All variable symbols and constant expressions are entered in FBD diagrams using small boxes. Press the following button in the FBD toolbar for inserting a variable tag:

Double-click on a variable tag to open the variable selection box and either select the symbol of the wished variable or enter a constant expression.

Variables tags must then be linked to other objects such as block inputs and outputs using connection lines.

You can resize a variable box vertically in order to display together with the variable name its tag (short comment text), its description text, plus its I/O location if the variable is mapped to an I/O channel. The variable name is always displayed at the bottom of the rectangle:

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