Bacnet Alarm Class Reassigner

The purpose of this module is to allow multiple BACnet Notification Classes to map to multiple Niagara Alarm Classes. By default, without this addition, the Niagara BACnet driver maps multiple NC's to a single Alarm Class defined on the BACnet Devices Alarm Ext.

Any alarm received by the Niagara Device is passed to all possible NC Alarm Class Reassign children until it has been published to an alarm class, as a result of an exact match to a Notification Class. If no matching pair is found the fallback class set by the user via the fallback property (described below) will be used to determine the destination Alarm Class.

In order to enable routing to the reassigner, set the process Id in the Bacnet Devices Alarm Ext (parent component of the CustomEventProcessor) to a numeric value not anticipated to be used by the BACnet network. If the process Id of the incoming alarm is found to match the Devices Alarm Device Ext current value, then the alarm will not be routed via the Alarm Class Reassigner logic.

Expected Parent Type: BacnetDevice

Bacnet Device
 |
 |-Alarms                       [ Change process Id to unused value to pass alarm to event processor below ]
 |  |
 |  |-CustomEventProcessor      [ Set process Id here to a desired/used value ]
 |
 |-BacnetAlarmClassReassigner   [ Set config properties eg fallback class ]
    |
    |-NCAlarmClassReassign1     [ Match NC Id to Alarm Class here ]
    |-NCAlarmClassReassign2
    ...

Usage Instructions

• The BACnet device should be configured to receive BACnet alarms as usual.
  
  
• Add a BacnetAlarmClassReassigner beneath the BACnet Device you will receive alarms from. Multiple reassigners can be added for different process Id's, event handlers are created beneath the Device Alarm Ext automatically to intercept alarm routing.
  
  
• Below the BACnet Devices Alarm Ext ensure at least one reassigner's process Id value matches the expected process Id of incoming alarms. If the AlarmDeviceExt is set to an unused process Id number, all alarms pass through re-assigner allowing change of Alarm Class or filtering, bypassing the normal alarm handling. If the process Id is not changed on the Alarm Ext then the reassigner will not be passed alarms to handle.
  
  
• Finally add NC Alarm Class Reassign Components beneath the BacnetAlarmClassReassigner. These will be used to configure rules matching of a specific Notification Class to Alarm Class.

Property Descriptions

• Fallback Alarm Class: The Niagara Alarm Class to which any incoming alarms not matched by an NC Alarm Class Reassign rule are routed.
  
  
• Filter Alarms From Unknown Objects: When enabled, alarms for which the associated Object ID cannot be found as a point added to the station are discarded. These would normally appear as alarms against the BACnet device object, had a relevant point not been added.
  
  
• Use Bacnet Alarm Priority: This option has been removed from the alarm router as it is not possible for it to function without other changes to Niagara NCCB- Retain the BACnet alarm priority, instead of replacing with the Niagara Alarm Class priority as the driver does by default.
  
  
• Set Alarm Hyperlink: When enabled this inserts the ord to the point as the alarm hyperlink value. If the point has a BOrd property added called "hyperlinkOrd" then use the value defined there for the hyperlink, or if the slot is added but nothing set (null), then don't set any hyperlink on the alarm record.
  
  
• Number Discarded: Records how many alarms have been 'filtered' due to their object being unknown (due to no associated point existing in the Station) since component startup.
  
  
• Replace Sourcename with Displayname: Should a point have been added to the station for this alarming object, and have a Display Name applied which differs from the Source Name, then use the Display Name in the Alarm Record, rather than the Source Name.
  
  This could be useful if the points have been added with the same name beneath Point Folders - for example Temperature for 10x VAV's allowing relativized Px graphics to be used. Using this setting the points can have the same name, but be more clearly identified in the alarm console if a Display Name is set on each point.

Troubleshooting

If alarms are being routed as normal, check the process Id configuration beneath the BACnet Device Alarm Ext does not match a process Id in use by the source device.

The logging for this component is enabled via bacnet.alarmClassReassigner.

See Also

Niagara Bacnet Alarm Operation