User's Guide _______________________________________________________________________
58 _______________________________________________________________________________
using the optional display module, and accessed through the serial
connections. See sections Graphic History on page 62 and Data
Recording on page 103.
The data logger module contains non-volatile flash memory providing
4 years 5 months of storage for 3 parameters at a 10 second sampling
interval. When the memory is full, the data recording will not stop.
Instead, the oldest data is overwritten. For each parameter and
observation period, the module stores the minimum and maximum
values during the interval, as well a data trend value that is averaged
from samples taken during the interval (see Table 7 on page 58).
Table 7
Observartion Periods and Resolution
Observation Period
Period for Trend/Max/Min
Calculations (Resolution)
20 minutes
10 seconds
3 hours
90 seconds
1 day
12 minutes
10 days
2 hours
2 months
12 hours
1 year
3 days
4 years
12 days
The quantities that are logged are the same that have been selected for
measurement using the display/keypad or the serial line. When taking
the transmitter into use, verify that the desired quantities are selected.
If you change the quantities later, the transmitter will start logging the
new quantities, and stop logging the quantities that are no longer
selected. Changing the quantities does not delete any measurement
data that is already in memory.
The data logger module has a real time clock with a battery back-up.
The clock has been set to the Coordinated Universal Time (UTC) at
the factory, and its time cannot be set by the user. The data that is
stored in the logger's memory is timestamped using the logger's clock.
When date and time are set on the transmitter, they are stored to the
transmitter's memory as an offset from the time on the logger's clock.
When browsing the stored data, the time offset is applied to the
timestamps shown in the graphical history, and data outputted from
the serial port. The timestamps in the data logger's memory remain as
they were originally stored.
You can compensate for the clock drift (less than ±2 min/year) by
setting the time on the transmitter. This updates the time offset used
on the display and the serial port. You can set the time by using the
keypad/display or the serial commands.
