Satlantic Suna User manual

Deep SUNA Manual
For SUNA running firmware version 2.4 or later
SAT-DN-00627, ev. E, 2014-Dec-01
Satlantic LP
3481 North Marginal Road
Halifax, Nova Scotia B3K 5X8
anada
[phone]
[e-mail]
www.satlantic.com
O N F I D E N T I A L
This document contains information proprietary to Satlantic or to a third party to which Satlantic may have legal
obligation to protect such information from unauthorized disclosure, use or duplication. Any disclosure, use or
duplication of this document in whole or in part, or of any of the information contained herein, for any purpose
other than the specific purpose for which it was disclosed is expressly prohibited except as Satlantic may
otherwise agree to in writing.
© 2013, Satlantic LP, All rights reserved

Deep SUNA Manual
For SUNA running firmware version 2.4 or later
Table of Contents
1. About This Manual..............................................................................................5
2. Start-up Guides...................................................................................................6
2.1 Start-up Guide for Terminal Interface..........................................................6
2.2 Start-up Guide for Analog Output.................................................................7
3. The SUNA Sensor..............................................................................................8
3.1 Introduction and Background.......................................................................8
3.2 Specifications...............................................................................................8
3.2.1 Build Variants........................................................................................8
3.2.2 Electrical Specification........................................................................11
3.2.3 Performance Specifications................................................................13
3.3 Operating Principles...................................................................................15
3.3.1 Absorbance Spectroscopy..................................................................15
3.3.2 Nitrate oncentration..........................................................................16
3.3.3 Interferences and Mitigation................................................................16
4. Terminal Interface of the SUNA.......................................................................18
4.1 Sensor Operating States............................................................................18
4.2 ommand Line Interface............................................................................18
4.2.1 Status and Maintenance ommands.................................................19
4.2.2 File ommands...................................................................................20
4.2.3 onfiguration ommands...................................................................21
4.2.4 Polled Mode ommands.....................................................................35
4.2.5 APF Mode ommands........................................................................35
4.2.6 Analog Output.....................................................................................39
5. onfiguration Parameters in ontext...............................................................42
5.1 Build onfiguration.....................................................................................42
5.2 Input / Output onfiguration.......................................................................43
5.3 Data Acquisition onfiguration...................................................................44
5.3.1 ontinuous and Fixed-time Operating Mode......................................44
5.3.2 Periodic Operating Mode....................................................................44
5.3.3 Polled Operating Mode.......................................................................45
5.3.4 APF Operating Mode..........................................................................45
5.4 Data Processing onfiguration..................................................................46
5.4.1 Basic Data Processing........................................................................46
5.4.2 Special ase: Temperature-Salinity orrection.................................47
5.4.3 Special ase: Bromide Tracing..........................................................47
5.4.4 Special ase: Highly Absorbing Water...............................................47
6. Use Scenarios...................................................................................................49
6.1 Profiling.......................................................................................................49
6.1.1 Objectives and onsiderations...........................................................49
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
6.1.2 Example..............................................................................................49
6.2 Moored........................................................................................................50
6.2.1 Objectives and onsiderations...........................................................50
6.2.2 Example..............................................................................................51
6.3 Free Floating Profiler..................................................................................52
6.3.1 Objectives and onsiderations...........................................................52
6.3.2 Example..............................................................................................52
7. SUNA Frame Definitions...................................................................................55
7.1 Frames with Synchronization Headers......................................................55
7.2 APF Frame.................................................................................................57
7.3 MBARI Frame.............................................................................................58
8. SUNA alibration File.......................................................................................59
8.1 File Name...................................................................................................59
8.2 File Format..................................................................................................59
8.3 File Interpretation........................................................................................59
9. Firmware Upgrade............................................................................................60
9.1 Firmware Upgrade Using SUNA om.........................................................60
9.2 Firmware Upgrade Using the Terminal Interface.......................................60
10. Troubleshooting..............................................................................................61
10.1 Sensor Is Not Responsive........................................................................61
10.2 Sensor Output Is Unexpected..................................................................62
11. Accessories.....................................................................................................63
