Pyxis ST-773 User manual

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ST-773 Dissolved Oxygen Sensor
User Manual
August 11, 2021
Rev. 1.0
Pyxis Lab, Inc.
1729 Majesc Dr. Suite 5
Lafayee, CO 80026 USA
www.pyxis-lab.com
© 2017 Pyxis Lab, Inc.
Pyxis Lab Proprietary and Condenal

Table of Contents
1 Introducon 2
1.1 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Specicaons 4
3 Unpacking Instrument 5
3.1 Standard Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Oponal Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Installaon 7
4.1 MA-150-1 Submersed Floang Installaon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 MA-120-B Submersed Fixed Installaon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3 Pipeline Installaon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.4 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.5 Connecng via Bluetooth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5 Setup and Calibraon with uPyxis® Mobile App 11
5.1 Download uPyxis® Mobile App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2 Connecng to uPyxis® Mobile App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.3 Calibraon Screen and Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.4 Diagnosis Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.5 Device Info Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Setup and Calibraon with uPyxis® Desktop App 16
6.1 Install uPyxis® Desktop App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2 Connecng to uPyxis® Desktop App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.3 Informaon Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.4 Calibraon Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.5 Diagnosis Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7 Outputs 21
7.1 4–20mA Output Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2 Adjusng 4–20mA Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.3 Communicaon using Modbus RTU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8 Sensor Maintenance and Precauon 23
8.1 Methods to Cleaning the ST-773 Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
9 Troubleshoong 24
10 Contact Us 24

Warranty Informaon
Condenality
The informaon contained in this manual may be condenal and proprietary and is the property of Pyxis
Lab, Inc. Informaon disclosed herein shall not be used to manufacture, construct, or otherwise reproduce
the goods described. Informaon disclosed herein shall not be disclosed to others or made public in any
manner without the express wrien consent of Pyxis Lab, Inc.
Standard Limited Warranty
Pyxis Lab warrants its products for defects in materials and workmanship. Pyxis Lab will, at its opon, repair
or replace instrument components that prove to be defecve with new or remanufactured components
(i.e., equivalent to new). The warranty set forth is exclusive and no other warranty, whether wrien or oral,
is expressed or implied.
Warranty Term
The Pyxis warranty term is thirteen (13) months ex-works. In no event shall the standard limited warranty
coverage extend beyond thirteen (13) months from original shipment date.
Warranty Service
Damaged or dysfunconal instruments may be returned to Pyxis for repair or replacement. In some in-
stances, replacement instruments may be available for short duraon loan or lease.
Pyxis warrants that any labor services provided shall conform to the reasonable standards of technical com-
petency and performance eecve at the me of delivery. All service intervenons are to be reviewed and
authorized as correct and complete at the compleon of the service by a customer representave, or des-
ignate. Pyxis warrants these services for 30 days aer the authorizaon and will correct any qualifying
deciency in labor provided that the labor service deciency is exactly related to the originang event. No
other remedy, other than the provision of labor services, may be applicable.
Repair components (parts and materials), but not consumables, provided during a repair, or purchased
individually, are warranted for 90 days ex-works for materials and workmanship. In no event will the in-
corporaon of a warranted repair component into an instrument extend the whole instrument’s warranty
beyond its original term.
Warranty Shipping
A Repair Authorizaon (RA) Number must be obtained from Pyxis Technical Support before any product can
be returned to the factory. Pyxis will pay freight charges to ship replacement or repaired products to the
customer. The customer shall pay freight charges for returning products to Pyxis. Any product returned to
the factory without an RA number will be returned to the customer. To receive an RMA you can generate a
request on our website at hps://pyxis-lab.com/request-tech-support/.
Pyxis Technical Support
Contact Pyxis Technical Support at [phone], [email protected], or by lling out a request for
support at hps://pyxis-lab.com/request-tech-support/.
ST-773 User Manual [email protected] | [phone]

1 Introducon
The Pyxis ST-773 opcal luminescent dissolved oxygen (DO) sensor is based on the principle of ‘uorescence
quenching’ to determine the dissolved oxygen content in water. It incorporates Pyxis’ advanced technol-
ogy in the eld of uorescence detecon and uses dual Blue/Red light detecon technology with excitaon
and reference light sources, oering a wide detecon range and very low detecon limit. The sensor also
integrates a temperature sensor for compensaon of the measurement of dissolved oxygen based on en-
vironmental condions. The ST-773 oers an easily replaceable, front loading DO membrane cap that has
been independently developed by Pyxis Lab, with a typical service life of up to two years. This unique
DO membrane cap design incorporates a black microporous PTFE membrane material designed to provide
extreme scratch resistance, extended life span and simple replacement. The at front-end design of the
ST-773 makes this plaorm less prone to contaminaon or fouling and is very easy to clean and brushable.
