pyroscience APHOX-S-O2 AquapHOx Underwater Oxygen Sensor User Manual

pyroscience APHOX-S-O2 AquapHOx Underwater Oxygen Sensor

INTRODUCTION

The APHOX-S-O2 is an underwater oxygen sensor. It combines the optical oxygen sensing technique of Pyro Science with a corrosion and biofouling resistant pressure housing. The sensor can be used for underwater operation down to 50 m water depth. An internal NTC temperature sensor provides automatic temperature compensation of the oxygen sensor. Digital communication is possible via a RS485-Modbus RTU. Additionally, the sensor features voltage (0-5V) and current (4-20mA) outputs. These interfaces allow an easy integration in existing custom systems. The sensor comes with a factory calibration. If required, the user can perform a simple 1-point calibration or a 2- point calibration for increased accuracy at low oxygen concentrations

Depending on the customer‘s application and existing system there are different usage scenarios for operation:

Option A: The software Pyro Developer Tool provides simple settings and calibration procedures. Furthermore, additional advanced settings provide full control of all features of the APHOX-S-O2 (see chapter 3.1). For connection to a PC, the digital interface can be converted to USB via an USB adapter cable (item no. APHOX-S-USB)

Option B: The APHOX-S-O2 features a standard RS485 interface with Modbus RTU protocol, supporting robust bus systems with up to 247 devices at a single bus. This very popular communication protocol allows easy integration of the APHOX-S-O2 into third-party systems (see chapter 3.2).

Option C: The APHOX-S-O2 also features 4 analog outputs (2x 0-5V and 2x 2-20mA). Configuration of the analog outputs, sample rate as well as calibration of the sensor can be performed by using the software Pyro Developer tool or the communication protocol (see chapter 3.3).

SPECIFICATIONS

Analytical performance

Accuracy at 95% a.s./8.8 mg/L after 2 point calibration after factory calibration| ±1% a.s.
±4% a.s.| ±0.1 mg/L
±0.4 mg/L
Resolution at 95% a.s./8.8 mg/L| 0.25% a.s.| 0.025 mg/L
Detection limit after 2-point calibration after factory calibration| 0.1% a.s.
2% a.s.| 0.01 mg/L
0.2 mg/L
Response time‡| < 15s
Drift| <1% rel. / 3 months
Max. sample rate| 1 s
Temperature sensor Resolution Accuracy Typical response time| NTC-thermistor for automatic temperature compensation 0.01°C 0.1°C 20 s

• The analytical performance of the factory calibrated sensor is only valid for 6 months after the purchase of the sensor.
• Typical response times for 90% signal change. For liquids: measured for the transition from air into a stirred solution of 1% Na2SO3

Environment

Interface

Mechanical

polycarbonate, POM
Cable type and length| Shielded Cat5e, Ø7mm, seawater resistant PUR sheath Standard length: 8m, Custom lengths available
Max. cable length| 55m

COMMUNICATION INTERFACES

Option A: Operating the underwater oxygen sensor with Pyro Developer Tool

The software Pyro Developer Tool offers simple settings and calibration procedures. Furthermore, additional advanced settings provide full control over all features of the module.

System requirements: PC with Windows 7/8/10 and min. 1000 MB free disk space.

Do not connect the USB adapter cable to your PC before the software has been installed!
The software will automatically install the appropriate USB-drivers.

Installation steps:

• Download the Pyro Developer Tool from APHOX-S-O2 – Pyro Science GmbH
• Unzip and start the installer and follow the instructions.
• Connect the APHOX-S-O2 to your windows PC using the USB adapter cable.
• Start the Pyro Developer Tool software.

For more information on the software, please refer to the Pyro Developer Tool manual available at APHOX-S-O2 – Pyro Science GmbH .

USB-interface cable

For the operation of APHOX-S-O2 with a Windows PC, a coded USB interface cable (item no. APHOX-S-USB) is available from Pyro Science. The cable enables to communicate with the module via the software Pyro Developer Tool. At the mounting adapter of the APHOX-S-USB cable, a label indicates the wire assignment.

Option B: RS485-Modbus interface

The RS485 interface of the module can be connected to a standard Modbus RTU bus. Up to 247 devices can be connected to a single bus consisting of the 4 wires required by the RS485 interface. The Modbus protocol is a popular industrial communication protocol reckoned by its simplicity and robustness. Modbus libraries are available for virtually any programming language. Numerous data logging systems support the Modbus protocol.

Please refer to chapter 5 for the electrical specifications and the wire assignment of the RS485-Modbus-interface.

The RS485 configuration is: 19200 Baud, 8 Data bits, 1 stop bit, even parity.

Modbus RTU

An essential element of the Modbus protocol are slave addresses and registers. Every Modbus device possesses a configurable slave address (range 1-247) and a certain set of registers, which contain e.g., integer numbers. There exist read-write registers (e.g., temperature offset) and read-only registers (e.g. the result of a temperature measurement). The Modbus RTU protocol provides commands, allowing a “master device” (e.g., a PC or a PLC) to read or write specific registers from a device with a specific slave address.

The Modbus interface APHOX-S-O2 is compatible with the Modbus RTU protocol as described in the official documentation “Modbus over serial line specification and implementation guide V1.02” and “Modbus application protocol specification V1.1b” provided by the Modbus Organization Inc. ( https://modbus.org ).

The APHOX-S-O2 devices are delivered with slave address 1.

