The invention relates to a rectangular baler comprising a bale chamber (15) delimited by a plurality of walls (70, 80) including a movable wall section (70), an actuator (71, 71a, 71b) for exerting a pressure on the movable wall section, a plunger (18) for compressing crop material in the bale chamber (15), and a control system (300) configured to control the plunger (18) to perform cyclic plunger strokes such that in each stroke the plunger force (F) exerted by the plunger (18) on the crop material increases to reach a maximum plunger force (Fmax) to compress a newly inserted slice of crop material. The control system (300) comprises a first module (301) to measure, at consecutive moments during a plunger stroke, a plurality of first values for the plunger force exerted by the plunger and/or for the pressure (Pd) in the actuator (71, 71a, 71b)； and a control module (303) to control at least one baling setting influencing the compressing of the crop material in the bale chamber (15) in function of the plurality of first values. The invention also relates to a control method and to a computer program product to perform one or more steps of the control method.