11.1 Foul Guard................................................................................................63
11.2 Flow ell...................................................................................................63
11.3 Glider Mounting Package.........................................................................64
12. Maintenance...................................................................................................65
13. Safety And Hazards........................................................................................66
13.1 Pressure Hazard.......................................................................................66
13.2 Electrical Hazard......................................................................................66
13.3 Deployment and Recovery Safety............................................................66
14. Warranty.........................................................................................................67
14.1 Warranty Period.......................................................................................67
14.2 Restrictions...............................................................................................67
14.3 Provisions.................................................................................................67
14.4 Returns.....................................................................................................67
14.5 Liability......................................................................................................67
15. ontact Information........................................................................................68
16. Revision History..............................................................................................69
Index of Tables
Table 1: Sensor dimensions, basic options............................................................8
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
Table 2: Optional features......................................................................................9
Table 3: SUNA dimensions depending on options.................................................9
Table 4: Power requirements................................................................................11
Table 5: Electrical pin assignments and descriptions..........................................12
Table 6: General performance specifications.......................................................13
Table 7: Accuracy specification for nitrate concentrations...................................13
Table 8: Precision specification for nitrate concentrations...................................14
Table 9: Limit of Detection and Limit of Quantification........................................14
Table 10: File access commands.........................................................................20
Table 11: Build configuration parameters.............................................................24
Table 12: Input / output configuration parameters...............................................27
Table 13: Data acquisition configuration parameters...........................................32
Table 14: Data processing configuration parameters..........................................35
Table 15: ombinations of data processing configuration parameters...............35
Table 16: Protocol for single-character APF commands.....................................38
Table 17: Protocol for multiple-character APF commands..................................39
Table 18: SUNA build variants.............................................................................43
Table 19: Data acquisition configuration parameters by operating mode...........47
Table 20: Data processing configuration parameters in use case context..........49
Table 21: onfiguration parameters illustrating a profiling deployment...............51
Table 22: onfiguration parameters illustrating a moored deployment...............53
Table 23: onfiguration parameters illustrating a float deployment.....................55
Table 24: Synchronization header frame definitions............................................57
Table 25: APF data frame definition.....................................................................58
Table 26: MBARI data frame definition................................................................59
Index of Illustrations
Illustration 1: Drawing of Deep SUNA..................................................................10
Illustration 2: Drawing of Deep SUNA with glider mounting option......................10
Illustration 3: SUNA Sub onn M BH8MNM bulkhead connector face view.......11
Illustration 4: Foul Guard......................................................................................64
Illustration 5: Flow ell..........................................................................................65
Illustration 6: Glider Mounting Package................................................................65
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
1. About This Manual
1. About This Manual
The SUNA is a versatile sensor that can operate in diverse environments. It is adaptable
to a wide variety of deployment scenarios and supports multiple interfaces. This manual
provides guidance on how to properly deploy the sensor and on how to interact with it.
Before operating the sensor, understand all warnings and cautions cited in section 13.
Safety And Hazards.
Section 3. The SUNA Sensor gives performance specifications, sensor dimensions, and
explains the measurement technology.
The SUNA om software provides a graphical user interface to facilitate working with the
sensor. It supports sensor configuration, system testing, data management, and data
re-processing. SUNA om has a separate user manual, which is available on the
installation D and from within the SUNA om application via context sensitive help.
SUNA om does not address the requirements for all deployment scenarios, particularly
those related to integrated systems. For this reason, the complete firmware interface is
specified in Section 4. Terminal Interface of the SUNA. Explanations on how to start
when working in this environment are found in Section 2.1 Start-up Guide for Terminal
Interface.
The decision on how to configure the sensor is driven by the type of deployment.
Section 5. onfiguration Parameters in ontext provides an explanation of configuration
parameters. Section 6. Use Scenarios discusses configuration choices for some types
of deployments, and Section 7. SUNA Frame Definitions defines the output data.
omponents supporting the deployment of the SUNA are specified in Section 11.
Accessories.
Some deployments benefit from components that can be added to the SUNA.
The SUNA is a versatile sensor and research is ongoing to expand its performance and
use. Support of new features can be coded into future SUNA firmware versions. Section
9. Firmware Upgrade provides instructions on how to install such a new firmware.
Explanation and remediation for some unexpected behavior of the SUNA are addressed
in Section 10. Troubleshooting, and guidance on handling is provided in Section 12.
Maintenance.