Pyro Science Unified Protocol

All optical meters from Pyro Science with firmware generation 4 (i.e., firmware version >= 4.0, introduced in 2020) comply to the so called Pyro Science Unified Protocol (PSUP). This communication protocol is based on registers and specific commands which are used to read and write the registers. All further details, including the Modbus register map, can be found in the reference manual Pyro Science Unified Protocol available for download on the Pyro Science website here:

APHOX-S-O2 – Pyro Science GmbH

Option C: Read-out using the analog outputs

The APHOX-S-O2 offers read-out using analog outputs. The settings for the analog outputs can be adjusted with the Pyro Science software Pyro Developer Tool or the communication protocols.

In the Pyro Developer Tool software the output parameter and the corresponding analog output can be selected. Further the so called “broadcast interval”, which represents the sample interval of the measurements given at the analog outputs needs to be adjusted.

For more information, please refer to the software manual Pyro Developer Tool (see link in chapter 3.1).

According to the Modbus-RTU communication protocol the analog outputs can be adjusted by writing the corresponding Modbus registers. For more information about the read write Modbus registers please refer to the PSUP communication protocol, which explains also the Modbus registers. Alternatively, the registers can be adjusted with the Pyro Science commands if the Modbus module is in transparent mode. Please refer to the PSUP communication protocol for more information about how to write and read the Pyro Science registers (see link in chapter 3.2.2).

HANDLING INSTRUCTIONS

This chapter provides general handling instructions to operate the APHOX-S-O2 successfully.

For in-depth information especially on sensor settings and sensor calibration, please refer to the respective Oxygen Sensor Manual available at APHOX-S -OXCAP-Pyro Science GmbH

Connecting the sensor screw cap

The sensor comes with a pre-calibrated sensor cap installed (item no. APHOX-S-OXCAP).
To replace the sensor cap, pull off the protection cap of the APHOX-S-O2, unscrew the old sensor cap, and screw on the new cap by hand. Please do not apply excessive force or use any tools to install the cap, as this might damage the sensor. Before calibration and measurement, please place the protective cap back on. The assembly is shown in Figure 1.

Calibration of Oxygen Sensors

The oxygen sensor can be calibrated with a 1-point or an optional 2-point calibration method. For the first calibration point, the sensor can be calibrated in air-saturated water or at ambient air (upper calibration). Optionally, the sensor can be calibrated in de-oxygenated water (0% calibration) to perform a 2-point calibration.

1-point calibration: Calibration in air saturated water or at ambient air Calibration in air saturated water

• For calibration in air saturated water, it is very important that the water is indeed 100% saturated with air. Fill an appropriate amount of water into a flask. Stream air through the water with an air stone connected to an air pump (available as commercial equipment for fish aquaria) for about 10 minutes. Alternatively, fill water into the flask leaving >50% air in the headspace, close it with a lid and shake the flask strongly for about 1 minute. Open the lid shortly for ventilating the headspace with fresh air. Close it again and shake the flask for 1 more minute
• Put the sensor in the liquid and enter all required parameters in the software or in the registers to perform a sensor calibration.

Calibration at ambient air

• For calibration at ambient air, put the sensor in contact to ambient air. Please enter all required parameters in the software or in the registers to perform a sensor calibration. For the requested humidity parameter, the measurements of an external humidity sensor or the data from a weather service can be used.

2-point calibration: Additional calibration in de-oxygenated water

• A 0% calibration is recommended at environmental conditions <50% a.s. or to achieve the highest possible accuracy of the sensor.
• For 0% calibration, use the 0% calibration capsules (item no.: OXCAL) from Pyro Science according to the oxygen sensor manual. Please put the APHOX-S-O2 in the solution and perform the 0% calibration by entering all required parameters in the software or writing the registers.

DO NOT use saline water (e.g. seawater) for this, but demineralized water. Saline water prevents proper dissolution of the reductant and can lead to false 0% sensor calibration.

MECHANICAL DIMENSIONS AND ELECTRICAL CONNECTOR

The wire assignment is as follows:

WARNINGS & SAFETY GUIDELINES

In case of problems or damage, disconnect the device and mark it to prevent any further use. Consult Pyro Science for advice! There are no serviceable parts inside the device. Please note that opening the housing will void the warranty.

Follow appropriate laws and guidelines for safety in the laboratory, like EEC directives for protective labor legislation, national protective labor legislation, safety regulations for accident prevention and safety data-sheets from manufacturers of chemicals used during the measurements and of Pyro Science buffer capsules.

Handle the sensors with care especially after removal of the protective cap! Prevent mechanical stress to the fragile sensing tip! Avoid strong bending of the fibber cable! Prevent injuries with needle-type sensors!

The sensors are not intended for medical or military purposes or any other safety-critical applications. They must not be used for applications in humans; not for in vivo examination on humans, not for human-diagnostic or any therapeutic purposes. The sensors must not be brought in direct contact with foods intended for consumption by humans.

The device and the sensors must be used by qualified personnel only, following the user instructions and the safety guidelines of the manual.

Handle the device with extreme care if there is any suspicion that it was flooded during deployment. Internal pressure might have built up as a consequence. Point the sensor side of the device away from people and material assets at all times, and carefully loosen the Subcon connector to relieve potential internal pressure before sending the instrument to Pyro Science for service.

Keep the sensors and the device out of reach of children!

CUSTOMERS SUPPORT

Pyro Science GmbH
Kackertstr. 11
52072 Aachen
Deutschland

Tel.: +49 (0)241 5183 2210
Fax: +49 (0)241 5183 2299
[email protected]
www.pyroscience.com

References

• Sensor technology - PyroScience GmbH
• The Modbus Organization
• APHOX-S-O2 - PyroScience GmbH
• APHOX-S-OXCAP - PyroScience GmbH

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