Dialog Box 'Trend storage'

Function: This dialog box includes the configuration for buffering the trend data of a trend recording.

Call: “Trend Storage” button in the editor of a trend recording.

“Maximum number of variables”

Maximum number of trend variables that can be managed in the database. If you increase this value afterwards, then will CODESYS perform a download and reconfigure the database.

“Store every N milliseconds”

Time interval (in ms) when the ‎CmpTraceMgr‎ runtime system component buffers the recorded data before storing it persistently in the database. The application calculates internally the number of task cycles from the time interval. The duration of a task cycle is defined in the task configuration.

A high value results in better runtime performance. The disadvantage is the increased risk of losing data if the controller crashes or shuts down. A low value reduces this risk. The disadvantage is the slower control over a trend visualization with large amounts of data.

“Limit”

_icon_radiobutton_acitvated : Limit the recording

“No Limit”: Unlimited number of data records (not recommended)
“Maximum number of records”: Maximum number of data records that are stored in the database. A data record consists of time stamp and the values of the trend variables at this time.
“Maximum storage size”: Maximum size of the trend storage. The application calculates internally the number of data records.

Clicking the "down" symbol () of the drop-down list will set the units to kilobytes (KB), megabytes (MB), or gigabytes (GB).