Xylem WQ-FDO Sensor and GL500-7-2 Data Logger - Manual (Page 33)

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partial pressure of the oxygen in the water. The sensor should read
about this pressure. For example, at sea level the average
atmospheric pressure is 1013mbar. The partial pressure of oxygen in
water exposed to air for a period of time will be about 0.21 x 1013mbar
or 212mbar. Because factors like atmospheric pressure and
temperature are constantly changing, this is not a recommended way
of calibration. This should be done for performance checks only.
e. Besides oxygen partial pressure, temperature is also important in
calculating oxygen levels. The WQ-FDO sensor has a temperature
output than can be checked. Compare the temperature reading of the
sensor in water to that of another measurement device. A stable
temperature can also be made with ice water. A mixture of water with
lots of ice being stirred constantly can achieve a stable ice water
temperature of 32ºF (or 0º C) +.2F.
f. Check the logger and other sensor calibrations and recalibrate if
necessary, saving the setup file first as described in section IX.
Because dissolved oxygen is dependent on temperature, pressure and
conductivity; it is important to have accurate data for the software to
make these calculations. Save the new setup file under a different
name each time the logger is recalibrated.
Issue: Cannot communicate with the logger.
a. Verify that sufficient power is applied and wired correctly.
b. Check the communication cable.
c. If the connection is through the USB port, use the Windows Device
Manager to confirm that the driver is loaded and the correct virtual
COM port is selected in the connection menu of the Global Logger
software, as described in sections III and IV.
d. Check the Device Manager in your operating system and confirm that
the USB COM port is not being used by another device.
e. Try reducing the baud rate in the connection screen of the Global
Logger software.
f. Try switching from RS-232 to USB or USB to RS-232.