CS120A and CS125 Visibility and Present Weather Sensors
54
down voltage to be set. If set this will put the sensor into a low power state
(which will not make measurements) before the battery voltage has fallen low
enough to damage a back-up battery. The RH threshold for a CS125 can also
be set from this menu. This applies if a CS215 sensor is attached and defines
the level of RH below which obscuration is deemed to be dry (that is haze,
SYNOP 04 or 05, METAR HZ) rather than wet (mist, SYNOP 10, METAR
BR or fog, SYNOP 30 etc. METAR FG). The default for Patchy Fog is ON in
which case the message outputs will include BCFG. If patchy fog is toggled to
OFF the message output will not include BCFG. It can be better sometimes to
not output BCFG with some aviation systems.
Menu 9 and 0: Exiting the menu system
Options ‘9’ and ‘0’ exit from the menu system. Note that typing ‘0’ will lose
all changes made including communications settings.
16. Calibrating the sensor
16.1 Visibility calibration
The sensor can be checked and adjusted using the optional sensor high grade
calibration kit. The calibration must be run using the onboard menu system. If
you have Campbell Scientific’s Device Configuration program a terminal
emulation screen is provided in the sensor screens to let you access this
function. To perform the calibration you will need a sensor calibrator disk and
a computer with a standard serial port compatible with the sensor. If your
sensor is not currently configured for RS-232 communications you can set the
internal switch, switch three, to temporarily set the sensor to RS-232 mode
38400 bps. If the sensor is already set in RS-232 mode it should not be
necessary to change any internal switches. (See Section
), for more information on the sensor internal switches.)
The test should ideally be performed in the following conditions:
•
Ambient temperature should be between 0ºC and 50ºC
•
The local visibility should be approximately 10,000 metres or higher.
The system is self-regulating. However, it is recommended that the sensor is
calibrated at least every two years.
The calibration is performed from menu item 3 on the main terminal screen.
Please refer to the menu section (Section
Entering the sensor menu system
(p. 49)
) of this manual for further information on how to access this menu.
CAMPBELL SCIENTIFIC LTD sensor menu exited.
