Measuring device for detecting a filling or limit level of a filling material in a container and method for filling or emptying a container with or of a filling material

A measuring apparatus for detecting a fill level or limit level of a filling material in a container, wherein the measuring apparatus is designed to be situated on the container and comprises a sensor for determining the fill or limit level, a power supply unit which is electrically connected to the sensor and is designed and configured to supply the sensor with electrical power, an activation unit which is connected at least to the power supply unit for signal communication and an associated method of use.