FILL-LEVEL MEASURING DEVICE

Disclosed is a method for determining the serviceability of a fill-level measuring device that includes at least one electronic unit. The method can be applied to any type of field device that includes at least one electronic unit supplied by an energy store of the field device. The method includes: measuring the capacitance of the energy store and/or measuring the power withdrawal at the energy store. The field device is classified as not operationally reliable if the capacitance of the energy store is below a defined minimum capacitance and/or if the power withdrawal deviates from a predefined normal consumption. An advantage of the method according to the invention is that, in addition to the functional diagnosis, in particular also a prediction up to the expected elapsing of the remaining operating time can be created by recording the power withdrawal or the capacitance over progressive measurement cycles.