Triggered Archiving

Although WinCC OA archiving is event-based (i.e. events are stored whenever value or quality changes), sometimes it is useful to archive specific values at a specific point of time even if they have not changed (i.e. before starting up an equipment, need for data for a report, …). This is what triggered archiving can be used for.

There are two types of triggered archiving:

Trigger archiving of one specific data point element:

When the boolean _archive.._archive detail of the archive config is set to true (e.g. in a Ctrl script) and it has been set to true before, the data point element is archived again with its current value. The timestamp used for this archiving operation is dependent on the config entry "triggeredArchiving" in the [NextGenArch] section.

Trigger archiving of a complete archive group:

This type of triggered archiving allows all current values of data point elements archived in an archive group (represented by a DP of '_NGA_Group' type) to be written to a database with the current timestamp. The feature is triggered for all DPEs in an archive group by writing TRUE' to its _NGA_G_Group.commands.triggerWrite DPE. The values for DPEs from this group are taken from the current process snapshot, bypassing all smoothing rules; the timestamp is taken from the trigger DPE _NGA_G_Group.commands.triggerWrite. The result of the operation is written to '_NGA_G_Group.commands.triggerWriteResponse' and is equal to the number of written DPEs in case of success and negative in case of a failure.