A first information indication is removed from a display screen of a liquid crystal display device, when a screen size display mode is switched into a full-screen display mode where only second information is displayed on the display screen. For example, data is received and delineated into one or more data groups and a data validity status is associated with each data group. Within or on the housing is a coupling device by which the housing couples, advantageously reversibly, to the underwater object. When a fault monitoring section which can accumulatively detect abnormal information is changed to the changed partial working path section, alarm generation in the fault monitoring section is prevented to release the prevention after completion of the change.