Alarm Handling

[tcpdump]

Hello all, I had a question for the alarm banner that appears on the top of the operator workstations, typically. I am just trying to get a grasp of whether or not the way alarms are handled are similar across different SCADA systems. We have different buttons/definitions: Accept: alarm has been dealt with, no further action necessary. Acknowledge: operator is aware of the alarm, and is currently investogating. Note: operator is aware of alarm, but will not action now, alarm will 'fleet' reappear in a certain amount of time. Do these definitions make sense to anyone?

[DanW]

>Acknowledge: operator is aware of the alarm, and is currently investogating. On many systems, 'acknowledge' turns off the hard DO (relay output ) associated with an alarm, as a 'silence' function. The indication remains for as long as the alarm is valid.

[paulengr]

Commonly inside SCADA systems that have the alarm stuff pre-wired, an alarm can be in one of 4 states: no alarm alarm, unacknowledged alarm, acknowledged no alarm, unacknowledged Typically the alarm only clears when the operator acknowledges it. So even if an alarm condition clears, the alarm will remain present (as unacknowledged) until the operator actually acknowledges it. The alternative states/actions that are out there are suppressed (alarm does not indicate...special function to effectively turn it off), and reset (skipping the acknowledgement step). Some plants have a separate "silence" function as well which turns off the audible alarm horn (for all active current alarms) but leaves the on-screen indicators alone. There is also "alarm blocking" or "chaining". For instance, if you have an alarm indicating that a conveyor belt tripped out due to overload, then it would block the "conveyor stopped" alarm or a "material stopped flowing alarm" since these are meaningless in light of the fact that the conveyor starter tripped.