Abstract: A system is described for transmitting data in a serial bidirectional bus with a control device (1) comprising a send and receiving unit (34) for data fields (7, 8 and 9) combined into a data frame (6), and with bus subscribers (2, 3 and 4) which comprise an evaluation circuit (10) for reading in and reading out data fields (7, 8, 9, 14, 15 or 16) in data frames (6, 11), with at least the bus subscriber (4) at the bus end opposite of the control device (1) comprising a send device (12) for a data frame (11). In order to provide simple constructional conditions it is proposed that at least the bus subscriber (4) at the end of the bus comprises a control stage (13) which is activated by a received data frame (6) and triggers the send device (12) depending on the receipt of a data frame (6) within the terms of the transmission of a data frame (11) for at least the data fields (14, 15 and 16) of the bus subscribers (2, 3 and 4).

Abstract: A method is proposed for braking a synchronous machine 1, with the armature windings (u, v, w) of the synchronous machine 1 being short-circuited, optionally by interposing at least one braking resistor. In order to keep the braking moment constant over virtually the entire speed range it is proposed that the short-circuit current is regulated by a pulse-width modulation depending on the difference between the setpoint value of the short-circuit current corresponding to the setpoint value of the braking moment and the actual value of the short-circuit current.

Abstract: A control panel is shown with at least one switch (12) whose actuating button (6) is situated in an opening (3) of a front panel (4), and with a housing (1) arranged in the region of the opening (3) of the front panel (4) and enclosing the switch (12), which housing forms between an inner and an outer circumferential wall (2, 5) an annular gap (8) for receiving at least one lighting means (11), which annular gap is open towards the front panel (3) and is covered in a light-transmitting manner. In order to provide advantageous constructional conditions it is proposed that that the housing (1) is inserted with its outer circumferential wall (2) in a flush manner into the opening (3) of the front panel (4) and encloses the actuating button (6) with its inner circumferential wall (5), and that the light-transmitting cover of the annular gap (8) between inner and outer circumferential wall (2, 5) consists of a foil (9) extending over the front panel (4).