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
2. Start-up Guides
2. Start-up Guides
Refer to the uick Start section of the SUNA om User manual available on your
installation D or bundled with the SUNA om software to test basic operation and
configuration. The following start-up guides will guide you through the process of
connecting to interfaces not available via SUNA om.
2.1 Start-up Guide for Terminal Interface
Terminal Emulator
The end user can interface with the SUNA by using terminal emulator software that can
connect to a serial com port. Some computers have pre-installed terminal emulators
(e.g., HyperTerm in some Microsoft Windows operating systems). Other terminal
emulators are, e.g., Putty, Tera Term, Bray's Terminal. This guide assumes that the
user is familiar with operating a terminal emulator.
Cable
In order to use the terminal interface, connect the sensor's serial cable to a com port of
the computer, and power the sensor with 8–18 VD , capable of providing a current of at
least 1 A.
Serial Interface
The SUNA communicates via serial port, using the RS-232 protocol at 8 bit, no parity, 1
stop bit and no flow control. The baud rate is factory set to 57600. If this baud rate does
not work, try the other possible baud rates (9600, 19200, 38400, 115200) or use
SUNA om to scan for the current baud rate.
Command Line
When power is applied to the SUNA, output and behavior depend on the current sensor
configuration. In all instances the user can bring the sensor to the command line by
repeatedly sending the $-character to the sensor.
The sensor indicates that it is accepting commands by outputting the SUNA> prompt. All
commands available at the command line are given in section 4.2 ommand Line
Interface.
An example command is selftest. It turns on all subsystems and briefly reports their
status.
Using the get opermode command will report the current operation mode. onsult
section 5.3 Data Acquisition onfiguration to understand the different operating modes,
and use the set opermode command if another operating mode is needed. Use the
get cfg command for the current sensor configuration.
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
2. Start-up Guides
2.2 Start-up Guide for Analog Output
The SUNA has an optional analog output system.
The end user can determine if the sensor is equipped for analog output either via the
SUNA om software or the terminal interface (see section 2.1 Start-up Guide for
Terminal Interfaceand section 4. Terminal Interface of the SUNA).
In SUNA om the DA calibration function will be visible under the Advanced, Sensor
menu item if this function is available.
At the terminal interface, use the get analgbrd command. The response will be either
Available or Missing.
Interpreting Analog Output
When analog output is available, the sensor automatically generates output voltage and
current.
The sensor generates an output voltage in the 0 to 4.096 V and an output current in the
4 to 20 mA range. The lower range of the respective output interval corresponds to the
DA Minimum and the upper range of the interval corresponds to the DA Maximum
configuration parameter.
Both the DA minimum and DA maximum values can be modified, either via
SUNA om or via the terminal interface, to tune the output range to the expected nitrate
concentration range.
While the output voltage and current generated by the sensor are highly accurate,
losses may occur across cables that are used. For details on calibration and data
interpretation, see section 4.2.6 Analog Output.
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
3. The SUNA Sensor
3.1 Introduction and Background
The SUNA (Submersible Ultraviolet Nitrate Analyzer ) is a chemical-free nitrate sensor.
It is based on the ISUS (In Situ Ultraviolet Spectroscopy) technology developed at
MBARI (cf. Kenneth S. Johnson, Luke J. oletti, In situ ultraviolet spectrophotometry for
high resolution and long-term monitoring of nitrate, bromide and bisulfide in the ocean,
Deep-Sea Research I 49 (2002) 1291–1305).
3.2 Specifications
3.2.1 Build Variants
The SUNA housing is made from anodized aluminum. The housing is designed to
withstand depths of up to 2000 m.
Table 1: Sensor dimensions, basic options.
Dimension Basic ersion
Material Anodized Aluminum
Depth Rating 2000 m
Diameter 57 mm
Length
(without connector and anode)
555 mm
UV Deuterium Lamp 900 h lifetime
Path length 10 mm
Displacement 1384 cm³
Weight 1.8 kg
Electrical connector Sub onn M BH8MNM
Storage temperature –20 to +50
Operating temperature --2 to +35
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
Optional features and accessories are available for each of the two build variants.
Optional features change some sensor dimensions, as shown below.
Table 2: Optional features
Feature / Accessory Comment
alibration n/a: NO3 only
Normal: NO3 & seawater
Analog output Optional
Internal data logging Optional 2 GB (or larger) solid state
Scheduling Optional
USB connectivity Optional
Advanced processing APF interface and real time temperature-
salinity correction
Power control Relay
Passive fouling control opper fouling guard
Sampling control Flow through cell
Power supply Battery pack
Table 3: SUNA dimensions depending on options.
