User Manual

Alarm man
agement
Alarm queuing
9
CM110664en_07 159 | 353
If the queue is full to overflowing, the oldest entries are deleted automatically,
and a system event message is generated. Entries are deleted irrespective of
alarm priority.
Alarm queuing has no effect on the alarm state of the alarm source.
Alarms destined for a temporary alarm recipient are not saved in the
automation station. If a temporary alarm recipient can no longer be reached,
the address of the recipient concerned is removed from the [RecpList] of the
device object.
The queuing of alarms is controlled by the following BACnet properties in the
device object of the Desigo PX automation stations. These properties are not
mapped to a function block, and can therefore only be viewed and modified
online.
This BACnet property defines the maximum number of entries which can be
saved in the queue.
A new value will only be accepted if it is greater than the record count
[RecCnt].
Buffer size [BufSize] of the alarm queue.
● Default = 100 (PXC) or 150 (PXR)
● Range = 10…500 depending on the available memory space
This BACnet property represents the number of entries currently stored in the
queue.
The alarm queue can be deleted by writing the value 0 to this property. A write
of a value not equal to 0 results in an error message.
If the queue is deleted, this information is entered as a system event in the
queue and transmitted to the receivers. This causes the value to change to 1 as
soon as [RecCnt] is set to zero.
This BACnet property defines the dial-out threshold, and the number of alarms
to be deleted in the event of a queue overflow.
If [RecCnt] is greater than or equal to [NotifThd], a connection is established
with any alarm recipients connected by cable (modem) which are destined to
receive alarms and events from the queue. The connection is established
provided that the remote alarm recipient concerned is listed in the notification
class object.
The message threshold also defines how many alarms are to be deleted in the
event of a queue overflow. As many alarm entries are deleted as necessary until
[RecCnt] is equal to [NotifThd]. This function does not distinguish between
local and remote alarm recipients in the notification class object.
To avoid deleting too many alarms, it is recommended that [NotifThd] be set to
approximately 80% of the [BufSize].
Alarm queue message threshold [NotifThd]:
● Default = 80 (PXC) or 130 (PXR)
● Range = 5…495
This BACnet property defines another independent threshold for dial-out.
An alarm priority which is less than or equal to [PrlmAlm] results in a
connection with any alarm recipients connected by cable (modem) which are
destined to receive alarms and events from the queue. The connection is
established provided that the remote alarm recipient concerned is entered in
the list of Notification Class objects.
Alarm priority limit [PrlmAlm]:
● Default = 2 (HighPrioAlarm or UrgentAlarm)
● Range 0…255
If the notification class object contains only local alarm recipients, then the
optimum results are achieved by use of the default values for control of alarm
queuing. The default values should therefore not be changed.
BACnet device object
properties
Buffer size [BufSize]
Record count [RecCnt]
Notification threshold
[NotifThd]
Alarm priority limit
[PrlmAlm]