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Chapter 3 _______________________________________________________________ Installation

VAISALA _______________________________________________________________________ 59

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 12 below).

Table 12 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.

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Vaisala PTU300 Guía de usuario Pagina 61