Historical data and symbol
Historical data are data from earlier times that are stored in a database.
Arbitrary server symbols of the TwinCAT HMI (e.g. numerical values from the PLC) can be historized by the TcHmiSqliteHistorize extension. The extension saves the data in a ring buffer in an SQlite database. The interval at which the data are saved in the database can be defined for each symbol. The data are saved in the database only as long as the server is running. No historical data are written to the database if the server is terminated.
The historical data are displayed in an included control – the Trend Line Chart. The control enables the display of various historical data at the same time.
More coming soon…