User Manual

Alarm management
Alarm queuing
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CM110664en_07 161 | 351
Acknowledge and reset
The alarm can be acknowledged by any alarm client. The AcknowledgeAlarm data record contains
information as to which alarm is being acknowledged and other details related to this alarm and the
acknowledging alarm client. The alarm acknowledgement is confirmed with a SimpleAck message by the
alarm server which generated the alarm. All other alarm clients in the network will be sent a Confirmed
Event Notification to notify them of the alarm acknowledgement. They, in turn, will send a SimpleAck
message to acknowledge the receipt of this notification, the objective being to ensure that all clients have
up-to-date and consistent information.
Local alarm acknowledgement
Alarms can also be acknowledged and reset locally on the alarm server. The alarm is acknowledged
internally in the alarm server that generated the alarm. Confirmed Event Notifications are now transmitted
to all alarm clients, to notify them that the alarm has been acknowledged. The alarm clients, in turn, send a
SimpleAck message to acknowledge their receipt of the Confirmed Event Notification.
Disabling the routing of alarms
Each alarm-generating object has an [EnEvt] parameter (data type: Boolean). Alarm messages (and system
events) are only transmitted over the network if [EnEvt=TRUE]. This does not affect the alarm monitoring
of the object, that is, the alarm state machine is always kept up to date.
9.8 Alarm queuing
Until they have been forwarded to all the pre-configured alarm recipients, all alarm messages are normally
stored in the automation station.
Each automation station has its own alarm queue for this purpose. Each incoming alarm and each system
event is entered in the queue. An entry remains in the queue until the alarm or system event has been sent
with a confirmed event notification to all recipients listed in the notification class object, and until the
relevant acknowledgements have been received.
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.
BACnet device object properties
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.
Buffer size [BufSize]
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.
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