Question:
How can I return the duration (in minutes) that the alarm was active?
Solution:
Alarm sources are Elipse E3‘s objects which set up all the information regarding to alarm conditions. Each alarm source allows you to configure its limits, event-related message, and severity, as well as whether the event needs acknowledgement.
There are five types of alarm in Elipse E3; they are: analog, digital, dead band, rate of change, and discrete. For further information on these alarms, their configurations, and how to use them with the Elipse system, check out our article E3: Alarm Types.
In order to return the duration that the alarm was active, you can use SQL’s DateDiff method. This method returns the count (as a signed integer value) of the specified datepart boundaries crossed between the specified startdate and enddate; that is to say, it will return the difference between the moment the alarm became inactive and the moment it became active.
DateDiff function’s syntax is as follows:
DATEDIFF ( datepart , startdate , enddate )
Its arguments are:
- datepart: The units in which the function reports the difference between the startdate and enddate. Commonly used datepart units include
monthorsecond. Its value can’t be specified in a variable, nor as a quoted string (like “month”). - startdate: an expression that resolves the initial timestamp.
- enddate: an expression that resolves the final timestamp.
For example, the query below illustrates how to return the difference between timestamps in minutes:
SELECT InTime, OutTime, DateDiff("n", InTime, OutTime) AS ActiveTime
FROM Alarms
WHERE (InTime>0 AND OutTime>0)
ORDER BY InTime Desc
For further information on DateDiff function, you can check out Microsoft’s official documentation on the subject.
