Casella CEL Sensus data logger unit User Manual
Page 18
4.
LOGGING
By default, the Sensus logs data to its internal record store at an interval
specified by the user. If the logger detects the presence of a compatible
CompactFlash card, it automatically uses this instead. When the card is
removed, the logger reverts to using its internal store. For information on the
use of CompactFlash cards please refer to Section 8 on CompactFlash.
4.1
Log Rate
The logger operates with two logging rates, one normal rate and one fast
rate. Switching between these two rates is handled automatically by the
alarm system. For further information please refer to Section 12 on Alarms.
Both logging rates can be set to any value between 5 seconds and
24 hours.
4.2
What Gets Logged ?
Any data channel that has its log active flag set will be included when the
next log event occurs. Logging globally can be disabled/enabled by changing
the log active flag held in the logging configuration. This allows logging to
be suspended temporarily without changing all the channel flags.
4.3
Internal Capacity
The Sensus Logger has 512 kBytes of internal Flash storage available to hold
logged information. This store is updated in a first-in-first-out manner so that
the earliest records are always being replaced with the newest ones. While
this means the logger will never stop recording data, only a set period of time
will remain available for collection at any time.
The number of records held and the period of time covered by the
internal store depend on both the number of channels being logged and the
logging interval.
The following equations let the user calculate the record capacity
and the store duration.
These equations should be used only as a guideline as the logging interval
may change during operation, especially if the fast mode option has been
enabled in the alarms.
Some example internal result capacities are shown in Table 2.
524288
7
4
+
=
(
)
Re
Channels x
cord Capacity
Re cord Capacity x Logging Interval
Store Duration
=
Logging
Page 18 of 44
SENSUS Digital Data Logger -
Users Handbook