User Manual

Alarm management
Alarm queuing
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162 | 351 CM110664en_07
● Default = 100 (PXC) or 150 (PXR)
● Range = 10…500 depending on the available memory space
Record count [RecCnt]
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.
Notification threshold [NotifThd]
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
Alarm priority limit [PrlmAlm]
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.
If the notification class object contains remote alarm recipients, then it may be appropriate to modify the
default values for control of alarm queuing.
The values for [NotifThd] and [PrlmAlm] determine when a remote cable connection (modem) is to be
established, in order to inform the user of the occurrence of alarms.
If low-priority alarms are to be forwarded immediately, the [PrlmAlm] value must be increased (the higher
the number, the lower the alarm priority). The value for [NotifThd] must not be modified.
The value for [NotifThd] can be reduced, however, in cases where a connection is to be established when
there is a smaller number of alarms in the alarm queue. It is important to ensure, however, that the
difference between [BufSize] and [NotifThd] does not become too great, as this is the value that controls
the deletion of alarms in the event of a queue overflow.
Note that modifying these values also affects connection costs.
It takes time to establish a connection by cable (modem). If it is likely that further alarms will occur during
this time, thereby causing the queue to overflow, the difference between [BufSize] and [NotifThd] should
be increased.
The following settings are recommended:
● Buffer size [BufSize] = 120
● Notification threshold [NotifThd] = 80
In cases of doubt, the default values should be left unchanged.