Evaluation of Gas Sensors

For the SGX range of electrochemical and pellistor (including thermal conductivity) gas sensors, sensor outputs can be measured and gas concentration levels can be calculated automatically using the SGX ECVQ-EK3 Gas Sensor Evaluation Kit.

Key Components of the SGX ECVQ-EK3 Gas Sensor Evaluation Kit

This user-friendly control and data logging PC application stored on a CD allows automatic monitoring of sensors through a USB interface. The use of a terminal program like HyperTerminal to provide simple commands to the on-board microcontroller is another approach.

A comprehensive set of commands are listed in the user manual. The performance of electrochemical and pellistor gas sensors can be assessed and performance data can be captured with the SGX data logging and control software.

Sockets are provided on the PCB for use with SGX electrochemical and pellistor gas sensors. It is possible to directly plug the electrochemical devices and VQ500 series pellistor heads onto the PCB. Terminal blocks are also available for connecting to VQ600 series pellistor head cables or individual pellistor devices. On the PCB, a temperature sensing IC is placed near the sensor socket positions.

It is possible to adjust or set the bias voltage to zero for electrochemical sensors and the output is displayed in nA or mA. Adjusting the bridge voltage for pellistor devices is also possible and the bridge output displayed in mV. The sensor response is linear to concentration in both cases and the supplied software allows performing a basic calibration to provide a concentration reading in %LEL (Lower Explosive Limit), %volume, or ppm.

With an expansion connector, four digital inputs, two analog outputs, and four configurable alarms (open collector) can be accessed. The status of each alarm is represented by the LEDs on the board. Advanced users can upload their own software to the microcontroller (MSP430F2616) and exploit the available interfaces with the help of a JTAG header. A universal mains adapter is also offered. A 9V power supply may also be used by the users to connect to the terminal block connector.

Key Features of the SGX ECVQ-EK3 Gas Sensor Evaluation Kit

The following are the key features of the SGX ECVQ-EK3 Gas Sensor Evaluation Kit:

  • Adjustable electrochemical bias voltage (-700mV to +350mV)
  • Adjustable pellistor bridge voltage (1.6-4.6V)
  • Simple control and set-up of sensors
  • Free PC application software for easy control and data logging
  • For use with SGX pellistor/thermal conductivity gas sensors such as individual bead pairs, VQ500 series heads, and VQ600 series heads
  • For use with SGX electrochemical gas sensors
  • Four digital inputs
  • Two configurable analog outputs (12-bit DAC)
  • Four configurable alarm outputs
  • USB interface to a Personal Computer (PC)
  • PCB mounted temperature sensor IC
  • Calibrate sensors with linear response and monitor gas concentration levels
  • 16-bit Analog to Digital Conversion (ADC) for sensor outputs
  • JTAG header for user software upload
  • Expansion header for additional applications
  • Gas flow hoods available separately
  • Supplied with user manual on CD
  • Supplied with universal mains adapter

Mechanical Data

Dimensions

   
Mains Adapter 72 x 45 x 29mm
Evaluation Kit PCB 130 x 55mm

Performance Data

ADC Resolution 16-Bit
DAC Resolution 12-Bit
Pellistor bridge voltage 1.6 to 4.6V (adjustable)
Electrochemical bias -700mV to +350mV (adjustable)
ADC Resolution (Pel) <0.1mV
ADC Resolution (Elect.) 5nA (low range, +/-164µA)
25nA (high range, +/-819µA)
Temperature sensor IC accuracy ± 2°C (at 25°C)
± 3°C (-25°C to +85°C)

Environmental Data

Operating Temperature Range

Mains Adapter Operating temp: 0°C to +40°C
Storage temp: -25°C to +85°C
Operating humidity: 10 to 90%
PCBs Operation and storage from -30°C to +75°C
Sensors See individual sensor data sheets

Recommended PC System

For Control and Data logging Software

Processor Pentium 4/M or equivalent
Operating System Windows XP, Vista or 7
Screen resolution 1024 x 768 Pixels
RAM 1GB
Disk Space 1.6GB

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