs on the assigned sensor.
6.9 Setting the Display Units
The notation used by the display is fully programmable to suit your needs using
the keypad (2) or the software provided. The following options are available to
you:
1. Oxygen: The oxygen reading can be displayed in percent (e.g. 20.95%),
ppm (e.g. 209500ppm) or in terms of pressure (using the pressure units set
as below). There is also an option to display the oxygen reading in terms of
a nitrogen balance (%N2) reading. In this case the reading displayed is 100-
O2% =N2so for example in air 21% the nitrogen balance reading will
display 79% N2. Note that this is NOT an actual nitrogen analysis.
2. Pressure: The reading can be displayed in mbar, bar, psi, torr or kPa.
To program these options scroll down to menu no. 4 “Set Units” and press ENT.
Use the ENT key to progress through the list and the UP & DOWN keys to select

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the required units. Once selected press ENT to store and return to run mode.
6.10 Setting the Display Options
The user can select the LCD refresh rate and the format of the line 2 display using
the keypad or the software provided. Scroll down the menu to option no. 5
“Display Setup” and press ENT. Use the UP & DOWN arrows to select either the
Line 2 Options or LCD refresh rate:
1. Line 2 Options: The information displayed on line 2 of the LCD can be
chosen by the user. The options are Pressure (displayed in mbar, bar, torr
or KPa), the date and time (the date is displayed in local format and the
time as HH:mm:ss) or None (blank line). Use the UP & DOWN arrows to
select the display required and press ENT to store and return to the main
menu.
2. LCD Refresh Interval: The display update interval be selected from 0.1 to
1.5 seconds. The current setting can be edited using the same method as
described in 0 for modifying the calibration gas values. Once edited press
ENT to store and return to the main menu. The default setting is 0.3
seconds.
6.11 Internal Pressure Sensor
The Rapidox 1100E is fitted with an internal absolute pressure sensor which
monitors small changes in pressure and vacuum inside the sensor head. The
pressure will normally be ambient absolute (e.g. 1013 mbar) under normal
operation but if the unit is being fed by a gas cylinder or connected to an
apparatus under partial vacuum then the pressure will change and this will have a
direct effect on the oxygen partial pressure and the sensor reading. You have the
option of displaying the pressure reading on the LCD display (1). Select no. 5
“Display Setup” and press ENT. Select “Line 2 Options” using the UP & DOWN
arrows and press ENT. You can set the display to read Pressure or None. Select
Pressure and press ENT. The display will now show the absolute pressure reading
from the internal sensor. If you want to view different units select no. 4 “Set
Units” from the menu and press ENT three times to reach the pressure screen.
Use the UP & DOWN arrows to select mbar, bar, torr, psi or kPa and press ENT.
The display will now show the pressure in the selected units.
6.12 Pressure Mode
The user has the option of using the reading from the internal pressure sensor to
automatically correct for changes in gas pressure and hence oxygen pressure. To
access this function scroll down to menu option 6 “Pressure Mode” and press
ENT. The desired mode can then be selected using the UP & DOWN arrows and
pressing ENT to store and proceed. The two modes available are:

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1. None:If this mode is selected then there is no pressure correction
performed on the oxygen reading. The pressure and oxygen sensor act
independently, and the oxygen reading will vary with the gas pressure.
2. Auto:This is the factory default setting. If the Auto mode is selected then
the Rapidox 1100E uses the absolute reading from the internal pressure
sensor to correct the oxygen partial pressure and maintain an accurate
concentration reading.
6.13 Setting the Baud Rate
If you are using the software for data logging you can chose the communications
speed (Baud Rate) by scrolling down the menu to option 7 “Set Baud Rate” and
using the UP & DOWN arrows to select either 9600, 57000 or 115200. Press ENT
button again to store and return to normal operation. The default factory setting is
115200. However if you are using an older PC you can decrease this to 57600 or
even 9600 to improve the reliability of the software and data communications.
6.14 Setting Date & Time
The date and time can be programmed either using the software programme or
from the menu on the analyser itself. Scroll up to menu option no. 8 “Set Date/
Time” and press ENT. The current date is displayed as “Date: dd/mm/yy” with the
flashing cursor under the year. The prompts at the bottom of the screen indicate
what to do: use the UP and DOWN arrows to change the value above the flashing
cursor and press ENT to progress. The cursor always starts under the year value
as this will dictate how the months behave e.g., during a leap year. Once all the
values are programmed correctly press ENT to change the time and finally ENT to
return to the main menu. If you make a mistake at any time you can press ESC to
return to the main menu and then press ENT again. Note that if you re-
programme the date and time using the software then this will overwrite any
changes you have just made and will use the current date and time of the PC.
Note that the exact date format will depend on the country you are in and the
language and local settings of the PC which you have used to connect to the
analyser: in order to set the local date format, use the “Utility” drop-down menu in
Cambridge Sensotec’s Rapidox data logging software, and “Set date and time”. So
for example in the USA you would now see the date as mm/dd/yy. The local date
format will be stored along with the date and time in the Rapidox.
6.15 Load Defaults
If you make a mistake programming the Rapidox it is possible to restore the
machine back to its factory calibration and settings by loading the unique default
configuration that is supplied on your software CD-ROM. This can be accessed

