1. An infusion system comprising an infusion pump and a pump module being separate therefrom and provided as a disposable product and thus replaceable which is configured to be arranged in a mount of the infusion pump, the pump module comprising a plunger-barrel unit operatively connectable to a drive mechanism of the infusion pump, the pump module further comprising a barrel and a plunger translationally movable within the barrel, the plunger being adapted to be coupled to the drive mechanism by a coupling structure operatively connected to the plunger and by a counter-coupling structure configured for connecting engagement in the coupling structure and being operatively connected to the drive mechanism, wherein the infusion pump has a control link which is operatively connected or operatively connectable to the pump module so that, when the pump module is arranged in the mount, the control link is positioned by force in a release position in which pumping action of the plunger is enabled, the control link being displaceable from the release position to a blocking position that disengages the counter-coupling structure from the coupling structure and allows decoupling of the plunger of the pump module from the drive mechanism of the infusion pump, and wherein the infusion pump includes a cover member configured to be positioned in a closing position closing the mount for the pump module, wherein the cover member, the mount and the pump module are adapted to each other and designed so that, when the pump module is not arranged in the mount, the cover member cannot be positioned in the closing position closing the mount.