Options Length Displacement Weight
Deep SUNA 555 mm 1384 cm³ 1.8 kg
Deep SUNA, glider mounting 594 mm 1482 cm³ 1.9 kg
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
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10
Illustration 1: Drawing of Deep SUNA.
Illustration 2: Drawing of Deep SUNA with glider mounting option.

Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
3.2.2 Electrical Specification
The SUNA requires power in the 8–18 VD range with a supply current of 1 A. Power
consumption depends on the operating state. During data acquisition, it is typically 7.5
W (±20%). In standby, at the command prompt, the current draw is around 20 mA.
Polled and APF operating modes will time out after a configurable time of inactivity,
bringing the SUNA processor into a low power state with a consumption below 3 mA. In
fixed-time operation and between periodic operation event, power control is handed to a
supervisor circuit, which reduces power consumption to less than 30 μA.
Table 4: Power requirements
State oltage Current
Supervised Sleep
8–18 VD
< 30 μA
Processor Sleep < 3 mA
Standby ~20 mA at 12 V
Sampling ~625 mA at 12 V (nominal)
The SUNA connector is a Sub onn M BH8MNM. With a face view numbering as in the
following illustration, the pin assignments are listed in the following tables.
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Illustration 3: SUNA SubConn MCBH8MNM bulkhead connector face view.

Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
Table 5: Electrical pin assignments and descriptions.
Pin Standard Optional
USB / Analog Out
Relay
1 VIN VIN VIN
2 GND GND GND
3 – USB V+ –
4 – – SW-PWR
5 TXD TXD / D+ TXD
6 RXD RXD / D– RXD
7 – VOUT TS
8 – IOUT –
Pin Assignment Description
VIN External D power supply, 8–18 VD
GND Power supply return, signal ground
USB V+ USB 5V power
SW-PWR Switched power
TXD RS-232 transmit (from SUNA)
RXD RS-232 receive (to SUNA)
D+ USB D+
D– USB D–
VOUT Analog volt output
IOUT Analog current output
TS lear to send, an RS-232 compatible signal from the SUNA
The relay option is specially designed for the APEX float interface. Float battery voltage
is applied to the VIN and GND pins continuously throughout a profile. To switch power
to the SUNA, the float controller briefly applies positive battery voltage to the switched
power pin, SW-PWR, to activate the relay. The relay connects VIN to the SUNA. The
relay remains latched until the SUNA releases it in response to a command. This
mechanism allows the SUNA to remain powered throughout a profile even when the
float controller is in a low-power state. The SUNA then switches between low-power and
data acquisition in response to commands from the float controller.
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
3.2.3 Performance Specifications
The SUNA sensor is designed to measure the concentration of nitrate ions in water. The
measurement result is in molar concentration, units of micro molar (μM). For user
convenience, this concentration is converted into units of milligram per liter (mg/l), and
output in digital form as well. 1 μM nitrogen corresponds to 0.014007 mg/l nitrate.
Table 6: General performance specifications
Measurement Nitrate concentration [NO3-]
Thermal compensation (optional) 0–35º
Salinity compensation (optional) 0–40 psu
Optical path length 10 mm, optional 5 mm
Spectral range 190–370 nm
The performance of the sensor depends on a number of factors. One factor is the
optical path length, normally at 10 mm, optionally at 5 mm. The optical path length
influences the concentration measurement range covered by the sensor, and the
accuracy of the results. Another factor is the type of calibration: a sensor specific
calibrations are more accurate than a class-based calibration. The former uses
extinction coefficients that are measured using the sensor itself; the latter uses
averaged extinction coefficients, that were obtained from many sensors.
Table 7: Accuracy specification for nitrate concentrations
Concentration Range 10 mm Path Length
For regular seawater and freshwater calibrations
up to 1000 μM 2 μM or 10%
up to 2000 μM 2 μM or 15%
up to 3000 μM 2 μM or 20%
up to 4000 μM out-of-range
For class-based freshwater calibrations
up to 1000 μM 2.5 μM or 20%
up to 2000 μM 2.5 μM or 25%
up to 3000 μM 2.5 μM or 30%
up to 4000 μM out-of-range
The precision of the sensor depends on its data processing configuration (see section
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
5.4 Data Processing onfiguration). In oceanographic or estuarine settings, data must
be processed for seawater, in freshwater settings data processing is ideally selected to
be for freshwater. In seawater settings, the sensor precision can be brought into the
freshwater precision by using Temperature-Salinity- orrection (see section 5.4.2
Special ase: Temperature-Salinity orrection).
