Zebra-Tech D-Opto User manual

D-Opto Logger
Dissolved Oxygen Logger
Operation Manual

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Table of contents
1Introduction....................................................................................................3
1.1 Optical Sensor Technology.....................................................................3
2Software ........................................................................................................4
2.1 Installation ..............................................................................................4
2.2 Operation................................................................................................4
3Operation.......................................................................................................9
3.1 Installation ..............................................................................................9
3.2 Sealing the D-Opto Logger .....................................................................9
3.3 Logging Endurance ................................................................................9
3.4 Routine Maintenance............................................................................10
3.5 Calibration ............................................................................................11
Appendix 1: Data File Format ......................................................................13
Appendix 2: Communication Cable Wiring Scheme ....................................14
Appendix 3: LED flash sequence codes ......................................................15
Appendix 4: Trouble shooting ......................................................................16
Appendix 5: Specifications...........................................................................17
Appendix 6: Pressure correction chart.........................................................18
Appendix 7: Useful Conversions..................................................................19

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1 Introduction
The D-Opto Logger is a fully self contained dissolved oxygen logger,
incorporating a DO sensor, battery, and low power data logger in a rugged
compact underwater housing.
The D-Opto Logger uses a field-proven solid-state optical sensing system to
measure dissolved oxygen that is highly stable over long periods of time, even in
harsh conditions. The data is stored onboard in non-volatile memory. The D-Opto
Logger is setup, and data offloaded using simple Windows based software,
supplied with the instrument.
1.1 Optical Sensor Technology
Unlike conventional dissolved oxygen sensors, the D-Opto Logger sensing
element utilises fluorescence to measure dissolved oxygen. The basic principle
involves subjecting a fluorescing compound (ruthenium) to a fixed wavelength of
light. When the light source is removed, the compound emits a fluorescence, the
intensity of which is dependent on the oxygen levels present in the surrounding
water. An extremely stable electronic circuit has been designed to firstly excite
the ruthenium, and then measure the intensity of the resulting fluorescence.
Therefore using this circuitry, the D-Opto Logger should provide accurate
dissolved oxygen measurements over long periods of time (many months)
without re-calibration.
Unlike conventional polarographic dissolved oxygen sensors, the optical method
does not consume oxygen. Consequently the measurement of dissolved oxygen
by the D-Opto Logger is unaffected by water movement. Similarly the D-Opto
Logger does not utilise a membrane or any other consumables, thus minimising
servicing requirements.

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2 Software
The D-Opto Logger is supplied with the custom designed Windows based
communication software program “D-OptoLog”. This software:
•Enables the user to communicate with the D-Opto Logger via a computer;
•Is used to setup the D-Opto Logger prior to deployment;
•Is used to download data from the D-Opto Logger to the PC after retrieval.
2.1 Installation
The D-Opto Logger is supplied with a software CD that contains the file “Install
D-OptoLogX.exe” (X = version number). Double clicking the file from Windows
Explorer will initiate installation onto the PC. There are no restrictions or
limitations on the distribution and installation of the D-OptoLog software.
During installation, the user can select the working path and directory, however it
is recommended that the default is used (“c:\Program Files\D-OptoLog”).
2.2 Operation
The D-Opto Logger is supplied with a communication cable. This cable has a 9
pin serial plug on one end, and a 3.5mm jack plug on the other end.
The 9 pin plug is plugged into the serial plug on the PC. If the PC does not have
a serial port, a USB to serial adaptor can be used. This adaptor plugs into the
USB port on the PC, and has a serial port that the communication cable 9 pin
plug can be plugged into.
The jack plug on the communication cable is plugged into the communication
socket, located inside the D-Opto Logger housing. This is accessed by removing
the D-Opto Logger end cap.
When D-OptoLog is started and the current port is unavailable, a port selection
window opens (Figure 1).

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Figure 1: D-OptoLog serial port selection window.
With most computers the D-Opto Logger will be connected to com port number 1.
However, if the D-Opto Logger is connected to the computer’s USB port via a
USB to serial converter, the port number will probably be either com port 4 or 5.
The selected com port is maintained in an configuration file on the PC.
Once the correct port has been selected, and the ‘OK’ button pressed, the
computer will start communicating with the D-Opto Logger. This may take up to 8
seconds, and when communication has begun the D-OptoLog main window will
open (Figure 2).

