The invention relates to a device and a method for operating a Coriolis mass flowmeter with at least one measuring pipe, and is characterized in that at least two operative assemblies, which can respectively be operated as an exciter (actuator) and/or as a measuring signal pickup (sensor), are attached to the measuring pipe. The operative assemblies are formed as plunger-type armature sensors with a magnetic core. Each operative,assembly is operated either as a sensor or as an actuator or simultaneously as an actuator and as a sensor. Each operative assembly is switched over between the operating mode as a sensor and as an actuator by a switch assigned to it.