Virtual Data Source Properties

The Virtual Data Source Properties dialog box comes up when adding a virtual data source from the Project | Manage Data Sources dialog box. This dialog box is used to set up a virtual data source for your project. The virtual data source lets you create a custom table that you can read from and write to. This is especially useful if you have only database and/or data file data sources in your project, but you need a place to write variables to be used in your project. (In server data sources and HTTP datalogger data sources, you can accomplish the same thing by writing to values in the Public table.) The virtual data source table you create is a single record table much like the Public table. It does not store historic data.

NOTE: The state of virtual variables is saved between RTMC Run-time sessions. The state of virtual variables is also saved between sessions, when viewing your project using CSI Web Server. The state of virtual variables is tracked separately for RTMC Run-time and for CSI Web Server (i.e., a change made to a virtual variable in RTMC Run-time will not affect the value of the variable in CSI Web Server).

Source Name

Designates the name that will be used for the virtual data source in the Data Source Browser and on the status bar.

Output Interval

Specifies how often the virtual data source will report a new record. The virtual data source will stay on an even interval. When a virtual data source value is set by RTMC, a new record will also be generated. Therefore, if you have an output interval of 1 minute, you will get records at 12:00:00, 12:01:00, 12:02:00, etc.  However, if you then set a value at 12:02:37, you will have records at 12:00:00, 12:01:00, 12:02:00, 12:02:37, 12:03:00, 12:04:00, etc.

Column Name

Clicking on an empty cell in the column name list will allow you to add new columns. You can also add a new column by pressing the ‘+’ button at the bottom of the dialog box. To delete a column, select the column and then press the ‘-‘ button at the bottom of the dialog box. Each column represents a value in each record generated by the virtual data source.

Default Value

Each column defaults to a value of 0. You can also initialize the column value to be a fixed value (e.g., 1234), a string (e.g., $"This is a string"), a predefined constant (e.g., PI), or a simple expression that does not use variables (e.g., EXP(5)).

Examples

See the online help for examples of using a virtual data source to set an alarm threshold at run-time, set a multiplier and offset at run-time, and select which values to plot at run-time.