L-VIS User Manual
185
LOYTEC
Version 6.2
LOYTEC electronics GmbH
How a global connection is created and configured is described in Section 10.8.5. Note that
the number of configurable global connections on a device is limited (see Section 15.10).
10.3 AST Features
10.3.1 Alarming
The alarming architecture comprises a number of entities. Objects that monitor values of
data points and generate alarms depending on an
alarm condition
are called
alarm sources
.
The alarms are reported to an
alarm server
on the same device. The alarm server maintains
a list of alarm records, called the
alarm summary
. The alarm server is the interface to
access the local alarms.
Generic alarm servers provide the maximum set of alarming. Data points of all network
technologies can be alarmed through generic alarm servers. Technology alarm servers can
be used to expose access to the alarms to network technologies that support it. Generic
alarm servers can be configured to report their generic alarms to technology alarm servers.
For example, a generic alarm server may report its alarms to both CEA-709 and BACnet
alarm servers.
An alarm record contains the information about a specific alarm. This includes information
about the alarm time, the source of the alarm (i.e., which data point caused the alarm), an
alarm message, an alarm value, an alarm type, an alarm priority, and an alarm state. An
alarm record undergoes a number of state changes during its life-cycle. When the alarm
occurs, it is
active
. At this point the alarm time, alarm message, alarm value is notified
using the alarm priority. When the alarm condition subsides, the alarm becomes
inactive
.
At this point the clear time and the clear message is notified using the normal priority. The
priority levels are configurable on the alarm server, where 0 is the highest and 255 is the
lowest priority.
Alarm transitions (to an alarm state, to the normal state) can be acknowledged by an
operator. Which of those transitions requires an acknowledgement is configurable on the
alarm server. If an active alarm is acknowledged it becomes
active acknowledged
. Active
alarms can also become inactive, but an acknowledgement is still required. Then they
become
ack-pending
. When an alarm is inactive and was acknowledged it finally
disappears from the alarm summary.
An alarm state can be of different alarm types. The alarm type specifies the class of the
alarm. The following alarm types exist:
Off-Normal Alarm
: This alarm type is a generic alarm class that applies to
binary and multi-state alarm conditions. It indicates that the alarmed data point is
on an off-normal operating condition that triggered the alarm. An alarm value is
supplied. In technology alarm servers, restrictions may apply.
High/Low Limit Alarm
: This alarm type is typical for analog alarm conditions.
It applies when the alarmed value is over or under the defined alarm limits. An
alarm value is supplied. In technology alarm servers, restrictions may apply.
Fault Alarm
: This alarm type is indicating that the monitored data point is in a
fault state. This is different from off-normal or high/low limit alarms. The value
of the data point is within the specifications of the alarm condition but the data
point itself is considered faulty. This can stem from an unreliable value or an
offline value, i.e., if the data point is offline. No alarm value is supplied.
Alarms may be generated from a given data point value (alarm value or value range) or by
comparing a data point command value with a feedback value (feedback alarm). When
defining a feedback alarm, the alarmed data point represents the command value and has a
‘feedbackValue’ property relation (see Section 10.1.10). This property relation can be
linked to another data point, which effectively provides the feedback value.