A field device for measuring the filling level, the pressure or the density of a medium in a container is described. The field device comprises two processors that are separate from each other. The first processor corresponds to a lower safety standard while the second processor corresponds to a higher safety standard. Functions of the field device that are directed towards safety are carried out in the second processor. Functions that are less critical to safety are carried out in the first processor. Data exchange between the two processors is controlled by way of an operating system.