Biosystems PhD Ultra Reference Manual - page 40
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“manual” PhD Ultra setup and download
procedures. Consult the Datalink Reference
Manual for complete instructions in the use of
Datalink software.
4.5.3 Adjusting record keeping parameters
It is possible to customize the way the PhD Ultra
records data in a number of different ways. Options
include extended recording time, tagging the
exposure data with time and date information, or
assigning a location number.
4.5.3.1 Entering the Datalogging Adjust mode
Turn on the PhD Ultra while holding down the "+"
button. (The unit must be in the Technician mode
prior to being turned on.) The Datalog Adjust screen
will briefly appear followed by a screen with further
instructions.
p
Press the Cal key to scroll through the adjustments
that are available. The sample interval adjustment
screen will be the first shown.
4.5.3.2 Adjusting the sampling interval
Whenever the PhD Ultra is turned on it immediately
begins to monitor, calculate, and log exposure
levels for the atmospheric hazards it is set up to
detect.
The datalogger samples continuously, so the data
stream must be broken into discreet intervals to be
recorded. The datalogging interval defines the
frequency of the breaks in the data stream. The
interval may be set anywhere between one second
and one hour as described below. The default
datalogging interval is 1 minute.
There is a finite amount of memory storage
available in the PhD Ultra. Once the memory is
“full”, the PhD Ultra will begin to write the new data
over the oldest data. In this way, the newest data is
always conserved. Different sensor configurations
and/or datalogging intervals may increase or
decrease the length of time before old data is
overwritten. A longer sampling interval will allow
the retention of more hours of data before old data
is overwritten making the PhD Ultra ideal for long-
term sampling projects.
Note: Calculations that are made on an ongoing
basis (i.e. TWA, STEL, Ceilings, and Peak
exposure values) are updated at regular
intervals by the PhD Ultra microprocessor.
Adjustments to the datalogging interval do not
effect the way in which TWA, STEL, Ceiling, and
Peak exposure values are calculated.
To modify the datalogger interval, first enter the
datalogging adjust mode as described in section
4.5.3.1. Once the interval adjustment screen is
reached, use the “+” and “-“ keys to adjust the
interval to any value between one second and one
hour. The PhD Ultra is capable of logging 3600
points of data. The “Duration” indicates the number
of hours at the current interval setting before the
oldest data will be overwritten by new data. For
instance, using the default datalogger interval
setting of 1 minute will allow 60 hours of data to be
recorded before the PhD Ultra memory is full. If an
interval value of 30 seconds is selected, the
duration will be cut in half, and the memory will be
filled in 30 hours as shown below:
Once the memory is “full”, the PhD Ultra will begin
to write the new data over the oldest data. In the
example above, that means that new data will start
replacing old data after 30 hours of monitoring.
Selecting a longer sampling interval will allow more
data to be retained before the oldest data is
overwritten. If an interval of 15 minutes is selected,
the detector is able to log 900 hours of monitoring
data, making the PhD Ultra ideal for long-term
sampling projects.
If datalogging is not desired, reduce the interval
setting to :00:00 to deactivate the datalogger.
To quit and save the new settings press and hold
the “CAL” button. Release the “CAL” button when
the instrument instructs you to release it. The
screen will then show that the datalogger
adjustments have been saved. Pressing the mode
button at any point in the procedure will return the
settings to their former levels. To proceed to other
adjustments, press and release the “CAL” button at
any time.
4.5.3.3 Setting the time and date
To access the time and date settings, first enter the
datalogger adjust mode as discussed in section
4.5.3.1. Then press and release the Cal button
twice to reach the time and date settings. The Time
and Date Screen accesses the PhD Ultra’s internal
real-time clock and calendar date. A cursor will
highlight the value to be adjusted. Pressing the "+"
and "
-" buttons will change the value. Pressing the
“Alarm” button will advance the cursor to the next
unit.