In an already created project set the database (Mervis DB) server address, user name, password, and communication interval in the PLC configuration.  Another important parameter is the Runtime ID, which shall be unique for every PLC which writes in a database.

Save, or upload, the configuration to PLC in the next step.

Create a new history definition by right-click to the History item, and select Add New History.

In the newly created history, set up the properties. The history data will be stored in the PLC as well as in the Mervis DB. Set the DB Save Period to one minute; the value is entered in ms.

Insert variables you want to be sampled. In the Variable browser tab select one or more variables, right-click one of them, and select Add to History. Choose one of the predefined history definitions.

If the project has history blocks defined, the recorded history data can be saved in a computer.

Right-click the selected histories, and select “Download history”.

In the opened window, set the target file to save history, required time range, time format, and PLC to download the data from.

The history will be saved in a .csv file. The record can be opened in a text viewer or table processor (MS Excel). The first row contains column headers, time stamp and variable names. The values are separated by semicolons.

The storage capacity for different controller types is below. After the memory is full, the oldest records are deleted and replaced by new ones.