I think it’s more accurate to say that it shows the current alarm state for each signal. That is, for every signal that currently has one or more raised alarms, it shows only the information about the most severe alarms that are currently in the raised state. If you want a comprehensive log of alarm state changes, you have a couple options. You can either use a historian to log alarm measurements and view them using historian tools or you can enable logging to the AlarmLog table in the database and view them using database tools.
To enable logging to the AlarmLog table:
- In the openPDC Manager, go to “Actions > Manage Custom Actions”.
- In the data grid at the bottom of the page, select the “ALARM!SERVICES” adapter.
- In the “Parameters” list box in the center of the page, scroll to the bottom and select the “UseAlarmLog” parameter.
- Change the value by selecting the radio button labeled “True” to the right of the “Parameters” list box.
- Click the “Save” button on the far right above the data grid.
- Click the “Initialize” button on the left above the data grid.
- Select “Yes” when prompted for confirmation.
Note that logging to the AlarmLog table is disabled by default for performance reasons. If your alarms are too chatty, it will degrade system performance.