Commanded status record alarming

Two types of alarm processing are associated with commanded status records: uncommanded change-of-state (COS) and command failure.

Note: State-based alarming is triggered whenever a COS occurs. A status record with a configured output can generate a state-based alarm if it changes state without being commanded.

Uncommanded Change-of-State

An uncommanded COS occurs when a status record changes state without being commanded. The alarm message and event log will display the name of the status record, its associated remote, and its description field.

When you acknowledge an uncommanded COS alarm, the alarm normally disappears immediately from the alarm summary. However, if the status record has been configured to sustain off-normal alarms, the system consults the Abnormal State (Abnormal State) table. If the state changed to an abnormal state, the alarm remains in the alarm summary even if you have acknowledged it.

Like state-based alarming, it is possible to independently disable alarming of transitions to normal or abnormal states, as well as the logging of an uncommanded COS.

Note: An alarm is not generated if you command a status record to an abnormal state.

Command Failure Alarming

There are two alarms associated with command failures: COS failure alarm and command failure timeout alarm.

The system generates a change-of-state alarm when a device, which has been directed or commanded to change state, takes a long time to change from its present state. Some devices, such as large block valves, can take several minutes to attain the commanded state. Rather than waiting for several minutes to generate a command failure alarm, you can specify a maximum amount of time to wait for the device to change state. The state which the device failed to reach is likely not the final state, but the fact that a change has occurred indicates that the commanded action is taking place.

Note: A COS alarm applies only to status records configured as outputs.

The system generates the command failure timeout when the commanded device does not reach the final commanded state within the maximum time allowed.

The only limitation on the time specifications is that the command failure timeout for the final commanded state must be larger than the change-of-state failure timeout.