D
NOTE - to record total rainfall it is necessary to set identical sample and log times. This will
give an accumulative rainfall measurement, otherwise an average or mean measurement
would be recorded, and the ‘average’ value may fall below the storage resolution in some
cases.
Spot logging also has use in sampling slowly changing parameters, especially when
measurements have to be synchronised with various events, processes or other
measurements.
The D logger is factory set to 30 seconds sample and 30 minutes storage intervals
as default (except for raingauge channels which have both sample and storage intervals set
at 30 minutes). The user can change these settings as preferred.
When a RS232 datalead is connected to the D and it transmits its ‘wake up’
message every 10 seconds to the PC, it will also transmit sensor readings each time a channel
is logged (but not each time a channel is sampled). So if the user requires the D to
log as well as transmitting data, simply set the logging interval to the transmitting interval
required and link up to the PC. Alternatively use Option E from the Main Menu, Log on
Demand mode - see Section 3.2.15. Remember that RS232 communication drains the
D’s internal batteries at a greater rate than remote logging, and an external
power supply should be considered for long term operation in this mode.
NOTE – always press Escape to leave Main Menu mode and return to Log Mode. Else the
logger will not record any data and batteries will drain quickly.
4.2.10 Option 9 - Set AX+B Calibration Factors
This routine sets the calibration factors for channels using the ‘Ax+B’ scaling, e.g. channels for
light sensors, anemometers, raingauges etc. Its function is to convert raw data from the sensor
into empirical units for ease of use. This option can be applied to each channel individually
as appropriate.
It is advisable to first set up the Channel Configuration using Option A (see Chapter 3.2.11)
before setting the Ax+B scaling.
On choosing ‘9’ from the Main Menu you are first asked to enter the software channel to
configure, choose from channel number 00 to 24. The following submenu is then displayed:
ENTER THE NUMBER FOR UNITS REQUIRED TO GIVE FULL SCALE
Calculate the Full Scale as follows
a) For Voltage Input channels 1 - 23
F/S = (SENSOR OUTPUT [Units per mV] / GAIN) * 2000
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