Keyboard for giving control operations

摘要

The pushbutton (14) forms part of a first signal generator (2). It has a shaft (15) moving a switching member from a first position to a second position. An input line (7) carries an input signal (S0) which may be connected to a first output line (8) or a second output line (10) connected to an evaluation circuit (9). This is connected to an output line (11) carrying an output signal (S3), and also to a fault warning light (13).