User Manual

Alarm management
Alarm routing over the network
9
160 | 351 CM110664en_07
Preconfigured alarm receivers
The preconfigured alarm receivers are entered in the notification class object:
● In the [DestList] for Desigo PX
● In the [RecpList] for Desigo room automation
Time response in the network
The routing of all alarm and acknowledgement ,messages between the alarm server and the alarm clients
takes place over the BACnet network using special BACnet services. These are:
● Confirmed Event Notification for all changes in the alarm state of an alarm-generating object
(TO_OFFNORMAL, TO_NORMAL, TO_FAULT), and for messages via local acknowledgements.
Direction: Direction: From alarm server to alarm client.
● AcknowledgeAlarm for the routing of acknowledgements (including reset) performed by the user on an
alarm client. Direction: From alarm client to alarm server.
The two services are referred to as Confirmed Services, that is, the receiving device always confirms the
receipt of a service by immediately returning a SimpleAck message. This tells the transmitting device that
its message has been received by the receiving device. If no SimpleAck message is received, the
transmitting devices tries to send the message again (up to three times).
An alarm is always issued by one (and only one) alarm server. Generally, however, there will be several
alarm clients on the network. To maintain consistency, all alarm clients must always display the same
alarm state. For this reason, all alarm-related functions must always be routed to all the alarm clients. The
procedure is the same for both temporary and pre-configured alarm receivers.
The following time-diagrams describe the communications via the network for the various alarm-related
events.
Change of alarm state
This procedure is carried out for every change in alarm state on an alarm server: TO_OFFNORMAL,
TO_FAULT und TO_NORMAL. The data record Confirmed Event Notification contains the following
information:
● BACnet address of the alarm server
● Object ID of the alarm-generating object
● Time stamp
● Alarm priority
● Initial and final state of the transmitted state transition (this is used to determine whether the state
transition is TO_OFFNORMAL, TO_FAULT or TO_NORMAL)
● Acknowledgement required [AckReq]: Does the notified state transition require acknowledgement or
not?
● Alarm text
● Other technical details
Based on this information, the alarm client can present the alarm in a comprehensible way; it may also read
additional information automatically from the alarm server, and if required, return any acknowledgement to
the correct address.
If a temporary alarm receiver does not confirm receipt with a SimpleAck message (via the Confirmed Event
Notification input), the alarm server will try three times more to transmit the alarm to the relevant alarm
receiver. The message for this alarm client will then be lost and its reference will be deleted from the
[RecpList] of the BACnet device object.
Alarm acknowledgement over the network
This process is performed for all acknowledgements made on an alarm client.
S
i
m
p
l
e
A
c
k
t
t
t
S
i
m
p
l
e
A
c
k