Xeos Ares User manual

Ares User Manual
OPTICAL TURBIDITY SENSOR
Version 1.0
Mar 2022

Ares User Manual Version 1.0
Shipped From
Contact Us
Email
[email protected]
Phone
[phone]
Fax
[phone]
Website
www.xeostech.com
Version History
Regular checks for the latest manual are suggested. Be sure to check Xeos Technologies’ manuals
page to compare versions and download the latest version.
Version No.
Date
Description
0.1
May 2021
Original draft document
0.2
Oct 2021
Expanded command description and adjusted timings for the
18-bit system, frame redefinition
0.3
Jan 2022
Frame redefinition to include checksum, added bulkhead
1.0
Mar 2022
Updated cover photo, corrected connector reference

Ares User Manual Version 1.0
Overview
The Ares Turbidity Sensor features state-of-the art technology for measuring water clarity for
environmental water quality monitoring, oceanographic research, marine operations and
aquaculture monitoring. The Ares is based on the optical measurement principle, using
ultrabright, energy-efficient infrared LEDs as an excitation source and detectors with filtering to
measure the infrared light scattered by suspended particulate material in a water volume. These
digital optical sensors are programmed with a calibrated response to the scattered light that can
be converted to quantitative measurements of turbidity (measured in Nephelometric Turbidity
Units or NTUs).
The excitation light from the LEDs is carried to the sample volume through optical fiber and
scattered light is returned through accompanying optical fiber angled at 90 degrees. The fiber
optics serve two key functions: to increase the efficiency of the light delivery and recovery thus
reducing power requirements, and to enable a much smaller optical head.
Specifications
Mechanical
Length (excluding connector)
10.5 cm / 4.13 inch
Diameter
3.175 cm / 1.25 inch
Weight in air
148 g
Depth Rating
500 m
Material
Acetal plastic with copper-nickel faceplate
Electrical
Input voltage
6-18 VDC
Current draw @ 12 V (analog-only sensor)
10 mA
Current draw @ 12 V (digital+analog sensor)
12 mA
Analog voltage out (nominal)
0-5 V
Baud rate
9600-115200 (38400 default)
Serial configuration
8 bits, no parity, 1 stop bit, no flow control
Optical
Wavelength
850 nm
Optical bandwidth
30 nm

Ares User Manual Version 1.0
General
Range
150 or 1500 NTU
Fixed for analog sensors
Configurable for digital+analog sensors
Temperature range (operating)
0 to +40 °C
Bulkhead Connector Pinout
Sensor bulkhead connector is a MCBH6M (face view below); mating connector is an MCIL6F.
Pin
Function
1
Voltage In (DC)
2
Ground
3
RS232 TX
4
RS232 RX
5
Analog Out
6
Ground
* In an analog-only sensor, the digital interface is disabled.
Safety
If sensor is suspected of being flooded, *slowly* loosen the bulkhead just enough to release the
pressure. Backing the bulkhead out of the body creates extra volume inside the housing,
reducing the pressure.
Cleaning and Maintenance
Cleaning the sensing area should be done carefully and without abrasive cleaners that could
scratch the epoxy windows. For example, mild detergent and a soft toothbrush are suitable.
Before each mating of the bulkhead connector, it should be greased with MolyKote 44 Medium.
Calibration
The Xeos Turbidity Sensor is currently only calibrated at the factory. User recalibration is not
recommended at this time.

Ares User Manual Version 1.0
Digital Configuration Commands
This section applies only to digital sensors.
The prompt is available after sending the Ares a carriage return (Enter key).
Command
Description
Argument Values
$help
Returns current settings and list of commands
$set range arg
Sets the turbidity saturation value in NTU
150, 1500
$set autogain arg
Turns autogain on/off
on, off
$set averaging arg
Turns averaging on/off
on, off
$set interval arg
Set the frame interval in milliseconds
300-3600000
$set lowgain cal arg1 arg2
Set calibration coefficients for 0-1500 range
a1 a0 (see notes)
$set highgain cal arg1 arg2
Set calibration coefficients for 0-150 range
a1 a0 (see note)
$set baud arg
Sets the sensor baud rate
9600, 19200, 38400,
57600, 115200
$set frame ??????
Set frame format. Fields are ’serial number’,
‘seconds’, ‘counts’, ‘NTU’, ‘LED’, ‘Ascii/Binary’
y/n y/n y/n y/n y/n
a/b
$exit
Leave menu and continue measurements
Range
The range of the sensor is configurable to either 150 or 1500 NTU. Autogain must be disabled
to guarantee all data is collected in a given range.
Autogain
Autogain works in one of two ways, depending on the sample interval.
If the sample interval is ten seconds or longer, then for each sample the Ares first tries a
measurement at high gain. If the sample is near saturation, then the Ares transmits a frame. If
it is near saturation, the Ares immediately switches to low gain, repeats the sample, and then
sends out the frame.
If the sample interval is less than ten seconds, then a near-saturation reading causes the Ares to
switch to the lower gain for the next sample. If Ares is in low gain, then three consecutive
samples below a threshold will cause it to switch to high gain for the next sample.
The threshold NTU values for gain switching include some hysteresis to limit repeated gain
switching for turbidities close to the thresholds.
Averaging
If averaging is enabled, and the sample interval is five seconds or longer, ten individual
measurements are collected. Those are then averaged and a single frame is transmitted.
If the sample interval is less than five seconds, Ares does not have time to perform averaging
and overrides the averaging setting.