The sensor body is composed of CPVC and is well suited for aggressive industrial applicaon use. The ST-773
may be ulized in a submersed xed/oang applicaon or inline with the Pyxis submersion assembly and
inline thread/tee accessory opons. The ST-773 comes with a 10-meter bulkhead cable as well as 1.5-meter
ying lead cable each with 7Pin quick adapters. The sensor output oers both 4-20mA and RS-485 Modbus
communicaon which is Bluetooth enabled when used in conjuncon with the MA-WB (7-Pin Bluetooth
Adapter).
The ST-773 series measures the paral pressure of the dissolved oxygen (DO) in water. In most applica-
ons, the source of DO is oxygen in the air. In other applicaon such as in aquaculture, the source of DO is
photosynthesis. The concentraon of dissolved oxygen is a derived value from the measured oxygen paral
pressure. The relaonship between the DO concentraon and the oxygen paral pressure is governed by
the law of thermodynamics. The ST-773 series uses the latest USGS equaon to convert the oxygen paral
pressure to DO in units of ppm or mg/L. Through setup using the uPyxis® Mobile of Desktop App, the ST-773
series sensor can output the measured oxygen paral pressure in other units such as percentage of oxygen
saturaon.
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1.1 Main Features
The ST-773 sensor includes the following features:
• 0.004–20.0 mg/L measurement range
• Built-in temperature sensor with automatic compensation
• Accurate and stable measurement with ultra-low dri
• Built-in transmitter without preamplifier or meter head
• Dual Outputs both 4-20mA isolated signal or RS-485 Modbus (7-Pin Format)
• Long-distance transmission with higher stability & accuracy
• Wireless Calibration, Diagnostics and Trend via uPyxis® App when used with MA-WB
Adapter
• The sensor can be Slope calibrated with air or air saturated water
• Zero-point calibration with 5% Sodium Sulfite solution or Nitrogen gas
• Suitable for dissolved oxygen monitoring of:
–Activated Sludge
–Aerated Basin
–Wastewater & Sewage Processing
–Chemical & Process Water
–Domestic Water Applications
–Filtration Applications
–Aquaculture
–Agriculture
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2 Specicaons
Table 1. ST-773 Specicaons
Specicaon*ST-773
Part Number (P/N) 53709
Body Material CPVC
Installaon Method Submerged and Inline Installaon
Measuring Range
(4-20mA Output
Scale)
0.004–20.0 mg/L or 0–200% Saturation
Resoluon 0.01 mg/L
Accuracy ±0.3 mg/L or ±3%, whichever is greater
Response Time <60 Seconds
Operaonal
Temperature
0–45 °C (32–113 °F)
Signal Output 4-20mA analog output / RS-485 digital output
Dimension (L ×D) 206 ×24.6 mm (8.11 ×0.97 inch)
Weight 188 g (0.41 lbs) cable excluded
Working Pressure 75 psi
Wet Material CPVC and Polycarbonate
Cables Provided 1 x 4.9/1.5m Flying Lead Cable — 7Pin Female Adapter
1 x 30/15m Bulkhead Cable — 7Pin Male Adapter
(Interconnecng Extension Cables Purchased Separately)
Calibraon Slope calibraon Air or Air Saturated Water
Zero calibraon: 5% Sodium Sulte or Nitrogen Gas
DO Membrane Cap
Life
1.5 years
Protecon Grade IP-67
Regulaon CE / RoHS
Compliance USEPA 40CFR Part 136.3 / ISO 17289:2014
*With Pyxis’s connuous improvement policy, these specicaons are subject to change without noce.
ST-773 User Manual [email protected] | [phone]

3 Unpacking Instrument
Remove the instrument and accessories from the shipping container and inspect each item for any damage
that may have occurred during shipping. Verify that all accessory items are included. If any item is missing
or damaged, please contact Pyxis Lab Customer Service at [email protected].
3.1 Standard Accessories
ST-773 Shipped with Standard Accessories (P/N 53709)
The following accessories are included in the ST-773 probe for submersed or inline installaons. Please note
submersion or inline adapters are purchased separately. Please see oponal accessories for details.
• One ST-773 Dissolved Oxygen Probe w 30/10m Bulkhead Cable (Male Adapter-7Pin)
• One DCC-6 DO Membrane Cap for ST-773
• One MA-1100 1.5 Meter/ 4.9  Cable (Female Adapter/Flying Lead-7Pin)
• One MA-WB Bluetooth Adapter for 7Pin Sensors
• One MA-NEB Bluetooth/USB Adapter for use with Desktop uPyxis APP
• User Manual available online at hps://pyxis-lab.com/support/
Figure 1.