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using the software provided (please see section 7.4 for further details).
Alternatively, you can reset to ‘generic’ factory defaults directly from the front
panel keypad. Press ENT to enter the user setup menu and select menu option 10
“Load Defaults” and press ENT to proceed. The next screen will say “Load
Defaults ?” with the prompt to press and hold ENT for 2 seconds to confirm. To
complete this press the ENT button until the bar graph has completed and the
screen says “Defaults Loaded”. This will give you all the basic settings that are
factory set. You will now need to re-calibrate the sensor and check all the settings
are suitable.
6.16 RS232 / RS485 Port
It is possible to factory set the data communications port to either RS232 or
RS485. Once configured at the factory it is not possible to change unless the unit
is returned to Cambridge Sensotec Ltd.
Data from the Rapidox is sent on demand to the 9-way 'D' type socket (7) on the
rear panel and can be read using a simple terminal programme such as
'HyperTerminal' in Windows, or with the user's own custom software.
Alternatively a simple and convenient data-logger programme is included with the
supplied software and is described in section 8 below.
6.16.1 RS232 Protocol
Rapidox data can be read from the RS232 port at the back of the unit. The default
RS232 configuration is 115200-8-N-1, as shown in this example for COM1:
Figure 4: Rapidox default COM properties box
Alternatively, the baud rate can be reduced to 57600 or 9600 via the “Set Baud
Rate” menu item, using the front panel keypad on the Rapidox. This setting is
stored in EEPROM.

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Connection: Connect to RS232 socket at the back of the Rapidox using a 9 way D-
type plug. Signals are as follows:
Rapidox D-type Socket: PC/PLC:
Pin# 2 = Data Out Data In (RX)
Pin# 3 = Data In Data Out (TX)
Pin# 5 = Common/Gnd -- Common/Gnd
Figure 5: Rapidox RS232 pin configuration
All other pins (1,4,5,7,6,9) = Don’t care
Reading Data: Data is read using command “D”. Send the single character “D” to
the Rapidox. The Rapidox replies with one of the following responses. All valid
responses end with [CR] & [LF] (where [CR] = ASCII 13 and [LF] = ASCII 10).
Response: !Initialising[CR][LF]
Meaning: Rapidox is still initialising
Response: !No sensor or sensor fault[CR][LF]
Meaning: Sensor is not connected, or there is a fault in the sensor
Response: d2.959E+05,1.426E+01,2.000E-03,23:19:40,14/01/00,
ALM1&2,0[CR][LF]
Meaning: “d” means data is being sent
“2.959E+05” is Oxygen reading in ppm
“,” = data separator
“1.426E+01” is Oxygen sensor reading in mV
“,” = data separator
“2.000E-03” is pressure sensor reading in bar
“,” = data separator
“23:19:40” is Rapidox time
“,” = data separator
“14/01/00” is Rapidox date
“,” = data separator
“ALM1&2” means that both alarm conditions 1 and 2 exist **
“,” = data separator
“0” is an integer indicating a sensor fault code: 0 = no faults
[CR] = ASCII 13 (Carriage Return character)
[LF] = ASCII 10 (Line Feed character)
RS232
5
4
3
2
1
9
8
7
6

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** If oxygen alarm is not set, this data is empty, so the response would look like:
d2.959E+05,1.426E+01,2.000E-03,23:19:40,14/01/00,,0[CR][LF]
Response: ?
Meaning: “D” command was not recognised. Try to send it again.
6.16.2 RS485 protocol
Please contact Cambridge Sensotec for further information on this feature.
6.17 Sensor Lifetime and Replacing
When a new sensor is fitted the Rapidox analyser checks the output of the sensor
in air and stores the output characteristic of the particular sensor. All the sensors
are very slightly different to each other when manufactured but will have a life
expectancy of 3-5 years depending on the nature of use.
Over time the output of the sensor drifts slowly downwards until it is no longer
sufficient to work correctly. At this point a new sensor should be purchased and
installed. The analyser will warn the user when the time is getting close to
replace the sensor. This point is defined as 70% of the output when it was brand
new.
When the output drops to 70% of the new-value a warning message stating
“Replace Sensor Soon” will flash on the screen each time the unit is switched on.
If no action is taken and the output drops below 65% of the new-value then the
analyser will upgrade the message to say “Sensor Must Be Replaced”
Contact Cambridge Sensotec for advice on purchasing and replacing the sensor
inside the unit.
6.18 Printing
If you have purchased the printer option then you can print data from the analyser
straight on to thermal paper. Simply connect the printer to the serial socket on
the rear of the Rapidox and make sure the printer is switched on (battery and
mains versions are available). To print the live values on the LCD at any time
simply press the RIGHT arrow button on the front panel. Each press of the button
will print out the serial number followed by the data in a tabbed format followed
by a blank line. If the button is held down, the printer will keep printing data (but
not the serial number).
When the printer is first connected or turned on, a “start-up” message like the one
displayed on the LCD when the Rapidox is switched on will be printed, and will