If a PLC contains an SD card, and the PLC application comprises Alarms, the PLC stores the first 8 Alarms in RAM, and then automatically transfers them to the Alarms folder on the SD card. You can view the Alarms file on PC via the SD Tools utilities.
When the PLC writes this type of data to the SD card, it creates a file with the extension .ual in the Alarms folder.
To cause the PLC to write the entire Alarms History to the SD Card, turn SB 352 ON in your application.
An Alarm is added to the History buffer after it has:
become Inactive
and
has no Pending actions: View, Acknowledge, Reset.
The History display records the time the Alarm became active, the time it became inactive, and when Acknowledge and Reset were performed.