ST-773 / MA-1100 Flying Lead / MA-WB Bluetooth Adapter / MA-NEB USB Adapter / DCC-6 Membrane Cap]
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3.2 Oponal Accessories
The following oponal accessories can be ordered from Pyxis Customer Service (or[email protected]) or
Pyxis E-Store at hps://pyxis-lab.com/shop/.
Table 2. Oponal Accessories
Oponal / Replacement Accessories Part Number
(P/N)
MA-WB Bluetooth Adapter for 7-Pin Pyxis Sensors MA-WB
MA-150-1 Floang Submersion Adapter Kit 53705
MA-120-B Fixed Submersion Adapter Kit 50783
ST-773 Threaded Adapter for Inline Installaon
(1inch NPT)
50700-A04
ST-001 and Collar Tee Assembly for Non-Threaded Inline Installaon
(3/4 inch NPT)
53726
DCC-6 Dissolved Oxygen Membrane Cap — Replacement 53723
MA-C50 (50’ Extension Cable w/7Pin Adapters) 50705
MA-C100 (100’ Extension Cable w/7Pin Adapters) 50706
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4 Installaon
4.1 MA-150-1 Submersed Floang Installaon
The ST-773 may be installed in a submersed/oang applicaon using the MA-150-1 Submersed Floang
Adapter Kit. This kit contains a swiveling conduit mounng bracket and ball oat-probe adapter assembly
in 1-inch FNPT. (Please note the ST773 outer diameter is 3/4 - inch NPT. A 3/4 to 1-inch NPT bushing is
required for installaon) The ST-773 dissolved oxygen sensor needs to be installed as shown in Figure 2. For
installaon, users only need to purchase the MA-150-1 from Pyxis Lab and may obtain water-ght conduit
and cable seal adapter from their supplier of choice. For sensor replacement and maintenance, users only
need to pull the MA-150-1 and DO sensor from xing bracket vercally (upward).
Figure 2. ST-773 in a submersed oang installaon
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4.2 MA-120-B Submersed Fixed Installaon
The ST-773 may be installed in a submersed/xed applicaon using the MA-120-B Submersion Adapter
Mounng Bracket and probe adapter coupler in 1-inch FNPT. (Please note the ST773 outer diameter is 3/4 -
inch NPT. A 3/4 to 1-inch NPT bushing is required for installaon) The ST-773 dissolved oxygen sensor needs
to be installed as shown in Figure 3. For installaon, users only need to purchase the MA-120-B from Pyxis
Lab and may obtain water-ght conduit and cable seal adapter from their supplier of choice. For sensor
replacement and maintenance, users only need to pull the MA-120-B and DO sensor from xing bracket
vercally (upwards).
Figure 3. ST-773 in a submersed xed installaon
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4.3 Pipeline Installaon
The ST-773 may be installed in a pressurized inline ow applicaon as high as 75 psi (5Bar) using oponal
accessories (Pyxis ST-001/Collar Kit or ST-771 1-inch Threaded Adapter Kit). Pyxis recommends installaon
in a vercal ow format from bottom up to reduce the impact of air bubbles. Install the probe collar on the
sensor and then install the sensor into the ST-001 tee assembly and ensure the DCC-6 membrane cap is in
the direcon of water ow as shown in Figure 4.
Figure 4. ST-773 in a pipeline installaon using oponal ST-001 Tee Assembly Kit (P/N -53726) or 1-inch
Thread Adapter Kit (50700-A04)
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4.4 Wiring
If the power ground terminal and the negave 4–20mA terminal in the controller are internally connected
(non-isolated 4–20mA input), it is unnecessary to connect the 4–20mA negave wire (green) to the 4–20mA
negave terminal in the controller. If a separate DC power supply other than that from the controller is used,
make sure that the output from the power supply is rated for 22–26 VDC @ 65 mA.
*NOTE*The negave 24V power terminal (power ground) and the negave 4–20mA ter-
minal on the ST-773 sensor are internally connected.
Follow the wiring table below to connect the ST-773 sensor to a controller:
Table 3.
Wire Color Designaon
Red 24V +
Black 24V Power ground
Green*4–20mA -
White 4–20mA +
Blue RS-485 A
Yellow RS-485 B
Silver GNDD
*Internally connected to the power
ground
4.5 Connecng via Bluetooth
A Bluetooth adapter (P/N: MA-WB) can be used to connect a ST-773 sensor to a smart phone with the
uPyxis® Mobile App or a computer with a Bluetooth/USB Adapter (P/N: MA-NEB) and the uPyxis® Desktop
App.