Table 8: Precision specification for nitrate concentrations
Processing configuration Freshwater or Seawater
with T-S-Correction
Seawater
[0–40 psu]
Short-term precision [at 3σ] 0.3 μM 2.4 μM
Drift [per hour of lamp time] <0.3 μM <1.0 μM
The limit of detection is defined as the nitrate concentration that has a value of 3 times
the standard deviation of the blank nitrate concentration. As such, it is 3 times the
standard deviation as measured for the sensor precision, which depends on the
processing mode.
The limit of quantification specifies the limit at which two samples can be reasonably
distinguished. Typically, it is 10 times the standard deviation of the blank nitrate
concentration.
Table 9: Limit of Detection and Limit of Quantification
Processing configuration Freshwater or Seawater
with T-S-Correction
Seawater
[0–40 psu]
Limit of detection [LOD] 0.3 μM 2.4 μM
Limit of quantification [LOQ] 1.0 μM 8.0 μM
Natural waters may contain a mixture of interfering species that are typically hard to
delineate. The impact of interfering species on the measured nitrate concentration was
determined under laboratory conditions. The specification covers two classes of
interfering species: suspended particulate matter (Turbidity) and colored dissolved
organic matter ( DOM). The impact is independent of the optical path length, from
theoretical considerations as well as experimentally confirmed. However, the SUNA can
only operate up to absorbances of approximately 1.5. This limit is typically reached at
625 NTU (Nephelometric Turbidity Units) for 10 mm path length, or at 1250 NTU for 5
mm path length. Naturally occurring DOM concentrations stay within the operating
range of the SUNA.
The following substances were uses as proxies for turbidity:
ARD Arizona Road Dust
Kaolin Kaolin Powder
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
TiO2 Titanium Dioxide
Turbidity
Sample
NTU
per mg/l
Absorbance at
225 nm (10 mm)
per mg/l
NO3 shift μM
in freshwater
per mg/l
NO3 shift μM
in seawater
per mg/l
ARD 1.25 0.0016 <-0.002 0.01
Kaolin 1.5 0.0085 <0.001 0.02
TiO2 15.0 0.0090 <0.001 <0.001
The following samples, obtained from the International Humic Substances Society, were
used as proxies for DOM:
PLFA Pony Lake Fulvic Acid – Reference (1R109F)
SRFA Suwannee River Fulvic Acid – Standard (1S101F)
PPHA Pahokee Peat Humic Acid – Reference (1R103H-2)
CDOM
Sample
QSD
per mg/l
Absorbance at
225 nm (10 mm)
per mg/l
NO3 shift μM
in freshwater
per mg/l
NO3 shift μM
in seawater
per mg/l
PLFA N/A 0.017 0.4 0.6
SRFA N/A 0.027 <0.1 <0.1
PPHA 42 0.003 <0.01 <0.1
An interfering species generates a spurious nitrate concentration when the spectral
characteristics of the interfering species resembles that of nitrate. Typically, an RMSE
value that is more than a few times the RMSE of a pure nitrate sample should be taken
as an indication that interfering species are impacting the measurement. The RMSE
value is the square root of the mean of the sum of the squared differences between the
measured and the fitted absorbance; it provides a measure for the quality of the fit.
Independent measurements of turbidity and DOM, as well as an analysis of the
absorption spectrum, can refine the impact analysis.
3.3 Operating Principles
3.3.1 Absorbance Spectroscopy
The SUNA measures the concentration of dissolved nitrate in water. The sensor
illuminates the water sample with its deuterium UV light source, and measures the
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
throughput using its photo-spectrometer. The difference between this measurement and
a prior baseline reference measurement of pure water constitutes an absorption
spectrum.
Absorbance characteristics of natural water components are provided in the sensor
calibration file. The Beer-Lambert law for multiple absorbers establishes the relationship
between the total measured absorbance and the concentrations of individual
components. Based on this relationship, the sensor obtains a best estimate for the
nitrate concentration using multi-variable linear regression.
