An infusion system includes a pump and a replaceable pump module. The pump module can be arranged in a mount of the pump and includes a plunger-barrel unit operatively connectable to a drive mechanism of the pump. The pump module includes a plunger that can be coupled to the drive mechanism by a coupling structure operatively connected to the plunger and a counter-coupling structure for connecting engagement in the coupling structure and operatively connected to the drive mechanism. In a securing position, the infusion system includes a securing member which locks the coupling structure and the counter-coupling structure to each other. In addition or in the alternative, the infusion pump includes a control link operatively connected to the pump module.