Figure 5. Bluetooth connecon to ST-773 sensor
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5 Setup and Calibraon with uPyxis® Mobile App
5.1 Download uPyxis® Mobile App
Download uPyxis® Mobile App from Apple App Store or Google Play.
Figure 6. uPyxis® Mobile App installaon
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5.2 Connecng to uPyxis® Mobile App
Connect the ST-773 sensor to a mobile smart phone according to the following steps:
1. Open uPyxis® Mobile App.
2. On uPyxis® Mobile App, pull down to refresh the list of available Pyxis devices.
3. If the connecon is successful, the ST-773 and its Serial Number (SN) will be displayed (Figure 7).
4. Press on the ST-773 sensor image.
Figure 7.
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5.3 Calibraon Screen and Reading
When connected, the uPyxis® Mobile App will default to the Calibraon screen. From the Calibraon
screen, you can perform calibraons by pressing on Zero Calibraon,Air Calibraon, and 4–20mA Span.
*NOTE*Before calibrang, remove the ST-773 sensor from the water and wipe it with a
damp cloth to remove debris and any biofouling. If there is water on the membrane, dry it
with a so cloth, taking special care not to damage the membrane.
Figure 8.
5.3.1 Zero Calibraon
1. Place the sensor in Nitrogen Gas or 5% Sodium Sulte soluon (anaerobic water).
2. Let the ST-773 sensor stand for a minimum of 15 minutes. Observe the values being displayed on the
Calibraon screen.
3. Once the displayed oxygen and temperature values are stable, press Zero Calibraon to perform a
zero calibraon.
4. If the calibraon is successful, the interface will return a message ”Calibraon Succeeded”. If the
calibraon fails, press Zero Calibraon again and repeat.
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5.3.2 Air (Slope) Calibraon
1. Place the ST-773 sensor in the air with a stable temperature or in air-saturated water.
2. Let the ST-773 sensor stand for a minimum of 6 minutes. Observe the values being displayed on the
Calibraon screen.
3. Once the displayed oxygen and temperature values are stable, press Air Calibraon to perform an air
(slope) calibraon.
4. Enter the local, real-me atmospheric pressure value in mbar. If a value is not entered the sensor will
default to 101.1 mbar.
5. Enter the humidity value:
• If you are using air for calibraon, you will need to enter the real-me (current) humidity value.
• If you are using air-saturated water for calibraon, you will need to enter a humidity value of
”1”.
6. If the air (slope) calibraon was successful, the interface will return a message ”Calibraon Suc-
ceeded”. If the calibraon fails, press Air Calibraon again and repeat.
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5.4 Diagnosis Screen
From the Diagnosis screen, you can check the diagnosis condion as well as Export & Upload. This feature
may be used for technical support when communicang with [email protected].
To preform a Cleanliness and Selife Check, rst select the Diagnosis Condion which denes the uid
type that the ST-773 sensor in currently measuring, then press Cleanliness and Selife Check. If the sensor
is clean, a Clean message will be shown. If the sensor is severely fouled, a Please replace the DO membrane
cap message will be shown. In this case, follow the procedure in the Methods to Cleaning the ST-773Sensor
secon of this manual.
Figure 9.
5.5 Device Info Screen
From the Device Info screen. You can name the Device or Product as well as set the Modbus address.
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6 Setup and Calibraon with uPyxis® Desktop App
6.1 Install uPyxis® Desktop App
Download the latest version of uPyxis® Desktop soware package from: hps://pyxis-lab.com/upyxis/ this
setup package will download and install the Microso.Net Framework 4.5 (if not previously installed on the
PC), the USB driver for the USB-Bluetooth adapter (MA-NEB), the USB-RS485 adapter (MA-485), and the
main uPyxis® Desktop applicaon. Double click the uPyxis.Setup.exe le to install.
Figure 10. uPyxis® Desktop App installaon
Click Install to start the installaon process. Follow the screen instrucons to complete the USB driver and
uPyxis® installaon.
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6.2 Connecng to uPyxis® Desktop App
Connect the ST-773 sensor to a Windows computer using a Bluetooth/USB adapter (P/N: MA-NEB) according
to the following steps:
1. Plug the Bluetooth/USB adapter into a USB port in the computer.
2. Launch uPyxis® Desktop App.
3. On uPyxis® Desktop App, click Device →Connect via USB-Bluetooth (Figure 11).
4. If the connecon is successful, the ST-773 and its Serial Number (SN) will be displayed in the le pane
of the uPyxis® window.
*NOTE*Aer the sensor and Bluetooth is powered up, it may take up to 10 seconds for the
adapter to establish the wireless signal for communicaon.
Figure 11.
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