The approach described above was initially developed at MBARI (cf. Kenneth S.
Johnson, Luke J. oletti, In situ ultraviolet spectrophotometry for high resolution and
long-term monitoring of nitrate, bromide and bisulfide in the ocean, Deep-Sea Research
I 49 (2002) 1291–1305) and the technology then transferred to Satlantic.
3.3.2 Nitrate Concentration
Nitrate processing uses the 217–240 nm wavelength interval, which contains
approximately 35 spectrometer channels. For each channel, the absorbance is
calculated, and decomposed into individual absorbers using the MBARI method.
The precision of the nitrate concentration depends on the number of absorbers into
which the measured absorbance is decomposed. Thus, in freshwater deployments, the
number of concentrations to be fitted should be set to 1.
High absorbance conditions introduce inaccuracies into the nitrate concentrations.
Therefore, channels with an absorbance greater than 1.3 are excluded from processing.
If less than about 10 channels remain, the sensor is unable to determine a nitrate
concentration, and the measurement is no longer valid (out-of-bounds). Users can
overturn the standard setting and increase the absorbance cutoff, obtaining reduced
accuracy nitrate concentrations at higher absorbances. There is, however, a limit at
around 2.5 absorbance units, when nitrate concentrations can no longer be determined.
3.3.3 Interferences and Mitigation
The quality of the nitrate measurements can be impacted in a number of ways. This
impact has been quantified (see section 3.2.3 Performance Specifications) for some
significant interfering influences. Here, interferences are explained, and mitigation
options are explored.
Sample temperature: Seawater is known to have a temperature-dependent absorption.
If this effect is not taken into account, a bias and/or imprecision are introduced to the
reported nitrate concentration.
This effect can be mitigated by providing sample temperature and salinity to the nitrate
calculation, either in real-time (supported in APF mode) or in SUNA om post-
processing (collection of spectra and accompanying temperature and salinity data is
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
3. The SUNA Sensor
required). Temperature-salinity correction follows the approach developed at MBARI (cf.
arole M. Sakamoto, Kenneth S. Johnson, Luke J. oletti, Improved algorithm for the
computation of nitrate concentrations in seawater using an in situ ultraviolet
spectrophotometer, Limnol. Oceanogr.: Methods 7, 2009, 132–143).
Uncharacterized species in sample: A number of substances occurring in natural
water absorb in the UV spectral range where nitrate absorbs. Usually, the spectral
signature of those substances differs from that of nitrate. However, certain combinations
of water constituents may cause a bias in the calculated nitrate concentrations.
If significant concentrations of interfering species are suspected, sporadic chemical
analysis of water samples allows quantification and correction for the optical
interference.
Sensor drift: Over time, lamp output and throughput of optical components exhibit drift.
This drift translates into a drift in the measured nitrate concentrations.
A regular update of the reference (baseline) spectrum minimizes drift.
Lamp temperature: The lamp output depends on its temperature. Thus, the reference
(baseline) spectrum is ideally collected under conditions that mimic deployment
conditions.
If deployment temperatures are expected to vary by more than 10 ° , a temperature
characterization and subsequent data correction may be attempted.
Optically dense constituents: The sensor performance is compromised in optically
dense conditions, which transmit less light than necessary for the regression analysis.
With increasing optical density, the quality of the measurement (signal-to-noise)
decreases. Accuracy and precision of the nitrate concentrations decrease with
decreasing data quality, until the data are essentially random (or are reported as out-of
range, depending on sensor configuration).
The sensor can be configured to respond to optically dense conditions by repeating the
measurement with an increased spectrometer exposure time, thereby extending the
operating range of the sensor.
High optical densities are often caused by DOM or turbidity in the water sample. It has
been found that the DOM concentration in natural waters does not cause optical
extinction. On the other hand, highly turbid waters can cause such high absorption that
the SUNA is not able to measure nitrate. The operation limit for the 10 mm path length
variant is 625 NTU, and for the 5 mm variant it is 1250 NTU.
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
4. Terminal Interface of the SUNA
4. Terminal Interface of the SUNA
4.1 Sensor Operating States
At power-up, the SUNA's micro-controller starts the firmware. After initialization, it
retrieves the current settings, and enters its operating mode.
