Method for the transmission of signals in a bus system, superposed on a direct supply voltage
First Claim
1. 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 (U1, U2), which are connected respectively through a switch (S1, S2) with a bus line (7), whereby a resistor (R1) is connected parallel to one of the switches (S1), b) in which a first voltage signal (Usignal1(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 U1(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 (Usignal2(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 (Usignal2(x;
t)) the central unit supplies the direct supply voltage U1(t) onto the bus line (7) over the interposed resistor (R1), and f) in the central unit, the second voltage signal (Usignal2(x;
t)) caused by the at least one transmitting module (2) is detected on the bus line (7) on the side of the resistor (R1) facing away from the direct supply voltage U1(t), g) each one of the modules (2) comprises a control electronics (5), a receiver device (6) and a transmitter device (S3), h) the transmitter device (S3) pulls the bus line (7) to a third voltage level deviating from the direct supply voltage U1(t) dependent on the control electronics (5), by means of a switch (S3), which is arranged between the bus line (7) and a third voltage level source (U3) that generates the third voltage level.
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Accused Products
Abstract
Previously in a bus system, voltage signals were transmitted from the central unit to the modules, which could reply thereto by variation of the current input. A disadvantage thereby is the relatively high susceptibility to interference of the current input, which itself already must be kept relatively small due to the energy consumption, as well as the correspondingly high effort and expense for an error-free recognition of the signals transmitted from the modules in the central unit. It is now suggested, that the modules also answer to the central unit by means of voltage signals superposed on the direct supply voltage, whereby for the time duration of the signal transmission by the modules, the central unit provides the direct supply voltage to the bus line over a resistor, so that the voltage signal of the module can be detected in the central unit on the bus line on the side of the resistor facing away from the direct supply voltage. A preferred application for bus systems in motor vehicles, especially for a sensor data bus, is provided.
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Citations
13 Claims
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1. 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 (U1, U2), which are connected respectively through a switch (S1, S2) with a bus line (7), whereby a resistor (R1) is connected parallel to one of the switches (S1), b) in which a first voltage signal (Usignal1(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 U1(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 (Usignal2(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 (Usignal2(x;
t)) the central unit supplies the direct supply voltage U1(t) onto the bus line (7) over the interposed resistor (R1), andf) in the central unit, the second voltage signal (Usignal2(x;
t)) caused by the at least one transmitting module (2) is detected on the bus line (7) on the side of the resistor (R1) facing away from the direct supply voltage U1(t),g) each one of the modules (2) comprises a control electronics (5), a receiver device (6) and a transmitter device (S3), h) the transmitter device (S3) pulls the bus line (7) to a third voltage level deviating from the direct supply voltage U1(t) dependent on the control electronics (5), by means of a switch (S3), which is arranged between the bus line (7) and a third voltage level source (U3) that generates the third voltage level. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- t)) is transmitted by the central unit (1) to at least one receiving module among the modules (2) superposed on a direct supply voltage U1(t) provided by the central unit (1) onto the bus line (7), and
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8. A method for transmitting voltage signals in a bus system including a central unit, a module, and a bus line connected to said central unit and to said module,
wherein said central unit includes a first voltage source providing a first voltage level, a second voltage source providing a second voltage level different from said first voltage level, a first switch connected between said first voltage source and said bus line, a second switch connected between said second voltage source and said bus line, and a resistor connected parallel to said first switch between said first voltage source and said bus line, wherein said module includes a control electronics, a receiver device connected to said bus line, a transmitter device that includes a third switch and is connected to said bus line, and a third voltage source providing a third voltage level, wherein said third switch is connected between said third voltage source and said bus line, wherein said method comprises the steps: -
a) said central unit applies a direct supply voltage onto said bus line through said resistor from said first voltage source;
b) said central unit transmits onto said bus line a first voltage signal superposed on said direct supply voltage by controlling said first and second switches to alternately connect said first and second voltage sources respectively through said first and second switches to said bus line;
c) at a time separate from said step b) and while said central unit applies said direct supply voltage onto said bus line, said module transmits onto said bus line a second voltage signal superposed on said direct supply voltage by controlling said third switch with said control electronics to selectively pull said bus line through said third switch to said third voltage level which deviates from said direct supply voltage; and
d) during said step c), said central unit detects said second voltage signal on a side of said resistor oriented away from said first voltage source. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification