A measuring device for determining and/or monitoring at least one process variable, comprising: a sensor unit; a first electronics unit which has a first microcontroller, and a second electronics unit which has a second microcontroller, and which is connected with the first electronics unit via a galvanically isolated transmission unit for energy- and data transmission. The first microcontroller produces at least one signal, which can vary in at least one characteristic, and supplies the signal to the transmission unit, that the signal controls the energy- and data transmission, that the first microcontroller and/or the second microcontroller determines at least one current operating parameter, and that the first microcontroller sets at least one characteristic of the signal as a function of the operating parameter.