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Alarm Handler Tree Structures
There will be different tree structures for different purposes. In at least one of the available tree structures, the ALH alarm status at the area/region level will need to match the alarm status on the CUD display. A PV or subtree can be present in more than one tree. However, please note that a PV should only log changes once to cmlog, i.e. logging should be turned off for all but one entry in the Alarm Tree.

Tree structure I: device-level PVs
Useful for debugging device failure.

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• All LCLS Devices
• Gun Spectrometer Mode
• Injection Spectrometer Mode
• TD11 Mode
• BSY Mode

The alh logging instance uses the "All LCLS Devices" mode tree only. All PVs should be present in the All LCLS Devices mode tree.

Acknowledging Alarms
ALH instances started from control room OPIs will run in global mode, which allows globally visible alarm acknowledgement. Other ALH instances will be run in local passive mode, and not allow acknowledgement. See LCLS use of Alarm Handler Alarm Handler Processes for running in these modes.

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• Summary PV databases are created by perl scripts from alhConfig files, with a summary PV for each node in the tree (group).
• The summary PVs are calcs that return 0, with maximize severity for INPs (standard summary method).
• !! !Since Summary PV definitions are derived from the alhConfig GROUP names, it's best to adhere to the naming convention below for GROUP names!!!
• Summary PV values
  • ALH group sevr value 0 = NO_ALARM
  • ALH group sevr value 1 = MINOR
  • ALH group sevr value 2 = MAJOR
  • ALH group sevr value 3 = INVALID
  • ALH group sevr value 4 = INVALID
• Summary PVs are booted into IOCs sioc-sys0-al00 and sioc-sys0-al01 (prod, on lcls-daemon1); sioc-sys0-al0d (on lclsdev) can be used for development.

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