Patent ID: 6870282

Claim:
Method for signal transmission in a bus system between a central unit ( 1 ) and a plurality of modules, a) in which the central unit ( 1 ) comprises first and second voltage sources for respective different first and second voltage levels (U 1 , U 2 ), which are connected respectively through a switch (S 1 , S 2 ) with a bus line ( 7 ), whereby a resistor (R 1 ) is connected parallel to one of the switches (S 1 ), b) in which a first voltage signal (Usignal 1 (x;t)) is transmitted by the central unit ( 1 ) to at least one receiving module among the modules ( 2 ) superposed on a direct supply voltage U 1 (t) provided by the central unit ( 1 ) onto the bus line ( 7 ), and c) at least one transmitting module among the modules ( 2 ) transmits a second voltage signal (Usignal 2 (x;t)), d) whereby the central unit ( 1 ) and the at least one transmitting module ( 2 ) transmit in a time-offset manner, and e) during the reception of the second voltage signal (Usignal 2 (x;t)) the central unit supplies the direct supply voltage U 1 (t) onto the bus line ( 7 ) over the interposed resistor (R 1 ), and f) in the central unit, the second voltage signal (Usignal 2 (x;t)) caused by the at least one transmitting module ( 2 ) is detected on the bus line ( 7 ) on the side of the resistor (R 1 ) facing away from the direct supply voltage U 1 (t), g) each one of the modules ( 2 ) comprises a control electronics ( 5 ), a receiver device ( 6 ) and a transmitter device (S 3 ), h) the transmitter device (S 3 ) pulls the bus line ( 7 ) to a third voltage level deviating from the direct supply voltage U 1 (t) dependent on the control electronics ( 5 ), by means of a switch (S 3 ), which is arranged between the bus line ( 7 ) and a third voltage level source (U 3 ) that generates the third voltage level.