Echelon DM-21 Device Manager - Manual (Page 74)

5-22 Installing and Getting Started with the Device Manager Software
this configuration property.
Queue Type Determines whether the Device Manager event log is
set up as a circular or linear queue.
A circular queue overwrites the oldest data point
once the available memory for the queue is reached,
maintaining only the most recent events or data
points.
A linear queue does not overwrite old events or data
points, and instead writes data until the queue is
full. Once full, no more data points are logged,
thereby retaining the old data-points.
Alarm at Percent Full The datalogger object can announce to the network
that its internal log is becoming full by using the
DL_Level_Full
network variable. Setting this
configuration property causes the Device Manager to
send
DL_Level_Full
when the event log reaches
the specified percentage full marks. One
DL_Level_Full
message is sent as the event log
fills past each mark. No messages are sent if the
event log is defined to be a circular queue.
For example, if this property is set to values of 65,
75, and 90, as the log fills three
DL_Level_Full
network variable updates will occur: one when the
log is 65% full; one when the log is 75% full; and one
when the log is 90% full.
Limit Period & Maximum
number of events logged per
limit period
These configuration properties limit the number of
events logged within a given period. In some
systems, failure conditions can cause the same event
(or data point) to be logged repeatedly over a short
period of time, filling the log with a single event or
data point that is registered many times over a short
period. Correctly setting these configuration
properties minimizes this effect. By establishing a
sliding window of time where only the defined
number of events may be logged.
Maximum number of events logged per
limit period
is an integer that defines the
maximum number of events that can be logged in
the time period specified by
Limit Period
.
Limit Period
is an integer representing the
length in minutes of the logging limit.