User Manual

Alarm management
Alarm response of the function blocks
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BACnet Device Info Object
All the alarm-generating objects described so far model specific types of
individual data points (physical or virtual). The BACnet device object by
contrast, models the properties of an automation station as a complete entity.
Alarm-relevant faults which cannot be allocated to a data point can be
generated in an automation station (see the examples further below). This is
why the BACnet device object includes an alarm mechanism. The alarm state
machine and the alarm-related variables are essentially the same as for all the
other alarm-generating block types. The difference lies in the possible causes
of the alarm:
The alarm conditions described below cause the generation of an OFFNORMAL
alarm in the BACnet Device Object:
The battery in an automation station is checked periodically. An alarm is
generated if the battery voltage is too low, or if the battery itself is missing.
When the required voltage level is reached again, the alarm is reset with
BATTERY_NOT_LOW.
This indicates that a memory-check error was found when the automation
station was switched on. If no memory-check error is detected when the
automation station is next switched on, the alarm will be reset.
A recipient name (e.g., the configured recipient of an alarm) could not be
resolved, because, e.g., the network connection to the recipient was
interrupted. This causes an alarm to be generated. The alarm is cleared as soon
as the subsequent name resolution process succeeds.
Each alarm-generating block includes a reference to a Notification Class block.
If the referenced Notification Class block does not exist, the BACnet Device
Object generates an alarm.
While the life check is in progress, the primary server finds that it is unable to
communicate with one or more of its backup servers (e.g., owing to a network
failure). This causes an alarm to be generated. The alarm is cleared when,
during a subsequent life check, all the backup servers are found again.
This bit is set when the backup server detects that the primary server is no
longer connected to the network. At the same time a notification (data-type
STRING) is sent, defining the source, target and reason. The bit is reset as soon
as the backup server detects the primary server on the network again.
FAULT alarms
The condition described below causes a FAULT alarm to be generated in the
BACnet Device Object:
The automation station checks periodically whether there is at least one free
page (64 kB) in the flash memory. This bit is set if the flash memory falls below
this value. The bit is reset when the flash memory contains at least one free
page again.
OFFNORMAL alarms
Battery low
RAM Pattern failed
Recipient not receivable
Notif. Class ref. missing
Life check error
Primary server not
found
Flash is full