| 摘要 |
A bus coupling circuit is used for coupling data between a transmitting subscriber and a receiving subscriber by way of a data transfer bus, each subscriber including: a bidirectional driver for transmitting and receiving data, each bidirectional driver including an apparatus for introducing for a direct voltage on the bus, and a direct voltage splitting device constituting a working impedance for the driver and connected between the driver and the bus. Each driver has a first input which is remote from the bus and a second input electrically connected to the bus. The bus coupling circuit includes a source of direct supply voltage; a hysteresis circuit connected to each driver, the hysteresis circuit including a voltage divider which is responsive to alternating signals on the bus and which is disposed between the first input of the driver and the source of direct supply voltage, the voltage divider having a divider tap disposed at the second driver input to provide a direct supply voltage at the second input of the driver. The voltage divider has a first voltage divider resistor connected between the first and second driver inputs and a second voltage divider resistor connected between the second driver input and the source of direct supply voltage, the first and second voltage divider resistors having respective resistance values R2x and R3x which satisfy the following relationship: <IMG> where x is a variable representing the sequential number of the respective subscriber, and n is the number of tolerable driver short circuits; whereby the bus is fault tolerant for a plurality n of driver short circuits.
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