Abstract: A control panel for regulating plural parameters is provided with plural displays, each associated with one parameter. A single manually moveable knob is provided for entering a manually variable signal. Individual actuators such as push buttons are disposed adjacent each of the display means. The control panel is arranged to interpret the variable signal provided by the maneuvering element or knob as a new value for a control constant associated with a particular parameter depending upon which push button is actuated. The operator may select a particular parameter for resetting by pressing the button adjacent the display for that particular parameter. The panel simplifies setting of plural parameters in complex control systems such as the control system for a hemodialysis apparatus. The control system may incorporate plural microprocessors.