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Figure 2: D-OptoLog main window
The main window displays current dissolved oxygen (% saturation and PPM) and
temperature (°C) data, and is updated approximately once every second.
The serial number displayed is factory set and is unique to each D-Opto Logger.
It corresponds to the number displayed on the outside of the D-Opto Logger
housing.
The logger setup section enables the operator to set the desired logging
parameters.
The “Plot” button enables a graphical plot of historic D-Opto Logger data to be
displayed on the screen.
The “Calibration” button opens the D-Opto Logger Calibration window (Figure 4).
All calibration values are calculated and stored internally by the D-Opto Logger.
The “Restore Defaults” button causes the D-Opto Logger to resort back to the
original factory calibrations. A full description of the calibration procedure is
outlined in the operation section.
The “Altitude Correction” button opens up the Pressure Correction Calculator
which provides a tool for pressure correcting the dissolved oxygen saturation

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content of fully aerated water (Figure 5). It will accept either altitude (m) or
barometric pressure (mBar).
By pressing the “Restore defaults” button, the original factory calibration values
are reinstated by the D-Opto Logger.
Figure 4: D-OptoLogger Calibration window.

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Figure 5: Pressure Correction Calculator

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3 Operation
3.1 Installation
A new battery should always be used when starting a deployment. Good quality
alkaline batteries such as, Duracell or Energizer, should always be used.
The D-Opto Logger can be mounted in any orientation. The body can be
clamped in position; however avoid using excessive force. A safety wire can be
attached to the eyelet swivel on the top cap of the logger. It is not recommended
that the D-Opto Logger is suspended solely from the eyelet swivel.
3.2 Sealing the D-Opto Logger
The D-Opto Logger end cap features a dual “O” ring sealing system. It is
essential that these “O” rings are properly serviced and maintained; otherwise
moisture may penetrate the housing.
The “O” rings must be cleaned and lubricated each time the end cap is replaced,
prior underwater deployment.
1) Using the “O” ring pick supplied, remove the “O” rings from the inside of
the end cap and the body of the D-Opto Logger
2) Using a lint free tissue, clean the “O” ring seats, the corresponding “O”
ring surfaces, and both “O” rings
3) Lightly grease both “O” rings with the grease supplied with the D-Opto
Logger.
4) Replace the “O” rings, ensuring no hairs or particles become trapped
under them.
5) Screw the end cap onto the D-Opto Logger body. Do not over tighten.
3.3 Logging Endurance
The D-Opto Logger can log 10,080 data records into non-volatile memory. Each
data record consists of the time and date, battery voltage, dissolved oxygen
percent saturation, PPM and temperature (See appendix 1).
Data is retained in the non-volatile memory until a new logging session is started,
at which point the memory is cleared of the previous data.
Memory logging endurance for different logging intervals are shown in table1. In
reality battery power may limit the deployment duration, not memory capacity.

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The D-Opto Logger will operate correctly until the battery voltage drops below
around 7.0 volts. If this occurs whilst the D-Opto Logger is in logging mode, the
last set of data values in the data file will be set to zero, and the D-Opto Logger
enters a low power sleep mode, with no further data values being logged.
Logging Interval
(minutes)
Memory Endurance (Days)
Standard D-Opto Logger
1 7
5 35
10 70
15 105
30 210
60 420
Table 1. Memory endurance
3.4 Routine Maintenance
As with all instruments, it is good operating practice to make regular checks on
the quality of data being generated by the D-Opto Logger. This can be carried
out on site, using one of the following two methods:
1. Place a recently calibrated transportable dissolved oxygen sensor next to
the D-Opto Logger and compare the measurements. It is important to
allow a sufficient period of time for temperature equilibration to occur.
2. Place the D-Opto Logger in a solution of known dissolved oxygen content.
A solution of 0% dissolved oxygen saturation can be created by adding a
few teaspoons of sodium sulfite to 1 litre of distilled or fresh tap water.
The D-Opto Logger can tolerate some biofouling, however where possible steps
should be taken to minimise this; for example covering the D-Opto Logger can
reduce the amount of bio-growth by restricting available light. . The copper
biofouling control ring should reduce bio-growth in the area around the optical
window; this ring is sacrificial and may require replacement on an occasional
basis. Always use the nylon bolts supplied with the replacement ring to attach the
ring to the D-Opto Logger, and avoid over tightening.
Periodically it may be necessary to clean the D-Opto optical window, to remove
bio-growth or other accumulated deposits. DO NOT use a brush or any object
that may scratch or damage the optical window. Only use the cleaning pads
supplied with the D-Opto.