Operation4.2 KeyboardOperating with the Local User InterfaceOperating Manual, 06/2017, A5E31930478-05 55LogbookThe device has a logbook for logging abnormal events, for example, error messages thatrequire acknowledgment. Module-specific messages are always stored permanently on themodule itself. With the LUI, the device provides a uniform user interface that logicallycombines all the individual logbooks. When a module is replaced, these logbook entriesdisappear from the logbook of the device.The logbook or logbooks are structured as a circular buffer. When the buffer is full, the oldestentries are overwritten by new ones. This means the logbook entries are displayed inchronological order. By setting filter functions you can limit the display range to meet yourrequirements.4.2 Keyboard4.2.1 StructureOverviewThe following schematic shows the structure and elements of the keyboard:① Keys with special functions ③ Cursor and command keys② Numeric keypad ④ HELP and UNDO keysFigure 4-3 Overview of the keyboard