A pneumatic connection is a place where a pneumatic line can be attached to. To simplify the line drawing process, a connection appears as a small circle in Edit Mode.
Pneumatic connections can be shut by means of a blind plug. An open pneumatic connection may result in leaking air; FluidSIM thus pops up a warning message, if some pneumatic connection was left open.
Note that at each pneumatic connection values for the flow and pressure can be displayed.