what does it mean when an alarm is crossed out in an alarm list?
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> What does it mean if the delete key is used on an alarm? The alarm is no longer in the list but what are the consequences?The ”Delete” function on the context menu of an alarm is a cleanup feature to be used when eg an OPC AE server (connectivity added to System 800xA) have failed to return the alarm back to state 2 (idle) = ENABLED, INACTIVE, ACKNOWLEDGED (in other terms, no longer to be presented in the HMI). One must remember that this deletion does not propagate any further than the Alarm Manager service in 800xA. If the deleted alarm still exist in the source OPC AE server, it will return upon next refresh or failover. Only system administrators with knowledge of when an alarm is ”in limbo” should use this function. Deletion of an alarm require high security privileges. In System 800xA, an OPC AE server govern the HMI, not vice versa. Having access to a third party OPC AE client is often very useful to prove an alarm to be in limbo state (eg once emitted by an OPC AE server but since removed from it without updating the HMI in which the HMI faithfully will keep the alarm until the AE server has announced it as idle)
”Disabled” is a state declared in the OPC AE Specification - www.opcfoundation.org
Disabling/enabling is possible by operator by right clicking an alarm. Privileges needed. In AC 800M, disabling can also be governed from the alarm block in controller. In AC 800M disabling inhibits the alarm from being fired.
In 800xA HMI a disabled alarm is visualised with strike-through text but can also be filtered on in lists. Be careful when removing disabled alarms from presentation, if operator cannot see the disabled alarm he may not enable it either, possibly forgetting about it.
The disabling feature can be removed by unchecking ”Supports Disabling” in Alarm Collection Definition.