Ares User Manual Version 1.0
Interval
Set the output frame interval from 300 ms (rate = 3.3 Hz) to 3600000 ms (rate = 1 per hour).
Calibration Coefficients
These should only be changed by advanced users. Contact Xeos for more information.
Baud
Sets the baud rate of the output frames. The change in baud rate is immediate, so the user end
will not longer be able to communicate with the sensor unless it also changes its baud rate.
Frame Configuration
The fields of a frame can be enabled or disabled, but the order of the fields is fixed. The fields
are:
Serial
number
Seconds since
power up
Counts
Calibrated turbidity
in NTU
Relative LED
output
Checksum
The number of seconds since power up is nominal - the Ares does not perform rigorous
timekeeping. If timing is critical for an application, then the frame should be timestamped
externally. The seconds value rolls over at 86400 (i.e. the number of seconds in 24 hours).
Counts will generally be positive values, but for low turbidities they may be negative. On the
other hand, calibrated turbidity is clamped to a minimum value of 0 NTU.
Relative LED output is a measure of the LED intensity, relative to the output at 20 C when the
sensor was calibrated. LED output is inversely proportional to temperature. Though the
temperature sensitivity of the Ares is small, advanced users may wish to apply an additional
correction using this field. Contact Xeos for more information.
The checksum is a two-letter code. The algorithm starts by summing all of the byes in the
frame before the checksum into a 32-bit value. It then takes the least significant byte of that
sum and converts each nibble into a printable ascii character by adding 65.
Note: At the time of writing, binary frames have not yet been implemented.
Exit
Data collection resumes with the exit command. If, while in the menu, no input is received for
one minute, then data collection automatically resumes.

Ares User Manual Version 1.0
Mounting and Field-use Considerations
The Ares is designed to be easy to use. Simply power it up and collect the output digital or
analog signal. However, some considerations will ensure that the data is of the highest quality.
These include sample volume, ambient light, bubbles, sediment, and biofouling.
The primary sample volume, defined as the volume of overlapping fields-or-view of the source
and detection fibers, is small and close to the end of the sensor. However, turbidity, by its
nature causes scattering in all directions. Some light scatters multiple times over a much larger
volume, before being detected by the Ares. For the most accurate measurements, an
unobstructed volume of about 10 cm around the end of the sensor is recommended. The
impact of objects in that volume will increase as they get closer to the Ares’ optical input and
output.
The Ares uses modulated light to make its measurement. This technique is the same as that
used by infrared remote controls for household electronics. The technique allows the signal of
interest to be separated from the unmodulated ambient light. However, very strong light levels
will reduce the margin available from the photodetector to make its measurements. Thus,
mounting the Ares pointing upward near the water surface would not be recommended.
Fortunately, water strongly absorbs infrared light, so mounting even at shallow depths below
the surface, either horizontally and facing downward is sufficient to reduce ambient light levels.
If the Ares is mounted in a place with many bubbles, they may become trapped in the copper
endplate if the Ares is mounted facing downward. In those environments, mounting
horizontally would be preferrable. However, generally below a few meters’depth, bubbles
should not be an issue. Similarly, mounting the Ares facing upward in a high sediment
environment could allow sediment to collect on the sensing face. In that case mounting
horizontal or downward is preferred.
Biofouling is a problem common to most aquatic sensors. The Ares uses a copper-nickel
endplate to deter biofouling. The time between required cleaning of the sensor will vary
greatly from site to site and between applications.

Ares User Manual Version 1.0
Warranty, Support and Limited Liability
Xeos Technologies Inc. warranties the Ares turbidity Sensor to be free of defects in material or
manufacturing for a period of one year following delivery. Liability is limited to repair or
replacement of the defective part and will be done free of charge.
LIMITED WARRANTY: Xeos Technologies Inc. warrants that the product will perform substantially
in accordance with the accompanying written materials for a period of one year from the date of
receipt.
CUSTOMER REMEDIES: Xeos Technologies Inc. entire liability and your exclusive remedy shall be
at Xeos Technologies Inc. option, either (a) return of the price paid or (b) repair or replacement
of the product that does not meet Xeos Technologies Inc. Limited Warranty and that is returned
to Xeos Technologies Inc. with a copy of your receipt. This Limited Warranty is void if failure of
the product has resulted from accident, abuse, or misapplication. Any replacement product will
be warranted for the remainder of the original warranty period or ninety (90) days, whichever is
longer.
NO OTHER WARRANTIES: Xeos Technologies Inc. disclaims all other warranties, either express or
implied, including but not limited to implied warranties of merchantability and fitness for a
particular purpose, with respect to the product or the accompanying written materials. This
limited warranty gives you specific legal rights. You may have others, which vary from state to
state.
NO LIABILITY FOR CONSEQUENTIAL DAMAGES: In no event shall Xeos Technologies Inc. or its
suppliers be liable for any damages whatsoever (including, without limitation, damages for loss
of equipment, for loss of business profits, business interruption, loss of business information, or
other pecuniary loss) arising out of the use of or inability to use this Xeos Technologies Inc.
product, even if Xeos Technologies Inc. has been advised of the possibility of such damages.