Within each operating mode, the firmware is in one of three states:
standby,
data acquisition,
command interface,
where the transition between the states is controlled by the firmware or driven by user or
controller input.
In standby, the sensor can be at different levels of power consumption. In periodic and
APF mode, the sensor achieves the lowest level between data acquisition events,
whereas in polled mode, the power level is a bit higher.
The user can interrupt the SUNA's regular operation in order to enter the command line.
Data Acquisition to Command Interface
Sending a $ character (possible multiple times) will bring the sensor to the command
line. The command line reports via the SUNA> prompt that it is ready to receive
commands.
Command Interface to Data Acquisition
The command line is terminated via the exit or the reboot command.
Data Acquisition to Standby
Only polled and APF modes have explicit commands (SLEEP and SLP, respectively) to
send the SUNA to standby mode.
In periodic mode, the sensor alternates between standby and data acquisition.
Standby to Data Acquisition
Any input will cause the SUNA to come out of its standby state. Then, it waits for 15
seconds for the $ input character to enter the command line, before returning to the
standby state. When entering standby, the sensor requires approximately 15 seconds to
completely discharge its internal circuitry. Any attempt to bring the sensor out of its
standby state occurring within this 15 second period can lead to undefined behaviour.
4.2 Command Line Interface
ommunication with the SUNA is conducted via RS-232 or USB connection. The sensor
checks for availability of a USB connection, and if present, uses a USB virtual com port
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Deep SUNA Manual
For SUNA running firmware version 2.4 or later
4. Terminal Interface of the SUNA
for input and output. Otherwise, the sensor communicates via RS-232.
ommands can be broadly grouped into the following categories:
1. Status and Maintenance
2. File Management
3. Query and Modify onfiguration
4. Polled Mode ommands
5. APF Mode ommands
4.2.1 Status and Maintenance Commands
Selftest
The selftest checks operation of sensor components, performs measurements, and
outputs the measurement results.
The last output line will be $Ok if all components performed according to expectations,
or $Error if one or more of the components failed the test. If a component did not
perform as expected, the output line of that component is terminated by an exclamation
mark (!), making it easier to locate the problem.
Get Clock and Set Clock
The get clock command outputs the time of the internal sensor clock. The time is
factory set to UT .
The set clock YYYY MM DD hh:mm:ss command sets the sensor clock to the
specified value.
Used Lamp Time
The firmware keeps track of the total on-time of the lamp, and outputs the number of
seconds via the get lamptime command.
DAC Low and DAC High
These commands are only available for SUNAs that have an analog output system.
The DAC Low command will generate the lowest analog output that is possible, and the
DAC High command will generate the highest analog output that is possible.
For details on how to make use of this feature, see section 4.2.6 Analog Output.
Upgrade
The firmware exits into the boot loader.
opyright © 2013, Satlantic LP, All rights reserved
19

Deep SUNA Manual
For SUNA running firmware version 2.4 or later
4. Terminal Interface of the SUNA
The boot loader allows installing of a new firmware onto the nitrate sensor. See section
9. Firmware Upgrade for details.
Reboot
This command causes the firmware to restart. It is equivalent to performing a power
cycle.
Exit
The command line exits, and data acquisition as configured in the operation mode
restarts. If the baud rate was changed in the current command line session, the sensor
will reboot in order to re-initialize with the new baud rate.
4.2.2 File Commands
File commands give access to data log, message log, and calibration files. All file
commands follow the syntax < ommand> <FileType> [<FileName>]. Data and
message log files are an optional feature. Use the selftest command to see if the sensor
has an internal file system, and if so, the space that is available.
File types are AL for calibration files, LOG for system log message files, and DATA for
files containing logged measurement data.
Table 10: File access commands
Command CAL LOG DATA Comment
List + + + Output a list of all files of the specified type
Output + + + Output the content of the specified file.
Recommended only for small AS II files.
The command cannot be interrupted.
Send + + + XMODEM transfer of file from sensor
Delete + + + Delete specified file from disk. Irreversible.
Receive + XMODEM transfer of file to sensor
The sensor can have many calibration files. The user can query the name of the
currently active file via the get activecalfile command. The active file cannot be
deleted from the sensor. When a calibration file is received by the sensor, it is made
active. The user can change the active file by the set activecalfile calfile-
name command.
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