Connection points are the start or end points of lines or nodes on the line itself.
The output connection point (short: output) of an FBD-element is connected by a line to the input connection point (short: input) of the other FBD-element.

Connected inputs and outputs of an FBD-element are always displayed as part of the line (see the inputs of the ADD block in the following illustration). In contrast to this, connection points on the line or at the start/end of an open line are displayed as red nodes .

Connection points on a line are necessary in order to create a line fork. A connection point at the start or end of an open line can be used in order to dock the line to other FBD-elements.